SOBEK User Manual SOBEK_User_Manual

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1D/2D modelling suite for integral water solutions

Hydrodynamics, Rainfall Runoff and Real Time Control

Hydrodynamics, Rainfall Runoff and
Real Time Control

Version: 1.00
SVN Revision: 55373
April 18, 2018

SOBEK, User Manual

Published and printed by:
Deltares
Boussinesqweg 1
2629 HV Delft
P.O. 177
2600 MH Delft
The Netherlands

For sales contact:
telephone: +31 88 335 81 88
fax:
+31 88 335 81 11
e-mail:
software@deltares.nl
www:
https://www.deltares.nl/software

telephone:
fax:
e-mail:
www:

+31 88 335 82 73
+31 88 335 85 82
info@deltares.nl
https://www.deltares.nl

For support contact:
telephone: +31 88 335 81 00
fax:
+31 88 335 81 11
e-mail:
software.support@deltares.nl
www:
https://www.deltares.nl/software

Copyright © 2018 Deltares
All rights reserved. No part of this document may be reproduced in any form by print, photo
print, photo copy, microfilm or any other means, without written permission from the publisher:
Deltares.

Contents
List of Figures

List of Symbols

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2 Getting started
2.1 Starting SOBEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Free trial options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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1 Introduction
1.1 About SOBEK . . . . . . .
1.2 Product Info . . . . . . . . .
1.3 Introduction to SOBEK-Rural
1.4 Introduction to SOBEK-Urban
1.5 Introduction to SOBEK-River
1.6 Support . . . . . . . . . . .
1.7 About Deltares . . . . . . .
1.8 Notation . . . . . . . . . .

3 Installation manual
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . .
3.1.1 System requirements . . . . . . . . . . . . .
3.2 Deltares License Manager . . . . . . . . . . . . . .
3.3 Installing SOBEK . . . . . . . . . . . . . . . . . . .
3.3.1 Installing the SOBEK using the command line
3.4 Starting SOBEK . . . . . . . . . . . . . . . . . . .

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4 Tutorials
4.1 Tutorial Hydrodynamics in open water (SOBEK-Rural 1DFLOW module) . .
4.1.1 Task block: Import Network . . . . . . . . . . . . . . . . . . . .
4.1.2 Task block: Settings . . . . . . . . . . . . . . . . . . . . . . . .
4.1.3 Task block: Meteorological Data . . . . . . . . . . . . . . . . . .
4.1.4 Task block: Schematisation . . . . . . . . . . . . . . . . . . . .
4.1.5 Saving the network and the model . . . . . . . . . . . . . . . . .
4.1.6 Task block: Simulation . . . . . . . . . . . . . . . . . . . . . . .
4.1.7 Task block: Results in Maps . . . . . . . . . . . . . . . . . . . .
4.1.8 Task block: Results in Tables . . . . . . . . . . . . . . . . . . .
4.1.9 Task block: Results in Charts . . . . . . . . . . . . . . . . . . .
4.1.10 Interpolation over a Connection Node . . . . . . . . . . . . . . . .
4.1.11 Saving the network and the model . . . . . . . . . . . . . . . . .
4.2 Tutorial Hydrodynamics in sewers (SOBEK-Urban 1DFLOW + RR modules)
4.2.1 Task block: Import Network . . . . . . . . . . . . . . . . . . . .
4.2.2 Task block: Settings . . . . . . . . . . . . . . . . . . . . . . . .
4.2.3 Task block: Meteorological Data . . . . . . . . . . . . . . . . . .
4.2.4 Task block: Schematisation . . . . . . . . . . . . . . . . . . . .
4.2.5 Task block: Simulation . . . . . . . . . . . . . . . . . . . . . . .
4.2.6 Task block: Results in Maps . . . . . . . . . . . . . . . . . . . .
4.2.7 Task block: Results in Tables . . . . . . . . . . . . . . . . . . .
4.2.8 Task block: Results in Charts . . . . . . . . . . . . . . . . . . .
4.2.9 Case Analysis Tool . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.10 Series simulation based on independent rainfall events . . . . . . .
4.2.11 Task block: Schematisation extending your schematisation . . . .

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SOBEK, User Manual

Tutorial Hydrodynamics - 1D2D floodings (SOBEK-Rural 1DFLOW + Overland
Flow modules) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.1 Starting with a 2D grid . . . . . . . . . . . . . . . . . . . . . . .
4.3.2 Flooding from the lake . . . . . . . . . . . . . . . . . . . . . . .
4.3.3 Flooding from the lake with a 2D dam break . . . . . . . . . . . .
4.3.4 Flooding from a 1D channel . . . . . . . . . . . . . . . . . . . . .
Tutorial Hydrology in polders (SOBEK-Rural RR module) . . . . . . . . . .
4.4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.2 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.3 Case management . . . . . . . . . . . . . . . . . . . . . . . . .
4.4.4 Task block: Import Network . . . . . . . . . . . . . . . . . . . .
4.4.5 Task block: Settings . . . . . . . . . . . . . . . . . . . . . . . .
4.4.6 Task block: Meteorological Data . . . . . . . . . . . . . . . . . .
4.4.7 Task block: Schematisation . . . . . . . . . . . . . . . . . . . .
4.4.8 Task block: Simulation . . . . . . . . . . . . . . . . . . . . . . .
4.4.9 Task block: Results in Maps . . . . . . . . . . . . . . . . . . . .
4.4.10 Task block: Results in Tables . . . . . . . . . . . . . . . . . . .
4.4.11 Task block: Results in Charts . . . . . . . . . . . . . . . . . . .
4.4.12 Extending your model . . . . . . . . . . . . . . . . . . . . . . . .
4.4.13 Epilogue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Graphical User Interface
5.1 Case management . . . . . . . . . . . . . . . . . . . .
5.1.1 Task block: Import Network . . . . . . . . . . .
5.1.1.1 Procedure for importing a Duflow model
5.1.1.2 Procedure for importing a Mike11 model
5.1.1.3 Import SVK19 files . . . . . . . . . . .
5.1.2 Task block: Settings . . . . . . . . . . . . . . .
5.1.2.1 Rural . . . . . . . . . . . . . . . . . .
5.1.2.2 River/Urban/Rural . . . . . . . . . . .
5.1.2.3 Water Quality . . . . . . . . . . . . . .
5.1.3 Task block: Metereological Data . . . . . . . . .
5.1.4 Task block: Schematisation . . . . . . . . . . .
5.1.5 Task block: Simulation . . . . . . . . . . . . . .
5.1.6 Task block: Results in Maps . . . . . . . . . . .
5.1.6.1 River/Urban/Rural . . . . . . . . . . .
5.1.6.2 Netter . . . . . . . . . . . . . . . . .
5.1.6.3 Incremental and GIS output files . . . .
5.1.7 Task block: Results in Charts . . . . . . . . . .
5.1.8 Task block: Results in Tables . . . . . . . . . .
5.2 SOBEK GIS interface (NETTER) . . . . . . . . . . . . .
5.2.1 Adjusting the scale settings . . . . . . . . . . . .
5.2.2 Curving a branch . . . . . . . . . . . . . . . . .
5.2.3 Background map layers . . . . . . . . . . . . . .
5.2.4 Customising NETTER Settings . . . . . . . . . .
5.2.5 Exporting results to a database . . . . . . . . . .
5.2.6 Model data editor . . . . . . . . . . . . . . . . .
5.2.7 Shortcuts to various menu options . . . . . . . .
5.2.8 The Active Legend . . . . . . . . . . . . . . . .
5.2.9 Create a list with user defined output . . . . . . .
5.3 Node description (hydrodynamics) . . . . . . . . . . . .
5.3.1 Flow - Bridge node . . . . . . . . . . . . . . . .
5.3.2 Flow - Calculation point . . . . . . . . . . . . . .
5.3.2.1 Flow - Calculation point (basic) . . . . .

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5.3.2.2 Flow - Fixed Calculation point . . . . . . . . . . . . . .
5.3.3 Flow - Compound Structure . . . . . . . . . . . . . . . . . . . . .
5.3.4 Different types of Flow - Connection nodes . . . . . . . . . . . . .
5.3.4.1 Flow - Connection node . . . . . . . . . . . . . . . . .
5.3.4.2 Flow - Connection node with Lateral Flow . . . . . . . .
5.3.4.3 Flow - Connection node with Storage and Lateral Flow . .
5.3.5 Flow - Cross Section . . . . . . . . . . . . . . . . . . . . . . . .
5.3.6 Flow - Culvert node . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.7 Flow - Database structure . . . . . . . . . . . . . . . . . . . . .
5.3.8 Flow - Extra Resistance . . . . . . . . . . . . . . . . . . . . . . .
5.3.9 Flow - Boundary . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.10 Flow - General Structure . . . . . . . . . . . . . . . . . . . . . .
5.3.11 Flow - Lateral Flow . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.12 Flow - Flow manhole . . . . . . . . . . . . . . . . . . . . . . . .
5.3.12.1 Flow - Flow manhole (basic) . . . . . . . . . . . . . . .
5.3.12.2 Flow - Flow manhole with level measurement . . . . . . .
5.3.12.3 Flow - Flow manhole with runoff . . . . . . . . . . . . .
5.3.13 Flow - Measurement station . . . . . . . . . . . . . . . . . . . .
5.3.14 Flow - Orifice node . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.15 Flow - Pump station node . . . . . . . . . . . . . . . . . . . . . .
5.3.16 Flow - River Advanced Weir . . . . . . . . . . . . . . . . . . . .
5.3.17 Flow - River Pump . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.18 Flow - River Weir . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.19 Flow - Universal Weir . . . . . . . . . . . . . . . . . . . . . . . .
5.3.20 Flow - Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.21 Flow - 2D-Boundary . . . . . . . . . . . . . . . . . . . . . . . .
5.3.22 Flow - 2D-Breaking Dam . . . . . . . . . . . . . . . . . . . . . .
5.3.23 Flow - 2D-Grid . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.24 Flow - 2D-History . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3.25 Flow - 2D initial water level point . . . . . . . . . . . . . . . . . .
Node description (Rainfall-Runoff) . . . . . . . . . . . . . . . . . . . . .
5.4.1 RR - Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.2 RR - Flow-RR Connection on Channel node . . . . . . . . . . . .
5.4.3 RR - Flow-RR Connection on Flow Connection node . . . . . . . .
5.4.4 RR - Greenhouse area . . . . . . . . . . . . . . . . . . . . . . .
5.4.5 RR - Industry . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.6 RR - Open water . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.7 RR - Orifice node . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.8 RR - Paved node . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.9 RR - Pump Station . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.10 RR - QH relation node . . . . . . . . . . . . . . . . . . . . . . .
5.4.11 RR - Sacramento node . . . . . . . . . . . . . . . . . . . . . . .
5.4.12 RR - Unpaved node . . . . . . . . . . . . . . . . . . . . . . . . .
5.4.13 D-NAM Input Screens . . . . . . . . . . . . . . . . . . . . . . .
5.4.14 RR - Wastewater Treatment Plant . . . . . . . . . . . . . . . . . .
5.4.15 RR - Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Branch description . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.1 Branch - Channel . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2 Branch - Flow 1D Dam Break branch and the Once Hydraulic Trigger
5.5.2.1 Application examples of the Flow 1D Dam Break Branch .
5.5.2.2 Method of modelling bbranching and Bbranch growth options/formulae . . . . . . . . . . . . . . . . . . . . . .
5.5.2.3 Specifying the point-in-time that bbranching should start in
a Flow 1D Dam Break Branch . . . . . . . . . . . . . .

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5.5.2.4 Input screens of the Flow 1D Dam Break Branch . . . .
5.5.2.5 Output available at a Flow 1D Dam Break Branch . . . .
5.5.3 Branch - Flow pipe . . . . . . . . . . . . . . . . . . . . . . . .
5.5.4 Flap Gates available for specific type of Pipes . . . . . . . . . . .
5.5.5 Branch - 1D-2D Internal Boundary Condition . . . . . . . . . . .
5.5.6 Branch - 2D Line discharge measurement . . . . . . . . . . . .
5.5.7 Branch - 2D-Line boundary . . . . . . . . . . . . . . . . . . . .
5.6 Cross Section types . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.6.1 Overview of available cross-sectional profiles . . . . . . . . . . .
5.6.2 Flow - Cross Section node (Arch type) . . . . . . . . . . . . . .
5.6.3 Flow - Cross Section node (Asymmetrical trapezium type) . . . .
5.6.4 Flow - Cross Section node (Closed Lumped Y-Z type) . . . . . . .
5.6.5 Flow - Cross Section node (Closed Tabulated type) . . . . . . . .
5.6.6 Flow - Cross Section node (Cunette type) . . . . . . . . . . . . .
5.6.7 Flow - Cross Section node (Egg-shape type) . . . . . . . . . . .
5.6.8 Flow - Cross Section node (Elliptical type) . . . . . . . . . . . .
5.6.9 Flow - Cross Section node (Open Lumped Y-Z type) . . . . . . .
5.6.10 Flow - Cross Section node (Open Tabulated type) . . . . . . . . .
5.6.11 Flow - Cross Section node (Open vertically segmented Y-Z type) .
5.6.12 Flow - Cross Section node (Rectangle type) . . . . . . . . . . .
5.6.13 Flow - Cross Section node (River Profile type) (beta functionality) .
5.6.14 Flow - Cross Section node (Round type) . . . . . . . . . . . . .
5.6.15 Flow - Cross Section node (Steel Cunette type) . . . . . . . . . .
5.6.16 Flow - Cross Section node (Trapezium type) . . . . . . . . . . .
5.7 SOBEK-Urban 1DFLOW (Sewer Flow) . . . . . . . . . . . . . . . . . .
5.7.1 Features SOBEK-Urban 1DFLOW . . . . . . . . . . . . . . . .
5.7.2 Flow - Pipe with Infiltration . . . . . . . . . . . . . . . . . . . .
5.7.2.1 Input screens of the Flow - Pipe with Infiltration . . . . .
5.7.2.2 Additional Output available for Flow - Pipe with Infiltration
5.7.3 Storage graph . . . . . . . . . . . . . . . . . . . . . . . . . .
5.7.4 Coupling with other modules . . . . . . . . . . . . . . . . . . .
5.7.5 Connecting the Rainfall-Runoff module to the 1DFLOW module . .
5.8 River Flow controllers and triggers . . . . . . . . . . . . . . . . . . . .
5.9 SOBEK-Rural/Urban/River Overland Flow (2D) . . . . . . . . . . . . . .
5.9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.9.2 Viewing 2D Grid Info . . . . . . . . . . . . . . . . . . . . . . .
5.9.3 Coupling with other modules . . . . . . . . . . . . . . . . . . .
5.10 SOBEK-Rural RR (Rainfall-Runoff) . . . . . . . . . . . . . . . . . . . .
5.10.1 Features SOBEK-Rural Rainfall-Runoff . . . . . . . . . . . . . .
5.10.2 Connecting the Rainfall-Runoff module to the 1DFLOW module . .
5.10.3 Selecting a subset period of a rainfall event . . . . . . . . . . . .
5.11 SOBEK-Urban RR (Rainfall-Runoff) . . . . . . . . . . . . . . . . . . . .
5.11.1 Features SOBEK-Urban RR (Rainfall-Runoff) module . . . . . . .
5.11.2 The SOBEK-Urban RR (Rainfall-Runoff) concept . . . . . . . . .
5.11.3 SOBEK-Urban RR (Rainfall-Runoff) input screens . . . . . . . .
5.12 SOBEK-Rural/Urban/River RTC (Real Time Control) . . . . . . . . . . .
5.12.1 Why a separate RTC (Real-time Control) module . . . . . . . . .
5.12.2 Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.12.3 Data locations in RTC . . . . . . . . . . . . . . . . . . . . . .
5.12.4 Data measurement location . . . . . . . . . . . . . . . . . . . .
5.12.5 Decision Parameters in RTC . . . . . . . . . . . . . . . . . . .
5.12.6 Decision rules in RTC - General . . . . . . . . . . . . . . . . .
5.12.7 External Data - His File in RTC . . . . . . . . . . . . . . . . . .
5.12.8 Example of a MATLAB M-file . . . . . . . . . . . . . . . . . . .

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5.12.9 Features Real-time Control . . . . . . . . . . . . . . . . .
5.12.10 Flow Measures in RTC . . . . . . . . . . . . . . . . . . .
5.12.11 Flow structure parameters in RTC and Matlab . . . . . . .
5.12.12 Measures – general . . . . . . . . . . . . . . . . . . . .
5.12.13 Precipitation Data in RTC . . . . . . . . . . . . . . . . . .
5.12.14 Rainfall-Runoff measure . . . . . . . . . . . . . . . . . .
5.12.15 Real-time Control concepts or elements . . . . . . . . . .
5.12.16 RR Data in RTC . . . . . . . . . . . . . . . . . . . . . .
5.12.17 RTC Communication-General . . . . . . . . . . . . . . . .
5.12.18 RTC definitions and options in Settings . . . . . . . . . . .
5.12.19 RTC does not overrule Flow Triggers . . . . . . . . . . . .
5.12.20 RTC - Matlab Coupling . . . . . . . . . . . . . . . . . . .
5.12.21 RTC - TCN (Telecontrolnet) coupling . . . . . . . . . . . .
5.12.22 RTC Output options in Settings . . . . . . . . . . . . . . .
5.12.23 RTC Time settings (Time-step) in Settings . . . . . . . . .
5.12.24 RTC Wind/Rain/Matlab/Reservoir Control options in Settings
5.12.25 Setpoints in RTC . . . . . . . . . . . . . . . . . . . . . .
5.12.26 Type of Measures available in Real-time Control . . . . . .
5.12.27 Wind Data in RTC . . . . . . . . . . . . . . . . . . . . .
5.12.28 1D Flow Data in RTC . . . . . . . . . . . . . . . . . . . .
5.12.29 2D Flow Data in RTC . . . . . . . . . . . . . . . . . . . .
5.13 SOBEK Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.13.1 Calibration data editor . . . . . . . . . . . . . . . . . . .
5.13.2 Online Visualisation (SOBEK-1D2D) . . . . . . . . . . . .
5.13.3 ReaHis (Convert HIS files to ASCII) . . . . . . . . . . . . .
5.13.4 Time tables in SOBEK . . . . . . . . . . . . . . . . . . .
5.14 1D Hydraulic friction concepts . . . . . . . . . . . . . . . . . . . .
5.14.1 Global (or Model-wide) friction concept . . . . . . . . . . .
5.14.2 Local (or Branch-wise) friction concept . . . . . . . . . . .
5.14.3 Cross-section friction concept . . . . . . . . . . . . . . . .
5.14.4 Culvert friction concept . . . . . . . . . . . . . . . . . . .
6 Conceptual description
6.1 Hydrodynamics D-Flow 1D . . . . . . . . . .
6.1.1 Model equations . . . . . . . . . . .
6.1.1.1 Continuity equation (1D) . .
6.1.1.2 Momentum equation (1D) .
6.1.2 Hydrodynamic definitions . . . . . . .
6.1.2.1 Model datum/reference level
6.1.2.2 Bed level . . . . . . . . . .
6.1.2.3 Water depth . . . . . . . .
6.1.2.4 Water level . . . . . . . . .
6.1.2.5 Flow area . . . . . . . . .
6.1.2.6 Storage area . . . . . . . .
6.1.2.7 Wetted area . . . . . . . .
6.1.2.8 Wetted perimeter . . . . . .
6.1.2.9 Flow velocity . . . . . . . .
6.1.2.10 Velocity . . . . . . . . . . .
6.1.2.11 Hydraulic radius . . . . . .
6.1.3 Inertia . . . . . . . . . . . . . . . .
6.1.4 Convection . . . . . . . . . . . . . .
6.1.5 Convection (1D) . . . . . . . . . . .
6.1.6 Water level gradient . . . . . . . . . .
6.1.7 Wind friction . . . . . . . . . . . . .

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SOBEK, User Manual

6.1.13
6.1.14
6.1.15
6.1.16

Initial conditions . . . . . . . . . . . . . . . . . . . . . . . . . .
Boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lateral discharges . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.11.1 Incorporating Lateral discharges in the Continuity Equation
6.1.11.2 Options for Assigning Lateral Discharges to ζ -calculation
point(s) . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.11.3 Examples of Lateral Discharges . . . . . . . . . . . . .
6.1.11.4 Area Based Point Lateral Flow . . . . . . . . . . . . . .
6.1.11.5 Pipe with infiltration (having a lateral diffusive discharge option) . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bed friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.1 Bos-Bijkerk . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.2 Chézy . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.3 Manning . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.4 Nikuradse . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.5 Strickler . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.12.6 White-Colebrook . . . . . . . . . . . . . . . . . . . . .
Froude number . . . . . . . . . . . . . . . . . . . . . . . . . . .
Boussinesq . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.1 Advanced weir . . . . . . . . . . . . . . . . . . . . . .
6.1.16.2 Bridge . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.3 Compound structure . . . . . . . . . . . . . . . . . . .
6.1.16.4 Culvert . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.5 Database structure . . . . . . . . . . . . . . . . . . . .
6.1.16.6 General structure . . . . . . . . . . . . . . . . . . . . .
6.1.16.7 Inverted siphon . . . . . . . . . . . . . . . . . . . . . .
6.1.16.8 Orifice . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.9 Pump station and Internal Pump station . . . . . . . . .
6.1.16.10 External Pump station . . . . . . . . . . . . . . . . . .
6.1.16.11 River Pump . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.12 River Weir . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.13 Siphon . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.16.14 Universal Weir . . . . . . . . . . . . . . . . . . . . . .
6.1.16.15 Vertical obstacle friction . . . . . . . . . . . . . . . . .
6.1.16.16 Weir . . . . . . . . . . . . . . . . . . . . . . . . . . .
Staggered grid . . . . . . . . . . . . . . . . . . . . . . . . . . .
Construction of the numerical bathymetry on basis of user-defined
cross-sections . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.18.1 The Y-Z type of profiles . . . . . . . . . . . . . . . . . .
6.1.18.2 All cross-section types except for the Y-Z type of profiles .
Method of interpolating between user-defined cross-sections . . . .
6.1.19.1 Method of Interpolating between Round cross-sections and
between Egg-shape cross-sections . . . . . . . . . . . .
6.1.19.2 Method of Interpolating between Open Vertical Segmented
Y-Z profiles and between Asymmetrical Trapezium profiles
6.1.19.3 Method of Interpolating between Cross-sections not being
a Round, Egg-shape, Open Vertical Segmented Y-Z profile
or Asymmetrical Trapezium profile . . . . . . . . . . . .
Methods for computing conveyance . . . . . . . . . . . . . . . . .
6.1.20.1 Lumped conveyance approach . . . . . . . . . . . . . .
6.1.20.2 Vertically segmented conveyance approach . . . . . . .

6.1.8
6.1.9
6.1.10
6.1.11

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Delft-scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drying/flooding . . . . . . . . . . . . . . . . . . . . . . . . . . .
Free board . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ground layer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurement station . . . . . . . . . . . . . . . . . . . . . . . .
Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.26.1 Branch . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.26.2 Branch length . . . . . . . . . . . . . . . . . . . . . .
6.1.26.3 Branch segment . . . . . . . . . . . . . . . . . . . . .
6.1.26.4 Connection node . . . . . . . . . . . . . . . . . . . . .
6.1.27 Robustness . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.28 Simulation output parameters at branch segments . . . . . . . . .
6.1.29 Time step reductions during the simulation . . . . . . . . . . . . .
6.1.30 Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.31 Stationary computation . . . . . . . . . . . . . . . . . . . . . . .
6.1.32 Summer dike . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.33 Super-critical flow . . . . . . . . . . . . . . . . . . . . . . . . . .
6.1.34 Surface level . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transport equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.1 Temperature: heat flux model . . . . . . . . . . . . . . . . . . . .
6.2.1.1 General . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.1.2 Heat balance . . . . . . . . . . . . . . . . . . . . . . .
6.2.1.3 Excess temperature model . . . . . . . . . . . . . . . .
6.2.1.4 Composite temperature model . . . . . . . . . . . . . .
6.2.1.5 Solar radiation . . . . . . . . . . . . . . . . . . . . . .
6.2.1.6 Effective back radiation . . . . . . . . . . . . . . . . . .
6.2.1.7 Evaporative heat flux . . . . . . . . . . . . . . . . . . .
6.2.1.8 Convective heat flux . . . . . . . . . . . . . . . . . . .
6.2.1.9 Input parameters for composite model . . . . . . . . . .
6.2.2 Salinity dispersion . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.3 Sediment transport capacity . . . . . . . . . . . . . . . . . . . .
Hydrodynamics Overland 2DFLOW . . . . . . . . . . . . . . . . . . . . .
6.3.1 Continuity equation (2D) . . . . . . . . . . . . . . . . . . . . . .
6.3.2 Momentum equations (2D) . . . . . . . . . . . . . . . . . . . . .
6.3.3 Branch growth formulae available at a "Flow 1D Dam Break Branch"
6.3.3.1 Verheij-vdKnaap(2002) bbranch growth formula . . . . .
6.3.3.2 vdKnaap(2000) bbranch growth formula . . . . . . . . .
6.3.4 1D-2D connection . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.5 2D-2D connection . . . . . . . . . . . . . . . . . . . . . . . . .
Triggers and Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.1 Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.1.1 Combinations of controllers . . . . . . . . . . . . . . . .
6.4.1.2 Hydraulic controller . . . . . . . . . . . . . . . . . . . .
6.4.1.3 Interval controller . . . . . . . . . . . . . . . . . . . . .
6.4.1.4 PID controller . . . . . . . . . . . . . . . . . . . . . .
6.4.1.5 Relative time controller . . . . . . . . . . . . . . . . .
6.4.1.6 Relative from value (time) controller . . . . . . . . . . .
6.4.1.7 Time controller . . . . . . . . . . . . . . . . . . . . . .
6.4.2 Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.2.1 Combinations of triggers . . . . . . . . . . . . . . . . .
6.4.2.2 Time trigger . . . . . . . . . . . . . . . . . . . . . . .
6.4.2.3 Hydraulic trigger . . . . . . . . . . . . . . . . . . . . .
6.4.2.4 Time & Hydraulic triggers . . . . . . . . . . . . . . . . .
Hydrology (Rainfall Runoff modules) . . . . . . . . . . . . . . . . . . . .

6.1.21
6.1.22
6.1.23
6.1.24
6.1.25
6.1.26

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SOBEK, User Manual

SOBEK-Rural RR (Rainfall Runoff) concept . . . . . . . . . . . . . .
6.5.1.1 Alpha reaction factor . . . . . . . . . . . . . . . . . . . .
6.5.1.2 Capillary rise . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.3 Crop factors agricultural crops . . . . . . . . . . . . . . .
6.5.1.4 Crop factors open water . . . . . . . . . . . . . . . . . .
6.5.1.5 De Zeeuw-Hellinga drainage formula . . . . . . . . . . . .
6.5.1.6 DrainageDeltaH option . . . . . . . . . . . . . . . . .
6.5.1.7 Dry Weather Flow (DWF) . . . . . . . . . . . . . . . . . .
6.5.1.8 Equal filling controller . . . . . . . . . . . . . . . . . . . .
6.5.1.9 Ernst drainage formula . . . . . . . . . . . . . . . . . . .
6.5.1.10 Evaporation (when using capsim) . . . . . . . . . . . . . .
6.5.1.11 Evapo(transpi)ration . . . . . . . . . . . . . . . . . . . .
6.5.1.12 Fixed level difference controller . . . . . . . . . . . . . . .
6.5.1.13 Fixed upstream level controller . . . . . . . . . . . . . . .
6.5.1.14 Hydrologic Cycle . . . . . . . . . . . . . . . . . . . . . .
6.5.1.15 Improved separated sewer . . . . . . . . . . . . . . . . .
6.5.1.16 Infiltration . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.17 Infiltration from open water . . . . . . . . . . . . . . . . .
6.5.1.18 Krayenhoff van de Leur drainage formula . . . . . . . . . .
6.5.1.19 Minimum filling percentage for greenhouse storage basin . .
6.5.1.20 Minimum level difference controller . . . . . . . . . . . . .
6.5.1.21 Mixed sewer . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.22 Open water node . . . . . . . . . . . . . . . . . . . . . .
6.5.1.23 Paved area node . . . . . . . . . . . . . . . . . . . . . .
6.5.1.24 Paved node surface runoff . . . . . . . . . . . . . . . . .
6.5.1.25 Percolation . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.26 QH-relation . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.27 Root zone . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.28 RR controllers . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.29 RR routing link . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.30 RR - Orifice . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.31 RR - Weir . . . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.32 Separated sewer . . . . . . . . . . . . . . . . . . . . . .
6.5.1.33 Silo capacity/Pump capacity . . . . . . . . . . . . . . . .
6.5.1.34 Soil surface level . . . . . . . . . . . . . . . . . . . . . .
6.5.1.35 Storage coefficient . . . . . . . . . . . . . . . . . . . . .
6.5.1.36 Surface runoff . . . . . . . . . . . . . . . . . . . . . . .
6.5.1.37 Target level controller . . . . . . . . . . . . . . . . . . . .
6.5.1.38 Time step output . . . . . . . . . . . . . . . . . . . . . .
6.5.1.39 Unpaved area node . . . . . . . . . . . . . . . . . . . .
6.5.1.40 Unpaved surface flow link . . . . . . . . . . . . . . . . .
Sacramento Rainfall-Runoff model . . . . . . . . . . . . . . . . . .
6.5.2.1 Sacramento, the Segment module: implemented in SOBEK
6.5.2.2 Upper zone storage . . . . . . . . . . . . . . . . . . . .
6.5.2.3 Lower zone storage . . . . . . . . . . . . . . . . . . . .
6.5.2.4 Percolation from upper to lower zones . . . . . . . . . . .
6.5.2.5 Distribution of percolated water from upper zone . . . . . .
6.5.2.6 Groundwater flow . . . . . . . . . . . . . . . . . . . . .
6.5.2.7 Actual evapotranspiration . . . . . . . . . . . . . . . . . .
6.5.2.8 Impervious and temporary impervious areas . . . . . . . .
6.5.2.9 Routing of surface runoff . . . . . . . . . . . . . . . . . .
6.5.2.10 Sacramento - Estimation of segment parameters . . . . . .
6.5.2.11 Segment parameter estimation for gauged catchments. . . .
Description of the D-NAM rainfall-runoff model . . . . . . . . . . . .

596
597
598
600
600
601
603
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604
605
606
607
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619
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632
639
639
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646
647
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649
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664

External forces acting on a D-NAM model . . . . . . . .
D-NAM storages and their water-storage capacity . . . .
D-NAM external and internal fluxes . . . . . . . . . . . .
Computing water depths in the surface flow storage . . .
Computing water depths in the lower zone storage and overland flow storage . . . . . . . . . . . . . . . . . . . . .
6.5.3.6 Evaporation from the surface storage . . . . . . . . . . .
6.5.3.7 Interflow out of the surface storage . . . . . . . . . . . .
6.5.3.8 Infiltrated water into the soil . . . . . . . . . . . . . . .
6.5.3.9 Overland flow out of the surface storage . . . . . . . . .
6.5.3.10 Infiltration into the lower zone storage and percolation into
the groundwater storage . . . . . . . . . . . . . . . . .
6.5.3.11 Transpiration from the root zone layer . . . . . . . . . . .
6.5.3.12 Capillary rise . . . . . . . . . . . . . . . . . . . . . . .
6.5.3.13 Fast and slow base flow component . . . . . . . . . . .
6.5.3.14 External (ground)water flowing into the lower zone storage
and groundwater storage . . . . . . . . . . . . . . . . .
6.5.3.15 Abstraction by the groundwater pump . . . . . . . . . .
6.5.3.16 Supply by the groundwater pump . . . . . . . . . . . . .
6.5.3.17 D-NAM output time-series . . . . . . . . . . . . . . . .
6.5.3.18 Comparing the D-NAM model and the NAM model . . . .
SOBEK-Urban RR (Rainfall Runoff) concept . . . . . . . . . . . .
6.5.4.1 Real Time Control (RTC module) . . . . . . . . . . . . .

6.5.3.1
6.5.3.2
6.5.3.3
6.5.3.4
6.5.3.5

664
664
665
666

666
667
668
668
669

669
671
672
672

674
676
677
678
679
680
683

A Dimension of Steel Cunnete Cross-sections

B River Flow controller options
B.1 Time controller . . . . . . . . . .
B.2 Relative time controller . . . . . .
B.3 Relative from value (time) controller
B.4 Hydraulic controller . . . . . . . .
B.5 Interval controller . . . . . . . . .
B.6 PID controller . . . . . . . . . . .

703
704
705
706
708
709
711

C Deprecated functionality
C.1 Linkage node . . . . . . . . . . . . . . . . . . . . . . . .
C.1.1 Flow - Linkage node (deprecated) . . . . . . . . .
C.1.2 How to replace linkage nodes with connection nodes
C.2 Rainfall Runoff Friction . . . . . . . . . . . . . . . . . . .
C.2.1 Flow - RR-Friction (deprecated) . . . . . . . . . . .
C.2.2 RR Friction node (deprecated) . . . . . . . . . . .

715
. 715
. 715
. 719
. 722
. 722
. 725

D SOBEK input file formats
D.1 SOBEK Input file formats: the Model Database 4.00 . .
D.1.1 Philosophy behind the Model Database . . . . .
D.2 Structure of the Model Database: subdivision into layers
D.3 1DFLOW and Overland Flow(2D) . . . . . . . . . . . .
D.3.1 General principles of the model database . . . .
D.3.2 Global definitions file . . . . . . . . . . . . . .
D.4 2D Grid layer . . . . . . . . . . . . . . . . . . . . . .
D.4.1 net-file (2D Grid layer) . . . . . . . . . . . . .
D.5 Condition layer . . . . . . . . . . . . . . . . . . . . .
D.5.1 flb-file (condition layer) . . . . . . . . . . . . .

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731
732
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735
735

SOBEK, User Manual

D.5.2 fll-file (condition layer) . . . . . . . . . . . . . . . . . . . . . . .
D.5.3 mob-file (condition layer) . . . . . . . . . . . . . . . . . . . . . .
D.5.4 mol-file (condition layer) . . . . . . . . . . . . . . . . . . . . . .
D.5.5 mon-file (condition layer) . . . . . . . . . . . . . . . . . . . . . .
D.5.6 net-file (condition layer) . . . . . . . . . . . . . . . . . . . . . . .
D.5.7 sab-file (condition layer) . . . . . . . . . . . . . . . . . . . . . .
D.5.8 sal-file (condition layer) . . . . . . . . . . . . . . . . . . . . . . .
D.5.9 wqb-file (condition layer) . . . . . . . . . . . . . . . . . . . . . .
D.5.10 wql-file (condition layer) . . . . . . . . . . . . . . . . . . . . . . .
Cross Section layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.6.1 dat-file (cross section layer) . . . . . . . . . . . . . . . . . . . . .
D.6.2 def-file (cross section layer) . . . . . . . . . . . . . . . . . . . . .
D.6.3 Tabulated cross section . . . . . . . . . . . . . . . . . . . . . . .
D.6.4 Trapezium cross section . . . . . . . . . . . . . . . . . . . . . .
D.6.5 Open circle cross section . . . . . . . . . . . . . . . . . . . . . .
D.6.6 Sedredge cross section . . . . . . . . . . . . . . . . . . . . . . .
D.6.7 Closed circle cross section: (only SOBEK Urban/Rural) . . . . . . .
D.6.8 Egg shaped cross section: (only SOBEK Urban/Rural) . . . . . . .
D.6.9 y-z table cross section: (only SOBEK Urban/Rural) . . . . . . . . .
D.6.10 Asymmetrical trapeziodal cross section: (only SOBEK Urban/Rural)
D.6.11 net-file (cross section layer) . . . . . . . . . . . . . . . . . . . . .
Dispersion layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.7.1 brm-file (dispersion layer) . . . . . . . . . . . . . . . . . . . . . .
D.7.2 gld-file (dispersion layer) . . . . . . . . . . . . . . . . . . . . . .
D.7.3 fwt-file (dispersion layer) . . . . . . . . . . . . . . . . . . . . . .
D.7.4 lod-file (dispersion layer) . . . . . . . . . . . . . . . . . . . . . .
D.7.5 mou-file (dispersion layer) . . . . . . . . . . . . . . . . . . . . .
Friction layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.8.1 bed-file (friction layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.8.2 exr-file (friction layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.8.3 glf-file (friction layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.8.4 wnd-file (friction layer) . . . . . . . . . . . . . . . . . . . . . . .
Grid layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.9.1 net-file (grid layer) . . . . . . . . . . . . . . . . . . . . . . . . .
D.9.2 seg-file (grid layer) . . . . . . . . . . . . . . . . . . . . . . . . .
Groundwater layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.10.1 gwm-file (groundwater layer) . . . . . . . . . . . . . . . . . . . .
D.10.2 gwn-file (runtime-data layer) . . . . . . . . . . . . . . . . . . . .
Initial Conditions layer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.11.1 ifl-file (initial conditions layer) . . . . . . . . . . . . . . . . . . . .
D.11.2 igl-file (initial conditions layer) . . . . . . . . . . . . . . . . . . . .
D.11.3 imo-file (initial conditions layer) . . . . . . . . . . . . . . . . . . .
D.11.4 isa-file (initial conditions layer) . . . . . . . . . . . . . . . . . . .
D.11.5 iwq-file (initial conditions layer) . . . . . . . . . . . . . . . . . . .
Measured Data layer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.12.1 net-file (measured data layer) . . . . . . . . . . . . . . . . . . . .
Meteo layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.13.1 air-file (meteo layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.13.2 sun-file (meteo layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.13.3 wat-file (meteo layer) . . . . . . . . . . . . . . . . . . . . . . . .
D.13.4 wnd-file (meteo layer) . . . . . . . . . . . . . . . . . . . . . . . .
Run Time Data layer . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D.14.1 flh-file (SOBEK River) (run time data layer) . . . . . . . . . . . . .
D.14.2 flm-file (run time data layer) . . . . . . . . . . . . . . . . . . . . .

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738
741
741
742
743
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746
746
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747
748
748
750
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753
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764
764
764
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767
767
768
768
769
769
769
770
770
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772
773

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D.14.3 fln-file (run time data layer) . . . . . .
D.14.4 flt-file (run time data layer) . . . . . .
D.14.5 lim-file (grid layer) . . . . . . . . . . .
D.14.6 moh-file (run time data layer) . . . . .
D.14.7 mom-file (run time data layer) . . . . .
D.14.8 pwq-file (run time data layer) . . . . .
D.14.9 mon-file (run time data layer) . . . . .
D.14.10 sah-file (run time data layer) . . . . .
D.14.11 sam-file (run time data layer) . . . . .
D.14.12 san-file (run time data layer) . . . . .
D.14.13 seh-file (run time data layer) . . . . .
D.14.14 sem-file (run time data layer) . . . . .
D.14.15 sen-file (run time data layer) . . . . .
D.14.16 wqh-file (run time data layer) . . . . .
D.14.17 wqm-file (run time data layer) . . . . .
D.14.18 wqn-file (run time data layer) . . . . .
D.14.19 wqt-file (run time data layer) . . . . .
Structure layer . . . . . . . . . . . . . . . .
D.15.1 cmp-file (structure layer) . . . . . . .
D.15.2 cms-file (structure layer) . . . . . . .
D.15.3 con-file (structure layer) . . . . . . . .
D.15.4 dat-file (structure layer) . . . . . . . .
D.15.5 dbs-file (structure layer in SOBEK RE)
D.15.6 def-file (structure layer) . . . . . . . .
D.15.7 net-file (structure layer) . . . . . . . .
D.15.8 sal-file (structure layer) . . . . . . . .
D.15.9 trg-file (structure layer) . . . . . . . .
D.15.10 Valve.tab (structure layer) . . . . . . .
Substance layer . . . . . . . . . . . . . . . .
D.16.1 sub-file (substance layer) . . . . . . .
D.16.2 Tables . . . . . . . . . . . . . . . .
D.16.3 Tables in network layer . . . . . . . .
Topography layer . . . . . . . . . . . . . . .
D.17.1 cpt-file (topography layer) . . . . . . .
D.17.2 dat-file (topography layer) . . . . . . .
D.17.3 net-file (topography layer) . . . . . . .
D.17.4 nfl-file (topography layer) . . . . . . .
D.17.5 nsa-file (topography layer) . . . . . .
D.17.6 nsm-file (topography layer) . . . . . .
Transport formula layer . . . . . . . . . . . .
D.18.1 dat-file (transport formula layer) . . . .
RR (Rainfall Runoff) . . . . . . . . . . . . .
D.19.1 Boundary layer . . . . . . . . . . . .
D.19.2 Control layer . . . . . . . . . . . . .
D.19.3 General layer . . . . . . . . . . . . .
D.19.4 Greenhouse layer . . . . . . . . . . .
D.19.5 Industry layer . . . . . . . . . . . . .
D.19.6 NWRW layer . . . . . . . . . . . . .
D.19.7 Open water layer . . . . . . . . . . .
D.19.8 Paved area layer . . . . . . . . . . .
D.19.9 Runoff layer . . . . . . . . . . . . .
D.19.10 NAM rainfall runoff model . . . . . . .
D.19.11 Walrus rainfall runoff model . . . . . .
D.19.12 Structure layer . . . . . . . . . . . .

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779
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787
788
789
797
798
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800
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801
802
803
803
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805
805
806
806
806
807
809
810
813
832
833
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837
839
842
844
847
851

SOBEK, User Manual

D.19.13 Topography layer . .
D.19.14 RR-Routing link layer
D.19.15 Unpaved area layer .
D.19.16 WWTP layer . . . .
D.20 RTC (Real Time Control) . .
D.20.1 Data Locations layer
D.20.2 Decision layer . . .
D.20.3 Measures layer . . .

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E Error Messages
E.1 Error Messages on Startup . . . . . . . . . . . . . . . .
E.2 General error messages or unexpected results . . . . . .
E.3 Error Messages Model data editor . . . . . . . . . . . .
E.4 Error Messages SOBEK-Rural / Urban 1DFLOW . . . . .
E.5 Error Messages SOBEK-Rural / Urban RR (Rainfall-Runoff)

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858
860
861
865
866
870
873
886

891
. 891
. 891
. 891
. 891
. 895

F The SOBEK OpenMI interface
897
F.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897
F.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897
F.3 The omi file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897

List of Figures

List of Figures
SOBEK welcome window . . . . . . . . . . . . . . . . . . . . . . .
Select installation window, Deltares Software License Manager selected
Select installation window, SOBEK selected . . . . . . . . . . . . . .
Previous Installation(s) Detected, Install New Version selected . . . .
SOBEK installation, select Product Line . . . . . . . . . . . . . . . . .
Enter SOBEK installation directory . . . . . . . . . . . . . . . . . . .
Select destination drive(s) . . . . . . . . . . . . . . . . . . . . . . . .
Select destination drive(s) . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous Options . . . . . . . . . . . . . . . . . . . . . . . . .
Check installation properties . . . . . . . . . . . . . . . . . . . . . .
Installation progress bar . . . . . . . . . . . . . . . . . . . . . . . .
Finish installation window . . . . . . . . . . . . . . . . . . . . . . . .

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13
13
14
15
16
17
18
18
19
20
21
21

4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
4.17
4.18
4.19
4.20
4.21
4.22
4.23
4.24
4.25
4.26
4.27
4.28
4.29
4.30
4.31
4.32
4.33
4.34
4.35
4.36
4.37
4.38
4.39

The case manager window. . . . . . . . . . . . . . . . . . . . . . . . . .
The import network window. . . . . . . . . . . . . . . . . . . . . . . . .
The settings window. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The case manager after completing the ’settings’ and ’import network’ tasks.
The meteorological data window. . . . . . . . . . . . . . . . . . . . . . .
The schematisation to be created in this tutorial. . . . . . . . . . . . . . .
Click this section of a toolbar to drag it to your screen! . . . . . . . . . . . .
Node functions toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . .
Create a network similar to this one . . . . . . . . . . . . . . . . . . . . .
An example of a side view animation. . . . . . . . . . . . . . . . . . . . .
The results in tables window. . . . . . . . . . . . . . . . . . . . . . . . .
The torrent branch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The entire network after adding the torrent branch . . . . . . . . . . . . . .
The filled in Data Edit screen for the ’Torrent_connection’ node . . . . . . .
The case manager screen. . . . . . . . . . . . . . . . . . . . . . . . . .
The import network window. . . . . . . . . . . . . . . . . . . . . . . . .
The settings window. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The case manager after completing the ’settings’ and ’import network’ tasks.
The meteorological data window. . . . . . . . . . . . . . . . . . . . . . .
The schematisation to be extended in this tutorial. . . . . . . . . . . . . . .
Open sloped area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Node functions toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reach segment names visualised on the map . . . . . . . . . . . . . . . .
Side view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
User Defined Output functions . . . . . . . . . . . . . . . . . . . . . . .
Time water on street, maximum . . . . . . . . . . . . . . . . . . . . . . .
The results in tables window. . . . . . . . . . . . . . . . . . . . . . . . .
The results in charts window. . . . . . . . . . . . . . . . . . . . . . . . .
The ODS_VIEW window. . . . . . . . . . . . . . . . . . . . . . . . . . .
An example of a graph created in the ’Results in Maps’ task block. . . . . .
Maximum difference between two cases . . . . . . . . . . . . . . . . . .
Window Structure Statistics. . . . . . . . . . . . . . . . . . . . . . . . .
Structure Statistics graph for external weir 00-8002, event 6 . . . . . . . .
Extended schematisation Urban. . . . . . . . . . . . . . . . . . . . . . .
Activating the ’1DFLOW (Rural)’ and ’Overland Flow (2D)’ modules . . . . .
Drag the toolbar containing Overland Flow node types to your screen . . . .
Drag the toolbar containing the 2D-grid edit actions to your screen . . . . .
Impression of the model within its GIS environment. . . . . . . . . . . . . .

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3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12

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SOBEK, User Manual

5.12
5.13
5.14
5.15
5.16
5.17
5.18
5.19
5.20
5.21
5.22
5.23
5.24
5.25
5.26
5.27
5.28
5.29
5.30
5.31
5.32
5.33
5.34
5.35
5.36
5.37
5.38
5.39

Rotate or shift coordinates during Duflow import. . . . . . . . . . . . . . .
Rotate and shift coordinates during MIKE11 import. . . . . . . . . . . . . .
The Import Network window. . . . . . . . . . . . . . . . . . . . . . . . .
Select SUF-HYD file. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shift coordinates during SVK19 import. . . . . . . . . . . . . . . . . . . .
Importing an optional Mouse runoff file. . . . . . . . . . . . . . . . . . . .
Opening a Mouse runoff file. . . . . . . . . . . . . . . . . . . . . . . . .
Converting Mouse HGF-runoff catchment types. . . . . . . . . . . . . . .
Prefixing SVK19 id’s with a district id. . . . . . . . . . . . . . . . . . . . .
The Settings window with only the Channel Flow module activated. . . . . .
Flowdiagram of running the Rainfall-Runoff module and Channel Flow module
sequentially. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flowdiagram of running the Rainfall-Runoff module and Channel Flow module
simultaneously. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selecting a simulation mode. . . . . . . . . . . . . . . . . . . . . . . . .
The Time settings tab of the Channel flow module. . . . . . . . . . . . . .
The Simulation settings tab of the Channel flow module. . . . . . . . . . .
The Advanced settings tab of the Channel flow module. . . . . . . . . . . .
The Initial data tab of the Channel flow module. . . . . . . . . . . . . . . .
The Nodes tab in the Channel flow Output options. . . . . . . . . . . . . .
The Branches tab in the Channel flow Output options. . . . . . . . . . . . .
The Structures tab in the Channel flow/Urban flow Output options. . . . . .
The Numerical Parameters tab of the Channel flow module. . . . . . . . . .
The Settings task block. . . . . . . . . . . . . . . . . . . . . . . . . . . .
The Simulation Settings window for the Overland Flow settings task block. .
The Advanced Settings window for the Overland Flow settings task block. . .
Example of a 1D2D schematisation. . . . . . . . . . . . . . . . . . . . .
Assume no dikes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assume Highest/Lowest Level of Embankments. . . . . . . . . . . . . . .
The initial data tab from the Overland Flow SETTINGS task block. . . . . .
GIS Output tab in the Overland Flow settings task block. . . . . . . . . . .
The incremental output tab for the Overland Flow settings task block. . . . .
The Meteorological Data task block. . . . . . . . . . . . . . . . . . . . . .
The Meteorological Data window. . . . . . . . . . . . . . . . . . . . . . .
Rainfall and corresponding sewer inflow for a flat closed paved area . . . . .
Rainfall and corresponding sewer inflow for three types of closed paved area
The precipitation window . . . . . . . . . . . . . . . . . . . . . . . . . .
Define meteo stations. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defining the name, start/end date and timestep of a new event. . . . . . . .
Editing event data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Task block settings, output options. . . . . . . . . . . . . . . . . . . . . .

5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
5.11

The 1D network of the tutorial case. . . . . . . . . . . . . . . . . . . . . .
Flooding from the lake. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding history stations. . . . . . . . . . . . . . . . . . . . . . . . . . . .
1D + 2D map output for a certain time step and time series graph . . . . . .
2D map output for a certain time step and graph showing the water depth . .
Cells after changing depth from 0 m to 8 m. . . . . . . . . . . . . . . . . .
Add a 2D dam break node. . . . . . . . . . . . . . . . . . . . . . . . . .
Growth of the breach depth (m) in time. . . . . . . . . . . . . . . . . . . .
The tutorial 2D grid extended with a 1D channel. . . . . . . . . . . . . . .
Filling in the 1D Q-boundary table. . . . . . . . . . . . . . . . . . . . . .
The dummy branch used to control the flooding of the Amstellandboezem into
the 2D grid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.40
4.41
4.42
4.43
4.44
4.45
4.46
4.47
4.48
4.49
4.50

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129
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149
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152
153
155
159
160
161
162
163
164
164
165
167

List of Figures

Results in charts, Flows at branch segments. . . . . . . . . . . . . . . . . . 168
Entering Edit Network mode. . . . . . . . . . . . . . . . . . . . . . . . . . 171
Entering Model Data mode. . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Example of a 2D Path under a particular user defined line of 2D cells. . . . . . 174
Example of a SideView. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Setup Animation of a SideView. . . . . . . . . . . . . . . . . . . . . . . . . 175
The SideView Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
The active legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
A waterlevel color range in the Active Legend of NETTER. . . . . . . . . . . 183
Changing the Active Legend color range and scale. . . . . . . . . . . . . . . 184
A straight river flowing from A to B. . . . . . . . . . . . . . . . . . . . . . . 185
A harmonica-shaped river from point A to B. . . . . . . . . . . . . . . . . . 185
A meandernig river from point A to B. . . . . . . . . . . . . . . . . . . . . . 186
The default map of The Netherlands in SOBEK. . . . . . . . . . . . . . . . . 186
The Default Map Settings window. . . . . . . . . . . . . . . . . . . . . . . 187
The global Netter options window. . . . . . . . . . . . . . . . . . . . . . . . 188
Adding a definition in the SOBEK Export Tool. . . . . . . . . . . . . . . . . 189
Starting the single data editor from the Model Data menu. . . . . . . . . . . . 190
The multiple data editor. . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Changing a whole column in the multiple data editor. . . . . . . . . . . . . . 191
Importing data in the multiple data editor. . . . . . . . . . . . . . . . . . . . 192
Enter the network editing mode. . . . . . . . . . . . . . . . . . . . . . . . . 193
Mouse-over a node to show its label. . . . . . . . . . . . . . . . . . . . . . 194
Output functions window . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Adding definitions in the Output functions window. . . . . . . . . . . . . . . 198
User defined output in the Active Legend. . . . . . . . . . . . . . . . . . . . 198
The Bridge tab of a bridge. . . . . . . . . . . . . . . . . . . . . . . . . . . 199
The Cross section tab of a bridge. . . . . . . . . . . . . . . . . . . . . . . . 201
The Friction tab of a bridge. . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Setting a calculation grid on all branches. . . . . . . . . . . . . . . . . . . . 204
The Branch tab of the Calculation points window. . . . . . . . . . . . . . . . 205
The 2D Grid tab of the Calculation points window. . . . . . . . . . . . . . . . 206
An example of a schematisation that contains calculation points. . . . . . . . 207
Branches connected to Flow connection nodes . . . . . . . . . . . . . . . . 210
Interpolating data over Branch 1 and 2 at a Flow - Connection Node . . . . . 211
The Bottom level tab of a Flow - Connection node with Storage and Lateral Flow.213
The Lateral flow tab of a Flow - Connection node with Storage and Lateral Flow.214
The Location tab of a Flow - Cross Section node type. . . . . . . . . . . . . 215
The Cross section tab of a Flow - Cross Section node of the Y-Z Profile type. . 216
Y-Z and Asymmetrical Trapezium friction input screen. . . . . . . . . . . . . 217
River profile friction input screen. . . . . . . . . . . . . . . . . . . . . . . . 218
Friction input screen for the remaining profile types. . . . . . . . . . . . . . . 219
Example of a valid network configuration containing a cross section. . . . . . 220
The Culvert tab of a Flow - Culvert node. . . . . . . . . . . . . . . . . . . . 222
The Cross section tab of a Flow - Culvert node. . . . . . . . . . . . . . . . . 223
The Friction tab of a Flow - Culvert node. . . . . . . . . . . . . . . . . . . . 224
The Controller tab of a Flow - Culvert node. . . . . . . . . . . . . . . . . . . 225
The Database Structure tab of a Flow - Database structure node. . . . . . . . 227
The Definitions tab of a Flow - Database structure node. . . . . . . . . . . . 228
The Structure Database window of a Flow - Database structure node. . . . . . 229
The Extra Resistance tab of a Flow - Extra Resistance node. . . . . . . . . . 230
Input Table for Extra Resistance coefficients of a Flow - Extra Resistance node. 231
The Boundary condition tab of a Flow - Boundary node. . . . . . . . . . . . . 232
Examples of valid configurations with Flow - Boundary nodes . . . . . . . . . 234

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SOBEK, User Manual

5.94 Data Edit window, General Structure tab . . . . . . . . . . . . . . . . . . .
5.95 Data Edit window, Definitions tab . . . . . . . . . . . . . . . . . . . . . . .
5.96 Cross-sectional view on general structure; definitions of vertical distances . . .
5.97 Top view on general structure; definitions of width distances . . . . . . . . . .
5.98 Data Edit window, Lateral flow tab . . . . . . . . . . . . . . . . . . . . . .
5.99 Change Table window . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.100 Data Edit window, Lateral flow tab . . . . . . . . . . . . . . . . . . . . . .
5.101 Example of network with a Lateral Flow node . . . . . . . . . . . . . . . . .
5.102 Data Edit window, Storage tab . . . . . . . . . . . . . . . . . . . . . . . .
5.103 The difference between Flow-manholes of the type "closed", "reservoir" and
"loss" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.104 Placement of a Flow Measurement Station node . . . . . . . . . . . . . . .
5.105 Data Edit window, Orifice tab . . . . . . . . . . . . . . . . . . . . . . . . .
5.106 Data Edit window, Controller tab . . . . . . . . . . . . . . . . . . . . . . .
5.107 Example of a valid network configuration containing a pump station. . . . . .
5.108 Example of a Flow - Pump Station . . . . . . . . . . . . . . . . . . . . . .
5.109 Data Edit window, Pump tab . . . . . . . . . . . . . . . . . . . . . . . . .
5.110 Data Edit window, Capacity Reduction Table tab . . . . . . . . . . . . . . .
5.111 Data Edit window, Capacity Reduction Table tab . . . . . . . . . . . . . . .
5.112 Data Edit window, Advanced Weir tab . . . . . . . . . . . . . . . . . . . .
5.113 Data Edit window, Definitions tab . . . . . . . . . . . . . . . . . . . . . . .
5.114 Data Edit window, River Pump tab . . . . . . . . . . . . . . . . . . . . . .
5.115 Data Edit window, Definition tab . . . . . . . . . . . . . . . . . . . . . . .
5.116 Data Edit window, River Weir tab . . . . . . . . . . . . . . . . . . . . . . .
5.117 Data Edit window, Definitions tab . . . . . . . . . . . . . . . . . . . . . . .
5.118 Data Edit window, Universal Weir tab . . . . . . . . . . . . . . . . . . . . .
5.119 Data Edit window, Cross section tab . . . . . . . . . . . . . . . . . . . . .
5.120 Data Edit window, Weir tab . . . . . . . . . . . . . . . . . . . . . . . . . .
5.121 Data Edit window, Controller tab . . . . . . . . . . . . . . . . . . . . . . .
5.122 Possible configuration of a 2D boundary node. Note: the white (transparent)
cells contain no-data values . . . . . . . . . . . . . . . . . . . . . . . . . .
5.123 2D-boundary edit window - boundary condition tab . . . . . . . . . . . . . .
5.124 Change table window . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.125 Data Edit window, Boundary condition tab . . . . . . . . . . . . . . . . . .
5.126 Example of 2D- Breaking Dams located on 2D grid cells . . . . . . . . . . .
5.127 Example of selecting the controller option for a 2D Breaking - Dam . . . . . .
5.128 Example of a Decrease in Height Time Table available at a 2D Breaking – Dam
5.129 Example defining a controller for a 2D Breaking – Dam . . . . . . . . . . . .
5.130 Edit network menu, Import 2D-Grid... menu . . . . . . . . . . . . . . . . . .
5.131 Grid properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.132 Node settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.133 2D Grid Order Window . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.134 Grid data window - 2D Grid location tab . . . . . . . . . . . . . . . . . . .
5.135 Grid data window - Grid Cell Bottom Depth tab . . . . . . . . . . . . . . . .
5.136 Grid data window - Friction tab . . . . . . . . . . . . . . . . . . . . . . . .
5.137 Grid data window - Grid Cell Friction tab . . . . . . . . . . . . . . . . . . .
5.138 Data Edit for Boundary Area window - Boundary tab . . . . . . . . . . . .
5.139 An example of RR boundary nodes connected to other nodes . . . . . . . . .
5.140 Data Edit for Boundary Area window - Boundary tab . . . . . . . . . . . .
5.141 Settings window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.142 Move node icon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.143 An example of a valid network . . . . . . . . . . . . . . . . . . . . . . . .
5.144 Data Edit for Boundary Area window - Boundary tab . . . . . . . . . . . .
5.145 Settings window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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5.146 Data Edit for Node window - Storage tab . . . . . . . . . . . . . . . . . .
5.147 An example of a valid schematisation containing a Flow - RR connection on
Flow connection node . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.148 Volume balance in the greenhouse areas . . . . . . . . . . . . . . . . . .
5.149 Data Edit for Greenhouse, Area tab . . . . . . . . . . . . . . . . . . . .
5.150 Data Edit for Greenhouse, Storage tab . . . . . . . . . . . . . . . . . .
5.151 Data Edit for Greenhouse, Silo tab . . . . . . . . . . . . . . . . . . . .
5.152 Data Edit for Industry, Industry tab . . . . . . . . . . . . . . . . . . . .
5.153 Data Edit for Open Water, Surface tab . . . . . . . . . . . . . . . . . . .
5.154 Data Edit for Open Water, Management tab . . . . . . . . . . . . . . . .
5.155 Data Edit for Open Water, Seepage tab . . . . . . . . . . . . . . . . . .
5.156 Data Edit for Open Water, Rainfall station tab . . . . . . . . . . . . . . .
5.157 Example of RR Open Water node connections. . . . . . . . . . . . . . . .
5.158 Data Edit for Gate/Orifice, Options tab . . . . . . . . . . . . . . . . . . .
5.159 Data Edit for Open Water, Orifice tab . . . . . . . . . . . . . . . . . . .
5.160 Data Edit for Open Water, Controller tab . . . . . . . . . . . . . . . . . .
5.161 An example of a network where RR Orifices are used . . . . . . . . . . . .
5.162 The storage on the street and the sewer storage can be considered as two
reservoirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.163 Data Edit for Paved Area window, the Area tab . . . . . . . . . . . . . .
5.164 Data Edit for Paved Area window, the Management tab . . . . . . . . . .
5.165 Sewer type: Mixed system . . . . . . . . . . . . . . . . . . . . . . . . .
5.166 Sewer type: Separate system . . . . . . . . . . . . . . . . . . . . . . . .
5.167 Sewer type: Improved separate system . . . . . . . . . . . . . . . . . . .
5.168 Data Edit for Paved Area window, the Dry Weather Flow tab . . . . . . . .
5.169 Data Edit for Paved Area window, the Rainfall Station tab . . . . . . . . .
5.170 Data Edit for Paved Area window, the Storage tab . . . . . . . . . . . . .
5.171 Select RR-Paved node connection . . . . . . . . . . . . . . . . . . . . .
5.172 Connecting an RR Paved node to an RR open water for the sewer overflows
and surface runoff and an RR boundary for the sewerage discharge. . . . .
5.173 Connecting an RR Paved node to an RR open water for the sewer overflows
and surface runoff and an RR Waste Water Treatment Plant for the sewerage
discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.174 Data Edit for Pump, the Options tab . . . . . . . . . . . . . . . . . . . .
5.175 Data Edit for Pump, the Pump tab . . . . . . . . . . . . . . . . . . . . .
5.176 Data Edit for Q-H relation window, Q-h relation tab . . . . . . . . . . . .
5.177 The rainfall-runoff processes that are included in the Sacramento concept. .
5.178 Flowchart of the processes that are covered by the Sacramento concept. . .
5.179 Catchment divided into a number of segments . . . . . . . . . . . . . . .
5.180 Data Edit for Sacramento node window, Area tab . . . . . . . . . . . . .
5.181 Data Edit for Sacramento node window, Unit Hydrograph tab . . . . . . .
5.182 Data Edit for Sacramento node window, Capacities tab . . . . . . . . . .
5.183 Showing the RR-Link connection type . . . . . . . . . . . . . . . . . . . .
5.184 Connecting an RR Sacramento node to an RR Open Water node . . . . . .
5.185 Two ways to connect an RR Sacramento node to a channel . . . . . . . . .
5.186 Representation of the rainfall-runoff process in unpaved areas . . . . . . .
5.187 Data for UnPaved Area window, Area tab . . . . . . . . . . . . . . . . .
5.188 Data for UnPaved Area window, Soil tab . . . . . . . . . . . . . . . . . .
5.189 Data for UnPaved Area window, Storage tab . . . . . . . . . . . . . . . .
5.190 Data for UnPaved Area window, Infiltration tab . . . . . . . . . . . . . . .
5.191 Data for UnPaved Area window, Drainage tab . . . . . . . . . . . . . . .
5.192 Data for UnPaved Area window, Seepage tab . . . . . . . . . . . . . . .
5.193 RR-link connection type . . . . . . . . . . . . . . . . . . . . . . . . . . .

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5.194 Connecting an RR Unpaved node to an RR Open Water node. Notice the
defined link directions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
5.195 Two ways to connect an RR Unpaved node to a channel (only available if you
have a license for the flow module). . . . . . . . . . . . . . . . . . . . . . . 339
5.196 The D-NAM Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . . 340
5.197 The Meteo Stations Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . 340
5.198 The Soil Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . . . . 341
5.199 The Soil2 Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . . . 341
5.200 The Initial Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . . . 342
5.201 The Runoff Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . . 343
5.202 The Base Flow Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . 343
5.203 The GW Pump Tab of the D-NAM ModelEdt Form . . . . . . . . . . . . . . . 344
5.204 Data for WWTP window, WWTP tab . . . . . . . . . . . . . . . . . . . . . 345
5.205 Typical example of a schematisation that contains a WWTP node . . . . . . . 346
5.206 Example of a broad crested weir. Photo: Dutch waterboard "Peel and Maasvallei" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
5.207 Data for Weir window, Options tab . . . . . . . . . . . . . . . . . . . . . . 348
5.208 Data for a normal RR-Weir window, Weir tab . . . . . . . . . . . . . . . . 349
5.209 Example of a broad crested weir . . . . . . . . . . . . . . . . . . . . . . . 349
5.210 Example of a V-notch weir . . . . . . . . . . . . . . . . . . . . . . . . . . 350
5.211 Example of a multiple-stage weir . . . . . . . . . . . . . . . . . . . . . . . 351
5.212 Data Edit for Weir window, Weir tab . . . . . . . . . . . . . . . . . . . . . 352
5.213 Data Edit for RR - Weir window, controller tab . . . . . . . . . . . . . . . . 353
5.214 Example of a network with RR Weirs . . . . . . . . . . . . . . . . . . . . . 354
5.215 Visualising the defined direction of a branch. . . . . . . . . . . . . . . . . . 355
5.216 Bbranching of a dike in a 2D model using a "Flow 1D Dam Break Branch" . . . 356
5.217 Bbranching of a river levee using a "Flow 1D Dam Break Branch" . . . . . . . 357
5.218 Bbranching of a 1D river dam using a "Flow 1D Dam Break Branch" . . . . . . 357
5.219 Development of a bbranch in a "Flow 1D Dam Break Branch" . . . . . . . . . 358
5.220 "Flow 1D Dam Break Branch"; Location Tab . . . . . . . . . . . . . . . . . . 361
5.221 "Flow 1D Dam Break Branch"; the Verheij-vdKnaap(2002) Dam Break Tab . . 362
5.222 "Flow 1D Dam Break Branch"; the vdKnaap(2000) Dam Break Tab . . . . . . 362
5.223 "Flow 1D Dam Break Branch"; Option 1", Controller Tab for the Verheij-vdKnaap(2002)
formula with an "Once Hydraulic Trigger" . . . . . . . . . . . . . . . . . . . 363
5.224 "Flow 1D Dam Break Branch"; Option 4, Controller Tab for the vdKnaap(2000)
formula and without an "Once Hydraulic Trigger" . . . . . . . . . . . . . . . 364
5.225 The Triggers Tab of the "Flow 1D Dam Break Branch" . . . . . . . . . . . . . 365
5.226 "Flow 1D Dam Break Branch"; Trigger Table of the "Once Hydraulic Trigger" . . 365
5.227 The Flap Gate input screen, that is available for specific type of pipes . . . . . 367
5.228 Placing a 1D-2D internal boundary in a model . . . . . . . . . . . . . . . . . 368
5.229 Data Edit, Boundary condition tab . . . . . . . . . . . . . . . . . . . . . . 369
5.230 Definition of the sign of the effective 2D Discharge passing a 2D Line discharge
measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
5.231 View Data window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
5.232 Possible configuration of a 2D Line boundary . . . . . . . . . . . . . . . . . 373
5.233 Data Edit, Cross section tab . . . . . . . . . . . . . . . . . . . . . . . . . 376
5.234 Asymmetrical trapezium cross section . . . . . . . . . . . . . . . . . . . . 377
5.235 Example of a closed Lumped Y-Z profile defined in ModelEdt . . . . . . . . . 378
5.236 User defined closed Lumped Y-Z profile . . . . . . . . . . . . . . . . . . . . 379
5.237 SOBEK adapted closed Lumped Y-Z profile . . . . . . . . . . . . . . . . . . 379
5.238 Symmetrical tabulated closed lumped Y-Z profile . . . . . . . . . . . . . . . 379
5.239 The Cross section tab of a cunette profile . . . . . . . . . . . . . . . . . . . 380
5.240 The corresponding tabulated profile data of the cunette profile in Figure 5.239 . 381
5.241 Example of an Open Lumped Y-Z profile defined in ModelEdt . . . . . . . . . 382

List of Figures

5.242 User defined open Lumped Y-Z profile . . . . . . . . . . . . . . . . . . .
5.243 SOBEK adapted open Lumped Y-Z profile . . . . . . . . . . . . . . . . . .
5.244 Symmetrical tabulated open lumped Y-Z profile . . . . . . . . . . . . . . .
5.245 Example of an Open Vertically Segmented Y-Z profile defined in ModelEdt .
5.246 Data Edit, Friction tab, Open vertically segmented YZ profile . . . . . . . .
5.247 Example of a ’river profile’ type cross section . . . . . . . . . . . . . . . .
5.248 Table where a cross section’s dimensions are defined. . . . . . . . . . . .
5.249 Activating the ’summer dike’ option . . . . . . . . . . . . . . . . . . . . .
5.250 The advanced settings tab for the SOBEK-River settings. . . . . . . . . . .
5.251 Defining subsections for unique friction values on different sections . . . . .
5.252 Window for friction settings of the main profile section. . . . . . . . . . . .
5.253 Entering friction values as a function of water levels and location . . . . . .
5.254 Locations for which the friction values are known, added to the table. . . . .
5.255 Data Edit, Cross section tab, Round type . . . . . . . . . . . . . . . . . .
5.256 Steel Cunette type Cross section input screen. . . . . . . . . . . . . . . .
5.257 Editing an existing Steel Cunette profile. . . . . . . . . . . . . . . . . . .
5.258 Construction of a Steel Cunette Cross-section, type 3 . . . . . . . . . . . .
5.259 Construction of a Steel Cunette Cross-section, type 4 . . . . . . . . . . . .
5.260 Data Edit, Cross section tab, Trapezium . . . . . . . . . . . . . . . . . .
5.261 Calculation points, General tab . . . . . . . . . . . . . . . . . . . . . .
5.262 Calculation points, Branch tab . . . . . . . . . . . . . . . . . . . . . . .
5.263 Pipe with Infiltration, a drainage pipe located in a trench . . . . . . . . . . .
5.264 The Location Tab of the Pipe with Infiltration . . . . . . . . . . . . . . . . .
5.265 The Cross Section Tab of the Pipe with Infiltration . . . . . . . . . . . . . .
5.266 The Friction Tab of the Pipe with Infiltration . . . . . . . . . . . . . . . . .
5.267 The Trench Profile Tab of the Pipe with Infiltration . . . . . . . . . . . . . .
5.268 The Trench Data Tab of the Pipe with Infiltration . . . . . . . . . . . . . . .
5.269 The "Settings for 1DFLOW module Form" available in the Settings Taskblock
5.270 To start the storage graph . . . . . . . . . . . . . . . . . . . . . . . . . .
5.271 Definition of storage graph options . . . . . . . . . . . . . . . . . . . . .
5.272 Storage graph result . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.273 Coupling a manhole ot the type loss with a 2D grid cell . . . . . . . . . . .
5.274 Coupling a manhole ot the type reservoir with a 2D grid cell . . . . . . . . .
5.275 Data Edit, Controllers tab . . . . . . . . . . . . . . . . . . . . . . . . . .
5.276 Data Edit, Triggers tab . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.277 Data Edit, Controllers tab . . . . . . . . . . . . . . . . . . . . . . . . . .
5.278 Example of a 2D Path under a particular user defined line . . . . . . . . . .
5.279 Available node types for the Overland Flow & Channel Flow modules . . . .
5.280 Example of a 1D dummy branch . . . . . . . . . . . . . . . . . . . . . .
5.281 Coupling a manhole ot the type loss with a 2D grid cell . . . . . . . . . . .
5.282 Coupling a manhole ot the type reservoir with a 2D grid cell . . . . . . . . .
5.283 Definition of simulation period for Rainfall-Runoff model. . . . . . . . . . .
5.284 Interactions of Rainfall-Runoff module with Flow module. . . . . . . . . . .
5.285 Illustration of rainfall-runoff process . . . . . . . . . . . . . . . . . . . . .
5.286 Data Edit for Sewerage Inflow, Surface tab . . . . . . . . . . . . . . . .
5.287 Data Edit for Sewerage Inflow, DWF tab . . . . . . . . . . . . . . . . .
5.288 Data Edit for Sewerage Inflow, Rainfall station tab . . . . . . . . . . . . .
5.289 Data Edit for Sewerage Inflow, Runoff tab . . . . . . . . . . . . . . . . .
5.290 Data Edit for Sewerage Inflow, Storage tab . . . . . . . . . . . . . . . .
5.291 Data Edit for Sewerage Inflow, Infiltration tab . . . . . . . . . . . . . . .
5.292 Concept of Urban runoff model . . . . . . . . . . . . . . . . . . . . . .
5.293 RTC Flow data locations input screen . . . . . . . . . . . . . . . . . . . .
5.294 Example of RTC input screen for Function (decision) parameters . . . . . .
5.295 Definition of RTC Flow Measures . . . . . . . . . . . . . . . . . . . . . .

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502
502
503
505
507

6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
6.18
6.19
6.20
6.21
6.22

5.296 SOBEK RTC Editor window, the tab Measure → RR Measure . . . . . . .
5.297 Definition of RR measure . . . . . . . . . . . . . . . . . . . . . . . . . .
5.298 Settings input screen for SOBEK-Rural 1DFLOW-RTC run . . . . . . . . .
5.299 RTC settings for the RTC - TCN coupling . . . . . . . . . . . . . . . . . .
5.300 Defining a RTC decision parameter, which data is transferred towards TCN .
5.301 Example of a file written by RTC to transfer data to TCN . . .
5.302 Defining a 1D flow controller to be overruled by TCN . . . . . . . . . . . .
5.303 Example of a file written by TCN to transfer data to RTC . . .
5.304 Example of a RTC-TCN definition (SOBEKTCN.ini) file . . . . . . . . . . .
5.305 Example of a RTC-TCN log file (sobektcn.log) . . . . . . . . . . . . . . . .
5.306 Example of a file used to start the RTC-TCN coupling . . . . .
5.307 RTC Output Options in Settings . . . . . . . . . . . . . . . . . . . . . . .
5.308 Settings for RTC module, the Time Settings tab . . . . . . . . . . . . .
5.309 RTC Control options . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.310 RTC Flow Data input screen . . . . . . . . . . . . . . . . . . . . . . . .
5.311 RTC 2D Flow Data input screen . . . . . . . . . . . . . . . . . . . . . . .
5.312 Hisfile editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.313 ODS view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.314 ODS View, parameter list . . . . . . . . . . . . . . . . . . . . . . . . . .
5.315 Examples of the Online Visualisation. . . . . . . . . . . . . . . . . . . . .
5.316 Enabling the Online Visualisation in the SOBEK Options window. . . . . . .
5.317 The Online Visualisation. . . . . . . . . . . . . . . . . . . . . . . . . . .
5.318 Explanation of cross-section for Onlie Visualisation . . . . . . . . . . . . .
5.319 Online Visualisation 2D velocity vectors. . . . . . . . . . . . . . . . . . .
5.320 A generic table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.321 This picture shows which part of your table will be continuously repeated if the
periodicity timespan that you choose is shorter than the available data in your
table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.322 In this graph you can see how SOBEK handles periodicities that exceed the
time span in your table. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Definition of model datum/reference level . . . . . . . . . . . . . . . . . .
Definition of bed level . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Definition of water depth h = ζ − zb . . . . . . . . . . . . . . . . . . . .
Definition of water level . . . . . . . . . . . . . . . . . . . . . . . . . . .
Definiton of flow area (AF ) and storage area (AS ) . . . . . . . . . . . . .
Wetted perimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wetted perimeter for the main channel . . . . . . . . . . . . . . . . . . .
Computation of hydraulic radius . . . . . . . . . . . . . . . . . . . . . . .
Wetted perimeter for the main channel (Subdivision in main channel and floodplains only in SOBEK-River) . . . . . . . . . . . . . . . . . . . . . . . .
Wind direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diffuse lateral discharge . . . . . . . . . . . . . . . . . . . . . . . . . .
Lateral discharges, point and line source . . . . . . . . . . . . . . . . . .
Pipe with Infiltration, a drainage pipe located in a trench . . . . . . . . . . .
Pipe with infiltration: definition of variables . . . . . . . . . . . . . . . . .
Definition of energy and water level . . . . . . . . . . . . . . . . . . . . .
Pillar bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A suspension bridge with abutments . . . . . . . . . . . . . . . . . . . .
Fixed bed bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Soil bed bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Side view of a culvert . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Good modelling practice, Culvert, Inverted Siphon and Siphon . . . . . . .
General structure, side view . . . . . . . . . . . . . . . . . . . . . . . . .

448
448
450
454
455
455
456
456
457
458
459
459
460
461
463
464
465
466
466
467
468
469
470
471
472

List of Figures

General structure, top view . . . . . . . . . . . . . . . . . . . . . . . . .
Drowned gate flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drowned weir-flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Side view of an inverted siphon . . . . . . . . . . . . . . . . . . . . . . .
Good modelling practice, Culvert, Inverted Siphon and Siphon . . . . . . .
Orifice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pump station with positive pump direction and two pump stages . . . . . .
Pump station with negative pump direction and two pump stages . . . . . .
External pump station with pump direction IN and two pump stages . . . . .
External pump station with pump direction OUT and two pump stages . . .
River pump with Upward control and start-level above stop-level . . . . . .
River pump with Upward control and stop-level above start-level . . . . . .
River pump with Downward control and start-level above stop-level . . . . .
River pump with Downward control and stop-level above start-level . . . . .
Free and drowned weir flow . . . . . . . . . . . . . . . . . . . . . . . . .
Drowned flow reduction curves . . . . . . . . . . . . . . . . . . . . . . .
Siphon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Good modelling practice, Culvert, Inverted Siphon and Siphon . . . . . . .
Crest level (Y-Z) profile of a Universal weir, divided into three rectangular weir
sections (2, 4 and 6) and four triangular weir sections (1, 3, 5 and 7) . . . .
Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Staggered grid, ζ - and u-calculation points at different locations . . . . . .
Construction of numerical bathymetry for Y-Z profiles . . . . . . . . . . . .
Construction of numerical bathymetry other than Y-Z profiles . . . . . . . .
Concept of the lumped conveyance approach . . . . . . . . . . . . . . . .
Example of constructed vertical segments in a Y-Z profile . . . . . . . . . .
Definition sketch of a vertical segment, considered in computing conveyance
for a Y-Z profile and an Asymmetrical Trapezium cross-section . . . . . . .
Free board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ground layer in circular cross section . . . . . . . . . . . . . . . . . . . .
Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Branch length in model network . . . . . . . . . . . . . . . . . . . . . . .
Branch segment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connection nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Summer dike option, available in a river profile . . . . . . . . . . . . . . .
Flow area behind the summer dike as function of local water levels. . . . . .
Total area behind the summer dike as function of local water levels. . . . . .
Overview of the heat exchange mechanisms at the surface . . . . . . . . .
Co-ordinate system position Sun
δ : declination; θ: latitude; ωt: angular speed . . . . . . . . . . . . . . . .
Dam break Bbranch vdKnaap(200), timestep subdivision . . . . . . . . . .
Bbranch width computation according vdKnaap(2000) . . . . . . . . . . .
Connections between 1D and 2D . . . . . . . . . . . . . . . . . . . . . .
Connections made between different grids . . . . . . . . . . . . . . . . .
Example of hydraulic controller . . . . . . . . . . . . . . . . . . . . . . .
Example of interval controller . . . . . . . . . . . . . . . . . . . . . . . .
Example of time controller . . . . . . . . . . . . . . . . . . . . . . . . .
Drainage levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surface run-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parallell drainage systems (default: DrainageDeltaH=-1) . . . . . . . .
Stacked drainage systems (DrainageDeltaH=0) . . . . . . . . . . . .
Principles of Ernst method . . . . . . . . . . . . . . . . . . . . . . . . .
Reduction coefficient for root water uptake, αE , as a function of soil water
pressure head h (Feddes et al., 1978). . . . . . . . . . . . . . . . . . . .

6.23
6.24
6.25
6.26
6.27
6.28
6.29
6.30
6.31
6.32
6.33
6.34
6.35
6.36
6.37
6.38
6.39
6.40
6.41
6.42
6.43
6.44
6.45
6.46
6.47
6.48
6.49
6.50
6.51
6.52
6.53
6.54
6.55
6.56
6.57
6.58
6.59

6.60
6.61
6.62
6.63
6.64
6.65
6.66
6.67
6.68
6.69
6.70
6.71
6.72

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507
508
509
512
514
515
517
517
522
522
527
528
528
529
531
533
533
536

537
540
542
543
543
545
546

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548
552
553
554
555
556
557
561
562
564
565

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568
582
583
584
586
589
591
593
597
598
603
604
605

SOBEK, User Manual

Infiltration from open water . . . . . . . . . . . . . . . . . . . . . . . . . . 612
Drainage according to Krayenhoff van de Leur . . . . . . . . . . . . . . . . 612
Representation of the rainfall-runoff process of an open-water area . . . . . . 615
Impact of delay coefficient on runoff pattern . . . . . . . . . . . . . . . . . . 616
Discharge from Paved to Open Water without delay . . . . . . . . . . . . . . 617
Discharge from Paved to Open Water using QH-relation . . . . . . . . . . . . 618
QH-relation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619
Example input data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Possible usage in a network . . . . . . . . . . . . . . . . . . . . . . . . . . 623
Orifice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
Weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Two-stage weir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
Two-stage weir, crest bottom width at crestlevel 1 . . . . . . . . . . . . . . . 626
V-notch broad-crested weir . . . . . . . . . . . . . . . . . . . . . . . . . . 627
Change table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Inundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Example of definition of reaction factor layers when the surface level is not
constant (in this case the number of sub-areas defined in the table is equal to 6)631
6.90 Rootzone sub areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
6.91 Output reductions in Settings . . . . . . . . . . . . . . . . . . . . . . . . . 641
6.92 Time step computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
6.93 Time step output = 12 ∗ time step computation . . . . . . . . . . . . . . . . 642
6.94 Conceptualisation of the rainfall-runoff process in a segment. . . . . . . . . . 644
6.95 Schematisation of the rainfall-runoff process in a segment . . . . . . . . . . . 645
6.96 Actual percolation demand representation . . . . . . . . . . . . . . . . . . . 647
6.97 Principle of computation of lower zone recession coefficient . . . . . . . . . . 648
6.98 Principles of the Clark method for simulating surface runoff and interflow. . . . 650
6.99 Calculation of PCTIM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653
6.100 UZK as function of number of days with significant interflow . . . . . . . . . . 655
6.101 Selection of period for LZTWM estimation . . . . . . . . . . . . . . . . . . . 657
6.102 Schematic cross-section through basin aquifer . . . . . . . . . . . . . . . . 662
6.103 Cases of multiple exponential decay of recession curve . . . . . . . . . . . . 663
6.104 Maximum water depths in lower zone storage and groundwater storage . . . . 665
6.105 Schematic representation of fluxes in the D-NAM rainfall runoff model . . . . . 666
6.106 Water depths, thresholds and fluxes related to the surface storage . . . . . . 666
6.107 Fluxes related to the lower zone storage and groundwater storage . . . . . . 667
6.108 Distributing infiltrated water over the lower zone storage and the groundwater
storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 670
6.109 Computing Fast base flow and Slow base flow . . . . . . . . . . . . . . . . 672
6.110 Determining the inflow of external (ground)water inflow . . . . . . . . . . . . 675
6.111 Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 684

6.73
6.74
6.75
6.76
6.77
6.78
6.79
6.80
6.81
6.82
6.83
6.84
6.85
6.86
6.87
6.88
6.89

River confluences with linkage nodes . . . . . . . . . . . . . . . . . . . .
River confluences for linkage nodes showing interpolation over linkage node
for main channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.3 Check mark Allow Edit for selected objects . . . . . . . . . . . . . . . . .
C.4 Select Flow - Linkage node . . . . . . . . . . . . . . . . . . . . . . . . .
C.5 Select branch to join . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C.6 Select action . . . . . . . . . . . . . . . . . . . . . . .
C.7 Join branches by the selectd path window . . . . . . . . . . . . . . . .
C.8 Existing node is replaced by Linkage Node . . . . . . . . . . . . . . . . .
C.9 A schematisation with a Flow - Linkage Node. . . . . . . . . . . . . . . . .
C.10 Example schematisation after the linkage node has been replaced by a connection node. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. 715
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716
717
717
718
718
719
719
720

List of Figures

The filled in Data Edit screen for the example connection node. . . . . . .
Data for friction, the friction tab . . . . . . . . . . . . . . . . . . . . .
Connecting two RR open water nodes through an RR friction node . . . .
Connecting an RR Open Water node to a Channel via an RR Friction node.
Explanation of symbols for calculating the wetted area . . . . . . . . . .

722
723
724
725
726

C.11
C.12
C.13
C.14
C.15

SOBEK, User Manual

5.10
5.10
5.10
5.10
5.11

Standard precipitation events . . . . . . . . . . . . . . . . . . . . . . . .
Special <*.asc> output files . . . . . . . . . . . . . . . . . . . . . . . .
Overview of Cross-section types that may lay on the same branch . . . . .
Overview of Cross-section types that may lay on the same branch . . . . .
Properties of available cross-section types . . . . . . . . . . . . . . . . .
Properties of available cross-section types . . . . . . . . . . . . . . . . .
Cross Section - Y-Z table . . . . . . . . . . . . . . . . . . . . . . . . . .
Examples of Steel Cunette Cross-sections . . . . . . . . . . . . . . . . .
Mathematical manipulations available for a set of data series . . . . . . . .
Data Type=Date/Time (yyyy-mm-dd; hh:mm:ss) . . . . . . . . . . . . . . .
Output (or set-point) of RTC Flow Measure as function of overruled Controller
type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data per structure type for RTC Matlab communication . . . . . . . . . . .
Data per structure type for RTC Matlab communication . . . . . . . . . . .
Data per structure type for RTC Matlab communication . . . . . . . . . . .
Data per structure type for RTC Matlab communication . . . . . . . . . . .
Table: Strings in a Matlab m-file for obtaining values of data series that are
available at data locations defined in the RTC module . . . . . . . . . . . .
Table: Strings in a Matlab m-file for transferring computed setpoints for a particular Flow or RR controller towards the RTC module. . . . . . . . . . . .

5.1
5.2
5.3
5.3
5.4
5.4
5.5
5.6
5.7
5.8
5.9

161
179
373
374
374
375
384
398
435
436

441
443
444
445
446

6.4
6.6
6.10
6.11
6.12
6.12
6.13
6.13
6.14
6.14

Example of switch-on-levels and switch-off-levels at the suction-side and
delivery-side of a pump station . . . . . . . . . . . . . . . . . . . . .
Example of switch-on-levels and switch-off-levels at the suction-side and
delivery-side of an external pump station . . . . . . . . . . . . . . . .
Flow-Pump station covers the options of a River pump with respect to
pump direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crest shape and coefficients for simple weir structure (default values) . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Average storage coefficients depending on soil type and dranaige basis.
Percolation exponent REXP for different soil types . . . . . . . . . . .
Overview of D-NAM output time-series . . . . . . . . . . . . . . . . .
Overview of D-NAM output time-series . . . . . . . . . . . . . . . . .
Default parameters of Delay of Runoff (Rational Method) . . . . . . . .
Default parameters of Delay of Runoff (Rational Method) . . . . . . . .
Default parameters Horton equation . . . . . . . . . . . . . . . . . .
Default parameters Horton equation . . . . . . . . . . . . . . . . . .

Steel cunette cross-section . . . . . . . . . . . . . . . . . . . . . . . . . . 693

Soil types and related Walrus parameter values.

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531
532
580
633
656
678
679
680
681
681
682

. . . . . . . . . . . . . . . 849

SOBEK, User Manual

List of Symbols

List of Symbols
Unit

AF
AR
AS
AT
Az
C
Cd
Cwind
fd

m2
m2
m2
m2
m2
m1/2 /s

g
h
h0
iR
is
O
Q
qlat
R
t
wf
x
y
zb

Cross sectional flow area
Rainfall runoff area
Cross sectional storage area
Cross sectional total area (i.e. AF + AS )
Surface area
Chézy coefficient
Drag coefficient
The wind friction coefficient.
Global design factor for overall extreme high or low load (rainfall)
Acceleration due to gravity (≈ 9.81)
Total water depth
average water depth in a branch
Intensity of rainfall
Intensity of seepage
Wetted perimeter
Discharge
Lateral discharge per unit length
Hydraulic radius
Time
Cross sectional width at water level
Cartesian coordinate along channel
Cartesian coordinate across channel
Bed level, positive up

ρw
ρair
τwind

mm/s
mm/s
m
m3 /s
m2 /s
m
s
m
m
m
m

kg/m3
kg/m3
N/m2

Angle between the wind direction and the local channel direction
Water density
Density of air
Wind shear stress

SOBEK, User Manual

1 Introduction
1.1

About SOBEK
SOBEK is named after the ancient Egyptian crocodile river god. Crocodiles were believed to
have predictive powers, as they would lay their eggs just above the level of the upcoming Nile
flood.

SOBEK is an integrated software package for river, urban or rural management. Seven program modules work together to give a comprehensive overview of waterway systems keeping
you in control. Its integrated framework also means that SOBEK can link river, canal and
sewer systems for a total water management solution. This program is very easy to configure
and quick to learn. It guides you in obtaining correct model descriptions. The graphically oriented interface makes it more user friendly than similar types of software. SOBEK is designed
to interface with your existing software. It can download information from a variety of standard
data formats and GIS systems. SOBEK is based on high performance computer technology.
That means it can handle water networks of any size - big or small. And because of the robustness of the numerical core, your computer will not crash no matter how complicated the
simulation.
Product Info

SOBEK, your answer to changing conditions
Water systems are influenced by many different factors. Heavier than expected, rainfall, high
winds and pollution loads can have an impact on the water system. SOBEK ’s unique integrated format means that you can check the effectiveness of measures taken to keep your
system running at peak efficiency. The manual or automatic operation of pumps, sluice gates,
weirs, storage tanks and other structures can all be incorporated into your model, giving you
a realistic picture of how your system behaves in extreme scenarios. Results are displayed
as maps, graphs, tables and animations helping you to analyse and communicate your ideas.
Product lines
SOBEK has three basic product lines covering any fresh water management situation in River,
Urban and Rural systems alike. Each product line consists of different modules to simulate
particular aspects of the water system. These modules can be operated separately or in
combination. The data transfer between the modules is fully automatic and modules can be
run in sequence or simultaneously to facilitate the physical interaction.

SOBEK, User Manual

All product lines use the same interface components. The interfaces of the urban and rural
product lines are fully integrated. So, when you know how to work with one module, you know
how to work with them all. The user interface is used to prepare your schematisation, control
your input data, check for possible schematisation errors, and helps you to analyse both input
data and all computed parameters.
Open interface
SOBEK has been developed by Deltares in partnership with the National Dutch Institute of Inland Water Management and Wastewater Treatment (RIZA), and the major Dutch consulting
companies. SOBEK is the concrete result of our experience with governments, city authorities, water boards, private consulting companies and research institutes. Because so many
people have helped to develop SOBEK, we’ve made the program as open as possible.
SOBEK is designed to interface with your existing software. It has a transparent ASCII
database and can download information from a variety of standard data formats and GIS
systems, so there’s no need for extra typing. The program is very easy to configure and
quick to learn. It checks extensively for data input and schematisation errors. The GIS oriented interface makes it more user-friendly than most other programs, especially for larger
networks. The computer screen automatically adjusts itself to your needs and expertise so
you can organise your water system information and tasks.
Application areas

The integrated approach makes SOBEK a valuable instrument for flood forecasting, navigation, optimising drainage systems, controlling irrigation systems, reservoir operation, sewer
overflow design, groundwater level control, river morphology regulation, and water quality
control. The integrated approach also means that SOBEK can combine river systems, urban
systems and rural systems for a total water management solution.
Size and complexity doesn’t matter
SOBEK is based on high-performance computer technology. That means it can handle water
networks of any size (big or small) and complexity.
It automatically configures itself to the type of water system you’re modelling. All numerical
computations have self-selecting time steps and are extremely robust.
1.3

Introduction to SOBEK-Rural

SOBEK-Rural gives regional water managers a high-quality tool for modelling irrigation systems, drainage systems, natural streams in lowlands and hilly areas. Applications are typically
related to optimizing agricultural production flood control, irrigation, canal automation, reservoir operation, and water quality control. SOBEK-Rural can also answer questions about increased pollution loads in response to growing urbanisation. SOBEK-Rural offers the support
you need for effective planning, design and operation of new and existing water systems.
The software calculates (easily, accurately and fast) the flow in simple or complex channel
networks, consisting of thousands of branches, cross sections and structures. You can define
all types of boundary conditions, as well as define lateral inflow and outflow using time series
or standard formulae. For more detail, the rainfall run-off process of urban areas and various types of unpaved areas can be modelled, taking into account land use, the unsaturated
zone, groundwater, capillary rise and the interaction with water levels in open channels. For
water quality and environmental problems the Water Quality module offers almost unlimited
possibilities.

SOBEK, User Manual

The graphic display superimposes your network over a (GIS or aerial photo) map of the area
so you can see the canals, reservoirs, weirs, pumping stations, treatment plants, urban and
rural areas at a glance. Animation options show the direction of flow through the network and
by varying the thickness and colours of selected network elements, all input and computed
parameters can be visualised. By clicking on the map you can draw your network and adjust
any detail to suit your needs. The network can also be viewed from the side. Side view allows
you to print the design and watch the water profiles and real-time operation of structures in
detail.

Introduction to SOBEK-Urban

SOBEK-Urban offers a comprehensive modelling tool for simple or extensive urban drainage
systems consisting of sewers and open channels. SOBEK-Urban allows you to design new
urban areas or analyse and improve existing ones. You can use it to find out what measures
will prevent drainage congestion, street flooding and water pollution from sewer overflows.
The return period of street flooding and sewer overflows can be analysed using long time
series of rainfall data or storm events.

SOBEK-Rural incorporates four modules:

The models help you to find out how the performance of the urban drainage system can be
improved by a better operation of the pumps gates and weirs. The impact of treatment plants
and sewer overflows on the receiving water can be analysed by combining everything into one
model. It’s the ideal tool for the design, management and renovation of urban sewer systems.
SOBEK-Urban models the rainfall run-off process for various types of paved and unpaved
areas. It doesn’t matter whether the urban drainage system consists of open channels and
sewer pipes, storage tanks and reservoirs. Even street flow can be modelled with SOBEKUrban.
The application handles all kinds of cross sections, control structures and any network configuration (branched and looped). The size and complexity of the system doesn’t matter either.
The computation is extremely fast, also for large networks (e.g. 25 000 sewer pipes and manholes in one model). On top of that, SOBEK-Urban offers virtually any real-time control option
for pumps, weirs and gates in the urban system.
The graphic display superimposes your network over a (GIS or aerial photo) map of the area
so you can see sewer pipes, manholes, canals weirs and pumping stations at a glance. By
clicking on the map you can draw your network and adjust any detail to suit your needs.
Animation options show the direction of flow and by varying the thickness and colours of
network elements all input and computed parameters can be visualised. The network can
also be viewed from the side and allows you to print the design and watch the filling and
drying process in detail.
The software conforms to strict Dutch guidelines for sewerage calculations.
SOBEK-Urban consists of three modules:

Introduction to SOBEK-River
SOBEK-River is the product line designed for simple and complex river systems and estuaries. It simulates the water flows, the water quality and morphological changes in river systems, estuaries and other types of alluvial channel networks. The networks can be branched
or looped. SOBEK-River is able to work with complex cross-sectional profiles consisting of
various sub-sections.

The Windows-based interface makes it easy to use and have the Windows look and feel that
you’re used to. Direct on-screen display of the river network gives you an overall view of your
system.

SOBEK-River works with one or more of the following modules:

General information
If you have a question about SOBEK for which you cannot find the answer in the manual, you
can contact SOBEK Support at Deltares.
You should have the following information ready:

the version number of SOBEK (visible in the upper-left corner of the window after the
program is started);

the type of hardware you are using;
the operating system you are using;
the exact wording of any message that appeared on your screen (write it down or take a
screenshot);

a description of what happened and what you were doing when the problem occurred;
a description of how you tried to solve the problem;
whether you are able to reproduce the problem by repeating what you did when the problem occurred.

It may also be necessary to send the project data to SOBEK Support. The best way to do
this is to close SOBEK, zip the relevant project folder (*.lit) and send it using an e-mail. If the
project is too large to be included as an attachment in an e-mail, SOBEK Support can provide
the credentials to an ftp account where the data can be uploaded.
Security software
FlexNet
Our software uses license managing software by Flexera Software. If you want to know more
about the security software, see the following link: http://www.flexerasoftware.com/products/flexnetpublisher.htm

SOBEK, User Manual

In case you have additional questions about the security software, Flexera Software support
can be found here: http://support.flexerasoftware.com/
It may be useful to seek out Flexera support if you are using various software packages using
different security systems.
The dongle manufacturers
If you want to know more about new and old dongle manufactures, see the link below. In this
document you can find links to drivers and other tools. It is also a comprehensive manual.
Note: You do not need to install any drivers linked to in this document, the program setup
will install the correct dongle drivers automatically as part of the Deltares License Manager
Installation. These links are provided for troubleshooting purposes only:

http://www.flexerasoftware.com/webdocuments/PDF/faq_FLEXid_dongles.pdf
A direct link to the drivers for the dongles used in our software:

http://www.aladdin.com/support/hasp/enduser.aspx
About Deltares

In 2008, four renowned Dutch organisations decided to pool their knowledge and expertise.
WL | Delft Hydraulics, GeoDelft, TNO’s Subsurface and Groundwater unit and parts of Rijkswaterstaat (the Dutch Directorate-General for Public Works and Water Management) joined
together to set up Deltares, an independent institute for the development, dissemination and
application of knowledge concerning water, soil and subsurface. The result is an organisation
superbly well-equipped to address complex, integrated issues relating to water, soil, subsurface management and spatial planning in deltas, coastal areas and river basins.
Clients
Our national and international clients include government authorities, policy makers and administrators responsible for the short- and long-term governance of bodies of water and related infrastructures. Our clients are also in the private sector: for example, among multilateral agencies, consulting engineers, contractors, and in industry. They all have one thing in
common: the need for solid, practical advice. They come to us because they know that we
understand their concerns and are prepared to approach their questions from independent,
fresh perspectives.
What we can do for you
Deltares brings together a long-standing reputation for excellence in hydrology, hydraulics,
morphology, water quality and ecology. Construction and design matters related to offshore,
coasts, harbours, estuaries, rivers and canals, and industry — also our forte — are approached in a manner tuned to the specific requirements of the client. In addition, we operate at the policy level by delivering decision support and carrying out environmental impact

assessments in the above mentioned working areas.
We have a full range of experimental facilities and computer programs, most of which have
been developed and validated by our experts in residence. On the basis of a sound understanding of the processes involved, all water systems can be simulated by us, numerically,
experimentally, or through a combination of the two. At Deltares, transfer of technology and
know-how is an inherent part of our approach. This is done through a variety of training
courses and seminars, and on the job.

More demanding
Demands of increased production and economic growth are frequently coming in direct — and
public — conflict with environmental concerns. Balancing the needs of one with those of the
other, not only for today, but also for the future, is often expressed in the phrase "sustainable
development".

No simple matter, it makes our clients’ jobs more demanding. In turn, they demand more of us,
not only for construction — and design — related issues, but also for far-branching policy and
management concerns. They expect and get from us optimal performance: a multidisciplinary,
scientifically rigorous approach linked to cost-conscious good business sense.
Notation

In this manual the following conventions in type style are used:
Type style

Buttons ( on the screen or on the keyboard) that perform the indicated
action or give access to a corresponding window. The text can be located on the button itself or next to the button.

Name of a window, shown in the name bar. Also used for subwindows,
indicating a group of buttons and/or data fields.

SOBEK, User Manual

2 Getting started
2.1

Starting SOBEK
To get a good insight of the capabilities of SOBEK please use the tutorials provided with this
SOBEK release.
The following tutorials are available:

section 4.1, Tutorial Hydrodynamics in open water (SOBEK-Rural 1DFLOW module)
section 4.2, Tutorial Hydrodynamics in sewers (SOBEK-Urban 1DFLOW + RR modules)
section 4.3, Tutorial Hydrodynamics - 1D2D floodings (SOBEK-Rural 1DFLOW + Overland
Flow modules)

section 4.4, Tutorial Hydrology in polders (SOBEK-Rural RR module)
The SOBEK-Rural 1DWAQ tutorial can be found in the D-Water Quality User Manual (D-

The following manuals provide information regarding this SOBEK release:

This manual (The Hydrodynamics, Rainfall Runoff and Real Time Control User Manual),
The D-Water Quality User Manual (D-WAQ UM, 2013),
The D-Water Quality Processes Library Description
The D-Water Quality Processes Tables (D-WAQ PLT, 2013).

Free trial options

If you do not have a license file, SOBEK can still be used in Free Trial Copy mode. In this
mode the following schematization restrictions apply:

SOBEK-Rural 1DFLOW (100 node limit)
SOBEK-Rural Overland Flow (2D) module - 2DFLOW (1000 active 2D cell limit)
SOBEK-Rural RR (5 node limit)
SOBEK-Urban 1DFLOW (100 node limit)
SOBEK-Urban RR (100 node limit).

The Water Quality module cannot be used in Free Trial Copy mode.

While in Free Trial Copy mode, the user has the full functionality of the Task blocks: Import,
Meteo, Results in Maps, Results in Charts and Results in Tables at her/his disposal.
The following Tutorials can be followed in Free Trial Copy mode:

4.1, Tutorial Hydrodynamics in open water (SOBEK-Rural 1DFLOW module)
4.2, Tutorial Hydrodynamics in sewers (SOBEK-Urban 1DFLOW + RR modules)
4.3, Tutorial Hydrodynamics - 1D2D floodings (SOBEK-Rural 1DFLOW + Overland Flow
modules)
4.4, Tutorial Hydrology in polders (SOBEK-Rural RR module)

SOBEK, User Manual

3 Installation manual
3.1

Introduction
Deltares has developed a unique, fully integrated modelling framework for a multi-disciplinary
approach and 1D-2D computations for river systems and estuaries, irrigation and drainage
systems and wastewater and storm water systems. It can carry out simulations of flows,
rainfall-runoff, sediment transports, water quality, morphological developments and ecology.
It has been designed for experts and non-experts alike. The framework is composed of several modules, grouped around a mutual interface, while being capable of interacting with one
another.

Operating Systems:

Windows Server 2008
Windows 7
Windows 8.1
Windows 10

System requirements

Administrative privileges are required in order to install and use the software.

Minimum hardware specifications:

1,5 GHz Intel Core processor or equivalent
2 GB of RAM
2 GB free hard disk space
a graphics adapter with 128 MB video memory and screen resolution of 800x600

Preferred hardware specifications:

3 GHz Intel Core processor or equivalent
6 GB of RAM, 64-bit Windows Operating System
20 GB free hard disk space
a graphics adapter with 256MB video memory and a screen resolution of 1024x768

SOBEK is a 32-bit application. On 32-bit Windows operating systems, SOBEK can use a
maximum of 2GB RAM (address space). On 64-bit Windows operating systems, SOBEK can
use a maximum of 4GB RAM.
Regional Settings format in Windows: SOBEK should be installed on machines using a dot
(.) as decimal separator symbol and a comma (,) as digit grouping symbol. For example as
English format.

SOBEK, User Manual

Deltares License Manager
For information about the Deltares License Manager, including installation manual and Frequently Asked Questions, please visit:

https://publicwiki.deltares.nl/display/LMADMIN/Deltares+License+
Management
In order to use SOBEK, the license manager must be installed.
Installing SOBEK

The installation consists of two parts:

This document describes the steps that should be taken to install SOBEK on your personal
computer.

The installation of the Deltares Software License Manager
The installation of the SOBEK software package

The licensing of your software is managed by the Deltares Software License Manager (DS_Flex),
which is based on the FlexNet Publisher licensing system. It provides a user friendly environment in which a range of license constructions can be arranged, varying from single user
licenses to multiple user network licenses.
Note that your license file may not be suitable for all mentioned license constructions.

Log on to the PC. You need to log on as administrator (or a similar account with similar
user privileges).

Start the program setup (named SETUPSOBEK.EXE or similar), from the installation CD
or the location where you downloaded it to.

Now you are lead through the setup procedure by a graphic user interface:
The first dialog is the SOBEK Welcome screen:

Installation manual

Figure 3.1: SOBEK welcome window

Click the Next button to go to the next dialog.

Figure 3.2: Select installation window, Deltares Software License Manager selected

This dialog gives the opportunity to choose to install the license manager or to install SOBEK.

SOBEK, User Manual

In this example the version of the Deltares Software License Manager is newer than the
already installed one. It is highly recommended to use always the most recent version of the
Deltares Software License Manager. If the license manager has not been installed yet, the
installed version will be displayed as ’None’.
Note:
The Deltares Software License Manager must always be installed in order to use SOBEK.
Even when trying out the Free Trial functionality of the software. Failure to install the license manager will result in a SOBEK Startup error. (Run-time error ’53’. File not found:
wlauth40.dll)

Click the Next button to install the Deltares Software License Manager.

The actual installation of the Deltares Software License Manager is described in a separate
paragraph. After it has been installed, the following situation will be displayed:

Figure 3.3: Select installation window, SOBEK selected

Select the SOBEK option if not selected yet.
Click the Next button to install SOBEK.

If there are already one or more SOBEK versions installed, the following dialog will appear:

Installation manual

Figure 3.4: Previous Installation(s) Detected, Install New Version selected

Here you can select the Update option and select a SOBEK version which you want to update.
In that case all the options of that installation will be taken from the selected installation, like
Installation ID, Product Line, Installation Type and the directories where the files are stored.
Ensure that in case of network installations the installation path is accessible and writable.
When you select to update an existing version, after clicking the Next button the Miscellaneous
Options dialog will appear. This dialog will be explained later.
When the Install New Version option is selected, clicking the Next button will activate the
following dialog:

SOBEK, User Manual

Figure 3.5: SOBEK installation, select Product Line

In this dialog the desired SOBEK Product Line can be selected. You can choose between
Rural, Urban and River.
Choosing one of these options will have the following consequences:

Typical Rural, Urban or River default numerical parameters will be selected for new projects.
Numerical parameters can always be changed later in the Settings menu.

A different background image for the SOBEK startup screen will be used.
Note:
Choosing between Rural, Urban and River has no consequences as to which modules you
can use. Which modules you can use is determined entirely by your license file.

Click the Next button to go forward to the Installation ID dialog.

Installation manual

Figure 3.6: Enter SOBEK installation directory

Here you must specify the name of the directory where SOBEK will be installed. This directory
name also will be used as entry in the Windows Start Menu under Delft Hydraulics and as
ID for storing installation data into the computer’s registry. You can install multiple versions of
SOBEK on the same computer, but you have to use a unique folder name for each installation.
The Installation ID is limited to 8 characters and may only contain A–Z, a–z, 0–9 and ’_’
(underscore).

Click the Next button to go to the Drive Selection dialog.

In the dialog below you must select the drive where the SOBEK system will be installed. The
actual directory will be

SOBEK, User Manual

Figure 3.7: Select destination drive(s)

In some case it is desired or even required to separate the programs and the model data. In
that case you can mark the checkbox and then select separate drives for the programs and the
model data. In the example below (using the Installation ID from the earlier example dialog)
the programs will be stored in and the model data in .

Figure 3.8: Select destination drive(s)

Installation manual

Click the Next button to got to the Miscellaneous Options dialog.

Figure 3.9: Miscellaneous Options

At this moment you can specify that you want to create a Desktop Icon to be able to start
SOBEK fast. To distinguish the several SOBEK installations, the Installation ID is added to
the Icon name. If you want to create the Desktop Icon, mark the checkbox ’Desktop Icon
"Sobek..."’.

Click the Next button to go to the last pre-install dialog.

SOBEK, User Manual

Figure 3.10: Check installation properties

The dialog above gives an outline of the options that you selected in the previous steps of the
installation. If you find anything incorrect, you can go back by clicking the Back button and
re-enter the installation information or quit the installation by clicking the Cancel button.
If everything looks OK, you can start the installation by clicking the Install button. The installation will start now and take some time. The duration depends on the type of installation that
you selected and the capacities of your computer. A few minutes is a normal time span.
During the installation the progress can be seen in the window as shown below:

Installation manual

Figure 3.11: Installation progress bar

After the installation process has been finished successfully, the following dialog will pop up:

Figure 3.12: Finish installation window

Click the button to leave the installation program.

SOBEK, User Manual

You will be asked for a reboot to conclude the installation. It is recommended to do so.
General information
If you have a question about SOBEK for which you cannot find the answer in the on-line
manual, you can contact SOBEK Support at Deltares.
You should have the following information ready:

the version number of SOBEK (visible in the upper-left corner of the window after the
program is started);

the type of hardware you are using;
the operating system you are using;
the exact wording of any message that appeared on your screen (write it down or take a

screenshot);
a description of what happened and what you were doing when the problem occurred;
a description of how you tried to solve the problem;
whether you are able to reproduce the problem by repeating what you did when the problem occurred.

It may also be necessary to send the project data to SOBEK Support. The best way to do this
is to close SOBEK, zip the relevant project folder <*.lit> and send it using an e-mail. If the
project is too large to be included as an attachment in an e-mail, SOBEK Support can provide
the credentials to an ftp account where the data can be uploaded.
Installing the SOBEK using the command line

Below, the various options for installing SOBEK using the command line are detailed. These
options are intended for advanced users only. Most of the input validations performed in the
user interface version of the SOBEK setup are not performed when using a command line
installation.
Run silent/unattended.
If present, a desktop icon will be created.
Specifies the drive to install SOBEK on.
Specifies the SOBEK product line. Default: Rural.
Can be Rural, Urban or River.
/SBID=SOBEK215 Installation ID and Directory name. E.g. for SOBEK 2.15, use SOBEK215.
Because SBID is used as directory name it has to be specified according to the rules for any directory name. Additionally, this ID is
limited to a maximum of 8 characters.

/SILENT
/DESKTOP
/DRIVE=D
/SBTYP=Rural

For example:
SetupSOBEK_2.15.001.exe /SILENT /DESKTOP /DRIVE=D /SBTYP=Rural /SBID=SOBEK215

If the switches are specified as above: SOBEK 2.15 Rural will be installed in
and a desktop icon will be created.

Installation manual

Starting SOBEK
The installation procedure creates a menu item for SOBEK on the ‘Programs’ menu under the
Windows Start button. To start SOBEK you must do the following:
Click on the Windows Start button;
Select the ‘Programs’ menu;
Select the ‘Delft Hydraulics’ menu;
Select the SOBEK menu item;
Click on the SOBEK icon.

SOBEK, User Manual

4 Tutorials
Tutorial Hydrodynamics in open water (SOBEK-Rural 1DFLOW module)
General
In this tutorial the basic principles of working with the 1DFLOW module of SOBEK-Rural are
explained step by step and you will be guided to set-up a simple network and to extend this
network with new elements. This tutorial will only show a limited number of the large amount
of options. It will teach the basic principles of working with the 1DFLOW module of SOBEKRural and give you enough experience to continue on your own. Some experience in working
with the Microsoft R Windows R operating system is required.

1 setting up a simple network;
2 editing boundary conditions;
3 editing profiles.

The tutorial contains:

The tutorial does not explain all options in all windows that appear. Once you get the hangand-feel of the modelling system, you may wish to browse through the options not dealt with
in the tutorial.

Getting started

Click the Windows Start button.
Select the ’All Programs’ or ’All Apps’ menu.
Select the ’Delft Hydraulics’ menu.
Select the ’SOBEK’ menu item (SOBEK215).
Click the ’SOBEK’ icon.
In the SOBEK main window: select the menu item ’Options’ - ’SOBEK Options’.
Select the tab ’Background Map’.
Select the file .
Press OK button to save and close SOBEK Options.
Click the New Project button.
Type the name ’T_CHANN’.
The program converts all the characters into upper case. If a project with the same name
already exists, the user has to enter a different name here.
Click the OK button.
You have added a new project with the name ’T_CHANN’. You are now asked: do you want
to work with this project?

Click the Yes button.
Case management
The screen of the so-called case manager appears. This tool automatically keeps track of
cases and the related files. For instance: you might want to save different scenario’s within a
project as cases with different names. This is organized through the case manager.

SOBEK, User Manual

Figure 4.1: The case manager window.

On the screen a number of blocks will appear:
1
2
3
4
5
6
7
8

Import Network;
Settings;
Meteorological Data;
Schematisation;
Simulation;
Results in Maps;
Results in Charts;
Results in Tables.

Each block represents a specific task. A task can be a model, a set of linked models, the
selection of a scenario or strategy, or a (graphical) presentation tool. The arrows between the
blocks represent the relations between the tasks. When an arrow is pointing from block "A" to
block "B", the task of block B can only be executed after the task of block A is finished.
The Case Manager has the following tasks:

1 Administration of cases (which data is related to which cases);
2 Checking whether the model calculations for the cases are performed in the predefined
order;
3 Logging the actions of the Case Manager (including view and print);
4 Providing access to the computational framework through a user interface, so the user
can:

manipulate a case (read, save, delete, etc.);
view and check the status of all tasks;
view the relation between the various tasks.
choose and run predefined tasks (modules);

When the Case Manager screen appears first after you have added a project all task blocks
are grey. To activate the task blocks you have to open the default case of this new project:

Select the menu option ’Case’ - ’Open’.
Select ’Default’ from the list.
Click OK button.
Another method is to double-click one of the grey task blocks and select ’Default’.
Once you have opened the default case the task blocks are no longer grey, but one of the
following colors:

1 yellow: the task can be executed;
2 green: the task has been executed at least once and can be executed again;
3 red: the task cannot be executed until the preceding task has been executed.

When the task is being executed the task block is purple. You can execute a task by doubleclicking on the task block. When you select a yellow or green task block, the color will change
to purple and then change to green again when the task is finished.
Now, we will discuss each task block.
4.1.1

Task block: Import Network

The color of this task block is yellow, which means that this task block is still waiting to be
executed.

Execute the task block ’Import Network’ by double-clicking it. The block then turns purple
and the Import network window will pop up:

Figure 4.2: The import network window.

In this task block the origin of the schematisation must be defined. Schematisations, used in
SOBEK, can be either imported from a database or set-up from scratch. If a schematisation is
already available in the standard exchange format it can easily be imported from the database
to SOBEK. Links with data formats can be custom made on request. For that reason some
radio buttons might be turned grey.

SOBEK, User Manual

Let’s set up a schematisation from scratch.

Select the radio button Start from scratch.
Press OK button.
Notice that you’re back in the Case Manager now and that the task block ’Import Network’ has
turned green.
Task block: Settings

The ’Settings’ task block is used to select the SOBEK modules that you want to use for your
project. Also computational parameters such as calculation time steps, simulation period and
initial water levels can be set in the ’Settings’ task block. Depending on the set of modules
that you purchased, some of them may be disabled (grey), and some may be enabled.

Figure 4.3: The settings window.

SOBEK-Rural 1DFLOW
The SOBEK-Rural 1DFLOW module is a sophisticated module that can be used for the
simulation of one-dimensional flow in irrigation and drainage systems. It is a tool that can
be used to simulate and solve problems in regional water management, such as irrigation
construction, drainage, automation of canal systems, dredging and flood protection. This
module can be used stand-alone or in combination with other modules, for example the
SOBEK-Rural RR module (Rainfall-Runoff).
SOBEK-Urban 1DFLOW
The SOBEK-Urban 1DFLOW module is a sophisticated module for the simulation of onedimensional flow in wastewater and storm water systems. It is a tool that can be used to
simulate and solve problems in urban drainage systems such as determination of urban
drainage capacities including treatment plants, assessment of sewer overflow frequency
and design of detention basins. The SOBEK-Urban 1DFLOW module can also be used
in combination with the SOBEK-Rural 1DFLOW module, the SOBEK-Urban RR (RainfallRunoff) module and other modules. One of the competitive advantages is the combination
with the SOBEK-Rural 1DFLOW module for environmental study on receiving waters.
SOBEK-River 1DFLOW

The SOBEK-River 1DFLOW module is a sophisticated module that can be used for the
simulation of one-dimensional water flow in river systems and estuaries. It is a tool that
can be used to simulate and solve problems in river water management such as flood
protection, flood-risk assessment, real-time forecasting, dam break analysis, navigation
and dredging. This module can be used stand-alone or in combination with other modules.

The RR (Rainfall-Runoff) module is a module that can be used for the simulation of
rainfall-runoff processes. This module is a part of a large family of modules which can
be linked. The list of modules includes (amongst others) SOBEK-Rural 1DFLOW module,
SOBEK-Urban 1DFLOW module and RTC (Real Time Control) module. The RR module is frequently used in combination with the SOBEK-Rural 1DFLOW and SOBEK-Urban
1DFLOW modules. It is then possible to either to perform calculations for both modules
simultaneously or sequentially.

The RTC (Real Time Control) module is a module that can be used for the simulation
of complex real time control of hydraulic systems. It can be applied to rainfall-runoff, hydraulics and water quality computations. In that case the rainfall-runoff and water quality
computations are run simultaneously with the hydrodynamics computations, thus incorporating full interaction between all processes.

The above mentioned modules can also be used in combination with modules for simulating water quality processes (1DWAQ module, 2DWAQ module and/or EM (EMission)
module).
Thus, several combinations of modules are possible. Depending on the problems to be solved
you can set the desired combination. The modules can easily be selected via the task block
’Settings’.

Double-click the ’Settings’ task block. Its colour changes and the settings window appears.
Unselect all the selected modules if any.
Select the ’1DFLOW (Rural)’ module.
Press the Edit... button of ’1DFLOW (Rural)’.

You have to define a number of settings.

Select the tab ’Time settings’.
Set the ’time step in computation’ to 10 minutes (type “10” in the ’min’ edit box and “0” in
the others).

Select the radio button Simulation period defined as below.
Enter the year of the start time of the simulation: “2006”.
Enter also the ’Month’, ’Day’, ’Hour’, ’Min’ and ’Sec’ data of the start time of the simulation:
“1”, “1”, “1”, “0”, “0”.

Enter the end time of the simulation: “2006”, “1”, “1”, “10”, “0”, “0” in the respective edit
boxes.
Select the tab ’Output options’.
Enter the output step: “30” minutes in the respective edit box.
Note that the simulation period data and the time step can also be changed by clicking the
arrows left of the edit boxes.

Select the tab ’Initial data’.
Select the radio button define local values in .
Deltares

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Press the OK button to return to the Settings window.
Finally press the OK button, to save your settings and return to the Case Manager.

You should now see the following screen, which indicates that both the ’Settings’ task and the
’Import Network’ task have been completed and that the Meteorological data task should still
be performed:

Figure 4.4: The case manager after completing the ’settings’ and ’import network’ tasks.

Task block: Meteorological Data

SOBEK Rural simulations require meteorological input data, i.e. precipitation data, evaporation data and wind data. The Meteorological data task block provides precipitation and evaporation data to the RR (Rainfall-Runoff) module and wind data to the 1DFLOW and Overland
Flow (2D) modules. For simplified rainfall-runoff processes precipitation data can optionally
be provided to the 1DFLOW and Overland Flow (2D) modules.
As this tutorial deals with hydrodynamics, the ’Meteorological data’ task block is of minor
importance. We will not include wind effects nor rainfall on the channel.

Double-click the ’Meteorological Data’ task block of the Case Manager.
The following screen will appear:

Figure 4.5: The meteorological data window.

In the dialog that pops up you can see how precipitation, evaporation and wind data are
defined.

Click OK to leave the Meteorological data window.

Now you have finished defining the meteorological data. Notice that this task block has turned
green too!
4.1.4

Task block: Schematisation

A schematisation can easily be set up with the help of the network editor. You will set up a
simple schematisation.

Double-click the ’Schematisation’ task block of the Case Manager.
You can choose to edit a new or an existing model by clicking the upper Edit Model button.

Click Edit model.

When the option Edit Model of the ’Schematisation’ is selected, the network editor starts.
The network editor is called NETTER and is a component of the Delft Hydraulics Decision
Support System (Delft-DSS) tools. NETTER offers the possibility to set-up the schematisation
on top of a background GIS map. NETTER also offers advanced analysis tools to show model
results linked to the schematisation and provide the user with full printing facilities to make high
quality prints.
Within NETTER you can do the following:
1 Interactively and graphically prepare a schematisation;
2 Generate schematisations upon GIS map Layers;
3 Carry out schematisation operations: search for a certain node, show node numbers and
names, show link numbers, etc.;
4 Carry out map operations: zooming in, zooming out, (de)activating map layers, colouring
of map layers, adding title information on the map, etc.;

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5 View results of simulation models for schematisations created in NETTER;
6 Print maps or schematisations.
Generally speaking, NETTER has two edit modes. The first mode is the mode to set-up the
schematisation, e.g. by adding new nodes. The second edit mode is the mode for editing
the attribute data. In this mode you provide the attributes of the schematisation objects. For
example, a pump station must have a pump capacity and switch on/off levels.

In this exercise you will work on a simple schematisation.

Figure 4.6: The schematisation to be created in this tutorial.

In order to focus on a small part of the map, you can use the zoom functionalities.
The View menu contains commands to zoom in, zoom out, centre the window, move the
window and show all schematisation or map layers.
The

button allows you to zoom in on any part of the "active main window".

The
button allows you to zoom out by shrinking the displayed part of the "active main
window".
The
button allows you to centre a schematisation or map GIS object. When choosing
this command and then clicking on an object NETTER, redraws the map centring the chosen
object to the NETTER window.

The
button allows you to shift the view by clicking the mouse anywhere in the NETTER
window and dragging the view to another position.
The
button redraws the view while fitting all schematisation objects into the NETTER
window.
The

button redraws the view while fitting all GIS map layers into the NETTER window.

button restores the view to the previous zoom state.
button restores the view to the state before the last ’Show Previous’ command.

You are now asked to zoom in on the area between the lake and the sea.

Select
button.
Move the mouse pointer to the main window.
Click and hold down the left mouse button, while dragging the pointer across the main

window. The size of the rectangle determines the magnification.

Release the left mouse button.

Now, you will build a simple schematisation. This schematisation consists of a small open
channel with a weir. We will now build this schematisation.

button, Edit Network, to start the edit network mode.

When you have selected the edit network mode all edit network functions and network objects
for the selected module will be available.

from the
section and click the ’General’ edit network functions to
unveil the General functions toolbar and move it to anywhere on your screen by clicking
the upper section of the selected toolbar and dragging it:

Figure 4.7: Click this section of a toolbar to drag it to your screen!

and the ’Node’ edit network functions to place the Node functions toolbar anywhere on your screen.

SOBEK, User Manual

Figure 4.8: Node functions toolbar

and the ’Connection’ edit network functions to place the Connection functions
toolbar anywhere on your screen.

and the ’Reach’ edit network functions to place the Reach functions toolbar
anywhere on your screen.

section and place the node objects toolbar anywhere on your

section to place the reach objects toolbar anywhere on your

If you desire more information explaining the large amount of objects, you can customize the
toolbars by clicking ’View’ - ’Toolbars’ - ’Customize...’. Caption only, Icon only and Icon and
Caption are the available options. ’Icon only’ means that you for the selected toolbar you will
only see the icons. Choosing Icon and Caption will also place a label explaining each symbol.
It is possible to define the identifiers (or ID’s) of the nodes and branches (links) automatically
or manually.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the ’ID’ group box, select the radio button Manual.
In the ’Name’ group box, select the radio button Manual.
Select the tab ’Link’.
Set the ’ID’ and ’Name’ to ’automatic’.
Click the OK button.

Create a schematisation:

Now you can start drawing your application. You will create a schematisation that is similar
to the one below. The schematisation will involve a river section that connects a lake to the
coast:

Figure 4.9: Create a network similar to this one

node, Flow-Boundary.

Select the
button to select the function ’Add node’.
Enter ’Upstream_Boundary’ in both input fields.
Click the OK button.
Locate the mouse at a position where you want to add the Upstream Boundary node and
click the left-mouse button again to actually add the node.

In order to see the identifiers on the map please:

button in the Active Legend or select the menu item ’Options’ - ’Network
Data...’.
Select the tab ’Node’.
Select the radio button Name.
Press the OK button.

Select the
button again.
Enter ’Downstream_Boundary’ in both input fields.
Click the OK button.
Add the Downstream Boundary node as before.

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node, Flow-Connection Node.

button again.
Select the
Enter ’Flow-Connection_Node’ in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Connection node on your screen.

button, Flow-Channel.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the upstream boundary node, and drag to the con-

nection node while keeping the button pressed. Release the left mouse button to add the
connection.
Click with the left mouse button on the connection node and drag to the downstream
boundary node while keeping the button pressed. Release the left mouse button.
Now the two boundary nodes and the connection node are connected.

The model will need a calculation grid. We will switch off the automatic generation of names
before generating this grid because we do not want to generate calculation points with names
for this tutorial.

button in the ’General’ tool bar, Edit settings, to show the edit network
options window.
Select the tab ’Node’.
In the ’Name’ data group, select the radio button No Names.
Press the OK button.
Several options are available to generate a grid.

button to select the function ’Calculation grid all reaches’.
Select the
Select the ’Split Vector’ option.
Select the node type ’Flow - Calculation Point’ from the drop down list.
Then enter ’100’ in the length edit box to set the calculation grid to a 100 m length.
Click the OK button.

Now we can view the defined direction of the links on which we just generated a calculation
grid. The option ’defined direction’ can be used to see the positive defined direction. This
option is enabled by default, and can also be manually enabled by following these steps:

Select ’Options’ - ’Network Data...’.
Select the tab ’Link’.
In the data group ’Show Direction’, select the radio button Defined.
Click the OK button.

To disable titles on links, if enabled:

Select ’Options’ - ’Network Data...’.
Select the tab ’Link’.
Under ’Show Titles’, Select the radio button None.

The vector layer:
To show schematizations with high performance, by default NETTER shows connections between two Flow - nodes in a straight line. However the length between the nodes may differ
from the distance between the nodes in a straight line. The actual length between Flow nodes is stored in the vector layer. You can edit the length in this layer.
button, ’Edit Reach Vectors’, to edit a selected reach vector.
Select the
Select either of the two reaches.

button to show the coordinates.

Select the
button to add a coordinate.
Click with the left mouse button on the reach to actually add a coordinate on your screen

and while keeping the button down drag the new coordinate to the new location.
Add and drag other coordinates of the selected reach.
button to stop adding coordinates.
De-select the
Select the other reach.

Select the
button to add a coordinate again.
Click with the left mouse button on the reach to actually add a coordinate on your screen
and while keeping the button down drag the new coordinate to the new location.
Add and drag other coordinates of the selected reach.

button, ’Edit Reach Vectors’, to stop editing the reach vector.

Add reach objects:

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’Name’, select the radio button Manual.
Press the OK button.

node, Flow - Cross Section node.

Select the
(add node) function.
Enter “Cross-Section1” in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Cross Section node on your screen,
near the ’Downstream_Boundary’ node.
Add the other three Flow-Cross Section nodes as shown in the example Figure 4.9.
node, Flow - Weir node.

Select the
function.
Enter “Weir” in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Weir node on your screen.

A schematisation has been set-up. The next step is to define the attribute data of the schematisation.

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Editing the boundary data:
Now, we will set the attribute data for the boundary nodes. The upstream node will be a
discharge boundary, whereas the downstream node will be a water level boundary.
Select the downstream boundary node (click on the node with the left mouse button).
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select ’water level (h)’.
Enter a constant value of “0”.
Click the OK button.
Select the upstream boundary node.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select ’flow (Q)’.
Enter a constant value of “50”.
Click the OK button.

Editing the cross section data:

For the calculation of the hydraulic conductivity, every reach needs to contain at least one Flow
- Cross Section node. On this node type the bed level and profile can be defined. SOBEK
offers the functionality to make re-usage of profile definitions. On each flow-cross section
node you can either create a new profile definition, or select a profile definition that you had
already created for another node!

Select (by using the left mouse button) the downstream Flow-Cross section node Cross

Section1.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select ’Location’ tab.
Set ’Bed level’ to “-2”.
Set ’Surface level’ to “3”.
Select ’Cross section’ tab.
Select ’Trapezium’ cross section type.
Enter “My profile 1” in ’Cross section: ’ field.
Press the Define dimensions button.
Set ’Slope’ to “1”.
Set ’Bottom width’ to “20”.
Set ’Maximum flow width’ to “26”.
Click the Save dimensions button (You changed the profile definition name, do you want
to add it as a new definition?).

Now we will add friction data. Note that you can choose to submit a global value or a local
value. The global value is used in all reaches for which no local value was defined. The local
values are used for the entire reach on which that cross section is located. If you choose to
submit local values, make sure that the "use local value for this cross section" box is checked
and that the "local values" are shown in the ’Show’ combo box.

Select ’Friction’ tab.
Select ’Use local value(s) for this cross section’.
Select ’Local value(s)’ in the ’Show’ combo box.
Select ’Chézy (C)’ for type friction (Bed).
Enter “35” for constant value.
Select ’Initial Value’ tab.

Select ’Use local initial value for this reach’.
Enter “2” for Initial ’water level’, local value.
Enter “0” for ’Initial flow in positive direction’, local value.
Click the OK button.

We will add the data for the remaining Flow-cross section nodes by using the Multiple Data
Editor.
bed level

profile definition

initial water
level/depth

Cross-Section2
(second
from
downstream)

local,
Chézy 35

Cross-Section3
(third from downstream)

local,
Chézy 35

Cross-Section4
(fourth
from
downstream)

local,
Chézy 35

Select the
button, ’Select by rectangle’.
Select the whole schematisation by dragging a rectangle around it.
Click right mouse button.
Select ’Model data’ - ’Flow Model’.
Select ’Flow - Cross Section’.
Select ’Cross Section’.
Select the column ’Cross Section’.
Click right mouse button.
Select ’Replace’
Select ’My profile 1’ from the list.
Press OK button.
Enter “-1” as Reference Level [m AD] of Cross-Section2.
Enter “4” as Surface Level [m AD] of Cross-Section2.
Enter “-1” as Reference Level [m AD] of Cross-Section3.
Enter “4” as Surface Level [m AD] of Cross-Section3.
Enter “5” as Reference Level [m AD] of Cross-Section4.
Enter “9” as Surface Level [m AD] of Cross-Section4.

All input data of the Multiple Data Editor can be viewed in Graphs.

Select the column ’Surface Level [m AD].
Click right mouse button.
Select ’Graph’.
Close the graph.

The data may also be shown on the map.

Select the column ’Reference Level [m AD].
Click right mouse button again.
Select ’Show on Map’.

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Click ’Cross Section’ of ’Model data’ in the Active Legend.
Click on the

button in the Active Legend or select the menu item ’Options’ - ’Network
Data...’.
Select the tab ’Node’.
Select the radio button Data value.
Press the OK button.
To stop showing Reference levels on the map:

Save the newly added data by choosing ’File’ - ’Save Data’ within the Multiple Data Editor.
Close the Multiple Data Editor by selecting ’File’ - ’Exit’.
button in the Active Legend or select the menu item ’Options’ - ’Network

Select the tab ’Node’.
Select the radio button Name.
Press the OK button.

Now we will add the friction data.

button, ’Select by rectangle’.
Select the
Select the whole schematisation again by dragging a rectangle around it.
Select ’Model data’ - ’Flow Model’ to open the multiple data editor.
Select ’Flow - Cross Section’.
Select ’Friction’.
In the remaining reach: Select Friction Type ’Chézy’.
Enter Value: “35”.

And last but not least we will add the initial values.

Select ’Initial values’.
Press the Yes button (Do you want to save the data?)

To get a good insight which objects you edit in the Multiple Data Editor, SOBEK offers the
functionality to mark these objects.

In the column ’Reach ID’ of the Multiple Data Editor, select the reaches and view on the

map which reach has been marked until the upstream reach has been selected.
Set the ’Discharge m3/s’ for this reach to ’0’.
Select ’Depth’ as the type of the initial level for the upstream reach.
Enter Value: “3”.
Select ’File’ - ’Exit’ of the Multiple Data Editor.
Press the Yes button (Do you want to save the data?).

Editing the weir data:
Select the Flow-Weir node.
Click right mouse button.
Select ’Model data’ - ’Flow Model’.
Enter “20” for the flow-weir’s crest width.
Keep the weir’s crest level at it’s default value of 0.7 m.
Click the OK button.

Saving the network and the model
The schematisation has been setup. Now we will save the map settings, the schematisation,
leave the task block ’Schematisation’ and save the case.

Select ’File’ - ’Save’ - ’Map’.
button in NETTER.
Select
Select the menu item ’File’-’Exit’, to leave NETTER.
Click the OK button in the schematisation window.

Select the menu item ’Case’-’Save As’.
Enter the name “Case_one” to save the case.
Click the OK button.
4.1.6

Task block: Simulation

Now only your schematisation has been saved in NETTER. The whole case must be saved
too!

The next step in the modelling process is to perform the calculations.

Double-click the task block ’Simulation’.

You will see a window appearing, showing a simulation status bar. After the simulation has
successfully finished, this window will disappear again, and the ’Simulation’ task block in the
case manager will turn green.
4.1.7

Task block: Results in Maps

Results in maps gives you a clear impression of the results in time. The program NETTER is
used in this task block. Since NETTER also is used to set up a schematisation, it will be easy
for you, being an experienced user now, to view the results.

Double-click ’Results in Maps’ task block to analyse the results.
Plotting the water levels
.

Select ’Results at nodes’ in the Active Legend.
Select a node.
Click the right mouse button.
Select ’Show Graph’.
Select another node.
Click the right mouse button.
Select ’Show Graph’.

The Graph Server window will show the data plot of the two selected nodes.

Select ’File’ - ’Exit’ to close the Graph Server.
To get a quick overview of the results data, you can make the nodes change colour and size,
according to their data value.

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Choose ’Options’ - ’Network data’ in the menu bar.
Click the ’All Data’ tab.
Activate the ’width’ checkbox for ’Show node data’.
Click the OK button.
Use the

buttons to animate the change of water levels in the model.

Plotting discharges
Notice that water levels are calculated at nodes, whereas discharges are calculated at reach
segments. To plot discharges in a graph you will therefore have to select reach segments:

Select ’Results at reach segments’ in the Active Legend.
Select a reach segment.
Click the right mouse button.
Select ’Show Graph’. Note: if both the ’Show Graph’ option and the

Now analyse your results!

button in the
View Data window do not appear, you’ve probably selected a node, in stead of a reach
segment. Zoom in a little to make sure you select a reach segment.

Animating the flows:

The direction of the flows through the model can be animated on the map:

Make sure that you have selected the item ’Results at reach segments’ from the Active

Legend.
Zoom in on a small part of the water system.
Choose ’Options’ - ’Network data’ in the menu bar.
Click on the tab ’Link’.
Select ’All data’ of the ’Show Direction’ topic.
Select the ’Arrow flow’ box.
Click OK button.
Use the

buttons from the ’View data’ window to animate the flows.

Note: If you do not see arrows moving trough the network, the arrows might be too small
compared to the reach thickness. You can enlarge them by changing the size of the arrows,
after selecting ’Options’ - ’Network options...’ and pressing the button Links....
User Defined Output

To reduce the number of user actions SOBEK offers the User Defined Output options in NETTER.

Select ’Tools’ - ’Output options’.
Select ’Flow module’ from the ’Module’ list.
Select ’water level’ from the ’Output title’ list.
Select ’maximum’ from the ’Function’ list.
Press Add button.
Select ’Flow module’ from the list again.
Select ’water depth’ from the list.
Select ’minimum’ from the list.
Press the OK button.

Now with only one user action the maximum water levels can be viewed on the map.

Select ’water depth, minimum’ in the Active Legend under User Defined Output.
The data is also available by selecting ’Results at nodes’ in the Active Legend, in the ’View
Data’ window, selecting ’Waterdepth [m]’ from the list, and in the menu bar, selecting ’Options’
- ’Data Statistics’ - ’Minimum’.

to watch the animation.

The animation will look like this:

Creating a Side view animation
Select the upstream Flow - Boundary node while holding down the Shift key. Keep
the Shift key pressed. Then click the downstream Flow-Boundary node. Now, you can
release the Shift key.
Click the right mouse button (on the selection) and select ’Side view’.
Press the OK button of the Set up animation.

Figure 4.10: An example of a side view animation.

In the side view the different network objects can easily be distinguished: the image depicts
the surface level (upper line), bed level (bottom line) and structures (thick vertical line). Various
options are available to plot object labels in the side view.
You can also select objects in Side view and view the input and output data of a selected
object.

Select the Flow - Weir structure in Side view.
Click the right mouse button.
Select ’Show Info’.
Press Close viewer.
Click the right mouse button again.
Select ’Show Graph’.
Multiple select ’Discharge [m3 /s]’ - ’Waterlevel up [m AD]’ and ’Waterlevel down [m AD]’.
Press OK button.
Select ’File’ - ’Exit’ of the Graph Server to close the graph.

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You can also load other results to be viewed in Side view.

Select ’View’ - ’User Data’ - ’Load other results..’.
Select ’Results at reach segments’.
Press the OK button.
Select ’Velocity [m/s]’.
Press OK button.
Click

to watch the animation.

Note that you may load any other results available for the selected objects. For example water
quality results, if available.

Do not forget to save the case!

Select the menu item ’Case’-’Save’.

Select ’File’ - ’Exit’ in the side view window [SOBEK Side view].
Select ’File’ - ’Exit’ to close NETTER.

Task block: Results in Tables

The ’Results in tables’ task block provides detailed reports about the simulation.

Double-click ’Results in tables’ task block.

Figure 4.11: The results in tables window.

Select ’Information about the Simulation’;
Select ’View’ and view the results. Important information regarding the water balance of
your computation and the total balance error are given in this file (amongst others);
Select ’File’ - ’Exit’ from the ’View’ window;
Click the Exit button in the ’Results in tables’ window.

Task block: Results in Charts
In the task block ’Results in Charts’ the user can easily depict result data in one graph.

Interpolation over a Connection Node

In order make it possible to easily add branches to a main drainage system, Flow - Connection
Nodes offer user-definable interpolation of cross-section bathymetry data. To demonstrate this
functionality we will add a torrent to the existing schematisation.

Double-click on the ’Results in Charts’ task block.
Select ’Water Balance’.
Click the View button.
Select the parameter ’Volume (1 000 m3)’.
Press the All button of Locations.
Press the All button of Timesteps.
Press the Graph button.
Select ’File’ - ’Exit’ to close the ’Graph Server’ window.
Press the Exit button to close ODS_VIEW.
Press the Exit button to close the task block ’Results in Charts’.

Figure 4.12: The torrent branch.

Double-click the ’Schematisation’ task block of the Case Manager.
Click the Edit model button.
The Tutorial map folder contains a map layer of the torrent.

Select ’Map’ in the Active Legend.
Select ’Torrent’ from the list of layers.
Click on the

button to move the selected layer to the bottom of the list. Now this layer

will be on top.

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Press OK button.
Now we will add the Flow - Connection node with which we connect the torrent to the existing
schematisation. A connection node can only be added to an existing reach by splitting the
reach. We will manually add a h-calculation point and split the reach at its location:

button, Edit Network, to start the edit network mode.

button, Flow - Calculation Point.

button to select the function ’Add node’.
Select the
Enter “Torrent_connection” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the Torrent_connection node on your
screen. The node should be placed in the intersection between the main river and the
torrent.

Remark:
It is possible that a h-calculation point is already present at the intersection between the
main river and the torrent in your tutorial model. In that case, it is also possible to split
the reach at the automatically generated calculation node. However, it should be noted
that this node will not have a name, and have an automatically generated ID. For the
purpose of this tutorial, it is assumed that the ’Torrent_connection’ node was manually
added as described above.
button, Flow - Connection node.
Now select the
Select the button ’Split reach at node’
in the ’Reach’ toolbar.
Use the left-mouse button on the Torrent_connection node to actually add the Flow - Connection node on your screen.

The h-Calculation Point is now changed to a Connection Node, splitting the reach and providing a location to which we can connect the torrent section of this network.

node, Flow-Boundary, by clicking on it.

Select the
button to select the function ’Add node’.
Enter “Upstream_Torrent” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the Upstream Torrent node on your
screen.
Zoom in to get a good view on the Torrent_connection node and the Flow - Boundary
node.

Figure 4.13: The entire network after adding the torrent branch

button, Flow-Channel, by clicking on it.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the upstream torrent node, which you have already
added and drag to the Torrent_connection node while keeping the button down. Release
the left mouse button.

Select the
button, ’Edit Reach Vectors’.
Edit the vector layer to introduce the correct distances.
Select the

button in the ’General’ tool bar, Edit settings, to show the edit network

options window.

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Select the tab ’Node’.
In the ’Name’ data group, select the radio button No Names.
Press the OK button.
Select the
button to select the function ’Calculation grid all reaches’.
Click the OK button.

Select the menu item ’Options’ - ’Network Data...’.
Select the tab ’Link’.
Select the radio button Reach.
Press the OK button.

Now we should enable interpolation along the connection node ’Torrent_connection’. When
we split the reach earlier, the upstream and downstream parts of the main river were also split
in two. For this tutorial we want the main river to be treated as a single river, as it was before
we split the reach.

The reach ID’s are now shown in the schematisation. This is useful when enabling interpolation along a connection node.
Select the Torrent_connection by left-mouse clicking it
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Left-mouse click the tab ’Interpolation Over node’.
Enable the option ’Interpolate Cross-section bathymetry (only) over Node’ by left-mouse
clicking it.
For ’First Reach’, select the upstream reach ’2’.
For ’Second Reach’, select the downstream reach ’3’.
Press the OK button.
Interpolation of Cross-section data over the Torrent_connection is now enabled.

Figure 4.14: The filled in Data Edit screen for the ’Torrent_connection’ node

We will now disable the showing of reach ID’s in NETTER:

Select the menu item ’Options’ - ’Network Data...’.
Select the tab ’Link’.
Under ’Show Titles’, Select the radio button None.
Press the OK button.

SOBEK offers a powerful tool to validate your network.

Select ’Tools’ - ’Validate network by model’ - ’Flow Model’.

The following message appears in the Network Validation window: "A Flow reach must contain
a Profile node".

Select the message in the Network Validation window. Now the torrent reach will be
selected on the map.

Press the Finished button.
Select the

button in the ’General’ tool bar, Edit settings, to show the edit network
options window.
Select the tab ’Node’.
In the ’Name’ data group, select the radio button Manual.
Press the OK button.

Select the
Select the
Deltares

node, Flow - Cross Section node.
(add node) function.

SOBEK, User Manual

Enter “Cross-Section _Torrent1” in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Cross Section node on your screen,
near the Upstream torrent boundary.

Select the
(add node) function.
Enter “Cross-Section_Torrent2” in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Cross Section node on your screen,
near the Torrent_connection node.

button, Select by rectangle, by clicking on it.
Select the
Select the part of the schematisation which includes the new Cross Section nodes by

clicking on the map and dragging while keeping the button down.
Release the left mouse button.
Click right mouse button.
Select ’Model data’ - ’Flow Model’.
Select ’Flow - Cross Section’.
Select ’Cross Section’.
Select the column ’Cross Section’.
Click right mouse button.
Select ’Replace’
Select ’My profile 1’ from the list.
Press OK button.
Enter “15” as Reference Level [m AD] of Cross-Section_Torrent1.
Enter “20” as Surface Level [m AD] of Cross-Section_Torrent1.
Enter “0” as Reference Level [m AD] of Cross-Section_Torrent2.
Enter “2” as Surface Level [m AD] of Cross-Section_Torrent2.

Now we will add the friction data.

Select ’Friction’.
Press Yes button.
Select ’Chézy’.
Enter “35”.

And last but not least we will add the initial values.

Select ’Initial values’.
Press Yes button.
Select ’Depth’ as the type of the initial level for the upstream reach. Note that the current

reach will be selected in NETTER.
Enter “0” for ’Discharge’.
Enter “1.25” for "Value".
Select ’File’ - ’Exit’ of the Multiple Data Editor.
Press Yes to save the data.

Select the ’Upstream Torrent’ node on the map.
Click right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the radio button flow (Q).
Enter the value “10”.
Press the OK button.

Saving the network and the model
The schematisation has been setup. Now we will save the map settings, the schematisation,
leave the task block ’Schematisation’ and save the case.

Select ’File’ - ’Save’ - ’Map’.
button in NETTER.
Select
Select the menu item ’File’-’Exit’, to leave NETTER.
Click the OK button in the schematisation window.

Select the menu item ’Case’-’Save As’
Enter the name “Case_two” to save the case.
Click the OK button.

Now only your schematisation has been saved in NETTER. The whole case must be saved
too!

Please run the simulation and view the results when using interpolation of cross-section bathymetry data over a Connection Node. SideView is a good tool for this.
Epilogue

In this tutorial the most important aspects of working with SOBEK have been discussed.
Extended documentation can also be found in the SOBEK Manual. All PDF files containing
documentation can be found in the "Manuals" directory in the Start menu, next to the SOBEK
start icon. Since you have now gained experience it will not be that difficult to find out the
options and possibilities of SOBEK that not have been discussed here. Good luck!
4.2

Tutorial Hydrodynamics in sewers (SOBEK-Urban 1DFLOW + RR modules)
General

In this tutorial the basic principles of working with the SOBEK-Urban 1DFLOW module and RR
(Rainfall-Runoff) module are explained step by step and you will be guided to set-up a simple
network on your own and to extend this network. This tutorial will only show a limited number
of the large number of options. It will teach the basic principles of working with SOBEK-Urban
and give you enough experience to continue on your own. Some experience in working with
the Microsoft R Windows R operating system is required.
The tutorial contains:

1 setting up a simple schematisation, using the Dutch Standard Exchange Format (SUFHYD);
2 analyzing results;
3 extending the schematisation.
The tutorial does not explain all options in all windows that appear. Once you get the hangand-feel of the modelling system, you may wish to browse through the options not dealt with
in the tutorial.

SOBEK, User Manual

Getting started
Click on the Windows Start button.
Select the ’All Programs’ or ’All Apps’ menu.
Select the ’Delft Hydraulics’ menu.
Select the ’SOBEK’ menu item (SOBEK215).
Click on the ’SOBEK’ icon.
Select the menu item ’Options’ - ’SOBEK Options’.
Select the tab ’Background Map’.
Select the file .
Press OK button to save and close SOBEK Options.
Click the ’New Project’ button.
Type the name “T_SEWER”.
The program converts all the characters into upper case. If a project with the same name
already exists, the user has to enter a different name here.
Click the OK button.
You have added a new project with the name ’T_SEWER’. You are now asked: do you want
to work with this project?

Click the Yes button.
Case management

The screen of the so-called "case manager" appears. This tool automatically keeps track of
cases and the related files. For instance: you might want to save different scenario’s within a
project as cases with different names. This is organized trough the case manager.

Figure 4.15: The case manager screen.

On the screen a number of blocks are visible:
1
2
3
4
5
6
7
8

Import Network;
Settings;
Meteorological Data;
Schematisation;
Simulation;
Results in Maps;
Results in Charts;
Results in Tables.

The Case Manager has the following tasks:

Each block represents a specific task. A task can be a model, or a set of linked models, or the
selection of a scenario or strategy, or a (graphical) presentation tool. The arrows between the
blocks represent the relations between the tasks. When an arrow is pointing from block "A" to
block "B", the task of block B can only be executed after the task of block A is finished.

1 Administration of cases (which data is related to which cases);
2 Checking whether the model calculations for the cases are performed in the predefined
order;
3 Logging the actions of the Case Manager (including view and print);
4 Providing access to the computational framework through a user interface, so the user
can:

manipulate a case (read, save, delete, etc.);
view and check the status of all tasks;
view the relation between the various tasks.
choose and run predefined tasks (modules);

When the Case Manager screen appears first after you have added a project all task blocks
are grey. To activate the task blocks you have to open the default case of this new project:

Select the menu option ’Case’-’Open’.
Select ’Default’ from the list.
Click OK button.

Another method is to click on one of the grey task blocks and select ’Default’.
Once you have opened the default case the task blocks are no longer grey, but one of the
following colors:
1 yellow: the task can be executed;
2 green: the task has been executed at least once and can be executed again;
3 red: the task cannot be executed until the preceding task has been executed.
When the task is being executed the task block is purple. You can execute a task by doubleclicking on the task block. When you select a yellow or green task block, the color will change
to purple and then change to green.
Now, we will discuss each task block.

SOBEK, User Manual

Task block: Import Network
The color of this task block is yellow, so this means that this task block must be executed.

Execute the task block ’Import Network’ by double-clicking.

The Import network window will pop up:

Figure 4.16: The import network window.

In this task block the origin of the schematisation must be defined. Schematisations, used in
SOBEK, can be either imported from database or set-up from scratch.
If a schematisation is already available in the standard exchange format it can easily be imported from the database to SOBEK. Links with data formats can be custom made on request.
For that reason some radio buttons might be turned grey.
Let’s import a SUF-HYD network. SUF-HYD is the Dutch standard exchange file format for
data regarding sewer systems.

Select the radio button Import Suf-HYD network by pointing at the corresponding radio

button with the mouse pointer and by clicking the left mouse button.
Press OK button.
Press OK button.
Select the file .
Press Open button.
Press Yes button. View the messages in the log file that is shown.
Select ’File’ - ’Exit’ to close the file.

Notice that you’re back in the Case Manager now and that the task block ’Import Network’ has
turned green.

Task block: Settings
The ’Settings’ task block is used to select the SOBEK modules that you want to use for your
project. Also computational parameters such as calculation time steps, simulation period and
initial water levels, can be set in the ’Settings’ task block.

Depending on the set of modules that you purchased, some may be disabled (grey), and
some may be enabled.

Figure 4.17: The settings window.

SOBEK-Rural 1DFLOW

The SOBEK-Rural 1DFLOW module is a sophisticated module that can be used for the simulation of one-dimensional flow in irrigation and drainage systems. It is a tool that can be used
to simulate and solve problems in regional water management, such as irrigation construction, drainage, automation of canal systems, dredging and flood protection. This module can
be used stand-alone or in combination with other modules, for example the SOBEK-Rural RR
module (Rainfall-Runoff).

SOBEK, User Manual

SOBEK-Urban 1DFLOW
The SOBEK-Urban 1DFLOW module is a sophisticated module for the simulation of onedimensional flow in waste water and storm water systems. It is a tool that can be used to simulate and solve problems in urban drainage systems such as determination of urban drainage
capacities including treatment plants, assessment of sewer overflow frequency and design
of detention basins. The SOBEK-Urban 1DFLOW module can also be used in combination
with the SOBEK-Rural 1DFLOW module, the SOBEK-Urban RR (Rainfall-Runoff) module and
other modules. One of the competitive advantages is the combination with the SOBEK-Rural
1DFLOW module for environmental study on receiving waters.
SOBEK-River 1DFLOW

The SOBEK-River 1DFLOW module is a sophisticated module that can be used for the simulation of one-dimensional water flow in river systems and estuaries. It is a tool that can be
used to simulate and solve problems in river water management such as flood protection,
flood-risk assessment, real-time forecasting, dam break analysis, navigation and dredging.
This module can be used stand-alone or in combination with other modules.

The RR (Rainfall-Runoff) module is a module that can be used for the simulation of rainfallrunoff processes. This module is a part of a large family of modules which can be linked. The
list of modules includes (amongst others) SOBEK-Rural 1DFLOW module, SOBEK-Urban
1DFLOW module and RTC (Real Time Control) module. The RR module is frequently used
in combination with the SOBEK-Rural 1DFLOW and SOBEK-Urban 1DFLOW modules. It is
then possible to either to perform calculations for both modules simultaneously or sequentially.

The RTC (Real Time Control) module is a module that can be used for the simulation of complex real time control of hydraulic systems. It can be applied to rainfall-runoff, hydraulics and
water quality computations. In that case the rainfall-runoff and water quality computations are
run simultaneously with the hydrodynamics computations, thus incorporating full interaction
between all processes.

The above mentioned modules can also be used in combination with modules for simulating
water quality processes (1DWAQ module, 2DWAQ module and/or EM (EMission) module).
Thus, several combinations of modules are possible. Depending on the problems to be solved
you can set the desired combination. The modules can easily be selected via the task block
’Settings’.

Double-click the ’Settings’ task block.
Unselect all the selected modules if any.
Select the ’1DFLOW (Urban)’ module.
And select the ’RR’ module.
Press the Edit... button of ’1DFLOW (Urban)’.
Enter the time step in computation: “1” minute.
Click on the tab ’Initial data’ with the left mouse button.
Select the radio button initial depth in channels [m].

Enter the value “0”.
Select the ’Output options’ tab.
Enter the output time step in computation: “1” minute.
Select the tab ’Branches’ of ’Output parameters’.
Select ’water level gradient’.
Press the OK button to return to the ’Settings’ window.
Press the Edit... button of ’RR’.
Enter the time step in computation: “1” minute.
Select the radio button Simulation period will be derived from meteorological data.
Select the ’Output options’ tab.
Enter the output time step in computation: “1” minute.
Press the OK button to return to the ’Settings’ window.
Finally press the OK button, to save your settings and return to the Case Manager.

You should now see the screen depicted below, indicating that both the ’Settings’ task and the
’Import Network’ task have been completed and that the Meteorological data task should still
be performed.

Figure 4.18: The case manager after completing the ’settings’ and ’import network’ tasks.

SOBEK, User Manual

Task block: Meteorological Data
SOBEK-Urban simulations require meteorological input data, i.e. precipitation data and evaporation data.
The evaporation data are connected with the time series of the precipitation data. The simulation period is determined by the start- and end date of the precipitation data.

Double-click the ’Meteorological Data’ task block of the Case Manager. The following

screen will appear:

Figure 4.19: The meteorological data window.

Now you can select and edit the precipitation data and evaporation data.

Click the Edit/Select button next to the Precipitation box.
Press the Select event... button.
Select the rainfall event named ’STNBUI07.BUI’.
Click the OK button.
Click OK again to leave the ’edit precipitation data’ window.
Select ’Values according Guideline Sewer systems’ for evaporation.
Click the OK button to leave the Meteorological Data window.

Now you have finished defining the meteorological data. Notice that this task block has turned
green too!

Task block: Schematisation
A schematisation can easily be set up with the help of the network editor.

Double-click the ’Schematisation’ task block of the Case Manager.
Click Edit model.
When the option Edit Model of the ’Schematisation’ is selected, the network editor starts.

Within NETTER you can do the following:

The network editor is called NETTER and is a component of the Delft Hydraulics Decision
Support System (Delft-DSS) tools. NETTER offers the possibility to set-up the schematisation
on top of a background GIS map. NETTER also offers advanced analysis tools to show model
results attached to the schematisation and provide the user with full printing facilities to make
high quality prints.

1 Interactively and graphically prepare a schematisation;
2 Generate schematisations upon GIS map Layers;
3 Carry out schematisation operations: search for a certain node, show node numbers and
names, show link numbers, etc.;
4 Carry out map operations: zooming in, zooming out, (de)activating map layers, colouring
of map layers, adding title information on the map, etc.;
5 View results of simulation models for schematisations created in NETTER;
6 Print maps or schematisations.

Generally speaking, NETTER has two edit modes. The first mode is the mode to set-up the
schematisation, e.g. by adding new nodes. The second edit mode is the mode for editing the
attribute data. In this mode you give attributes to the schematisation objects. For example, a
pump station must have a pump capacity and switch on/off levels.
In this exercise you will work on a simple schematisation.

SOBEK, User Manual

Figure 4.20: The schematisation to be extended in this tutorial.

Several zoom options are available. The View menu contains commands to zoom in, zoom
out, centre the window, move the window and show all schematisation or map layers.
The

button allows you to zoom in on any part of the "active main window".

The
button allows you to zoom out by shrinking the displayed part of the "active main
window".
The
button allows you to center a schematisation or map GIS object. When choosing
this command and then clicking with the left mouse button on an object, NETTER redraws the
map centering the chosen object to the NETTER window.
The
button allows you to shift the view by clicking the mouse anywhere in the NETTER
window and dragging the view to another position.
The

button redraws the view fitting all schematisation objects into the NETTER window.

button redraws the view fitting all GIS map layers into the NETTER window.

button restores the view of the map before the last zoom command was given.

button restores the view of the map before the last ’Show Previous’ command was

In order to focus on a small part of the map you can use the zoom functionalities.
Now you will zoom in to the city.

Select
button.
Move the mouse pointer to the main window.
Click and hold the left mouse button, make a rectangle by dragging the pointer across the
main window. The size of this rectangle determines the magnification.

Release the left mouse button.

Select ’File’ - ’Save’ - ’Map’.

The schematisation, showing a part of the city’s sewer system, including attribute data, was
directly imported from a SUF-HYD file (standard file format used for sewer network data). We
will view and adjust the schematisation later on. Now we will save the schematisation; leave
the task block ’Schematisation’; save the case and go to the task block ’Simulation’.

button, to save the network.

To get a good insight of the schematisation it is possible to show all the input data on the map
or in graphs.

Select the
button, Select by rectangle, by clicking on it.
Select the whole schematisation by clicking on the map and dragging while keeping the

button down. Release the left mouse button.
Click right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select ’Flow - Manhole with Runoff’.
Select ’Sewerage Runoff’.
Select the column ’Open Sloped area [m2]’.
Click the right mouse button.
Select ’Show on Map’.
Select ’Sewerage Runoff’ in the Active Legend.

button in the Active Legend or select the menu item ’Options’ - ’Network

Select the ’All Data’ tab.
Select ’Width’ of ’Show node data’.
Press the OK button.
The following figure appears:

SOBEK, User Manual

Figure 4.21: Open sloped area

In this way all input data available in the Multiple Data Editor can be viewed on the map with
colour and size of the objects according to their data value!
Now we will close the Multiple Data Editor and we will return to the default visualisation mode.

button in the Active Legend.
Click on the
Select the ’All Data’ tab.
Unselect ’Width’ of ’Show node data’.
Press the OK button.
Select ’File’ - ’Exit’ in the Multiple Data Editor.

The identifiers of all objects can be viewed on the map, using the following options:

button in the Active Legend.
Click on the
Select the ’Link’ tab.
Select ’ID’.
Press the OK button.

Now we are going to provide street names to Flow - Pipes:

button, Edit Network, to switch to the edit network mode.

When you have selected the edit network mode all edit network functions and network objects
for the selected module will be available.

button and the ’Node’ edit network functions to place the ’Node functions’
toolbar anywhere on your screen.

Figure 4.22: Node functions toolbar

Select the network editing option ’Properties’.
To search the Flow - Pipe with ID 00-1011-00-1010, press the Ctrl key plus the F key.
Click ’ID’ of ’Link’.
Enter “00-1011-00-1010” (without the quotes).
Press the OK button.
Now click on the selected Flow - Pipe on the map using your mouse.
Enter the Name “Market Street”.
Press the OK button.
Press the Ctrl key plus the F key.
Enter “00-1010-00-1009”.
Click on the selected Flow - Pipe on the map.
Enter the Name “Market Street” again.
Press the OK button.
Now rename the Flow - Pipes ’00-1009-00-1008’, ’00-1008-00-1007’, ’00-1007-00-1006’
and ’00-1006-00-1005’ to ’Market Square’.
And the Flow - Pipes ’00-1005-00-1004’ and ’00-1004-00-1003’ to ’Cherry Street’.

The Names can be viewed on the map, using the following options:

Click on the
button in the Active Legend.
Select the ’Link’ tab.
Select ’Name’.
Press the OK button.

SOBEK, User Manual

Now your model will look as depicted in Figure 4.23.

Figure 4.23: Reach segment names visualised on the map

Another way to get good insight in the schematisation is make a side view. Note that the street
names, used more than once, are displayed only once for the whole street.

Select the network editing option ’No edit action’ to return to using the normal cursor.

Click on the
button in the Active Legend.
Select the ’Node’ tab.
Select ’ID’.
Press the OK button.
To search for the objects with the ID 00-10003 and ID 00-8002, press the Ctrl key plus
the F key
Click ’ID’ of ’Node’.
Enter “00-10003”
Press the OK button.
Search for the object ’00-8002’ too.

Click simultaneously the Shift key on the keyboard and select the Flow - External Weir
with the ID 00-10003 with the left mouse button. Keep the Shift key pressed. Then click
the Flow - External Weir with the ID 00-8002. Now, you can release the Shift key.
Click the right mouse button (on the selection).
Select ’Side view’.

Select ’Options’ - ’Sideview Settings ..’.
Select the tab ’Branch Settings’.
Select the checkbox ’Show branch labels’.
Select the item ’Branch Name’.
Click the OK button.

In the side view the different network objects can easily be distinguished: the image depicts
the surface level (upper line), pipe diameter (middle and bottom line), manholes (vertical lines),
structures (thick vertical line). Various options are available to plot object labels in the side
view.

Figure 4.24: Side view

You can save this side view path:

Select ’File’ - ’Save’.
Enter the file name “Path1.ids”.
Press the Save button.
Select ’File’ - ’Exit’.

SOBEK, User Manual

We will re-use this path later in this tutorial.
Now we will disable the showing of Link and Node ID’s and names:

Click on the
button in the Active Legend.
Select the ’Node’ tab.
Select ’None’.
Select the ’Link’ tab.
Select ’None’.
Press the OK button.

Select ’Tools’ - ’Storage Graph’.
Select ’whole network’.
Select ’use storage in nodes’.
Press the Process button.

The following figure appears.

And last but not least you can make a storage graph.

Figure 4.25: Storage graph

Click the Close button.
Press the Exit button.
To start the simulation you will have to leave NETTER.

Select the menu item ’File’-’Exit’, to leave NETTER.
Click the Yes button to save the name changes.
Click the OK button.
Select the menu item ’Case’-’Save As...’
Enter the name “Case_one” to save the case.
66 of 900

Click the OK button.
4.2.5

Task block: Simulation
The next step in the modelling process is to perform the calculations.

Double-click the task block ’Simulation’.
You will see a bar appearing, showing the progression from the simulation. After the simulation
has finished, the Results in Maps, Results in Charts and Results in Tables task blocks will
become yellow.
Task block: Results in Maps

Results in maps gives you a clear impression of the results in time. The program NETTER is
used in this task block. Since NETTER also is used to set up a schematisation, it will be easy
for you, being an experienced user now, to view the results.

Double-click ’Results in Maps’ task block to analyse the results.

Creating a side view animation
Select ’Tools’ - ’Side view’.
Select the file .
Press the Open button.
Press the OK button of the Set up Animation.

to watch the animation;

If you would like to add other side views in the same SideView application, just select another
path on the map, click the right mouse button, select ’Side view’ and press the OK button.

Select ’File’ - ’Exit’.

User Defined Output
Select ’Tools’ - ’Output options’.
Select ’global SOBEK’ from the list button ’Use definition as defined in: ’.
Press the Add button a few times until the total number of rows is 4.
Fill in the data as shown in Figure 4.26.

SOBEK, User Manual

Figure 4.26: User Defined Output functions

Press the OK button.
In ’User Defined Output’ of the Active Legend, select ’Time water-on-street, maximum’.
The following figure appears:

Figure 4.27: Time water on street, maximum

Plotting water levels
Select the item ’Results at nodes’ in the Active Legend.
Select several nodes by using simultaneously the Ctrl key on the keyboard.
In the ’View Data’ window, select the item ’Waterlevel [m AD].
button on the ’View Data’ window.
Click the
Select ’File’ - ’Exit’ of the ’Graph Server’ window.

SOBEK, User Manual

Plotting discharges
Notice that water levels are calculated at nodes, whereas discharges are calculated at reach
segments. To plot discharges in a graph you will therefore have to select reach segments:

Select ’Results at reach segments’ in the Active Legend.
Select a pipe.
In the ’View Data’ window, select the item ’Discharge [m3 /s]’.
Click the
button on the ’View Data’ window.
Select ’File’ - ’Exit’ of the ’Graph Server’ window.
Animating the flows
The direction of the flows through the model can be animated on the map:
end.
Select ’Options’ - ’Network Data...’.
Select the ’Link’ tab.
Under the ’Show Direction’ topic select ’All Data’.
Click the ’arrow flow’ box.
Select the ’All Data’ tab.
Un-select the ’Width’ of ’Show branch data’, if it is still turned on.
Click the OK button.

Make sure that you still have selected the ’Results at reach segments’ in the Active Leg-

buttons from the ’View data’ window to animate the flows.

Note: If you do not see arrows moving trough the network, the arrows might be too small
compared to the reach thickness. You can enlarge them by changing the size of the arrows,
after selecting ’Options’ - ’Network options...’ and pressing the button Links....

Select ’File’ - ’Exit’ to leave NETTER.
4.2.7

Task block: Results in Tables

The ’Results in tables’ task block provides detailed reports about the simulation and the input
and the output data.

Double-click the ’Results in Tables’ task block.

Figure 4.28: The results in tables window.

Select ’Information about the Simulation’.
Select ’View’ and view the results. Important information regarding the water balance of
your computation and the total balance error are given in this file (amongst others).

Select ’File’ - ’Exit’.
Click the Exit button in the ’Results in tables’ window.
4.2.8

Task block: Results in Charts

In the task block ’Results in Charts’ the user can easily depict result data in one graph.

Double-click on the Results in Charts task block.

Figure 4.29: The results in charts window.

Select ’Results at nodes’.
Click the View button.

SOBEK, User Manual

Figure 4.30: The ODS_VIEW window.

To plot a graph of your model results, select one or more parameters in the left box, select
one or more locations for which you want to view results, and select the time span that you
want to view results for.
Use the Ctrl or Shift keys to select more than one item within a box.

After creating a graph, feel free to explore the wide range of possibilities for display management. Adjust the axes according to your wishes, apply different graph templates, plot one
parameter on the left axis and another parameter on the right one, etc.

Figure 4.31: An example of a graph created in the ’Results in Maps’ task block.

One can also choose to export the data to different file formats such as a spreadsheet. To do
so, click the Export data button in the ’Results in Charts’ window.

Select the parameter ’Waterlevel [m AD]’.
Select the location 00-1004, 00-1005 and 00-1006.
Press the All button of Timesteps.
Press the Export data button.

Feel free to export the data in any of the possible formats.
Now, we will exit the ’Results in Charts’ task block:

Select ’File’ - ’Exit’ to close the ’Graph Server’ window.
Press the Exit button to close ODS_VIEW.
Press the Exit button to close the task block ’Results in Charts’.
Select ’Case’ - ’Save’ to save the case.

SOBEK, User Manual

Case Analysis Tool

Double-click the task block ’Meteorological Data’.
Press the Edit/Select button.
Press the Select event... button.
Select ’STNBUI10.BUI’ from the list.
Press the OK button.
Press the OK button.
Press the OK button.
Double-click the task block ’Schematisation’.
Press the OK button.
Double-click the task block ’Simulation’.

Select ’Case’ - ’Save as...’.
Enter the name “Case_two”.
Press the OK button.
Select ’Case’ - ’Exit’.

In ’Case_one’ we used the rain event ’STNBUI07.BUI’. The total rainfall in this event is 19.8
mm. To show the impact of a much larger rainfall event we will select the rainfall event
’STNBUI10.BUI. The total rainfall in this event is 35.7 mm.

Select ’Projects’ - ’Case Analysis Tool’.
Select ’T_SEWER’ from the list.
Press the OK button.

Select the tab ’Cases’.
Select ’Case_one’ from the cases list.
Select the item ’FLOW: results of nodes’.
Select ’Case_two’ from the cases list.
Select the item ’FLOW: results of nodes’.
Check ’Case_one’ as the Reference Case.

Select the tab ’Locations’.
Press the button

to select all locations.

Select the tab ’Parameters’.
Double click on the item ’Water level [m AD] FLOW: results at nodes’.
Select the tab ’Functions’.
Click ’CaseFunctions’.
Double click ’Difference with base case’.

Press the button

To easily visualize the maximum difference:

Select ’Options’ - ’Data Statistics’ - ’Maximum’.
Select ’Options’ - Network Data..’ - ’All Data’ and enable the option ’Width’ of ’Show node
data’.
The following figure appears. This figure shows the maximum difference between the two
cases.

Figure 4.32: Maximum difference between two cases

Now reset the network visualisation to normal:

Select ’Options’ - Network Data..’ - ’All Data’ and disable the option ’Width’ of ’Show node
data’.

Select ’File’ - ’Exit’.
Select ’Application’ - ’Exit’.
Press the button No.
4.2.10

Series simulation based on independent rainfall events

Simulating a long period of time, for example 50 years, may take a lot of time. If you are only
interested in the sewer overflows, the method of independent rainfall events may be of interest
to you since it reduces the computation time and focuses on the events that matter. SOBEK
offers the functionality to run in series mode (multiple independent rainfall events). It offers
also structure statistics functionality, such as Total Volume [m3], Volume / Year [m3], Net Spill
Time [min].

Select ’Projects’ - ’Open Project’.
Select ’T_SEWER’ from the list.
Press the OK button.
Select ’Case’ - ’Open as new’.
Select ’Case_two’.
Enter the name “T_SEWER.RKS”.
Press the OK button.

Double click the ’Meteorological Data’ task block.

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Press the Edit/Select button.
Press the Select series... button.
Select the item ’T_SEWER.RKS’ from the list.
Press the OK button.
Press the OK button.
Press the OK button.

Double click the ’Schematisation’ task block.
Press the OK button.

Double click the ’Results in Maps’ task block.
Select ’Tools’ - ’Structure Statistics’.
Press the Process button.

The following figure appears:

Double click the ’Simulation’ task block.
Press the Yes button, to select the mean output option.

Figure 4.33: Window Structure Statistics.

Select the cell with ID ’00-8002’.
Click the right mouse button.
Select ’Show Graph’.
Scroll to event number 6.

The following figure appears:

Figure 4.34: Structure Statistics graph for external weir 00-8002, event 6

Press the OK button.
Select ’File’ - ’Exit’.
Press the Exit button.
Select ’File’ - ’Exit’.
Select ’Case’ - ’Save’.

Task block: Schematisation extending your schematisation
Now, you will extend the simple schematisation.

Select ’Case’ - ’Open as new’.
Select ’Case_two’.
Enter the name “Extended case”.
Press the OK button.
Double-click the ’Schematisation’ task block.
Press the Edit model button.

button, Edit Network, to switch to the edit network mode.

When you have selected the edit network mode all edit network functions and network objects
for the selected module will be available.

button from the
section and the ’General’ edit network functions to unveil the ’General functions’ toolbar and move it to anywhere on your screen by
clicking the upper part of the selected toolbar and dragging it:

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button and the ’Connection’ edit network functions to place the ’Connection’
functions toolbar anywhere on your screen.

button and the ’Reach’ edit network functions to place the ’Reach functions’
toolbar anywhere on your screen.

section and the place the objects toolbar anywhere on your screen.

section and place the objects toolbar anywhere on your screen.

If you desire more information explaining the large amount of objects, you can customise the
toolbars by clicking ’View’ - ’Toolbars’ - ’Customize...’. Caption only, Icon only and Icon and
Caption are the available options. ’Icon only’ means that, for the selected toolbar, you will only
see the icons, but no label explaining them. Choosing Icon and Caption will also place a label
explaining each symbol.
It is possible to set the identifiers (or ID’s) of the nodes and branches (links) automatically or
manually.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’ID’, select the radio button Manual.
In the group box ’Name’, select the radio button Manual.
Select the tab ’Link’.
In the group box ’ID’, select the radio button Manual.
In the group box ’Name’, select the radio button Manual.
Click the OK button.

In order to see the identifiers on the map please:

button in the Active Legend or select the menu item ’Options’ - ’Network
Data...’.
Select the tab ’Node’.
Select the radio button ID.
Select the tab ’Link’
Select the radio button ID.
Press the OK button.
Select ’Select ’ - ’Search...’ from the menu bar.
Enter “00-7003”.
Press the OK button.
Zoom in towards node ’00-7003’ .

Now we will start drawing the extended schematisation with node ’00-7006’ and link ’00-700600-7003’. When finished with this chapter, your extended schematisation will look as follows:

Figure 4.35: Extended schematisation Urban.

button, Flow-Manhole, by clicking on it.

button, Flow-Pipe with Runoff, by clicking on it.

Activate the
button, ’Add connect’, by clicking on it.
Enter “00-7006” as the ID of the Node definition.
Enter “00-7006” as the Name of the Node definition.
Enter “00-7006-00-7003” as the ID of the Link definition.
Enter “00-7006-00-7003” as the Name of the Link definition.
Press the OK button.
Next, click the desired location on the screen to actually add the node, keep you mouse
button down while dragging to node ’00-7003’ and release the mouse button.

Now the new Flow-Manhole object is connected to the simple schematisation. The option
’defined direction’ can be used to see the positive defined direction. The defined direction can
be viewed by selecting ’Options’-’Network Data...’-’Link’-’Defined’.
The vector layer

To show schematizations with high performance, NETTER shows by default connections between two Flow - nodes in a straight line. However the length between the nodes may differ
from the distance between the nodes in a straight line. The actual length between Flow nodes is stored in the vector layer. You can edit the length in this layer.
For the purpose of this tutorial, either the default straight line or a user-defined vector layer
will suffice. The vector layer can be edited as follows:
button, ’Edit Reach Vectors’, to edit a selected reach vector.
Select the
Select the reach.

button to show the coordinates.

Select the
button to add a coordinate.
Click with the left mouse button on the reach to actually add a coordinate on your screen

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and while keeping the button down drag the new coordinate to the new location.
Add and drag other coordinates.

button, ’Edit Reach Vectors’ to leave the ’vector layer’ mode.

button, ’Edit network’, to leave the ’edit network’ mode.

The schematisation has been extended. The next step is to define the attribute data of the
schematisation. Therefore you have to switch to the model attribute data mode.

Editing node (manhole) data
Select the Flow-Manhole ’00-7006’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the tab ’Storage’.
Enter “1.6” for the Bottom Level.
Enter a constant value of “4” of the storage area at Storage Reservoir.
Select ’Reservoir’ of the Water on street type.
Select the constant value option.
Enter “3.5” of the Street Level.
Enter “500” for the Storage Area at Water on Street.
Press the OK button.
Editing reach (pipe) data
Select the newly added Flow-Pipe with Runoff object.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the tab ’Cross section’.
Select Cross sections type ’Round’.
Select the Cross section ’Round 800 mm’.
Select the tab ’Location’.
Press the Get Levels button.
Click the OK button.

Select the new Flow - Pipe ’00-7006-00-7003’, the Flow - Pipe ’00-7004-00-7003 and the

Flow - Pipe ’00-7005-00-7002’ by clicking simultaneously the "Shift" key on the keyboard
and the objects one by one with the left mouse button. Now, you can release the "Shift"
key.
Click with your right mouse button.
Select ’Model data’ - ’Rainfall-Runoff Model’.
Select the item Flow - Pipe with Runoff’ in the tree.
Select ’Sewerage Runoff’.
Select the column ’Open Sloped area [m2]’.
From edit menu, select ’Edit Column’ - ’Distribute catchment area’
Enter the value “2000”.
Click the OK button.

button.
Select
Select ’File’ - ’Exit’.
Select ’Tools’ - ’Validate network by model’ - ’Flow Model’.
Press the OK button.
Select ’Tools’ - ’Validate network by model’ - ’Rainfall Runoff Model’.
Press the OK button.

Select
button.
Select the menu item ’File’-’Exit’, to leave NETTER.
Press the OK button.
Select ’Case’ - ’Save’.

Please start the simulation and analyze the results.
Epilogue

Tutorial Hydrodynamics - 1D2D floodings (SOBEK-Rural 1DFLOW + Overland Flow
modules)

In this tutorial the most important aspects of working with SOBEK have been discussed.
Extended documentation can also be found in the SOBEK Manual. All PDF files containing
documentation can be found in the "Manuals" directory in the Start menu, next to the SOBEK
start icon. Since you have now gained experience it will not be that difficult to find out the
options and possibilities of SOBEK that not have been discussed here. Good luck!

The Overland Flow (2D) module of SOBEK-Rural is designed to calculate two-dimensional
flooding scenarios. The module is fully integrated with the 1DFLOW module for accurate
flooding simulation. It is especially designed to simulate dam breaks and dike breaks. The
hydrodynamic simulation engine underneath is based upon the complete Saint Venant Equations. It can simulate steep fronts, wetting and drying processes and sub critical and supercritical flow.
This tutorial will guide you through a certain number of basic steps of both the Overland Flow
(2D) module and the 1DFLOW module. Some experience in working with the Microsoft R
Windows R operating system is required.
Good luck!

Setting up a combined 1DFLOW and Overland Flow (2D) system
Click on the Windows Start button.
Select the ’All Programs’ or ’All Apps’ menu.
Select the ’Delft Hydraulics’ menu.
Select the ’SOBEK’ menu item (SOBEK215).
Click on the ’SOBEK’ icon.
Select the menu item ’Options’ - ’SOBEK Options’.
Select the tab ’Background Map’.
Select the file .
Press OK button to save and close SOBEK Options.
Click the ’New Project’ button.
Type the name “T_1D2D”.
The program converts all the characters into upper case. If a project with the same name
already exists, the user has to enter a different name here.
Click the OK button.
You have added a new project with the name ’T_1D2D’. You are now asked: do you want to
work with this project?

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Click the Yes button.
Select the menu option ’Case’-’Open’.
Select ’Default’ from the list.
Click OK button.
Double click the ’Import Network’ task block.
Select ’Start from scratch’.
Click OK button.

At the ’Settings’ task block, you have to activate the two dimensional ’Overland Flow (2D)’
module. Notice that you cannot choose the Overland Flow (2D) module alone. It will always
work in combination with the ’1DFLOW (Rural)’ module (see figure):

Figure 4.36: Activating the ’1DFLOW (Rural)’ and ’Overland Flow (2D)’ modules

Double click the ’Settings’ task block.
Unselect all the selected modules if any.
Select the ’1DFLOW (Rural)’ module.
And select the ’Overland Flow (2D)’ module.

Edit the 1DFLOW (Rural) settings:
Press the Edit button of the ’1DFLOW (Rural)’ module.
Select the tab ’Time settings’.
Choose ’1 minute’ as the ’Time step in computation’ (Simulation time step).
Select the option ’Simulation period defined as below’ for Simulation period.
Define the ’start of simulation’ as ’2006/01/01; 00:00:00’.
Define the ’end time’ as ’2006/01/01 02:30:00’.
Select the tab ’Simulation settings’.
Choose (of course) the ’unsteady calculation’.
Select the ’Initial data’ tab.
Choose the initial water depth option ’initial depth in channels [m]’.

Set 1m as the initial water depth.
Select the ’Output options’ tab.
Define an output time step of ’00:01:00 (hh:mm:ss)’.
Leave the Settings editor for ’1DFLOW (Rural)’ by clicking the OK button.

Edit the Overland Flow settings:
Click the Edit button of the ’Overland Flow(2D)’ module.
Select the ’Simulation settings’ tab.
Choose for the option ’use as height’, because the values in the 2D grid that we will use
are defined as heights with relation to the reference level.
Select the ’GIS Output options’ tab.
Switch off all output parameters.
Select the ’Incremental output’ tab, keep the values as they are.
Select the ’history output’ tab
Choose Time step output equal to 1 time step.
Click the OK button to leave the settings for the ’Overland Flow(2D)’ module window.
Click the OK button to leave the Settings window.

Double click the ’Meteorological Data’ task block. There is no special data input necessary.
Click the OK button.
The following section describes the steps that must be followed to create a schematisation
and provide data to the model.
4.3.1

Starting with a 2D grid
The 2D grid

A predefined 2D grid will be used in this tutorial. This 2D grid file is named <2D_OF Tutorial.asc>
and is available in the directory.
During this tutorial, we will show you how to add this grid file to your network.
Perform the following actions to open it in your schematisation:

Double click the ’Schematisation’ task block.
Click the Edit model button.
Enter the ’edit network’ mode by clicking the

It is possible to define the identifiers (or ID’s) of the nodes and branches (links) automatically
or manually.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’ID’, select the radio button Manual.
In the group box ’Name’, select the radio button Manual.
Select the tab ’Link’.
In the group box ’ID’, select the radio button Automatic.
In the group box ’Name’, select the radio button Automatic.
Click the OK button.

button from the

section, click on the ’Overland Flow model’ option

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and drag the toolbar that shows its node types to your screen.

Figure 4.37: Drag the toolbar containing Overland Flow node types to your screen

Select ’2D Grid tool bar’and drag it to your screen.

Figure 4.38: Drag the toolbar containing the 2D-grid edit actions to your screen

Select ’2D - Grid’ object from the overland flow node types toolbar (white square).
Now select the ’Import 2D-Grid...’ option from the ’Edit 2D Grid’ toolbar.
Enter “2D-Grid” in both input fields.
Click the OK button.
Browse to the <2D_OF Tutorial.ASC> file ().
Open the <2D_OF Tutorial.ASC> file.

Zoom in on the entire network by clicking the
button (show full network).
Finally, make the grid cells visible by choosing ’Options’ - ’2D-Grid options...’ - ’General’.
In the window that pops up, select ’Solid’ from the combo-box under the topic named
’Lines’.

Click the OK button.
The grid you imported should now look like this:

Figure 4.39: Impression of the model within its GIS environment.

The model shows a grid of the ’Groot Mijdrecht’ polder, located alongside the ’Vinkeveense
Plassen’ in the Netherlands.
With the menu option ’Select’ - ’2D grid cell info’ and selecting 2D grid cells you can investigate
the altitude of the 2D grid at several places. The grid has an altitude of 0 m from above datum,
except for some dikes which are 1 or 2 m higher. The dike which splits the polder in two parts
is a railway dike.

Now change the appearance of the grid under ’Options’, followed by ’2D Grid options...’

’Model data’.
Click on the classify button.
Enter at minimum “0” and maximum “6”.
Click the OK button.
Click the OK button to close the ’Properties 2D - Grid: ’ window.

In the menu bar, select ’Edit’ - ’Model data’.
In the ’Model Data’ window, select ’2D-Grid’ in the list box.
Press the Edit button.
Select the ’Friction’ tab.
Select the option ’Manning (mn)’ for friction type.
Enter a constant value of “0.02”. Keep the ’Friction value (Vertical Obstacle Friction)’ at 0.
Press the OK button.
Close the ’Model Data’ window.

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Adding a simple network

Now we can start the 1D part: the channel flow network. Our schematisation of a ditch will be
modeled as shown in Figure 4.40.

Figure 4.40: The 1D network of the tutorial case.

button, Flow-Connection Node.

Select the
button to select the function ’Add node’.
Enter “North” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the Flow-Connection Node on your
screen, in the Northern part.

Select the
button, ’Add node’, again.
Enter “South” in both input fields.
Click the OK button.

Click on the left-mouse button again to actually add the Flow-Connection Node on your
screen, in the Southern part.

button, Flow-Channel, by clicking on it.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the node "North" and drag to the node "South". Release
the mouse button.
The model will need a calculation grid. Before generating this grid we will switch off the
generation of names.

button to select the function ’Calculation grid all reaches’.
Select the
Select the ’Split Vector’ option.
Select the node type ’Flow - Calculation Point’ from the drop down list.
Then enter “150” in the length edit box to set the calculation grid to a 150 m length.
Click the OK button.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’ID’, select the radio button Automatic.
In the group box ’Name’, select the radio button No Names.
Select the tab ’Link’.
In the group box ’ID’, select the radio button Automatic.
In the group box ’Name’, select the radio button Automatic.
Press the OK button.

Now re-enable the naming of new nodes:

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’Name’, select the radio button Manual.
Press the OK button.

For a useful way of identifying the important nodes in your network, set the following options:

button in the Active Legend or select the menu item ’Options’ - ’Network
Data...’.
In the tab ’Node’, select the radio button Name.
Select the tab ’Link’.
Under ’Show Titles’, Select the radio button None.
SOBEK offers a powerful tool to validate your network.

Select ’Tools’ - ’Validate network by model’ - ’Flow Model’.
The following message appears: "A Flow reach must contain a Profile node".

Select the message in the Network Validation window. Now the torrent reach will be
selected on the map.

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Press the Finished button.

node, Flow - Cross Section node.

Select the
(add node) function.
Enter “Cross-Section_Ditch1” in both input fields.
Click the OK button.
Click on the left-mouse button to actually add the Flow-Cross Section node on your screen.

Now, set the model data for the cross section:

Select the ’Cross-Section_Ditch1’ node.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the ’Location’ tab.
Enter the value “-1” as the bed level. The ditch has a bed level at -1 meters with respect
to reference level.
Enter the value “0” as the surface level. The ditch has a surface level at 0 m with respect
to reference level.
Select the ’Cross section’ tab.
Select the type ’Trapezium’.
First enter the name “profile” at ’Cross section: ’.
Click the Define dimensions button.
Set the slope at ’1’.
Set the bottom width at ’1 m’.
And set the maximum flow width at ’3 m’.
Press the Save dimensions button.
Press the OK button.
Select ’Friction’ tab.
Select ’Use local value(s) for this cross section’.
Select ’Local value(s)’ in the ’Show’ combo box.
Select ’Chézy (C)’ for type friction (Bed).
Enter “50” for constant value.
Click OK to close.

Flooding from the lake

The next step in this tutorial will be to add a 2D boundary node, called ’Lake’ at the edge of
the grid. This node will schematise the lake, which has a constant water level of 0 m reference
level. For the time being we assume that the water from the lake has free access to the polder
(so no dikes or dike breaks in that area).

Figure 4.41: Flooding from the lake.

In 2D - nodes toolbar, select the

button, 2D - Boundary Node.

Select the
button to select the function ’Add node’.
Enter “Lake” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the 2D - Boundary Node on your
screen, at column number 30, and row number 36. The row and column numbers are
shown in the bottom right corner of the NETTER screen, while you move the mouse
pointer over the grid cells. Starting from the right, the first and second number display the
column and row number, and the third number displays the (inverted) height of the grid
cell.
Select the ’Lake’ node.
Click with your right mouse button.
Select ’Model data’ - ’Overland Flow Model’.

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Select the tab ’Boundary condition’.
Select the type ’water level (h)’.
Enter a constant water level of “3.85” m.
Click the OK button.

at the (approximate) locations in the polder, as de-

Next, add some 2D history stations
picted below.

Figure 4.42: Adding history stations.

button, 2D - History Node, by clicking on it.

Select the
button to select the function ’Add node’.
Enter “History-node1” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the 2D - History Node on your screen,

at column number 27, and row number 32.

button to select the function ’Add node’.
Select the
Enter “History-node2” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the 2D - History Node on your screen,
at column number 18, and row number 20.
Add ’History-node3’ at column number 12, and row number 39.
Add ’History-node4’ at column number 5, and row number 39.
Add ’History-node5’ at column number 8, and row number 32.
Add ’History-node6’ at column number 28, and row number 12.
Add ’History-node7’ at column number 21, and row number 11.
Add ’History-node8’ at column number 8, and row number 12.
Add ’History-node9’ at column number 7, and row number 6.

History stations will save the calculated results for each time step for water levels at their
locations. Place these nodes at ’interesting’ places (e.g. behind a breach). These nodes
need no extra data input in Model data.

Select
button.
Select the menu item ’File’-’Exit’, to leave NETTER.
Click the OK button to leave the schematisation window.

Select the menu item ’Case’-’Save As’.
Enter the name “Tutorial 1D2D with 2D boundary node” to save the case.
Click the OK button.
Proceed with the simulation by double clicking the block ’Simulation’ in the case window.
Once the simulation is completed you can proceed to view the results in maps and in
charts.

The visualisation of 1D results are explained in the Tutorial Hydrodynamics in open water
(SOBEK-Rural 1DFLOW module) Together with the visualisation of 1D results, the user can
see the 2D results.

Double-click the ’Results in Maps’ task block. The Netter GIS application will re-appear.
Select ’Depths (incremental)’ from the Active legend.
Click the

buttons and keep them pressed to animate the flooding of the area!

If one or several 1D-elements are selected, it is possible to observe time history graphs at
those locations for the computed parameters (see figure below). The same can be done for
the 2D - History stations.
The figure shows a 2D map water depth output at a certain time step and a graph showing the
water depth variation at selected 2D cells. The latter one (made by choosing ’Select’- ’2D grid
cell info’, selecting a 2D cell and clicking the
button), is based on incremental information
and it shows the moments where the water depth in one cell changes from one class to the
next while flooding proceeds.

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Figure 4.43: Results of the visualization on maps; 1D + 2D map output for a certain time
step and time series graph showing the water level history at two different
2D History stations (which actually are 1D objects)

Figure 4.44: Results of the visualization on maps; 2D map output for a certain time step
and graph showing the water depth variation at selected 2D cells based
on incremental information (this graph shows the moments when the water
depth class changes)

Select ’File’ - ’Exit’ to leave the Results in Maps task block.
Select ’Case’ - ’Save’.
Flooding from the lake with a 2D dam break
Select ’Case’ - ’Open as new’.
Select the case ’Tutorial 1D2D with 2D boundary node’.
Enter the name “Tutorial 1D2D, flooding from 2D breach growth node”.
Press the OK button.
Double-click the ’Schematisation’ task block.
Press the Edit model button.

The idea behind this case is to simulate a breach of the dike, followed by a flooding from the
lake.
Choose ’Edit’ - ’Model data’.
Select ’2D - Grid’ from the list box.
Select the node ’2D-Grid’.
Click the Edit button.
Select the tab ’Grid Cell Bottom Level’.
Enter a value of “8” in the following cells:

31
30
29
28
28
28

34
34
34
34
35
36

Click the OK button.
Enter the file name “2D_DAMBREAK.ASC”.
Save the grid under the directory .

Select ’Options’ - ’2D-Grid options’ - ’Model data...’.
Press the Classify... button.
Enter the maximum legend scale into 8 (minimum = “0”, maximum = “8”).
Click the OK button.
Click the OK button.

The result should look like Figure 4.45.

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Figure 4.45: Cells after changing depth from 0 m to 8 m.

As you can see after saving, the cell beneath the 2D boundary node is raised to 8 m +
reference level. Between the lake and the polder is a sort of a dike now, that will break by a
breach.
Enter the ’edit network’ mode by clicking the
Select the

button, 2D - Breaking Dam Node, by clicking on it.

button to select the function ’Add node’.
Select the
Enter “Breaking_Dam” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the 2D - Breaking Dam Node on your
screen, in the cell with column number 29 and row number 34.

Figure 4.46: Add a 2D dam break node.

Select the node ’Breaking_Dam’.
Click with your right mouse button.
Select ’Model data’ - ’Overland Flow Model’.
Select the tab ’2D Breaking Dam’.
Press the Table... button.
Click on Add Row button.

Enter “1”.
Press OK button.
Fill in the table as shown in Figure 4.47.

Figure 4.47: Growth of the breach depth (m) in time.

Press the OK button to leave the ’Edit table window’.
Press the OK button to leave the data edit window.

This data means that the cell will decrease in height from 8 m to 2 m with respect to the
reference level in 30 minutes time.
Select
button in NETTER.
Select the menu item ’File’-’Exit’, to leave NETTER.
Press the OK button.
Select ’Case’ - ’Save’.

Double click the ’Simulation’ task block.
Double click the ’Results in Maps’ task block.
Select ’Depths (incremental)’ from the Active legend.
Click the

buttons and keep them pressed to animate the flooding of the area.

Select ’File’ - ’Exit’ to leave the Results in Maps task block.
Select ’Case’ - ’Save’.
Select ’Case’ - ’Close’.
4.3.4

Flooding from a 1D channel

In the final case of this tutorial, the flooding will occur from a 1D channel, in stead of from
a 2D boundary like in the first two cases. This type of model is used when enough detailed
information is available about the river/channel network to incorporate a river/channel into the
model (1D2D). So the 1D channel network replaces the 2D - Boundary node.
The flooding itself will occur from one of the surrounding channels of the Dutch ’Amstellandboezem’, and will happen due to a planned inundation of the polder, and not because of a
dike break. This kind of inundations may be necessary to prevent dikes from breaking at
some other point in the channel, causing great economic damage and possibly loss of human
lives. The inundation will occur by opening a structure next to the channel.

Select ’Case’ - ’Open as new’.
Select the case ’Tutorial 1D2D with 2D boundary node’.
Enter the name of the new case “Flooding from 1D”.
Press the OK button.
Double click the ’Settings’ task block.
Press the Edit... button of the 1DFLOW (Rural) module.
Select the ’Initial data’ tab.
Select the option ’define local values in Edit network option.

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Press the OK button.
Press the OK button to leave settings.
Double click the ’Schematisation’ task block.
Press the Edit model button.

Enter the ’edit network’ mode by clicking the

, ’Delete node’.
Select the button
Select the ’Lake’ node.
Press the Yes button.
Zoom out a little bit, until you have a clear view of the channel branch to the North-West
of the polder. Take a look at Figure 4.48 for an example.

Next, you will model a part of a channel branch by defining two 1D boundary nodes and a
channel reach between them, by adding two profile to the channel, and by defining a calculation grid of 150 meters between every h-calculation point. Finally, you will change the course
of the channel according to the map by using the vector layer mode. The result should look
something like Figure 4.48:

Figure 4.48: The tutorial 2D grid extended with a 1D channel.

node, Flow-Boundary.

Select the
button to select the function ’Add node’.
Enter ’Boundary_North’ in both input fields.
Click the OK button.

Click on the left-mouse button again to actually add the ’Boundary_North’ node on your
screen.

Select the
button again.
Enter ’Boundary_South’ in both input fields.
Click the OK button.

SOBEK, User Manual

Click on the left-mouse button again to actually add the ’Boundary_South’ node on your
screen.

button, Flow-Channel, by clicking on it.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the ’Boundary_South’ node and drag to the ’Boundary_North’ node while keeping the button down. Release the left mouse button.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’Name’, select the radio button ’No Names’.
Press the OK button.

button to show the coordinates.

Select the
button, Edit Reach Vectors’, to edit a selected reach vector.
Select the reach.

Select the
button to add a coordinate.
Click with the left mouse button on the reach to actually add a coordinate on your screen
and while keeping the button down drag the new coordinate to the new location.

Add and drag other coordinates of the selected reach.
De-select the

button, Edit Reach Vectors’, to stop editing the reach vector.

Select the
button to select the function ’Calculation grid all reaches’.
Select the ’Split Vector’ option.
Select the node type ’Flow - Calculation Point’ from the drop down list.
Then enter ’150’ in the length edit box to set the calculation grid to a 150 m length.
Click the OK button.

Add reach objects:

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the group box ’Name’, select the radio button ’Manual’.
Press the OK button.

node, Flow - Cross Section node.

Select the
(add node) function.
Enter ’Amstellandboezem1’ in both input fields.
Click the OK button.

Click on the left-mouse button to actually add the Flow-Cross Section node on your screen,
near ’Boundary_South’.

node, Flow - Cross Section node.

Select the
(add node) function.
Enter ’Amstellandboezem2’ in both input fields.
Click the OK button.

Click on the left-mouse button to actually add the Flow-Cross Section node on your screen,
near ’Boundary_North’.

Select the node ’Amstellandboezem1’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the ’Location’ tab.
Enter the value 2 as the bed level.
Enter the value 4.5 as the surface level.
Select the ’Cross section’ tab.
First enter the name ’Amstellandboezem’ at ’Cross section: ’.
Click the Define dimensions button.
Set the slope at ’2’.
Set the bottom width at ’10 m’.
And set the maximum width at ’20 m’.
Press the Save dimensions button.

Select ’Friction’ tab.
Select ’Use local value(s) for this cross section’.
Select ’Local value(s)’ in the ’Show’ combo box.
Select ’Chézy (C)’ for type friction (Bed).
Enter ’50’ for constant value.
Select ’Initial Value’ tab.
Select ’Use local initial value for this reach’.
Select initial ’water level’.
Enter the value 3.85 m.
Enter the value 1 m3/s for the initial flow in positive direction.
Click the OK button to close the data edit window.

Select the node ’Amstellandboezem2’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the ’Location’ tab.
Enter the value 1.9 as the bed level.
Enter the value 4.4 as the surface level.
Select the ’Cross section’ tab.
In the combo box ’Cross section: ’ select: ’Amstellandboezem’.
Select ’Friction’ tab.
Select ’Use local value(s) for this cross section’.
Select ’Local value(s)’ in the ’Show’ combo box.
Select ’Chézy (C)’ for type friction (Bed).
Enter ’50’ for constant value.
Select ’Initial Value’ tab.
Select ’Use local initial value for this reach’.
Select Initial ’water level’.
Enter the value 3.85 m.
Enter the value 1 m3/s for the initial flow in positive direction.
Click the OK button to close the data edit window.

Select the node ’Boundary_South’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
In tab ’Boundary Condition’, select the option ’flow (Q)’.
Select ’Function of time :’.
Press Table....
Press Add Row.
Enter 5.
Press the OK button.

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Fill in the table as shown in Figure 4.49.

Figure 4.49: Filling in the 1D Q-boundary table.

Press the OK button.
Press the OK button.
Select the node "Boundary_North".
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the option ’Q-h relation’.
Press the Table... button.
Press the Add Row.
Enter 4.
Press the OK button.
Fill in the table as shown in the figure below.

Press the OK button.
Press the OK button.

Now we have defined the channel branch from which the flooding will occur. The next step is
to model the ’dummy branch’ containing the structure that is used to control the flooding. We
will use a Connection Node to connect the dummy branch to the Amstellandboezem at the
location shown in Figure 4.50. We will also add a cross-section and a structure, a weir.

Figure 4.50: The dummy branch used to control the flooding of the Amstellandboezem
into the 2D grid.

button, Flow - Calculation Point.

Select the
button to select the function ’Add node’.
Enter ’Dummy_connection’ in both input fields.
Click the OK button.

Click on the left-mouse button again to actually add the Dummy_connection node on your
screen. This node should be placed at the location where we want to connect the dummy

SOBEK, User Manual

branch to the existing branch as shown in Figure 4.50).

Select the
button, Flow-Connection Node, by clicking on it.
Select the button Split reach at node
in the ’Reach’ toolbar.
Use the left-mouse button on the Dummy_connection node to actually add the Flow Connection node on your screen.
By following the above steps, we have split the reach at the location of the Dummy_connection
h-calculation node and replaced it with a connection node. Next, we will set the Cross-section
bathymetry to interpolate along the two reaches:

Select the ’Dummy_connection’ node by left-mouse clicking it
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Left-mouse click the tab ’Interpolation Over node’.
Enable the option ’Interpolate Cross-section bathymetry (only) over Node’ by left-mouse
clicking it.
For ’First Reach’, select the upstream reach ’2’.
For ’Second Reach’, select the downstream reach ’3’.
Press the OK button.
button to select the function ’Add node’.
Select the
Enter ’Connection_node1’ in both input fields.
Click the OK button.

Click on the left-mouse button again to actually add the Flow-Connection Node on your
screen.

button, Flow-Channel.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the node ’Dummy_connection’ and drag to the node
"Connection_node1" while keeping the button down. Release the left mouse button.

node, Flow - Cross Section node.

(add node) function.
Select the
Enter ’Dummy1’ in both input fields.
Click the OK button.

Click on the left-mouse button to actually add the Flow-Cross Section node on your screen.

Select the
(add node) function.
Enter ’Weir1’ in both input fields.
Click the OK button.

Click on the left-mouse button to actually add the Flow-Weir node on your screen.
Select the Cross section node ’Dummy1’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Select the ’Location’ tab.
Enter the value 2 as the bed level.
Enter the value 4 as the surface level.
Select the ’Cross section’ tab.
Select ’Rectangle’ as the cross section type.
First enter the name ’Dummy1’ at ’Cross section: ’.

node, Flow - Weir node.

Click the Define dimensions button.
Enter 10 m as width.
Enter 2 m as height.
Press the Save dimensions button.
Press the OK button.

Select ’Friction’ tab.
Select ’Use local value(s) for this cross section’.
Select ’Local value(s)’ in the ’Show’ combo box.
Select ’Chézy (C)’ for type friction (Bed).
Enter ’50’ for constant value.
Select ’Initial Value’ tab.
Select ’Use local initial value for this reach’.
Select Initial ’water level’.
Enter the value 3.85 m.
Enter the value 0 m3 s−1 for the initial flow in positive direction.
Click the OK button to close.

Select the Weir node ’Weir1’.
Click with your right mouse button.
Select ’Model data’ - ’Flow Model’.
Enter 2 m as width.
Enter 0.7 m as crest level.
Select the ’Controller’ tab.
Select ’Time’ as type of controller.
Enter ’Weir1’ as name.
Press the Table... button.
Press the Add Row.
Enter 2.
Press the OK button.
Fill in the table as shown in the figure below.

Press the OK button.
Press the OK button.

Your new schematisation is now ready.

Select
button in NETTER.
Select the menu item ’File’ - ’Exit’, to leave NETTER.
Press the OK button.

Select ’Case’ - ’Save’.
Double click the ’Simulation’ task block.
Double click the ’Results in Maps’ task block.
Select ’Depths (incremental)’ from the Active legend.

buttons and keep them pressed to animate the flooding of the area.

SOBEK, User Manual

The resulting flooding is shown in the figure below:

Select ’File’ - ’Exit’ to leave the Results in Maps task block.
Select ’Case’ - ’Save’.
Select ’Case’ - ’Close’.
Select ’Case’ - ’Exit’.
Select ’Files’ - ’Exit Sobek’.

Tutorial Hydrology in polders (SOBEK-Rural RR module)
Introduction

In this tutorial the basic principles of working with the Rainfall-Runoff module of SOBEK-Rural
are explained step by step and you will be guided to set-up a simple schematisation. RainfallRunoff offers a wide range of options. This tutorial however only shows a limited number of
them. After finishing the tutorial, one will have enough experience to continue oneself. Some
experience on working with the WINDOWS Operating System is required.
The tutorial contains:
1
2
3
4

setting up a simple model;
computing;
viewing the results;
extending your model.

The tutorial does not explain all options in all windows that will appear. Once you get the
hang-and-feel of the modelling system, you may wish to browse through the options not dealt

with in the tutorial by browsing through the menu system.
Getting started
Click on the Windows Start button.
Select the ’Programs’ menu.
Select the ’All Programs’ or ’All Apps’ menu.
Select the ’Delft Hydraulics’ menu.
Select the ’SOBEK’ menu item (SOBEK215).
Click on the ’SOBEK’ icon.
Select the menu item ’Options’ - ’SOBEK Options’.
Select the tab ’Background Map’.
Select the file ’Tutorial1.map’.
Press OK button to save and close SOBEK Options.
Click the New Project button.
Type the name ’T_RR’.
The program converts all the characters into upper case. If a project with the same name
already exists, the user has to enter a different name here.
Click the OK button.

You have added a new project with the name ’T_RR’. You are now asked: do you want to work
with this project?

Click the Yes button.
4.4.3

Case management

The screen of the so-called "Case Manager" appears. This tool automatically keeps track of
cases and the related files. For instance: you might want to save different scenarios within a
project as cases with different names. This is organized through the Case Manager.

SOBEK, User Manual

The case manager screen.

On the screen a number of blocks are visible:
1
2
3
4
5
6
7
8

Import Network;
Settings;
Meteorological Data;
Schematisation;
Simulation;
Results in Maps;
Results in Charts;
Results in Tables.

Each block represents a specific task. A task can be a model, a set of linked models, the
selection of a scenario or strategy, or a (graphical) presentation tool. The arrows between the
blocks represent the relations between the tasks. When an arrow is pointing from block "A" to
block "B", the task of block B can only be executed after the task of block A is finished.
The Case Manager has the following tasks:
1 Administration of cases (which data is related to which cases);
2 Checking whether the model calculations for the cases are performed in the predefined
order;
3 Logging the actions of the Case Manager (including view and print);
4 Providing access to the computational framework through a user interface, so the user
can:

manipulate a case (read, save, delete, etc.);
view and check the status of all tasks;

view the relation between the various tasks.
choose and run predefined tasks (modules);
When the Case Manager screen appears first after you have added a project all task blocks
are grey. To activate the task blocks you have to open the default case of this new project:

Select the menu option ’Case’ - ’Open’.
Select ’Default’ from the list.
Click the OK button.
Another method is to click on one of the grey task blocks and select ’Default’.

Once you have opened the default case the task blocks are no longer grey, but one of the
following colors:

1 yellow: the task can be executed;
2 green: the task has been executed at least once and can be executed again;
3 red: the task cannot be executed until all preceding tasks have been executed.
When the task is being executed the task block is purple. You can execute a task by doubleclicking the task block. When you select a yellow or green task block, the color will change to
purple and then change to green.
Now, we will discuss each task block.
4.4.4

Task block: Import Network

The color of this task block is yellow, which means that this task block must be executed.

Execute the task block ’Import Network’ by double-clicking.

In this task block the origin of the schematisation can be defined. Schematisations, used in
SOBEK, can be either imported from a database or set-up from scratch.
If a schematisation is already available in the standard exchange format it can easily be imported to SOBEK. Links with data formats can be made upon request. For that reason some
radio buttons might be turned grey.
Let’s set up a schematisation from scratch.

Select the radio button ’Start from scratch’.
Press the OK button.

Notice that you’re back in the Case Manager now and that the task block ’Import Network’ has
turned green.

SOBEK, User Manual

Task block: Settings
The ’Settings’ task block is used to select the SOBEK modules that you want to use for your
project. Also computational parameters such as calculation time steps, simulation period and
initial water levels, can be set in this task block.

Depending on the set of modules that you purchased, some may be disabled (grey), and
some may be enabled.

SOBEK-Rural 1DFLOW

The SOBEK-Rural 1DFLOW module is a sophisticated module that can be used for the simulation of one-dimensional flow in irrigation and drainage systems. It is a tool that can be used
to simulate and solve problems in regional water management, such as irrigation construction, drainage, automation of canal systems, dredging and flood protection. This module can
be used stand-alone or in combination with other modules, for example the SOBEK-Rural RR
module (Rainfall-Runoff).
SOBEK-Urban 1DFLOW
The SOBEK-Urban 1DFLOW module is a sophisticated module for the simulation of onedimensional flow in wastewater and storm water systems. It is a tool that can be used to simulate and solve problems in urban drainage systems such as determination of urban drainage
capacities including treatment plants, assessment of sewer overflow frequency and design
of detention basins. The SOBEK-Urban 1DFLOW module can also be used in combination
with the SOBEK-Rural 1DFLOW module, the SOBEK-Urban RR (Rainfall-Runoff) module and
other modules. One of the competitive advantages is the combination with the SOBEK-Rural
1DFLOW module for environmental study on receiving waters.

SOBEK-River 1DFLOW
The SOBEK-River 1DFLOW module is a sophisticated module that can be used for the simulation of one-dimensional water flow in river systems and estuaries. It is a tool that can be
used to simulate and solve problems in river water management such as flood protection,
flood-risk assessment, real-time forecasting, dam break analysis, navigation and dredging.
This module can be used stand-alone or in combination with other modules.

The RR (Rainfall-Runoff) module is a module that can be used for the simulation of rainfallrunoff processes. This module is a part of a large family of modules which can be linked. The
list of modules includes (amongst others) SOBEK-Rural 1DFLOW module, SOBEK-Urban
1DFLOW module and RTC (Real Time Control) module. The RR module is frequently used
in combination with the SOBEK-Rural 1DFLOW and SOBEK-Urban 1DFLOW modules. It is
then possible to either to perform calculations for both modules simultaneously or sequentially.

The RTC (Real Time Control) module is a module that can be used for the simulation of complex real time control of hydraulic systems. It can be applied to rainfall-runoff, hydraulics and
water quality computations. In that case the rainfall-runoff and water quality computations are
run simultaneously with the hydrodynamics computations, thus incorporating full interaction
between all processes.

The above mentioned modules can also be used in combination with modules for simulating
water quality processes (1DWAQ module, 2DWAQ module and/or EM (EMission) module).
Thus, several combinations of modules are possible. Depending on the problems to be solved
you can set the desired combination. The modules can easily be selected via the task block
’Settings’.
Start editing the settings for the Rainfall-Runoff module:

Double-click the ’Settings’ task block.

The number of active modules depends on which modules you bought. In this tutorial we will
only activate the Rainfall-Runoff module, the other modules are inactive.

Unselect all the selected modules if any.
Select the ’RR’ module.
Press the Edit... button of the ’RR’ module.
You have to define certain settings, such as the

Click the ’Time Settings’ tab.
Set the ’time step in computation’ to 30 minutes (type ’30’ in the ’min’ edit box and ’0’ in
the others).

Select the ’Output Options’ tab (located on the right side of the window).
Define ’output time step’ to 30 minutes.

SOBEK, User Manual

Activate the following output options:
Flows at links
Open water node
Structure node
Unpaved node

Press the OK button.
For this guided tour all remaining default values are fine.
Did you notice that you did not have to define the begin and end of the simulation period?
Rainfall-Runoff will automatically derive this from the rainfall data. The rainfall data are incorporated in the ’Meteorological Data’ task block. The next section deals with this task block.

Press the OK button to exit this task. Your settings are then saved.

You should now see the following screen, indicating that both the ’Settings’ task and the
’Import Network’ task have been completed and that the Meteorological data task should still
be performed.

Task block: Meteorological Data
SOBEK-Rural simulations require meteorological input data, i.e. precipitation data and evaporation data.
The evaporation data are linked to the time series of the precipitation data. The simulation
period is determined by the start- and end dates of the precipitation data.

Double-click the ’Meteorological Data’ task block of the Case Manager.

The following screen will appear:

Now you can select and edit the precipitation data and evaporation data.

Click the Edit/Select button next to the Precipitation box.
Click the Select event button.
Select the rainfall event named .
Press OK button.
Press OK button again to leave the ’edit precipitation data’ window.
Select ’Long term average’ for evaporation.
Click the OK button to leave the Meteorological Data window.

Now you have finished defining the meteorological data. Notice that this task block has turned
green too!

SOBEK, User Manual

Task block: Schematisation
A schematisation can easily be set up with the help of the network editor. You will set up a
simple schematisation.

Double-click the ’Schematisation’ task block of the Case Manager.
You can choose to edit the model by clicking the upper button Edit model.

Click the Edit model button.
When the option Edit model of the ’Schematisation’ is selected, the network editor starts.

Within NETTER you can do the following:

The network editor is called NETTER and is a component of the Delft Hydraulics Decision
Support System (Delft-DSS) tools. NETTER offers the possibility to set-up the schematisation
on top of a background GIS map. NETTER also offers advanced analysis tools to show model
results linked to the schematisation and provide the user with full printing facilities to make high
quality prints.

1 Interactively and graphically prepare a schematisation;
2 Generate schematisations upon GIS map Layers;
3 Carry out schematisation operations: search for a certain node, show node numbers and
names, show link numbers, etc.;
4 Carry out map operations: zooming in, zooming out, (de)activating map layers, colouring
of map layers, adding title information on the map, etc.;
5 View results of simulation models for schematisations created in NETTER;
6 Print maps or schematisations.
Generally speaking, NETTER has two edit modes. The first mode is the mode to set-up the
schematisation. The second edit mode is the mode for editing the attribute data. In this mode
you provide attributes for the schematisation objects. For example, a pump station must have
a pump capacity and switch on/off levels.
In this exercise you will work on a simple schematisation.

In order to focus on a small part of the map you can use the zoom functionalities.
The View menu contains commands for zoom in, zoom out, centre the window, move the
window and show all schematisation or map layers.
The

button allows you to zoom in on any part of the "active main window".

The
button allows you to zoom out by shrinking the displayed part of the "active main
window".
The
button allows you to centre a schematisation or map GIS object. When choosing this
command and then clicking with the left mouse button on an object NETTER redraws the map
centring the chosen object to the NETTER window.
The
button allows you to shift the view by clicking the mouse anywhere in the NETTER
window and dragging the view to another position.
The

button redraws the view fitting all schematisation objects in to the NETTER window.

button redraws the view fitting all GIS map layers in to the NETTER window.

SOBEK, User Manual

button restores the view of the map before the last zoom command was given.

button restores the view of the map before the last ’Show Previous’ command was

Select
button.
Move the mouse pointer to the main window.
Click and hold the left mouse button, make a rectangle by dragging the pointer across the
main window. The size of this rectangle determines the magnification.

Release the left mouse button.

Now, you will build the simple schematisation. This schematisation consists of a small open
channel with a weir.
button, Edit Network, to start the edit network mode.

In the edit network mode, all edit network functions and network objects for the selected
module are available.

and the ’General’ edit network functions to place the General functions toolbar
anywhere on your screen.

and the ’Node’ edit network functions to place the Node functions toolbar anywhere on your screen.

and the ’Connection’ edit network functions to place the Connection functions
toolbar anywhere on your screen.

and the node objects to place the ’Rainfall-Runoff Model’ node objects toolbar
anywhere on your screen.

and the ’Rainfall-Runoff Model’ link objects to place the reach objects toolbar
anywhere on your screen.

It is possible to define the identifiers (or ID’s) of the nodes and branches (links) automatically
or manually.

button in the ’General’ tool bar, Edit settings, to go to the edit network
options.
Select the tab ’Node’.
In the ’ID’ group box, select the radio button Manual.
In the ’Name’ group box, select the radio button Manual.
Select the tab ’Link’.
Set the ’ID’ and ’Name’ to ’automatic’.
Click the OK button.

Now you can start drawing you application.

Select the
button to select the function ’Add node’.
Enter “Unpaved1” in both input fields.
Click the OK button.
Locate the mouse at a position where you want to add the RR-Unpaved node and click
the left-mouse button again to actually add the node.

button, RR-Unpaved node.

button, RR-Open Water node.

Select the
button.
Enter “Open_water1” in both input fields.
Click the OK button.
Click on the left-mouse button again to actually add the node on your screen.

button, RR-link.

button to select the function ’Connect nodes’.
Select the
Click with the left mouse button on the RR-Unpaved node and drag to the RR-Open Water
node while keeping the button down. Release the left mouse button.
In order to see the identifiers on the map please:

button in the Active Legend or select the menu item ’Options’ - ’Network
Data...’.
Select the tab ’Node’.
Select the radio button ’Name’.
Select the tab ’Link’.
Select the radio button ’None’.
Press the OK button.

button, RR-Unpaved node.

button, RR-link.

Select the
button to select the function ’Add connect’.
Enter “Unpaved2” in both input fields.
Click the OK button.
Click with the left mouse button on the map where the second RR-Unpaved should be
placed and drag to the RR-Open Water node while keeping the button down. Release the
left mouse button.

SOBEK, User Manual

Now the two unpaved area nodes are connected to the open water node.
Downstream of an unpaved area node should be an open water or a boundary node. The
option ’defined direction’ can be used to see the downstream site. The defined direction
can be viewed by selecting ’Options’-’Network Data...’-’Links’-’Defined’. Note that the arrow
is pointed towards the open water node. This means that downstream of the unpaved area
node is the open water node and the unpaved area discharges on the open water node.

Select the
button.
Enter “Pump1” in both input fields.
Click the OK button.
Click on the left-mouse button again to add the node on your screen.

Select the
button.
Enter “Boundary1” in both input fields.
Click the OK button.
Click on the left-mouse button again to add the node on your screen.

button, RR - Boundary node.

button, RR - Pump Station.

button, RR-link.

button to select the function ’Connect nodes’.
Select the
Click with the left mouse button on the RR - Open Water node and drag to the RR - Pump
Station while keeping the button down. Release the left mouse button.

Click with the left mouse button on the RR - Pump Station and drag to the RR - Boundary
node while keeping the button down. Release the left mouse button.

The schematisation has been set-up. The next step is to define the attribute data of the
schematisation.
You will provide the following data step-by-step during this tutorial:
Unpaved area node
1
2
3
4
5

6
7
8
9
10
11
12
13
14
15

Area per crop = 280 ha grass;
Groundwater area = 400 ha;
Surface level = 1 m above reference level (constant value);
Soil type = sand_maximum (µ = 0.117 per m);
Thickness groundwater layer = 5 m. This information is only relevant for computing of
salt concentration, thus for computing the volume of this node. The option to compute
salt concentrations can be turned on in the "settings task block", but is turned off in this
tutorial;
Initial groundwater level = equal to target level open water or level at boundary node;
Storage, Maximum on land = 3 mm;
Storage, Initial = 0 mm;
Infiltration capacity = 10 mm/hr;
Computation option for drainage = De Zeeuw - Hellinga
Reaction factor Surface runoff = 100 1/day;
Reaction factor Horizontal inflow = 0.05 1/day;
Reaction factor Drainage 0 - 1 m alpha = 0.4 1/day;
Reaction factor Drainage 1 - 2 m alpha = 0.4 1/day;
Reaction factor Drainage 2 - 3 m alpha = 0.4 1/day;

16 Reaction factor Drainage 3 - infinity alpha = 0.4 1/day;
17 Seepage = 0 mm/day.

Unselect the
button, Edit Network, to close the edit network mode.
Select the ’Unpaved1’ node.
Click right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select the ’Area’ tab.
In the group box ’Area per crop’, select [ha] as the unit.
Click the Table... button.
Enter “280” for the crop ’grass’.
Click the OK button.
Check the check box ’Use different area for groundwater computations:’.
Enter the value “400”.
In the group box ’Surface level’, select ’constant value’.
Enter the value “1”.
Select the ’Soil’ tab.
Select ’sand_maximum (µ = 0.117 per m)’.
Type ’5’ in the input box ’Thickness groundwater layer’.
Type ’1.5’ in the input box ’Maximum allowed groundwater level:’
In the ’Initial groundwater level’ group box, select ’equal to initial target level open water or
level at boundary node’.
Select the ’Storage’ tab.
Type the name ’storage1’ in the combo box.
Click the Define button.
Select [mm] as the unit.
Enter the value of “3” mm for maximum storage on land.
Enter the value of “0” mm for initial storage.
Then press the Save button.
Then press the OK button (You have added a Storage definition. Accept this as a new
definition?).
Select the ’Infiltration’ tab.
Type the name ’infiltration1’ in the text box.
Click on the Define button.
Select [mm/hr] as the unit.
Enter the value for infiltration capacity of “10” mm/hr.
Click the Save button.
Click the OK button (You have added an Infiltration definition. Accept this as a new definition?).
Select the ’Drainage’ tab.
Select the radio button ’De Zeeuw-Hellinga’ in the ’Computation option for drainage’ group
box.
In the ’Definition’ group box, enter the name “drainage1”.
Click the Define button.
Enter “100” as the surface runoff reaction factor [1/d].
Enter “0.05” as the horizontal inflow reaction factor.
In the ’Reaction factor [1/d]’ group box, check the top check box. A table appears in which
the reaction factor data can be entered.
To define the top drainage layer from 0 - 1 m below surface, enter “1” in the input box.
Enter “0.4” as the reaction factor for this layer.
Enter the following data:

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Reaction factor Drainage 1 – 2 m

Reaction factor Drainage 2 – 3 m

Reaction factor Drainage 3 – ∞

Click the Save button.
Click the OK button (You have added a definition. Accept this as a new definition?).
Select the Seepage tab.
Type the name ’seepage1’.
Click on Define button.
Select the option constant for seepage.
Enter the value “0”.
Click the button Save to save this set of parameters.
Click the OK button (You have added a Seepage definition. Accept this as a new definition?).
Click the OK button.

For the second RR - Unpaved node data you will use the Multiple Data Editor.
button, Select by rectangle.
Select the
Select the two RR - Unpaved nodes by clicking on the map and dragging while keeping

the button down. Release the left mouse button.
Alternatively, select both RR - Unpaved nodes by left-clicking the two nodes while keeping
the Ctrl pressed.
Click right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select ’RR-UnPaved’.
Select ’Unpaved area’.
Select the row of ’Unpaved1’.
Select ’Edit’ - ’Copy’.
Select the row of ’Unpaved2’.
Select ’Edit’ - ’Paste’.
Select ’File’ - ’Save Data’.
Select ’File’ - ’Exit’.

Select the open water node.
Click the right mouse button.
Select ’Model data’ - ’Rainfall-Runoff Model’.
Select the ’Surface’ tab.
Enter the ’Bottom level’ at “-1” m above datum.

This information is only relevant for computing of salt concentration, thus for computing the
volume of this node.

Select ’constant area’.
Choose ’ha’ for area unit.
Enter a surface area of “20” hectares.
Select the ’Management’ tab.

Select ’Fixed target level [m above datum]’.
Enter “0” as the fixed target level.
Enter “0” m above datum as the maximum permissible level.
Select the ’Seepage’ tab.
Type the name ’seepage open water1’ in the combo box.
Click the Define button.
Enter a seepage of “0” mm/day.
Then press the Save button.
Click the OK button (You have added a Seepage definition. Accept this as a new definition?).
Click the OK button.
Pump

Select the RR - Pump Station.
Click right mouse button.
Then select ’Model data’ - ’Rainfall Runoff Model’.
Select the ’Options’ tab.
Select ’Normal’ as the ’Pump type’ (Note that the upstream level is checked only).
Select the ’Pump’ tab.
Choose ’m3/min’ as the capacity unit.
In the group box ’Low capacity’, enter the capacity of “30”.
In the group box ’Low capacity’, click the Table (Day) of ’Switch on/off levels’.
Enter the following values:

Date [dd/mm/yyyy]

Time [hh:mm:ss]

Switch on level during the day - target
level [m]

Switch off level during the day - target
level [m]

Click the OK button.

If you changed the default values in this table: Click the OK button. (’Enter the table
name’)

In the group box ’High capacity’, enter the additional capacity of “0”.
Click the OK button to leave the ’Data Edit for Pump’ window.
Boundary node

Select the RR - Boundary node.
Click the right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select the ’Boundary’ tab.
Select the ’Fixed boundary’ option.
Enter “0.5” m above datum as the fixed boundary level.
Click the OK button.

Select ’File’ - ’Save’ - ’Map’.
Select

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Select the menu item ’File’ - ’Exit’, to leave NETTER.
Click the OK button.
Now only your schematisation has been saved in NETTER. The whole case must be saved
as well!

Select the menu item ’Case’ - ’Save As...’.
Enter the name “Case_one”.
Click the OK button.
4.4.8

Task block: Simulation

Double-click the task block ’Simulation’.
Task block: Results in Maps

Results in maps gives you a clear impression of the results in time. The program NETTER is
used in this task block. Since NETTER also is used to set up a schematisation, it will be easy
for you, being an experienced user now, to view the results.

The next step in the modelling process is to perform the calculations.

Double-click ’Results in Maps’ task block to analyse the results.
Select the item ’Open water nodes’ in the Active Legend.
Select the node ’Open_water1’ by clicking it.
Click the

button on the ’View Data’ window.

Now analyse your results!

Suppose, you want to analyse the open water level and the groundwater level. Therefore it
should be useful to depict both variables in one graph.

Do not close the graph server.
Select the item ’Unpaved nodes’ in the Active Legend.
In the ’View data’ window, select the item ’Groundw.Level [m]’.
Select the ’Unpaved1’ node.

button in the ’View data’ window.

As you see a graph appears containing two variables!

Select ’File’ - ’Exit’ to close the Graph Server.
Select ’File’ - ’Exit’ to close NETTER.

Task block: Results in Tables
The ’Results in tables’ task block provides detailed reports about the simulation and the input
and the output data.

Double-click ’Results in tables’ task block.

Select ’Information about the Simulation’.
Select ’View’ and view the results. Important information regarding the water balance of
your computation and the total balance error are given in this file (amongst others).

Select ’File’ - ’Exit’.
Click the Exit button.
4.4.11

Task block: Results in Charts

In the task block ’Results in Charts’ the user can easily depict result data in one graph.

Double-click on the ’Results in Charts’ task block.
Select ’System Balance per timestep’.
Click the View button.
Select the parameters ’Rainfall’ - ’Storage Unpaved’ - ’Storage OpenWater’ - ’Boundaries
out’ by using the Ctrl key.
Select the location ’Total RR system’.
Press the All button of Timesteps.
Press the Graph button.
Select ’File’ - ’Exit’ to close the ’Graph Server’ window.
Press the Exit button to close ODS_VIEW.
Press the Exit button to close the task block ’Results in Charts’.

Select ’Case’ - ’Save’ to save the case.

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Extending your model

In this exercise we are using a combined schematisation of the SOBEK-Rural RR module and
the SOBEK-Rural 1DFLOW module. This part is only possible if you have finished the tutorial
’Hydrodynamics in open water (SOBEK-Rural 1DFLOW module)’ and the end results of the
tutorial are available on the computer you are now using.

The RR model determines the runoff of various types of areas each with their characteristic
influence on the dynamics of the rainfall-runoff process. The different area types can be
described by various types of so-called runoff-nodes. The computed runoff is used as input

for a one-dimensional hydrodynamic flow model. The 1DFLOW model computes the water
levels and flows in a network of open canals.
The exchange of data between the two models can be both sequentially and simultaneously.
In the sequential mode the RR model can be considered as a pre-processor for the 1DFLOW
model while in the simultaneous mode real on-line interaction can be taken into account.
Running 1DFLOW and RR simultaneously

Double-click the ’Settings’ task block.
Press the Edit... button of ’RR’.
Select the tab ’Time Settings’.
Enter the time step in computation: “10” minutes.
Select the tab ’Output options’.
Enter the output time step : “10” minutes in the respective edit box.
Click the OK button.
Turn on the checkbox ’1DFLOW (Rural)’.
In the ’Simulation mode:’ group box, select the mode ’Run RR (Rainfall-Runoff) and
1DFLOW (Rural) module simultaneously’.
Press the Edit... button of ’1DFLOW (Rural)’.
Select the tab ’Time Settings’.
Enter the time step in computation: “10” minutes.
Select the radio button ’simulation period will be derived from meteorological data’.
Select the tab ’Simulation settings’.
Select the radio button ’unsteady calculation’.
Select the tab ’Initial data’.
Select the radio button ’define local values in Edit network.
Select the tab ’Output options’.
Enter the output time step : “10” minutes in the respective edit box.
Press the OK button.
Press the OK button to exit the ’Settings’ task and save your settings.
Double-click the ’Schematisation’ task block.
Click the Edit model button.

button, Edit Network, to start the edit network mode.

To give the whole RR schematisation unique identifiers we will add a preposition for all links.

Select the
button, Select by rectangle.
Select the whole schematisation by clicking on the map and dragging while keeping the
button down. Release the left mouse button.

Select the
button to select the function ’Change IDs’.
Enter the preposition “RR-”.
Uncheck the ’Nodes’ check box.
Check the ’Branches’ check box.
Click the OK button.

Note:
Please note that for larger models than this tutorial, it is recommended to also run the "Clean
Up Utility" on both the models before combining them. This is recommended in order to
prevent the IDs of removed or unused network objects for both models conflicting with each
other, causing further simulations to stop with an error message "Double ID in file ...". Adding
a prefix without cleaning up the models is not enough to guarantee unique IDs. This utility can

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be found in the schematisation menu, button "Cleanup 1D/2D Model Data".
Now we will import the schematisation of the tutorial ’Hydrodynamics in open water’.

Select ’File’ - ’Import Case...’.
Select ’Case_one’ of the project ’T_CHANN’.
Click the OK button.
Click the Yes button (Do you want to combine the new Network with the existing network?).

Now we will connect the two schematisations.

Select the
button to select the function ’Add node’.
Enter “1DFLOW-RR_connection1” in both input fields.
Click the OK button.
Locate the mouse at a position where you want to add the Flow - RR Connection on
Channel node and click the left-mouse button again to actually add the node.

node, Flow - RR Connection on Channel.

button to select the function ’Delete node’.
Select the
Select the ’Boundary1’ node.
Press the Yes button (Are you sure you want to delete RR - Boundary: RR-Boundary1?).

button, RR-link.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the RR - Pump Station and drag to the ’1DFLOWRR_connection1’ node while keeping the button down. Release the left mouse button.
Note:
Take care not to accidentally connect the pump station to a calculation point rather than the
1DFLOW - RR Connection node!

Select the
button to select the function ’Add node’.
Enter “Unpaved3” in both input fields.
Click the OK button.
Locate the mouse at a position where you want to add the RR - Unpaved node and click
the left-mouse button again to add the node.

node, RR - Unpaved.

node, Flow - RR Connection on Channel.

Select the
button to select the function ’Add node’.
Enter “1DFLOW-RR_connection2” in both input fields.
Click the OK button.
Locate the mouse at a position where you want to add the Flow - RR Connection on
Channel node and click the left-mouse button again to actually add the node.

button, RR-link.

Select the
button to select the function ’Connect nodes’.
Click with the left mouse button on the ’Unpaved3’ node and drag to the ’1DFLOW - RR
connection2’ node while keeping the button down. Release the left mouse button.

Select ’Tools’ - ’Validate network by model’ - ’Rainfall Runoff Model’.
Click the OK button (No errors detected).

Select the
button to exit the edit network mode.
Select the ’1DFLOW-RR_connection1’ node.
Click right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select the ’Boundary’ tab.
Select the radio button ’Variable boundary’.
Select the radio button ’Online from Flow Module’.
Click the OK button.
Do the same for the ’1DFLOW-RR_connection2’ node.

Select the
button, Select by rectangle.
Select the whole schematisation by clicking on the map and dragging while keeping the
button down. Release the left mouse button.
Click right mouse button.
Select ’Model data’ - ’Rainfall Runoff Model’.
Select ’RR-UnPaved’.
Select ’Unpaved area’.
Select the row of ’Unpaved1’.
Select ’Edit’ - ’Copy’.
Select the row of ’Unpaved3’.
Select ’Edit’ - ’Paste’.
Select ’File’ - ’Save Data’.
Select ’File’ - ’Exit’.

button.
Select
Select the menu item ’File’ - ’Exit’, to leave NETTER.
Click the OK button.
Select the menu item ’Case’ - ’Save As...’.
Enter the name “Extended”.
Click the OK button.

Double-click the task block ’Simulation’.

Note:
This step cannot be completed while in Free Trial mode. The number of nodes in the schematisation now exceeds the amount of nodes allowed in a free trial computation.

Double-click ’Results in Maps’ task block.
Select the item ’Lateral Flows’ in the Active Legend.
Select the nodes ’1DFLOW-RR_connection1’ and ’1DFLOW-RR_connection2’ by using
the Ctrl key.

button on the ’View Data’ window.

Now analyse your results!
4.4.13

Epilogue
In this tutorial some of the most important aspects of working with SOBEK have been discussed. Since you have gained experience now it’s not that difficult to find out other options
and possibilities of SOBEK which not have been discussed here. Good luck!

SOBEK, User Manual

5 Graphical User Interface

Task block: Import Network
Procedure for importing a Duflow model
Duflow models for the computation of the water levels and flows in water systems can be imported into SOBEK-Rural. As SOBEK makes use of a Geographical Information environment,
its models need coordinates for the nodes. These coordinates are available in models that
are used in Duflow for Windows. For older models the Duflow file must be
filled with coordinates for all connection nodes according to the format of Duflow for Windows
(example):
NOD NOD00000 150912 421819 1
NOD NOD00001 153064 419729 2
NOD NOD00002 141070 417258 6
SCH SCH00000 149755 416906 3
ARE ARE00000 149755 416906 3 1
WEI WEI00000 144207 417130 4 5

Case management

If a model is stored in the binary format of Duflow, the model must be converted to the original
ASCII-format (.net). This can be done as follows:

Open the model (.dms).
Select Calculation from the menu.
Select Convert network.
Select Write Duflow files. Now the .net and .sid files are saved.

The following Duflow functionalities are imported into SOBEK:

Network topography (Duflow for Windows format)
Profiles (Tabulated profiles containing flow and storage widths)
Bed friction (Chézy and Mannings)
Boundary conditions. (Constant and time table of discharges and water levels)
Structures. (Broad crested weir and round, rectangular and elliptical culverts. Flow factor
µ on a culvert is not used in SOBEK. Instead an inlet and outlet loss coefficient must be
selected)

Manually the following functionalities have to be added.

Initial conditions
Simulation time and time step
Pump stations
Inlet and outlet loss coefficient of culverts.

The import procedure is as follows:

Open a project.
Open a new case .
Click the block in the Case Manager, Select the module ’Channel Flow’, directly followed by OK .

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Click the block , directly followed by OK .
Click the block .
Select ’Import Duflow network’.
Press OK.
Open a Duflow scenario file at any location (other files of the scenario must be available
in the same location).

After the reading of the file, the user is asked for a shift, rotation or scaling of the coordinates
that are given in the Duflow geometry file :

Figure 5.1: Rotate or shift coordinates during Duflow import.

Modify the coordinates shift if required and press OK. After converting the data the network

editor is started and the topology of the network is displayed. If the network is not visible
select ’View’ from the menu followed by ’Show full network’.
The location of the nodes can be moved with ’Edit’, ’Vector Layer’. Also curves in branches
can be constructed by adding vector points (See SOBEK manual for details).
If the topology is satisfactory, the network can be saved with ’File’, ’Save’, ’Network’. In
older versions of the network editor the procedure is: ’File’, ’Save as’, ’Network’, change
the name from network.sob into network.ntw, ’Save’ and replace the existing network.ntw;
Select ’File’, ’Exit’.
The log-file is shown.
Close the log-file.
The import procedure is executed successfully and can now be started
to finalize the model manually.

Procedure for importing a Mike11 model
Mike11 models for the computation of the water levels and flows in water systems can be
imported into SOBEK-Rural. To convert the cross sections, these cross sections should first
be exported in Mike11 as raw data. The file name must be identical to the binary cross section,
except the extension should be changed to .txt.
The following Mike11 functionalities are imported into SOBEK:

Graphical User Interface

Network topography
Profiles (first exported as raw data)
Locations of boundary conditions and type of boundary condition (water level or flow). The
values of the boundary conditions are stored in a binary format and can therefore not be
read by the conversion program.
Weirs with a fixed width
Weirs with a varying width over the height

Initial conditions
Simulation time and time step
Calculation grid
Boundary condition values
Friction values

The import procedure is as follows:

Manually the following functionalities have to be added.

Open a project.
Open a new case .
Click the block in the Case Manager, Select the module ’Channel Flow’, directly followed by OK .
Click the block , directly followed by OK .
Click the block .
Select ’Import Mike11 network’.
Press OK.
Open a Mike11 simulation file (*.sim) at any location (other files of the scenario must be
available in the same location).

A shift, rotation of the coordinates can be applied with the window that pops up (scaling is not
possible):

Figure 5.2: Rotate and shift coordinates during MIKE11 import.

SOBEK, User Manual

Modify the coordinates shift if required and press OK.After converting the data the network
editor is started and the topology of the network is displayed. If the network is not visible
select ’View’ from the menu followed by ’Show full network’
The location of the nodes can be moved with ’Edit’, ’Vector Layer’. Also curves in branches
can be constructed by adding vector points (See SOBEK manual for details). If the topology is satisfactory, the network can be saved with ’File’, ’Save’, ’Network’. In older versions
of the network editor the procedure is: ’File’, ’Save as’, ’Network’, change the name from
network.sob into network.ntw, ’Save’ and replace the existing network.ntw;
Select ’File’, ’Exit’.
The log-file is shown.

Close the log-file.
The import procedure is executed successfully and can now be started to
finalize the model manually.
Import SVK19 files

SVK19 is the standard Scandinavian exchange format for sewer systems, comparable with the
SUF-HYD exchange format in the Netherlands. This functionality enables SOBEK to import
Mouse schematisations.
Importing Mouse files is available under the Import menu, Import sewerage networks (SUFHYD), and selecting the file type *.txt.

Figure 5.3: The Import Network window.

Graphical User Interface

Figure 5.4: Select SUF-HYD file.

It is possible to adjust the coordinates from the imported SVK19 file to your own coordinate
system by a north/east shift, to be specified in the next screen:

Figure 5.5: Shift coordinates during SVK19 import.

When the SVK19 file is imported, it is possible also to import a Mouse runoff file (HGF file).

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Figure 5.6: Importing an optional Mouse runoff file.

Figure 5.7: Opening a Mouse runoff file.

The standard Mouse HGF-runoff catchment types have to be converted to the standard
NWRW types of area (combination of surface type and slope).

Graphical User Interface

Figure 5.8: Converting Mouse HGF-runoff catchment types.

Finally, the SVK19 id’s can be prefixed with a district id.

Figure 5.9: Prefixing SVK19 id’s with a district id.

Task block: Settings
Rural

Settings window for Channel Flow
In the Settings window, you can define general settings for the module of your choice. Here
the section on the Channel Flow module is discussed. The Settings window can be accessed
by double-clicking the "Settings" task block in the Case Management Tool window.
One can define:

The simulation period & the computational time step
Initial data, restart data
Output options: which output, and by which time interval
and more

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Figure 5.10: The Settings window with only the Channel Flow module activated.

Clicking the Edit button, next to the Channel Flow check box, will open the "Settings for Channel Flow module" window. The options for that module are discussed in the next chapters.
Simulation options
If the Channel Flow module is combined with other modules, the modeller has various simulation options. For example, one can run the Rainfall-Runoff module and the Channel Flow
module simultaneously or sequentially:

Figure 5.11: Flowdiagram of running the Rainfall-Runoff module and Channel Flow module sequentially.

Graphical User Interface

Figure 5.12: Flowdiagram of running the Rainfall-Runoff module and Channel Flow module simultaneously.

These options can be selected in the "Simulation mode" section:

Figure 5.13: Selecting a simulation mode.

Tab - Time settings
One of the options when opening "Settings" for Channel Flow is "Time settings". These can
be found on the "Time settings" tab. The options are explained below.

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Figure 5.14: The Time settings tab of the Channel flow module.

Simulation time step
Here, you can define the computational time step that SOBEK uses in its hydrodynamic computations. Note that the time scale for hydrodynamic processes lies in the order of minutes
to even seconds. For most computations, a time step of 10m should be sufficient, but for
river systems with a very quick respond-time (such as mountain streams), a smaller time step
might be more appropriate.
Note: SOBEK will automatically reduce its computational time step if necessary. Information
about whether this has happened during your simulation can be found in the results "simulation info at branch segments".
Simulation period
The simulation period can be defined in two ways: it can be derived from the precipitation
event that you have defined (Meteorological data task block), or it can be defined manually.
If the Rainfall-Runoff module is active too, only the first option is available. In the Edit section
of the Rainfall-Runoff module, you can then define a simulation period manually or refer to a
precipitation event.
Tab - Simulation settings
One of the options when opening "Settings" for Channel Flow is "Simulation settings". These
can be found on the "simulation settings" tab. The options are explained below.

Graphical User Interface

Figure 5.15: The Simulation settings tab of the Channel flow module.

Simulation mode

Unsteady calculation means that the computation will be simulating a certain time span,
where it will not branch a steady state, but where all conditions within the model may
change during time (rainfall, boundary conditions etc.)
Steady calculation means that the simulation will only calculate one situation: the equilibrium state. All boundary conditions will be fixed values (non-variable in time) and the
model will calculate the situation where an equilibrium is branched.
Restart data
A restart file contains all information of the state of a simulation during its last time step. This
file can optionally be used to define the initial values for a new simulation.
The option "write restart file" allows you to create a restart file from the last time step of the
simulation that you are about to run. You can give this file a name. If you want to use it later
on for the initialisation of another simulation, select it on the "Initial data tab".
Note: Restart files are no longer usable if a network has changed since the restart file was
written. Additionally, it is recommended to create a new restart file when updating a SOBEK
model to a new SOBEK version.
Extended options

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Generate output for water quality module. This option is activated only when the Water

Quality module is active. However, if you run the Channel Flow stand alone, and you consider to run the WQ module in the future, it is wise to activate this option.If not, you would
have to re-calculate the flow computations first to make future water quality computations
with this case.
Maximum Lowering of Cross-section Bed Level at Culvert. If the bed level of a (interpolated) cross-section in front of a culvert is lying more than the value defined for "Maximum Lowering of Cross-section Bed Level at Culvert" above the ground-layer level (=
invert level + ground-layer thickness), the bed level of the cross-section is lowered to the
ground-layer level. For all (interpolated) cross-sections in front of a culvert, having bed levels lying more than the value defined for "Maximum Lowering of Cross-section Bed Level
at Culvert" above the ground-layer level, no changes are made only a warning is given in
the SOBEK.Log message file. It is advised to avoid that the bed level of a cross-section
in front of a Culvert is above the ground-layer level, since such situation can result in very
small computational time-steps (e.g. long required wall-clock times) or even in a termination of the simulation (for more information, see section Culvert, Good modelling practice
aspects ). The same as discussed for a Culvert also applies for a Siphon and an Inverted
Siphon.
List box: Lateral Assigned to Lowest (or Nearest) Water Level Point. Using this
list box, the user can specify if lateral flows are to be assigned to the lowest water level
point or that lateral flows are to be assigned to the nearest water level point. For more
information on the difference between assigning to the lowest or to the nearest water level
point, reference is made to section 6.1.11.2
No Lateral Outflow when no Water Available By checking the check-box in front of "No
Lateral Outflow when no Water Available", SOBEK reduces the user-defined lateral inflow
in case insufficient water is available for meeting the user-defined lateral outflow. The
advantage of this option is that SOBEK does not apply (extremely) small time-steps, that
require a lot of computational effort (wall-clock time). Using this option, even a termination
of a simulation might be avoided. The ratio "Allowable Outflow Volume/Available Volume"
can be specified. SOBEK provides as output both the user-defined lateral outflow (Defined
Lateral) and the actual applied lateral outflow (Lateral Actual).
Use RR interaction as saved in this case If you don’t want to have to re-calculate the
Rainfall Runoff computations again for every case where you only change things in the
flow module, it is wise to activate this option. Note: in order to click this option, the Rainfall
Runoff module should be active.

Tab - Advanced settings
One of the options when opening "Settings" for Channel Flow is "Advanced settings". These
can be found on the "Advanced settings" tab. The options are explained below.

Graphical User Interface

Figure 5.16: The Advanced settings tab of the Channel flow module.

Design Factor for Area Based Lateral Flow
The "Design Factor for Area Based Lateral Flows" is a multiplication factor (expressed as
percentage) that is applied to only those lateral flows, that are calculated using the so-called
"Area Based" method (see Figure 5.100 and Equation (6.14)).
Tab - Initial data
One of the options when opening "Settings" for Channel Flow is "Initial data". These can be
found on the "Initial data" tab. The options are explained below.

SOBEK, User Manual

Figure 5.17: The Initial data tab of the Channel flow module.

Define global initial values If this option is chosen, the initialisation values that you enter
in this section will be applied to the entire model.

Define local values in . This option allows you to define initial water
levels and/or depths individually for every branch in the model. For those branches where
you do not enter the initial state, the values from the "Define global initial values" section
apply.
Use restart file Get the initial situation for the model from the results of a previous simulation. In order to do this, there should be a restart file available.You can create a restart
file by defining one on the "Simulation settings" tab and running the simulation. After this
simulation has run, the results of the last time step will be written to the restart file.
Tab - Output options
One of the options when opening "Settings" for Channel Flow is "Output options". These can
be found on the "Output options" tab. The options are explained below.

Time step Output For most simulations, it is not useful to have simulation results for every
computational time step. That would require enormous disk space and would not give
useful extra information. Therefore, an output time step can be defined.You can choose
to have current, average or maximum values written to the result file. For example: if
the computational time step is 10 min, and the output time step is 1 hour, there will be 6
computational results available for 1 result to be written. Thus, you can choose to have
the actual computed value written for every output time step (current), or you can choose
to take the maximum or the average of those 6 results.
Output parameters Here you can define which results should be written to file.

Graphical User Interface

The different Output parameters for Nodes:

Figure 5.18: The Nodes tab in the Channel flow Output options.

It is possible to choose between:

water level [m AD]
water depth [m]
freeboard [m]
volume [m3 ]
The different Output parameters for Branches:

SOBEK, User Manual

Figure 5.19: The Branches tab in the Channel flow Output options.

It is possible to choose between:

Discharge [m3 /s]
Velocity [m/s]
Water Level Gradient
Conveyance
(Subsection) Pars. (Q, Chézy, A, W, and Hydr. Rad.)
Frijlink Sediment Transport Cap. [m3 /s]
Van Rijn Sediment Transport Cap. [m3 /s]
Wind (velocity, direction)
Froude Number [-]

The different Output parameters for Structures:

Graphical User Interface

Figure 5.20: The Structures tab in the Channel flow/Urban flow Output options.

It is possible to choose between:

Discharge [m3 /s]
waterlevel up and down [m AD]
head [m]
Velocity [m/s]
crest level [m AD]
pump data
structure flow area [m2 ]
crest width [m]
gate level (lower edge) [m AD]
pressure difference [N/m2 ]
water level at crest [m AD]

This item is only available for General Structures.

Tab - Numerical Parameters
One of the tabs in settings of Channel Flow is the "Numerical Parameters" tab. The numerical
parameters are explained below. Note: Modifying these advanced numerical parameters
is not supported. Only modify these settings when necessary for specific purposes, and
carefully verify results after making changes.

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Figure 5.21: The Numerical Parameters tab of the Channel flow module.

Default settings

Typical Rural schematisation A default selection of numerical parameters that are most
suitable for hydrodynamics in open water systems, mainly channels and small rivers.

Typical Urban schematisation A default selection of numerical parameters that are most
suitable for hydrodynamics in urban water systems, mainly sewer pipes.
User defined
An option to choose your own numerical settings:

Accuracy factor
minimum time step
epsilon for volume
epsilon for water depth
threshold water depth for flooding of channels
threshold water depth for flooding of land
factor for structure dynamics (Channel Flow & Sewer Flow only)
To the structure equations an inertia term is added. This inertia term acts as a kind of
numerical demping. This is done to avoid numerical oscillations/instabilities in case of
unsteady flow conditions. The numerical parameter "factor for structure dynamics" is a
factor/scalar applied to this inertia term. Default value of 1.0 is suggested for the "factor for structure dynamics" Note: for steady flow conditions the inertia term equals zero.

Graphical User Interface

Hence, the "factor for structure dynamics" is not of influence for the computed steady-state
discharge through a structure.
structure inertia dampening factor (River Flow only)
In settings a default value for the so called structure inertia damping factor can be defined, that is applied for the River weir, the Advanced weir, the General structure and the
Database structure both as single structure or member of a compound structure. In the
schematization Task block, this default value can be overruled for each individual afore
mentioned structure type. In the linearization of the concerning structure equation a term
α∂U/∂t is added, where
structure inertia damping factor [−];
flow velocity [m/s]; and
computational time [s].
The structure inertia damping factor can be used for avoiding instabilities during computation.
relaxation factor
theta
minimum length of branch segment
volume based on water level or discharges (0=false; 1=true)

In SOBEK there are two options for computing the volume of a ζ -calculation point (or branch
segment) at a specific point-in-time, viz:
1 Volumes based on water level or discharges (0=false; 1=true)

If the option "Volumes based on water levels" is selected, this means that the volume at
each ζ -calculation point (or each segment) follows from the computed water level and its
corresponding cross-sectional profile.
If the option "Volumes based on discharges" is selected, this means that the volume at each
calculation point (or branch segment) is the summation of its volume in the previous time-step
and the resulting net inflow during the computational time-step.
In Water Quality computations especially use is made of volumes and discharges. By choosing the option "Volumes computed based on discharges" a more coherent set of volumes and
discharges is obtained, than in case the option "Volumes computed based on water levels" is
selected.
Note: The selected way in which volume is computed also yields for 2D hydrodynamic computations.

maximum flow (1D) and velocity (2D) Courant number
maximum degree of nodal points to be eliminated by Gaussian elimination
maximum number of iterations
rho (density of fresh water)
gravity acceleration
minimum surface in node
minimum surface on street
extra resistance for general structure
In settings a default value can be defined for the so called extra resistance coefficient of
the General structure type, both as a single structure and as a member of a compound
structure. In the schematization Task block, this default value can be overruled for each
individual General structure type. The so called extra resistance refers to a bed shear
stress force, that is accounted for in the impuls balance, that is solved in case of drowned

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gate flow or drowned weir flow. The bed shear stress force reads

LgW2 ρ2 u22 /C 2 or λρ2 W2 u22

λ = (Lg/C 2 ) extra resistance coefficient;
L
length of hydraulic jump behind the structure [m];
g
acceleration due to gravity [m2 /s];
C
Chézy coefficient [m1/2 /s];
ρ2
density of water in hydraulic jump [kg/m3 ];
U
downstream flow velocity [m/s]; and
W2
downstream structure width [m].

factor on 1D acceleration term dU/dt (can vary between 0 and 1)
0 means that DU/Dt or ∂U/∂t + U ∂U/∂x terms in all 1D hydrodynamic momentum

equations are neglected, hence waves are computed/considered as diffusive waves.
1 means no reduction on DU/Dt or ∂U/∂t + U ∂U/∂x terms in all 1D hydrodynamic
momentum equations are neglected, hence waves are computed/considered as dynamic
waves.
In case user defines a factor on 1D acceleration term ∂U/∂t < 0, SOBEK applies factor=
0. In case user defines a factor > 1, SOBEK applies factor= 1.
use time step reduction on structure (0= false; 1= true)
In case the user defines a value for "use time step reduction on structure" equal to 1,
at the point-in-time of the wetting of the crest of a structure (i.e. for weirs and orifices
only) a time step reduction will be applied during a time-span equal to two times the user
defined time step. This functionality was implemented for avoiding oscillation in specific
Urban schematisations which having sharp inflow hydrographs, it can be applied in Rural
schematisations as well. Unneccessary use of this option might result in a longer computational time needed.
River/Urban/Rural

General
The settings task block gives the user the following two options (see Figure 5.22):

The combination of SOBEK modules used for the simulation can be selected here, and
For every module selected general settings can be defined.

Graphical User Interface

Figure 5.22: The Settings task block.

Simulation settings tab

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Figure 5.23: The Simulation Settings window for the Overland Flow settings task block.

Definition of data in Digital Elevation Map (DEM)
Here, the user can specify how the data within the DEM to be used is oriented: as heights or
as depths.

heights: a higher z-value means a higher level
depths: a higher z-value means a lower level

With the checkbox "Use precipitation and evaporation as defined for the first meteo station"
you can define whether the rain fall and evaporation is to be included on your 2D grid. The
precipitation and evaporation from the first rainfall station defined in the "Meteorological data"
task block is then applied. If the checkbox is switched off, no rainfall or evaporation will considered on the 2D grid.
Note:
1) Rainfall and evaporation is applied to all active 2D grid cells (i.e. 2D grid cells not having a
missing value). At present only spatially uniform distributed rainfall and evaporation can be defined, meaning that each active 2D grid obtains the same amount of rainfall and evaporation.
The spatially uniform distributed rainfall and evaporation can be a function of time.
2) Rainfall and evaporation can not be directly entered on 1D open channel network. Using the Rainfall-Runoff module, the outflow of catchment areas as result of nett precipitation
can be provided as inflow on a 1D open channel network. The same applies for a sewer

Graphical User Interface

network/system.
Restart data
Restart data allows users to create realistic initial conditions for their calculation. When the
"write restart file" option is checked and the model is run, the results for the last time step
of the calculation are written to a file with the name you entered. For other calculations the
available restart file may then be referred to define the initial conditions.

Advanced Settings tab

Figure 5.24: The Advanced Settings window for the Overland Flow settings task block.

The Conservative 2D Advection scheme allows for a more accurate computation of the propagation speed of flood waves, over initially dry bed or wet bed.
Special care has been taken to ensure that weir flow is computed accurately, even when weirs
are represented by only 1 grid cell that is raised above the field level. Weir discharges are
reproduced accurately both for the sub critical and the supercritical flow regime. These features are demonstrated and compared to analytical solutions by test computations in several
geometries.
The Conservative 2D Advection scheme is based upon ‘A staggered conservative scheme for
every Froude number in rapidly varied shallow water flows’ (Stelling and Duinmeijer, 2003).

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In order to invoke the Conservative 2D Advection scheme, one can select in ‘Settings, Overland Flow (2D), Advanced settings’, the Conservative 2D Advection scheme. In order to invoke
the special treatment for weir flow, select ‘Use Dike Limiter’. Grid cells will be flagged as ‘dikes’
when the height difference with surrounding grid cells exceeds a user specifiable ‘Dike limiter’
treshold value.
Note that the less accurate Carlson scheme is still available for use. The use of the Conservative 2D Advection scheme is recommended.

Limiting super critical flow velocities on a steep 2D flow: If there are steep slopes within
the topography of a 2D grid, it is possible that sheet-flow with super critical flow velocities
occurs on these steep 2D slopes. In other words that a thin layer of water runs down these
steep slopes with very high flow velocities. These very high flow velocities may result in severe
reductions of the user-defined time-step and hence increase in the required computational
effort. These super critical flow velocities can be limited by checking the option "Limiting
super critical velocities in sheet flow on steep 2D slopes" available on the "Advanced settings
Tab" of the "Overland Flow (2D) module" in "Settings" (see Figure 5.24).

Method of overflowing 1D channel
Here the user can specify a number of general options for the 2D simulation, starting with the
method of overflowing 1D channel. This is a very important option which will greatly influence
the results of the simulation, so it is very important that you set this option wisely.
It concerns the connection of the 1D cross-section with the underlying 2D grid cell, and is
explained in the following example:

Figure 5.25: Example of a 1D2D schematisation.

A 1D channel delimited by dikes passes through a low lying area, say a polder. When the
water level inside the 1D channel overtops the dikes, water will start to flow into the underlying
2D grid elements. The dikes of the 1D channel can be modelled in two different ways, as is
shown in the following two cross-sections of the schematisation depicted in Figure 5.25.
Options 1: Assume No Embankments.

Graphical User Interface

Figure 5.26: Assume no dikes.

Notice: At this moment, the option of method of overflowing 1D-channel refers to all 1D cross
sections.
In this case, water enters the 2D grid as soon as the channel water level branches the terrain
level in the 2D grid, so the part of the dike in the 1D cross-section above this level is neglected.

Option 2: Assume Highest/Lowest Level of Embankments.

Figure 5.27: Assume Highest/Lowest Level of Embankments.

In this case, water enters the 2D grid when the highest level of the 1D profile is overtopped,
and not earlier. So, the dikes form a barrier between the channel and the 2D area. Moreover,
they form a barrier for water flowing towards this 1D cross section over the 2D grid.
The terms highest and highest refers to both sides of the cross section. If Assume Highest
Level of Embankments is chosen, and the left bank’s surface level is higher than the right
bank’s, then the surface level from the left bank is used as the level for overtopping.
If Assume Lowest Level of Embankments is chosen, the surface level from the right bank is
used.
Note: if overtopping takes place, water will always overtop on both sides of the channel, no
matter if one side has a higher surface level. If you want to prevent this from happening, create
an additional elevation in the grid on one side of the channel.
Initial Data Tab

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Figure 5.28: The initial data tab from the Overland Flow SETTINGS task block.

Note: The first option, define global values, cannot be selected at the present.
At this moment, there are either one or two options available here. If you haven’t run a
simulation before with a restart file as output, you won’t be able to select the second option
use restart file, so you will need to use the default option, define local initial values per 2D-grid.
There are a number of things you need to remember when using the restart option:

make sure you select the use restart file option in both the overland flow module AND
the channel flow module !!

The restart file can only be used as input for exactly the same schematisation that was
used in the simulation that generated the restart file.

The restart file itself is saved under the project directory; this means that you will only be
able to use this restart file as input for a (any) case within the same project, but not for a
case in another project.
GIS output options tab

Graphical User Interface

Figure 5.29: GIS Output tab in the Overland Flow settings task block.

The output for GIS systems, like ARCView, is one of the three types of 2D-specific output
available. In this screen, you can select if you want this output to be generated or not, and
for which time steps. If any (combination) of the available variables is selected here, SOBEK
will automatically create ’.ASC’ output files which can be imported into a GIS based program.
There are some additional rules to remember, which will be explained further on.
The GIS output data is written to a number of different files. The first type consists of output
files in .asc format (see also section 5.1.6.3). SOBEK creates these output files only when
the switch ’create ASCII-output for water depth, water level and velocity’ is switched on! One
of these is generated for every selected output time step and for every selected variable. In
general, it is a good idea to wait with generating this output (if you need it at all, of course) until
you are pretty sure that the simulation is going to give you the results that you need. Suppose
your simulation lasts 24 hours, and you want GIS output for every time step (of, for example,
one minute) and for all five variables, you would get 5x24x60 equals 7 200 output files!
Warning: Right now, SOBEK can handle only a certain maximum number of files in the case
directory. If you decide to switch on the ’ASCII-Output Option’, you might actually branch
this maximum number of files (because of all the .asc files generated), which means that you
might not be able to save your case properly! In that case you will get the message with saving
your case: "too many files in case directory; Check the configuration of the application;
erase unregistered files". In this case you should reconsider you output choices to decrease
the number of output files.

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The second type of output files is the binary ’.map’ file. For every variable chosen, a file is
produced. It contains the values of that variable for every time step and every grid element
of one particular grid. In results in maps, the user can select these .map files and produce
.asc files out of them. So actually, the .map file contains the same information as the .asc files
described earlier, but in a compressed format. Please note that whether MAP files are written
or not, only depends on the Output Parameters chosen in the GIS Output Options tab, and
not on the ASCII-Output option switch!
The last type of GIS output files are ’special’ .asc files. These files contain the following
variables:

maximum water depth (d_max)
time of maximum water depth (t_dmax)
maximum water level (h_max)
time of maximum water level (t_hmax)
maximum velocity (v_max)
time of maximum velocity (t_vmax)
time of wetting (t_wet)
time of wetting per class (steady state’) (t_wet/class)
time of drying (t_dry)
time of drying per class (steady state’) (t_dry/class)
rate of change of water depth (dd/dt)

These files are only produced when the corresponding ’basic’ variable is selected in the GIS
tab, see figure. For example, the maximum depth is generated only when the option ’water
depth’ is checked. The same goes for other variables like the maximum velocities (linked to
’velocity’) or maximum levels (linked to ’water level’). The files giving a time (period) and the
rate of change of water depth are all linked to the ’water depth’ output option.
Incremental Output Tab

Graphical User Interface

Figure 5.30: The incremental output tab for the Overland Flow settings task block.

The second type of 2D output is the so-called ’incremental output’. This is output that is
generated specifically for result analysis in SOBEK (’results in maps’) itself, so you should
normally have at least some of these options turned on. Otherwise, you will not be able to
visualize the results in SOBEK.
The incremental file system was developed to reduce the enormous amount of data generated
by the 2D simulations. It works by defining a number of classes for every output variable which
are then used in the output files instead of the actual data value itself. So, for example, if a
water depth in a certain 2d grid cell equals 0.43 m, it would fall in class ’0.4 - 0.5’ (if you
have specified such a class). This is also the result you would get when examining the results
for that particular grid cell in ’results in maps’. So, this output is especially useful for getting
a quick idea as to how the water flows through the 2d grid system; if you are interested in
the exact values for the variables for a certain number of grid cells, there is another option
available to the user, which is the history output, explained in the next paragraph.
The incremental output always has the same time step as the actual calculation time step
chosen in the channel flow module.
Concerning the output parameters, it is important to know that the velocity (u component) and
the velocity (v component) are necessary if you are interested in seeing the velocity vectors
later on, when viewing the results in results in maps.
The number of classes can be selected manually, and influences the detail you will get when

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viewing the results; ten classes of 10 cm difference show much more information than 2
classes of 50 cm difference, but also require more disk space and computation time. The
number of classes will be the same for all variables, so it’s not possible to have 5 classes for
the water depth and 15 for the velocity. But, if you have defined 15 classes (for all variables),
and you need only 5 for one particular variable, you can define the unnecessary classes as
no-data values (-999).
A few rules to remember:

The water depth can be only positive, so it’s no use to define negative classes here
The ’u’ and ’v’ velocity components can be both positive and negative. It is important to
remember to use exactly the same classification for both variables.

This classification needs to be classified symmetrical around zero for correct determina-

tion of the vectors!

History Output Tab
If you are interested in the exact values of all variables on specific locations in the 2D grid, it
is possible to use a special kind of node called a History station. For more information, please
see the 2D-History node chapter.
2D Bathymetry input as heights (or levels)
Functionality:

2D bathymetry input as Heights (or levels) refers to the fact that the user can define bed
elevations of a 2D grid according to a vertical axis, having its positive axis pointing in upwards
direction.
Up to now 2D bathymetry input could only be defined as Depths, meaning that bed elevations
are defined according to a vertical axis, having its positive direction pointing in downwards
direction. All 2D bathymetry input is either defined as Heights or as Depths. Hence it is not
possible to define a particular 2D bathymetry input grid as Height while another is defined as
Depths.
How to define Bathymetry input as Heights (or levels):

Double click the ‘Settings’ task block.
In the ‘Settings’ window, take care that the Overland Flow (2D) check-box is checked and

click on the Edit button next to it
In the ‘Settings for Overland Flow (2D) module’ window under Definition of data in Digital
Elevation Map (DEM), define whether you want bathymetry input defined as Heights (or
levels) or bathymetry input defined as Depths.
Close the ‘Settings for Overland Flow (2D) module’ window by clicking the OK button,
Close the ‘Settings’ task block by clicking in the ‘Settings’ window on the OK button,
Now start to import your 2D bathymetry input grids under the ‘Schematisation’ task block.

Graphical User Interface

Water Quality
Editing time settings
The simulation period for the Water Quality module can be derived from a selected meteorological event (if the Rainfall-Runoff module is active) or specified by hand. In the latter case, it
is necessary that the simulation period for the Water Quality module is the same or lies within
the simulation period for the Water Flow module.
The simulation time step may be equal to, smaller than and larger than the time step for the
other modules. However, we advise you to select a time step either equal to the time step of
the Water Flow module, or equal to the time step of the Water Flow module multiplied by a
whole factor (2, 3, 4, etc.) or equal to the time step of the Water Flow module divided by a
whole factor (2, 3, 4, etc.).

Furthermore, the selected numerical method may impose a stability limit on the time step (see
below). Also, the modelling of water quality processes may impose a stability limit on the time
step (see par. 4.2).

Make sure that the "Channel Flow" and "Water Quality" modules are activated in the "Settings" Window.

Click the Edit button of the "Water Quality" module.
Adjust the simulation period and/or the time step in the corresponding edit boxes.

Editing simulation settings
The simulation options include the choice between fraction computations and regular water
quality computations, as well as the selection of initial conditions. Optionally a user-defined
file with boundary conditions can be connected.

Click the "Simulation options" tab form.
Select "Calculate fraction" or "Calculate water quality".
Make sure that the tick box "processes active" is on, if you have selected "Calculate wa

ter quality" (unless you want to run a water quality simulation without substance-specific
processes).
If you intend to run the current case in batch mode, decide whether or not you want the
previous flow results used in batch mode. If you do, check the associated tick box. (See
also: the ’Simulation’ task).
Select the appropriate option for the initial conditions:
select a file with initial conditions you generated yourself (.RSF file);
select a file with initial conditions generated by earlier SOBEK runs;
start with 100% initial water (fraction computation) or model-wide initial conditions.
To edit the model-wide initial conditions click the Edit button.

If you specify a Water Quality computation and you click the Edit button belonging to the "start
simulation with global initial values" option, the "Initial Values" window appears.
Note: The user-supplied files with initial conditions must have the extension <*.RSF>. They
should be located in the directory (mentioned in the "Simulation Options"
tab form).
Note: The option to use files with initial conditions computed by earlier SOBEK runs is only
active if such files exist.
Warnings:
If you use hand-made restart files, be sure that the state variables or fractions are in

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agreement with the current selection. The Water Quality module does not check this!
If you use restart files from an earlier run, be sure that you have not changed the state
variables or fractions (or your Water Quality schematisation) since you generated the
file. The Water Quality module does not check this!
Task block: Metereological Data
Time-dependent and spatial constant wind-fields
Functionality:

The user can define time-dependent and spatial constant wind-fields acting on 2D flow. No
distinction can be made between different 2D grids. Wind velocity and wind direction can
vary as function of time. The wind is taken into account in the momentum equations as
an additional shear-stress acting on the water surface (see manual). Please note that once
the user defines wind, this wind will act both on the 1D Channel flow and on the 2D water
movement.

For how to define time-dependent and spatial constant wind-fields acting on 2D grids, reference is made to the explanation given in the user manual concerning 1D Channel flow.

Time-dependent and spatial constant rainfall or evaporation
Functionality:

The user can define time-dependent and spatial constant rainfall or evaporation acting on 2D
flow only (hence not on 1D flow). No distinction can be made between different 2D grids or
different rainfall stations (i.e. only one station can be considered). The rainfall or evaporation
is respectively taken care as an external lateral inflow or outflow in the continuity equations.
How to define:

For how to define time-dependent and spatial constant rainfall or evaporation acting on 2D
grids, reference is made to the explanation given in the user manual under ‘Meteorological
Data’ task block.
Meteorological Data
After opening or creating a SOBEK project and case, you’ll see the Case Manager screen
appear, which consists of a number of task blocks. Each block represents a different part of
the modelling process. In this chapter, the Meteorological Data Task Block is discussed:

Graphical User Interface

Figure 5.31: The Meteorological Data task block.

Under the Meteorological Data task block, you can define the meteorological circumstances
that apply to your study.
These are:

Precipitation
Evaporation
Wind data

SOBEK contains a default precipitation event ().
************** IMPORTANT *****************************************

The meteorological data is stored in a separate directory <\SOBEK215\Fixed>, which is
accessible for all SOBEK projects. If you make adjustments in a meteorological file that is
also used within another project, these adjustments will also affect the results of that project
(after running its computation again)!
*******************************************************************

Remark:
File names of meteo files are limited to a maximum of 8 characters. Files created
in the user interface will automatically be limited to 8 characters. When renaming or
creating meteo files outside of the user interface, make sure the file name length does
not exceed 8 characters. This 8 character limitation holds true for most SOBEK files,
including .lit directories.
After double-clicking the task block, the following window will appear:

SOBEK, User Manual

Figure 5.32: The Meteorological Data window.

Each of the Meteorological components will be discussed in the chapters hereafter.
Evaporation
During dry periods evaporation plays an important role in the water balance of natural water
systems. Especially for Rainfall-Runoff computations.
SOBEK contains two evaporation series: a long term average series and the time series of
daily values measured between 1951 and 1994 at the De Bilt , the weather station at the Royal
Dutch Meteorological Institute.
Precipitation
A precipitation event is characterised by either consecutive periods with intensive rainfall, or a
longer period with continuous precipitation. A precipitation series contains precipitation events
separated by periods with very little or no rainfall.
Whether a precipitation event can be used as a design event depends on the problem at issue.
For the design of the storage- and pumping capacity, it is mainly the behaviour of the sewer
system during extreme precipitation that is of interest. For the evaluation of target levels of
pumps and weir settings more moderate events are of interest.
SOBEK-RR-SF meets the Dutch guidelines ’sewer systems computations, hydraulic functioning’. This implies that both storm events and long time series can be simulated.
The guidelines prescribe ten standard events which must be used to analyse the behaviour of
sewer systems. The ten standard precipitation events are derived from 15 minutes time series
measured at De Bilt, a meteostation of the Royal Dutch Meteorological Institute (KNMI), in the
period 1955-1979. Six different return periods and two different shapes are used to determine
the events. The shape is characterised by the location of the peak. The criteria used for the
selection of the standard events are described in the guidelines. The standard events with
characteristic return period and location of the peak are described in Table 5.1.

Graphical User Interface

Table 5.1: Standard precipitation events

01
02
03
04
05
06
07
08
09
10

0.25
0.25
0.50
0.50
1.00
1.00
2.00
2.00
5.00
10.00

front
back
front
back
front
back
front
back
front
front

The events in Table 5.1 are available within SOBEK-RR-SF.

Figure 5.33 shows the rainfall of standard event 05 and the inflow into the sewer for a flat
closed paved area of 1 ha. as determined by the RR-module:

Figure 5.33: Rainfall and corresponding sewer inflow for a flat closed paved area

Figure 5.34 shows the rainfall of standard event 05 and the inflow into the sewer for three
closed paved areas (with a slope, flat, flat stretched) of 1 ha each:

SOBEK, User Manual

Figure 5.34: Rainfall and corresponding sewer inflow for three types of closed paved area

Precipitation options
Under the Meteorological Data task block, you can define rainfall intensities that apply to your
schematisation. In this chapter, the precipitation editor is discussed.

Graphical User Interface

Figure 5.35: The precipitation window

Rainfall Events v.s. Rainfall Series

The basis of the precipitation editor is formed by rainfall events. These are characterised by
either consecutive periods with intensive rainfall, or a longer period with continuous precipitation.
A chain of rainfall events may form a rainfall series. Rainfall series allow you to model a long
time span of precipitation without having to model the dry periods in between.
Rainfall events:

The option: This option allows you to select an existing rainfall series. Notice that you can view each individual event from that series by choosing it in the
box on the left side of the screen.
The option: This option allows you to generate a rainfall series,
based on hourly data between 1951 and 1994 from the Dutch De Bilt rainfall station.
Based on criteria that you define, the individual rainfall events are extracted from that
data. It is not (yet) possible to enter your own long-term rainfall data and generate series
from them.
Wind
In channel systems with long stretches of narrow channels and/or large open water surfaces
strong winds can cause a local increase in water level. In areas where the storage capacity is
small this can cause problems under wet conditions. Water Flow takes the influence of wind
into account.
Specifying multiple wind fields

In SOBEK up to version 2.05, the user interface only supported a global wind field.

SOBEK, User Manual

The computational core of SOBEK 2.07 was extended to support the functionality of specifying
multiple wind station data independent of the coupling of SOBEK-branches to wind stations.
The user-interface does not support this functionality.
Model data base
First the changes to the model database are described. The changes pertain to the existing
wind data file, and the introduction of a new wind location data file.
Wind data file

a variable or a constant global wind field;
a wind definition per branch;
using more than one wind.

An example of a global wind field:

The wind data file of the meteo data layer contains the wind definitions. This can be one of
the following options:

GLMT MTEO id ‘1’ ci ‘-1’ wu 1 wv tv 1 TBLE .... tble wd td 1 TBLE .... tble mteo glmt
or

GLMT MTEO id ‘1’ ci ‘-1’ wu 1 wv tv 0 3 wd td 0 270 ... mteo glmt
An example of a wind field per branch:

MTEO id ‘2’ ci ‘1’ wu 1 wv tv 1 TBLE ... tble wd td 1 TBLE .... tble mteo

The exact lay-out of these records has not changed. A more detailed description is available
in the on-line help (Model data base). One can also check with existing wind files (*.WND in
the <\Fixed> subdirectory of the directory where SOBEK is installed)
Using wind stations the user can specify the wind field table per wind station, and specify the
coupling of branches to wind stations separately.
The functionality of a wind field per wind station is made available using the WSTA keyword.
The records are very similar to the existing MTEO or GLMT records. An example:
WSTA id ‘Windstation’ wu 1 wv tv 1 TBLE ... tble wd td 1 TBLE .... tble wsta
with
id
wu
wv tv
wd td

wind station id
wind used (as in MTEO records)
wind velocity (as in MTEO records)
wind direction (as in MTEO records)

The appendix contains an example file.
Wind location file
WLOC ci ‘1’ st ‘Windstation1’ wloc
WLOC ci ‘3’ st ‘Windstation1’ wloc with

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carrier id (branch id)
wind station id; this id should match with a wind station id in the WSTA records

of the wind data file
If a SOBEK-branch is not coupled explicitly to a wind station, the global wind data will be used
by default.

Settings
In Settings, you can specify the desired output. Additional available output is the wind direction
and wind speed per branch. Just select the additional item wind (velocity, direction) in the
’Output options’ tab form with output for ’Branches’.

Figure 5.39: Task block settings, output options.

Meteo
Use Meteo only to select a wind file. A wind data file containing other data than only global
data should never be edited in the user interface using Meteo. It should be done ’behind the
screens’ using a text editor.
Behind the screens
The wind data file and wind location file should be edited using an ASCII text editor.

SOBEK, User Manual

The wind file is located in <\SOBEK215\Fixed>. The name of the file is taken from the name
of the rainfall file. Only the extension is different: the wind file has extension .WDC (constant
wind field) of .WND (variable wind field).
The wind location data file Wnd_Loc.Dat can be different for each case. For a fixed set of
wind stations, you can investigate the impacts of allocating SOBEK-branches to wind stations
without needing to change the wind station data.
The wind location file should only be edited in the Work directory.
The simplest and safest way to do this is: Open a case, than double-click on the schematisation task-block, and press OK in the next menu. Then you get the question: "Nothing has
been changed. Do you want to continue to the task?". Answer Yes.

After that the wind location data file is in the WORK directory, where it
can be edited.

Post-processing
The extra available output per branch (wind velocity and wind direction) can be viewed in the
’Results in charts’ and ’Results in maps’ task block.
In the ’Result in charts’ task block, first select the ’Flows at branch segments’ output and then
select the wind data you want to see from the next screen.

Figure 5.40: Results in charts, Flows at branch segments.

In the ’Result in maps’ task block, you will get the network schematisation on the screen. After
that, open the output data ’Flows at branch segments’, select the appropriate output variable
(default is the first parameter, i.e. discharge mean [m3 /s], and click on the desired output

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location.
Example wind file and wind-location file
Wind Location file (Wnd_Loc.Dat)
WLOC ci ’1’ st ’Test1’ wloc
WLOC ci ’3’ st ’Test1’ wloc
WLOC ci ’5’ st ’Test1’ wloc
WLOC ci ’7’ st ’Test1’ wloc
WLOC ci ’389’ st ’Test2’ wloc
WLOC ci ’388’ st ’Test2’ wloc
WLOC ci ’386’ st ’Test2’ wloc

Wind data file (e.g. Sept1994.Wnd)

Note:
The branches with id 1, 3, 5 and 7 will be using the wind data from wind station Test1. The
branches with id 386, 388 and 389 will use the wind data from station Test2. All other branches
in the schematisation will be using the global wind data.

The example wind file below contains the definition of a global wind field and 2 other wind
fields.
GLMT MTEO nm ’(null)’ ss 0 id ’0’ ci ’-1’ lc 9.9999e+009 wu 1
wv tv 1 0 9.9999e+009 ’Wind Velocity’ PDIN 0 0 ” pdin
CLTT ’Time’ ’Velocity’ cltt CLID ’(null)’ ’(null)’ clid
TBLE
’1994/10/23;00:00:00’ 6.000000 <
’1994/10/23;02:00:00’ 6.000000 <
’1994/10/23;04:00:00’ 5.000000 <
’1994/10/23;06:00:00’ 6.500000 <
’1994/10/23;08:00:00’ 6.000000 <
’1994/10/23;10:00:00’ 7.500000 <
’1994/10/23;11:00:00’ 9.500000 <
’1994/10/23;12:00:00’ 9.500000 <
’1994/10/23;13:00:00’ 8.500000 <
’1994/10/23;16:00:00’ 6.000000 <
tble

wd td 1 0 9.9999e+009 ’Wind Direction’ PDIN 0 0 ” pdin
CLTT ’Time’ ’Direction’ cltt CLID ’(null)’ ’(null)’ clid
TBLE
’1994/10/23;00:00:00’ 170.000000 <
’1994/10/23;01:00:00’ 180.000000 <
’1994/10/23;03:00:00’ 190.000000 <
’1994/10/23;06:00:00’ 190.000000 <
’1994/10/23;07:00:00’ 180.000000 <
’1994/10/23;11:00:00’ 190.000000 <
’1994/10/23;13:00:00’ 200.000000 <

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’1994/10/23;15:00:00’ 190.000000 <
’1994/10/23;16:00:00’ 180.000000 <
tble
su 0 sh ts 0 9.9999e+009 9.9999e+009 tu 0 tp tw 0
9.9999e+009 9.9999e+009 au 0 at ta 0 9.9999e+009 9.9999e+009 mteo
glmt
WSTA id ’Test1’ nm ’Teststation1’ wu 1 wv tv 1 0 9.9999e+009 ’Wind Velocity’ PDIN 0 0 ” pdin

TBLE
’1994/10/23;00:00:00’ 16.000000 <
’1994/10/23;02:00:00’ 16.000000 <
’1994/10/23;03:00:00’ 15.500000 <
’1994/10/23;04:00:00’ 15.000000 <
’1994/10/23;06:00:00’ 16.500000 <
’1994/10/23;11:00:00’ 19.500000 <
’1994/10/23;13:00:00’ 18.500000 <
’1994/10/23;14:00:00’ 18.500000 <
’1994/10/23;15:00:00’ 17.500000 <
’1994/10/23;16:00:00’ 16.000000 <
tble

CLTT ’Time’ ’Velocity’ cltt CLID ’(null)’ ’(null)’ clid

wd td 1 0 9.9999e+009 ’Wind Direction’ PDIN 0 0 ” pdin CLTT ’Time’ ’Direction’ cltt CLID
’(null)’ ’(null)’ clid
TBLE
’1994/10/23;00:00:00’ 279.000000 <
’1994/10/23;01:00:00’ 289.000000 <
’1994/10/23;03:00:00’ 299.000000 <
’1994/10/23;06:00:00’ 299.000000 <
’1994/10/23;07:00:00’ 289.000000 <
’1994/10/23;12:00:00’ 299.000000 <
’1994/10/23;16:00:00’ 289.000000 <
tble

su 0 sh ts 0 9.9999e+009 9.9999e+009 tu 0 tp tw 0

9.9999e+009 9.9999e+009 au 0 at ta 0 9.9999e+009 9.9999e+009
wsta
WSTA id ’Test2’ nm ’Teststation2’ wu 1 wv tv 1 0 9.9999e+009 ’Wind Velocity’ PDIN 0 0 ” pdin
CLTT ’Time’ ’Velocity’ cltt CLID ’(null)’ ’(null)’ clid
TBLE
’1994/10/23;00:00:00’ 26.000000 <
’1994/10/23;06:00:00’ 26.500000 <
’1994/10/23;12:00:00’ 29.500000 <

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’1994/10/23;16:00:00’ 26.000000 <
tble

TBLE
’1994/10/23;00:00:00’ 179.000000 <
’1994/10/23;01:00:00’ 189.000000 <
’1994/10/23;03:00:00’ 199.000000 <
’1994/10/23;07:00:00’ 189.000000 <
’1994/10/23;11:00:00’ 199.000000 <
’1994/10/23;13:00:00’ 209.000000 <
’1994/10/23;15:00:00’ 199.000000 <
’1994/10/23;16:00:00’ 189.000000 <
tble
su 0 sh ts 0 9.9999e+009 9.9999e+009 tu 0 tp tw 0

wd td 1 0 9.9999e+009 ’Wind Direction’ PDIN 0 0 ” pdin CLTT ’Time’ ’Direction’ cltt CLID
’(null)’ ’(null)’ clid

9.9999e+009 9.9999e+009 au 0 at ta 0 9.9999e+009 9.9999e+009

Task block: Schematisation

General
Within this task block the actual schematisation is built and verified. As mentioned before, this
manual will only deal with the 2D additions to the 1D channel flow version of SOBEK. Please
refer to the general SOBEK user manuals for more details on the outline of schematisation
task block and the use of the 1D channel flow module in specific.
Just like the 1D schematisation, the 2D schematisation is built in two steps using a number
of building blocks. In the first step, the edit network mode, the grids and the other building
blocks, like initial water level nodes, are being placed on the map. In the second step, the edit
model data mode, the characteristics of all these building blocks are defined. Both steps will
be explained in detail in the following two paragraphs.
Edit Network mode
To start creating a network, you have to switch to the ’Edit Network’ mode. To do so, choose
"Network" from the "Edit" menu:

Figure 5.41: Entering Edit Network mode.

SOBEK, User Manual

Edit Model Data mode
To start editing the parameters for your model objects, choose "Model Data" from the "Edit"
menu.

Figure 5.42: Entering Model Data mode.

The next step in building the schematisation is specifying the parameters for the different 2D
elements defined in the edit network mode. The order in which the 2D elements are handled
is the same as in the previous paragraph.
An object needs to be selected before its data can be defined. After the Model Data option
has been selected from the edit menu, the model data window appears. This window can
be used to browse through all objects and select them for editing. The objects can also be
selected by clicking on them in the main Netter screen.
Viewing 2D Grid Info
Functionality:

Using the 2D Grid Info option, information can be obtained on:

individual 2D grid cells, or
on a path of 2D grid cells.

The user can add the information of various individual 2D grid cells to one and the same
graph. A path of 2D grid cells can cross at any angle over a 2D grid. At present the path of
2D grid cells can not pass over nested grids (i.e. parent grid and child grid) in such way that
only the active parent and child 2D grid cells are being selected.
Further on a distinction is to be made between static values and dynamic values. Static values
refers to the values on the underlying 2D grid (for instance a bed elevation) or underlying
map file (for instance maximum water depths). Dynamic values refers to time-dependent
computation results (for instance incremental water depths).
How to make a 2D path:
Both in the ‘Schematisation’ and ‘Results in Maps’ Task blocks.

In the main menu, click on Select/2D-Grid cell info
Click on the 2D grid cell at which you like to start your 2D path (i.e. starting 2D grid cell).
Note that in the ‘Path2D-Grid Info’ window, the column and row number of the starting 2D
grid cell are given in the two boxes in front of the Path check-box.
Click the Path check-box,
While pressing on the Shift key, place the mouse-pointer on the 2D grid cell at which you
like to end your 2D path (i.e. the end 2D grid cell). Releasing the Shift key will result in the

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selection of the end 2D grid cell. The column- and row number of the end 2D grid cell are
now filled in the two boxes behind the Path check-box.
Click on the button in the ‘2D-Grid info’ window to visualise the 2D grid cells
contained in your 2D Path.
Remark: In case you have more than 1(one) 2D grid (for instance in case of nested grids), the
2D grid cell of the 2D grid that lies on top will be selected. Using the Next Grid button the grid
cell on the underlying 2D grid will be selected. Note that in this case the Grid ID will change.
How to retrieve 2D Grid Info:

Under the ‘Schematisation’ Task block only information on static values of the 2D grid

cells are available. In case the 2D path option is not used, the static value of the selected
2D grid cell is depicted on the one most last line in the ‘2D-Grid Info’ window (Note that
dynamic values are not available under the ‘Schematisation Task’ block). In case a 2D
path is selected, the static values of the concerning 2D grid cells can be obtained by
clicking the Graph button. Note that in the main menu of this graph the x-axis can be
changed to either value (distances) or labels (column and row number of the 2D grid).
Under the ‘Results in Maps’ Task block, information on both static- and dynamic values of
the 2D grid cells are available. In case the 2D path option is not used, the static- and actual
dynamic value of the selected 2D grid cell is depicted on the last two lines in the ‘2D-Grid
Info’ window. Please note that static values are displayed in grey. Clicking the most left
button, provides a graph of dynamic values of each selected 2D grid cell as
function of time. Please note that by clicking on another 2D grid cell and sequentially
clicking on this button again, the user can add the dynamic results of various
2D grid cells in one and the same graph. In case a 2D path was selected, clicking on the
most left Graph button results in a graph of the dynamic values of the starting 2D grid cell
of the 2D path. Clicking the most right Graph button provides a graph, showing for all 2D
grid cells lying on the 2D path, its static value as well as its dynamic values for a particular
point-in-time.
Notes:
1) the x-axis of this graph can be plotted as function of value (distance) or labels (column
or row number);
2) dynamic values are only available in case they are selected beforehand (Click in main
menu on File/Open Data/ Depth Incremental (in the ‘Select Item’ window));
3) using the ‘View Data’ window dynamic values can be added to the graph; and
4) using the forward and backward buttons in the ‘View Data’ window, the point-in-time for
which the dynamic values are shown under the most right Graph button can be changed.

SOBEK, User Manual

Figure 5.43: Example of a 2D Path under a particular user defined line of 2D cells.

Task block: Simulation

Task block: Results in Maps

River/Urban/Rural

SideView
In the "Results in Maps" mode, you can create an animation of your hydrodynamic results,
plotted alongside a channel, river or sewer pipe. Note: SideView is only available for the
SOBEK 1D Flow modules: Channel Flow, Sewer Flow and River Flow.

Figure 5.44: Example of a SideView.

This chapter explains:

How to create a SideView
Advanced SideView options
Creating a SideView

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Go to the "Results in Maps" task block
Click the starting node (left side of the animation) on the map.
Press the Shift key on your keyboard and keep it pressed
Click the end node (right side for the animation) on the map
SideView now automatically selects the shortest connection between both selected points.
Right-click your mouse and select "SideView" from the pop-up menu.

The "Setup Animation" window is then loaded:

Figure 5.45: Setup Animation of a SideView.

Here, you can select the period for which an animation should be shown.

After pressing OK, the "SideView" window is opened:

SOBEK, User Manual

Figure 5.46: The SideView Window.

With the
With the
The

buttons, you can start, pause and stop the animation.

buttons, you can record the animation and save it as a movie file.

button toggles whether you will see the rainfall intensities in a graph during the
animation.

Advanced SideView options

If you desire to select another path than the shortest way between the start- and endpoint,

you can sequentially add parts of the desired path by keeping the Shift Button pressed,
thus forcing the path to follow the route that you desire.
Note: if a specific branch cannot be selected with the Shift key, because it is never the
shortest route, you may release the Shift key, and select it (including its surrounding
nodes) with the Ctrl key.
You can save the path for a SideView you have chosen. Choose "File" - "Save" or press
Ctrl-S to store the path and give it a name.
You can add the results form another case to your current SideView. Choose "View" "User data" - "Get from case" to add them. These results will become visible as red dots
in your animation.
You can view multiple SideViews in one window by opening previously stored paths in
addition to your current selection. Choose "File" - "Open" to do so.
You can create graphs of the results at nodes, branch segments and structures from
within the SideView window. Click the object in the SideView for which you desire to
create a graph, right-click your mouse and select "show graph".

Graphical User Interface

General
The ’results in maps’ task is the most important of the three task blocks when viewing and
analyzing results from a simulation. It is usually the first place to go to if you want a quick
scan of the results, because the Netter environment provides you with many tools to help
you. Once again, the user is expected to have a working knowledge of SOBEK and Netter
before reading this manual. This paragraph focuses on explaining the additions to the Netter
environment concerning the viewing and exporting of 2D data. It starts with explaining the
use of the active legend, which is a great help to quickly understand exactly what results you
are viewing and to turn data layers on and off. After that, some more information will be given
concerning the three output formats: incremental (only for use within Netter) and GIS (for
output to GIS applications). The third output format, History stations (for use in Netter or as
output to for example EXCEL), is not explained any further in this document, as it is a standard
SOBEK output format which is already explained in the regular SOBEK documentation.
Viewing model and output data in NETTER
Active Legend
The active legend is one of the major additions to this new version of SOBEK/Delft-1D2D. It
can be switched on in Netter in both the schematisation task and the results in maps task, by
selecting options → active legend. It is a great help with identifying and selecting output data.

Figure 5.47: The active legend

Once the active legend has been switched on, the model and output data become visible
as groups in the legend window (Figure 5.47). All groups can be turned on or off using the
check-boxes. Selecting a group in the legend window activates a shortcut to the properties/
settings of the group. The triangle-like symbol on the right hand side of the group names turn
the group-legends on and off.
Depending on the schematisation and the type of currently selected output data (under file →
open data), one or more of the following groups become available:

map (model data)
The currently loaded map-layer.

Network nodes (model data).
All nodes, both 1D and 2D, in the schematisation

Network branches (model data).
All branches in the schematisation

SOBEK, User Manual

Map/model data for every grid (called ’domain’)

This data layer can contain either model data OR output data:
z-data (model data)
terrain levels with respect to reference level. Positive means downward. The topography *.asc files are examples of the z-data.
depths/levels/velocities (output ’map’ data)
output results for a selected time step. It is not possible to ’scroll’ through the simulation
time.

Animated (output) data for every grid.
Depths
Levels
as opposed to the z-data, the levels are always defined as positive in Upward direction!
Velocities
Should always be positive.

This layer can contain any one of the following output data:

This layer can contain the results of a selected 1D-output option (i.e. water levels at nodes)
OR the 2D results at history stations.
Incremental and GIS output files

Incremental files are generated by SOBEK mainly as a means to visualise animated results
in Netter. However, it is also possible to generate an .ASC output file of the current time step
and for a selected grid via the export option (file → Export → 2D Grid data → Animated
data). Remember that the incremental files contain classes instead of actual values, so the
.ASC file generated as output will contain classes as well. In most cases it will be more useful
to create .asc files from either a MAP file or use a GIS .asc file directly.
These files are created mainly for the purpose of exporting output data to a GIS-based system
such as ARCview.
The GIS files are the .asc output files that the user selected in the settings task. A distinction
is made between ’normal’ asc files and ’special’ asc files. One ’Normal’ asc file is generated
automatically for every (in Settings) selected GIS output time step and variable. One ’Special’
asc file is generated for every special variable, but only one for the whole simulation period!
The exception to this rule are the files for the dD/dt variable, which are generated every GIS
output time step. After the simulation has completed and the case has been saved, these
files are written to the -directory. Remember that these files contain the actual
values and not the classes. Each file represents the actual values for a particular variable and
for a particular time.
The following table summarizes the available special .asc output files:
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Parameter

Table 5.2: Special <*.asc> output files

maximum water
depth

dmNMAXDX.ASC/
dNNMAXDX.ASC

in each cell the maximum
water depth of all calculated
timesteps is written

time of maximum
water
depth

dmNTMAXD.ASC/
dNNTMAXD.ASC

in each cell is written after what period this maximum water depth has been
branched

maximum water
level

dmNMAXHX.ASC/
dNNMAXHX.ASC

in each cell the maximum
water level of all calculated
timesteps is written

time of maximum
water
level

dmNTMAXH.ASC/
dNNTMAXH.ASC

in each cell is written after what period this maximum water level has been
branched

maximum
velocity

dmNMAXCX.ASC/
dNNMAXCX.ASC

in each cell the maximum
velocity (absolute value) of
all calculated timesteps is
written

time of maximum velocity

dmNTMAXC.ASC/
dNNTMAXC.ASC

in each cell is written after
what period this maximum
velocity (absolute value) has
been branched

time of wetting

dmNTWTXX.ASC/
dNNTWTXX.ASC

in each cell the first timestep
is written at which the cell
starts to become wet. If the
cell doesn’t become wet it
remains ‘-999’

time of wetting per class
(‘steady state’)

dmNWTCII.ASC/
dNNWTCII.ASC

for each incremental class in
each cell the first timestep at
which this class is exceeded
is written. If the class is
never exceeded it remains ‘999’

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Symbol

dmNTEMXX.ASC/
dNNTEMXX.ASC

in each cell the last timestep
is written at which the cell
starts to become dry again
after wetting.
If the cell
doesn’t become dry after
wetting it remains ‘-999’

time of drying
per
class(‘steady
state’)

dmNEMCII.ASC/
dNNEMCII.ASC

for each incremental class in
each cell the last timestep
at which the water depth is
lower than this class is written. If the water depth is always higher than a class, it
remains ‘-999’

rate of change
of water depth

dmNRSSSS.ASC/
dNNRSSSS.ASC

in each cell the difference
in water depth is written between two GIS output files
divided by the GIS output
options timestep Dt

Notice that in the files, where ‘hr’ is the unit, t = 0 is at the start of the simulation.
Example for the ‘rate of change of water depth’: if you run 10 hours of simulation period, and
you choose in ‘GIS output options’ Dt = 02:00:00 hh:mm:ss, then this will result in 5 maps.
Filename structure

Most of the .asc filenames generated have the following structure:
dmNVSSSS.asc/dNNVSSSS.asc

General notations used for ASC and MAP files are :

’dm’ or ’d’ → an abbreviated form of ’domain’ (another name for ’grid’), dm is used when
domain number is between 1 and 9, and d is used for domain numbers between 10 and 99.
’N’ → domain number, from 1-9. This is an internal number, which is not the same as the
domain ID.
’NN’ → If domain number is from 10 onwards till 99, then the name of the .asc file will begin
with ‘dNN’ i.e. for say domain 19 it will be d19VSSSS.ASC
To check which domain number is related to which domain ID, please refer to file
file in your case directory.
’V’ → type of variable:
d

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level
current
velocity in x-direction
velocity in y -direction
Dd/Dt

’SSSS’ → represents chosen output time step number (not the time step chosen for the
calculation!). In other words, if the time step selected is 15 minutes, then at start of simulation,
SSSS = 0000, at 15 minutes after the start of simulation , SSSS=0001 and so on.
’XXXX’ or ’XX’ or ’X’ → represents 0 or 1 placed to make the filename 8 character long.

‘II’ → represents the class interval number as given in the Incremental file for a selected
parameter.
Similar to the ASC file a MAP file is also created with the name
dmNVXXXX.map/dNNVXXXX.map

The main differences between the ASC and MAP file are that ,
MAP file is a binary file as opposed to ASC file

MAP file contains actual values for all time step, while one ASC file contains actual values for
a one time step. Hence no matter how many time steps are defined by the user, there will be
only one map file created.
There are a number of other .ASC file created for variables like maximum water depth/ maximum water level/ time at which maximum depth occurs/ time at which maximum water level
occurs etc.. These files can be identified from their filenames:
The filenames for such variables are:
Maximum water depth

dmNMAXDX.ASC/dNNMAXDX.ASC
dmNTMAXD.ASC/dNNTMAXD.ASC

The maximum water depth value for the whole simulation run is written in dmNMAXDX.ASC/
dNNMAXDX.ASC while the corresponding timestep when the maximum water depth occurs
is written in dmNTMAXD.ASC/ dNNTMAXD.ASC. These files are generated when the option
of water depth is checked on in Settings.
Rate of change of water depth
dmNRSSSS.ASC/dNNRSSSS.ASC
The rate of change of depth per selected output time step is written in dmNRSSSS.ASC/dNNRSSSS.ASC.
These files are generated when the option of water depth is checked on in Settings. The time
step at which these files are written is same as the selected time step for incremental file and
thus irrespective of what the output time step is for generation of GIS/MAP files in settings.
Maximum velocity

SOBEK, User Manual

dmNMAXCX.ASC/dNNMAXCX.ASC
dmNTMAXC.ASC/dNNTMAXC.ASC
The maximum velocity value for the whole simulation run is written in dmNMAXCX.ASC/ dNNMAXCX.ASC while the corresponding timestep when the maximum velocity occurs is written
in dmNTMAXC.ASC/ dNNTMAXC.ASC. These files are generated when the option of velocity
is checked on in Settings.
Maximum water level
dmNMAXHX.ASC/dNNMAXHX.ASC

dmNTMAXH.ASC/dNNTMAXH.ASC

The maximum water level value for the whole simulation run is written in dmNMAXHX.ASC/
dNNMAXHX.ASC while the corresponding timestep when the maximum water level occurs is
written in dmNTMAXH.ASC/ dNNTMAXH.ASC. These files are generated when the option of
water level is checked on in Settings.
Time of wetting/drying

dmNTWTXX.ASC/dNNTWTXX.ASC
dmNTEMXX.ASC/dNNTEMXX.ASC

These two files are special output files. The values in the file dmNTWTXX.ASC/ dNNTWTXX.ASC
gives the maximum time span the grid cell remains flooded i.e wetted and dmNTEMXX.ASC/
dNNTEMXX.ASC gives the maximum time span the grid cell remains dry i.e empty. These
files are generated when the option of water depth is checked on in Settings.
Time of wetting/drying per class
dmNWTCII.ASC/dNNWTCII.ASC
dmNEMCII.ASC/dNNEMCII.ASC

These two files are special output files. The values in the file dmNWTCII.ASC/ dNNWTCII.ASC
gives the time step when a water depth in a grid cell is high enough to be in the particular
class. For examples: if there are three classes for depth values i.e. less than 0.1 m, greater
than or equal to 0.1 m but less than 1.0 m, and greater than or equal to 1.0 m. So in total
three files will be generated for each domain i.e dmNWTC01.ASC/ dmNWTC02.ASC/ dmNWTC03.ASC. When a grid is just flooded but the water depth is still less then 0.1 m then
the time step at which the grid cell is flooded is written in dmNWTC01.ASC, when the water
depth in grid cell becomes just higher or equal to 0.1 m but less than 1.0 m that time step is
written in dmNWTC02.ASC, and when the water depth becomes just higher or equal to 1.0m
that time step is written in dmNWTC03.ASC.
Similarly the values in the file dmNEMCII.ASC/ dNNEMCII.ASC the time step when a water
depth in a grid cell is receding and is low enough to be the particular class.
These files are generated when the option of water depth is checked on in Settings.

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Task block: Results in Charts

Task block: Results in Tables
Description of the task

Double-click the "Results in tables" task box. The Results in Tables window appears.
Select the appropriate output file and click the View button.
The available files are:

SOBEK GIS interface (NETTER)
Adjusting the scale settings

General Balances Output: cumulative mass balances for the whole model area and the
whole simulation period (the file).
Water Balance for Water Quality network: cumulative water balance for the whole model
area and the whole simulation period (the file).

When simulation results are opened in NETTER (Task block "Results in Maps"), a scale is
automatically created and plotted in the Active Legend. However, you may want to define
your own scale settings and re-use them for other cases.

Activate the "Results in Maps" task block
Open a set of simulation results of your choice
Open the Color Range window by clicking the name of the results in the Active Legend
For example: water level.

Figure 5.48: A waterlevel color range in the Active Legend of NETTER.

Alternatively, you can choose "Options" - "Data value options" from the Netter menu and then
click Scale.

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Figure 5.49: Changing the Active Legend color range and scale.

Adjust the colours and values until they meet your taste. You can then choose to save
these settings by pressing . Use the Save style check box if you want to
save these settings only for the currently active type of output. Thus:

means: save the current settings only for the currently active results type (i.e. results at
nodes)

means: save the legend settings. Depending whether "save style" is switched on, this
legend will then apply to all output, or only to the currently active results type. The legend
settings (style) are always stored in the file. Additional settings are stored
in the file.
Optionally, you can choose to save the legend settings to a file. Choose "File" - "Export
style" in order to do so
Important: depending on your SOBEK settings, the customised legends will apply either to
one project only or to all SOBEK projects. See the topic "Saving your custom NETTER
settings" to learn more about that.

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Curving a branch
The length of the thalway (low water bed) from a river or channel may differ from the distance
between two nodes in a straight line. The meanders which cause this can be implemented
by switching to the ’vector layer’ mode, adding coordinates and dragging them to their natural
position on the map. A quicker method is to simply submit a value for the real length. In the
vector layer, the branch will then show as a harmonica, forcing itself to adapt the user defined
length.

Example:
Suppose there is a river flowing from point A to B:

Figure 5.50: A straight river flowing from A to B.

The distance in a straight line between A and B is approximately 1 000 m. However, in reality
the river meanders, thus making the real length of the river 1 300 meters. Now, how to make
SOBEK uses 1 300 meters for the calculation of hydrodynamics?
The simple method to submit the ’real’ river length is to:

button from the "branch" toolbar, click the branch and

enter the value of 1300m.

See effect this action had in the vector layer by clicking the

button. Notice that in
the vector layer the branch has been given a harmonica shape, thus forcing it to be 1 300
m:

Figure 5.51: A harmonica-shaped river from point A to B.

Back in the normal mode you will only see these artificial meanders when you add objects
to the branch.
The advanced method to submit the ’real’ river length is to:

Activate the vector layer by clicking the
Click the
Deltares

(show coordinates) button and select the branch.

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button and add coordinates to the branch by clicking and dragging.

Thus you can make the branch follow the real meandering of the river. The result will look like
this:

Figure 5.52: A meandernig river from point A to B.

Don’t be surprised if the meanders disappear again when you leave the "vector layer" mode:
the coordinates you just added will only show in the normal mode where there is an object
(cross section, calculation point, structure) placed on the branch!
5.2.3

Background map layers

SOBEK offers a library of geographical map layers, such as the map of The Netherlands.

Figure 5.53: The default map of The Netherlands in SOBEK.

These maps can be used as the default background for your schematisations. This chapter
explains explains how to do this.

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Choose ’Options’ - ’SOBEK options’ from the main menu on the SOBEK startup screen.

The ’Default Map Settings’ window will pop up:

Figure 5.54: The Default Map Settings window.

In this window, you can choose which map should be the default for all your new projects.
Every time you create a new SOBEK project, that map will be used as the default map.
The option ’maintain current map layers’ means that your maps will be stored in the specified directory only. This will save disk space, since the maps will not be copied to each
new project. However, if you intend to send your project-files to a third-party, it might be
handy if the maps are included in the project directory. In that case, choose the ’copy map
layers in new project’ option.
What if your country is not in the list?
If your country does not appear in the list of available maps, you can create one yourself:

Don’t bother about the default map for the time being, but simply start creating a project,

based on the existing default map.
Learn how to work with projects first by completing a tutorial!
Once you’ve branched the point where the model schematisation is created (SOBEK’s
GIS environment), compose your own map by choosing "Options" - "Map Options" and
importing various GIS map layers that you might have. Note: the distance-units of your
maps should always be meters, as SOBEK interprets them as such! Map layers in lat/lon
co-ordinates, yards, inches or feet are not supported!
All the map-based data (including background maps) that you want to use in SOBEK need
to be in a UTM-type (WGS84) cartesian projection, with XY coordinates in meters (and
not in degrees).
When you’re satisfied with the composition, you can export it. Choose ’File’ - ’Export’ ’Map’ and give it a proper name.
The next time you start SOBEK, you can go back to the ’Default Map Settings’ option
and select your newly created map as the default one! Click the
location where you stored the map.

button to select the

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Customising NETTER Settings
There are different possibilities to configure NETTER. You can choose to store these configurations on a global level, or to specify them per project:

Choose "Options" - "Netter options" from the menu in the SOBEK Startup window. The "Netter
options" window will appear:

Figure 5.55: The global Netter options window.

Here you can choose whether the settings you will define in NETTER (legend and node/branch
settings) should be applied globally (to all projects) or per project.
Note: For the ‘node and branch options’, the results are stored in the file .
The Netter Legend options are stored in the file. When stored as ’global’, they
can be found in <\SOBEK215\Fixed\User>; when stored per project they can be found in the
<\Fixed> directory of the project.
5.2.5

Exporting results to a database

It is possible to automatically gather specific results and prepare them for exporting to a Microsoft Access (<*.MDB>) database. This is useful for generating standardised reports.
The export definitions can be stored on three different levels:

On a case level - for each case, you will have to create a new definition of the desired
output combination

On a project level - within every case of the project, the standard export settings will remain
the same

On a global SOBEK level
For every case, you can select which of the above level should apply.

Go to the "Results in Maps" task block
Choose ’Tools’ - ’Export Options’. The "SOBEK Export tool" window will appear:

Graphical User Interface

Figure 5.56: Adding a definition in the SOBEK Export Tool.

Define for which level your definition should be saved (case, project, global) in the field

"save definition at level of:"
Define a name for the output file
Select in the fields "Module" and "Output file"
Select the type of output: as a matrix or as a table
Click Export to actually create the MDB file

Model data editor

For many objects in your network, you will have to submit parameter values. For example,
these can be the bed level or shape of a river’s cross section, the friction value of a sewer
pipe, the infiltration capacity of an unpaved area, and so on.
(If you don’t know how to create a network, view the chapter basics of network editing or follow
one of the tutorials provided in this document).
There are two ways to define the parameter values (model data) to the schematisation:

Using the single data editor(editing one object at a time)
Using the multiple data editor(editing multiple objects at a time)
Using the single data editor
To submit parameters to an individual object at a time, the following steps can be followed:
Option 1: accessing the single data editor through the menu

Make sure that you are in the SOBEK model editing environment (’schematisation’ task,
’edit model’)

Switch to the ’Model data’ mode by clicking ’Edit’ - ’Model data’

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The following window will appear:

Figure 5.57: Starting the single data editor from the Model Data menu.

Select from the combo box and list for which object you want to edit the parameters.
Click the Edit button. You’ll see an edit-window appearing for the object that you selected.
Option 2: selecting from the map

Make sure that you are in the SOBEK model editing environment (’schematisation’ task,
’edit model’)
Switch to the ’Model data’ mode by clicking ’Edit’ - ’Model data’

toolbar to activate the "select" tool.

Click with the right mouse button on the object for which you want to edit the data.
Choose ’Model data’ from the window that appears.
Notice that an edit-window for the selected object appears.
Using the Multiple Data Editor
To submit parameters to multiple objects at a time, the following steps can be followed:

Choose one of the

buttons to drag an area on the map, covering all the objects
you want to edit.
Click with the right mouse button
Choose ’Model data’ from the window that appears.
Notice that the "multiple data editor" is opened. Here you can edit data for several objects
at the same time, in a spreadsheet-like manner.

Some extra options are added to the multiple data editor, allowing quick manipulation of data.
For sewer applications, it is useful to have the option to multiply a unit runoff area per meter

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pipe with the actual pipe length. This option is available by using the right mouse button menu
after selecting a column. Also, the option to import data from a database has been added.

Figure 5.58: The multiple data editor.

The following edit options are possible:

Change individually;
Select a whole column, use the right mouse button, several options are available(Add,
Multiply, Replace);

Figure 5.59: Changing a whole column in the multiple data editor.

Select a whole column, use the right mouse button, Import option to import a column from
a DBF file is available. After selecting the DBF file, the coupling of the id’s in the DBF file
to the SOBEK id’s, and the data column to be imported can be indicated in the following
screen. If the DBF contains multiple records for the same id, the data of all records with
the same id can be added together using the switch ’Add all occurences together’.

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Figure 5.60: Importing data in the multiple data editor.

Select a whole column, use the right mouse button, Distribute Catchment option. The

specified catchment will be distributed over the runoff area. If it concerns pipes with runoff,
the distribution will be according to pipe length. If it concerns manhole, the distribution will
be proportionally (all manholes with the same runoff area).
When selecting Flow - pipes, there are also options to interpolate the pipe levels between
the first and the last selected row, or to design the pipes with a fixed slope. In order to
apply this in a meaningful way, the pipe must be in logical sequence and all in the same
direction.
Not every object type is available for editing in the Multiple Data Editor. These objects
should be modified with the Single Data Editor.
Although friction for Y-Z and Asymmetrical Trapezium profiles may appear to be editable
by using the multiple data editor, this is not recommended. The friction concept that is
used in the Multiple Data Editor is the Local (or Branch-wise) friction concept. However,
Y-Z and Asymmetrical profiles make use of the so-called Cross-section friction concept.
This can cause the (Local type) friction value reported in the Multiple Data Editor to differ
from the (Cross-section type) friction value reported in the Single Data Editor for Y-Z and
Asymmetrical Trapezium profiles. See the chapter 1D Hydraulic friction concepts for more
information.

Basics of network editing
One of the first things to do when you start working with SOBEK is to create a network that
represents your water system. Whether it is a river, channel or sewer system, the principles
are the same: it will be a GIS-based network or grid. In this chapter the general concepts
behind editing your hydraulic model schematisation are explained.
1. Start SOBEK’s GIS environment (NETTER)
After you’ve opened or created a case, you’ll see the Case Management Tool (CMT), showing
eight different task-blocks that can be executed. Read more about the CMT in the chapter

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Managing SOBEK projects and cases. If a task-block is yellow or green, it means that this
task is ready to be executed.

Make sure that the ’Schematisation’ task-block is ready to be executed;
Double click it;
Click the Edit model button on the window that appears. Now SOBEK’s GIS-environment
named NETTER is started.
2. Switch to the network editing mode
After entering SOBEK’s GIS environment under the "Schematisation" task block, one can
toggle between three modes:

The data-editing mode
The network-editing mode (discussed in this chapter)
The vector layer mode

Figure 5.61: Enter the network editing mode.

Choose ’Edit’ - ’Network’ to switch to the mode where you can adjust or create a schematisation.
Switch to the network-editing mode by choosing ’Edit’ - ’network’ in the main menu or click the
button. You’ll see the following toolbar appearing:

3. Network editing toolbars
The toolbar shown above consists of three main sections:

an action section
a node type section
a connection type section
The philosophy behind it is as follows: when creating or editing a 1D hydraulic model, you
choose to perform an certain action that applies for a certain node type and/or a certain
connection type. So when performing edit actions, make sure you select the right node type

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(for instance a Flow-cross section) and the right connection type (for instance a Flow-branch
with lateral flow).
Each of the sections can be opened by clicking the

button next to it.

Notice that all toolbars underneath can be dragged to your screen by clicking their blue line
on the top!

An example: you can drag the ’General’ toolbar, under the ’action’ section to your screen by
clicking it’s upper part, as shown below.

In a similar way, you can drag the ’node types’ toolbar to your screen. When moving with the
mouse over the different node types in that toolbar, it will then tell you which types they are.

Helpful hints for the user:

Add labels to the node types shown in the toolbar! If you have difficulty recognising the
various node- or branch types in the objects-toolbars, you can have their label shown:
’Choose ’View’ - ’Toolbars’ - ’Customise’ and select ’Icon and caption’ for node types
and/or branch types.
Note: In recent SOBEK versions, labels are enabled by default.
See what type of node is shown in the toolbar After you dragged the toolbar containing
node types to your screen, you can move over it with the mouse. The node type will then
be shown:

Figure 5.62: Mouse-over a node to show its label.

See what node type is shown in the "nodes" toolbar by moving over it (only after the toolbar
has been dragged to your screen)
ID’s of nodes and branches Object ID’s are directly used by the calculation core so users
should be very careful when modifying or manually setting such an ID.
It is recommended to let SOBEK pick the ID. Users should preferably use the name field to
add additional information about network objects. Although it is possible to use spaces in
object ID’s, this is not recommended. If the user wishes to manually set an ID, underscores
’_’ should be used instead of spaces. When using the Water Quality module, ID’s should
contain no more than 19 characters. See the water quality documentation for more details.
To get started creating a model schematisation, you can learn to: Create a branch, Curve a

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branch, Place objects on a branch, or do one of the tutorials for Channel Flow, Sewer Flow or
Overland Flow
Save unique display settings for a specific type of output
After opening a certain type of results, you may customise the way in which they are plotted, and save these settings for the next time. The procedure is best explained through an
example.
Example:
Say, that every time we open the results at branch segments we want them plotted in such a
way that:

In order to do so, you will need to do the following

All nodes are invisible
The flow direction will be shown by animated arrows

Open the Results at branch segments by clicking on it in the Active Legend
Uncheck the checkbox
left from the category "Nodes" in the Active Legend
Click the button

, in the right upper corner of the Active Legend to activate the "Settings" menu.
Click the "links" tab and activate the options "all data" and after that: "arrow flow"
Click OK to leave the Settings menu.
Open the "Scale settings" window by clicking the "Network data" in the Active Legend.

Activate the checkbox

left from the option ’save style’. With this option, you will save
the output ’style’ that belongs to "results at branch segments".
Click OK to leave the Scale settings window.

You can check it by first clicking the "Results at nodes" (which will restore the default settings
again) and then clicking the "Results at branch segments" again. The results will again be
shown in the way you had previously stored. You can load a series without a saved style/user
legend, the last style in use will then still be used.
5.2.7

Shortcuts to various menu options

You can click the header of each category to customise its settings. The headers provide a
shortcut to the corresponding menu options

Clicking Map will open the Map properties window. This will allow you to arrange, and
adjust the settings for the GIS layers that you use as a background in the schematisation.
Clicking Network Nodes will open the Node Settings window, which will allow you to
adjust the way (size, shape, colour) nodes are plotted in the main window. It also allows
you to select which node types should be visible, and which not.
Clicking Network Branches will open the Link Settings window, which will allow you to
adjust the way (size, colour) branches (branches and links) are plotted in the main window.
It also allows you to select which node types should be visible, and which not.
Clicking Network Data will open the Scale Settings window, which will allow you to customise the scale and colours for the data legend.

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The Active Legend
The active legend is an interactive legend, showing all objects and results that are available
within the GIS interface. The Active Legend can be customised entirely to the user’s wishes.
If the Active Legend is not yet visible in NETTER, it can be activated with the menu option
"Options" - "Active Legend".
Features of the Active Legend:

Gives Shortcuts to various menu options, such as the windows: Settings, Map Properties,
Node Settings, Link Settings and Scale settings

Allows you to save the display settings for each different type of output. For example: it

can remember that you want nodes to be invisible when viewing the results at branches.
This feature is explained further in this chapter.
Allows you to create a list with user defined output; shortcuts to simulation results that you
frequently view.

The following categories can be activated:
Simulation results (select the kind of computational results that should be opened)
Map layers (GIS layers for background plotting)
Network Nodes (shows the used node types in your
schematisation)
Network branches (shows the used branches and links
in your schematisation)
Network data (showing the legend of the results of a
simulation)

General usage of the Active Legend

With the check boxes

, each category can be made visible or invisible in the main

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buttons will respectively show and hide each category’s contents.

button opens the Settings window, which allows you to plot labels next you the
objects of your choice. This button is a shortcut to the menu "Options" - "Network Data"

Create a list with user defined output
If there’s certain output that you often need to watch, you can make it accessible quicker in
the following way:

Open the NETTER menu option "Tools" - "Output options"

The Output functions window will pop up:

Figure 5.63: Output functions window

In this window, you can add the time series that you desire to access quickly every time
after a calculation. Use the fields "module" - "output title" and "function" to define a certain
time series.
Example:

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Figure 5.64: Adding definitions in the Output functions window.

Note: If you choose in the function field, all values that are available for all time
steps from the time series are taken. The other options speak for themselves.

After clicking OK the series that you’ve selected here, will become available under the
header "user defined output" in the Active Legend:

Figure 5.65: User defined output in the Active Legend.

Note: Also on these customised series, you can save your unique display settings, as
described in the chapter above!
5.3
5.3.1

Node description (hydrodynamics)
Flow - Bridge node
Description

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In this chapter, the Flow - Bridge node type is described.

For a detailed description of this node’s input parameters: see the "Flow - Bridge node
input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the Flow Bridge node topology section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the
"Bridge section from the Technical Reference Manual".

Pillar bridge
Abutment bridge
Fixed bed bridge
Soil bed bridge

With a Flow - Bridge node you can simulate four types of bridges:

Input screens
When starting the model data editor for an Flow - Bridge node type, the following tabs will be
available for input:
Bridge:

Figure 5.66: The Bridge tab of a bridge.

A bridge of the type Pillar Bridge requires the following parameters:

Total pillar width (sum of the width of all pillars, perpendicular to the flow direction)

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Shape factor
Possible flow direction
See the Technical Reference manual, ‘Bridge Section’ in order to see how these parameters
are used in the structure’s equations.
A bridge of the type Abutment bridge requires the following parameters:
Bed level
Length
Inlet loss coefficient
Outlet loss coefficient
Possible flow direction

A bridge of the type Fixed Bed Bridge requires the following parameters:
Bed level
Length
Inlet loss coefficient
Outlet loss coefficient
Possible flow direction

A bridge of the type Soil Bed Bridge requires the following parameters:

Bed level
Length
Inlet loss coefficient
Outlet loss coefficient
Possible flow direction
Ground layer depth (note: this parameter is defined on the Cross Section tab)

Below, all of the mentioned parameters will be discussed.

Bed level: Represents the bottom of the construction, in meters w.r.t. reference level.
Length: Represents the length (in the flow direction) of the bridge.
Inlet loss coefficient: Represents the energy loss of water that enters the bridge (through
contraction). See the "Bridge" section from the Technical Reference Manual to see how
this parameter is embedded in the structure’s equations.
Outlet loss coefficient: Represents the energy loss of water that leaves the bridge. See
the "Bridge" section from the Technical Reference Manual to see how this parameter is
embedded in the structure’s equations.
Possible flow direction: This parameter defines in which direction(s) water can flow
through the orifice. The directions are defined with relation to the defined branch direction. Positive means: in the same direction as the defined branch direction; negative
means: in the opposite direction than the defined branch direction. If you don’t know the
defined direction of the branch, read the Flow - Branch topology section of the Functional
Reference Manual.
Cross Section: (Note: Not available when bridge type "pillar" has been chosen)

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Figure 5.67: The Cross section tab of a bridge.

On this tab the cross sectional shape of the culvert should be defined. This is done by means
of cross section definitions, very similar to the ones you define for the shape of a river bed.
The only real difference is that the number of cross section types is limited to two:

Table-form
Rectangle

For a detailed description of all available cross section types and their input parameter, see
the "Functional Reference Manual" - "Channel Flow module" - "Cross section types" section.
The ground layer option is available only for bridges of the type "Soil layer bridge". For that
type of bridges you can enter a ground layer depth, which represents a layer of sediment that’s
often present in structures. On the "Friction" tab, this layer can be given its own hydraulic
roughness value. Note: the option "use ground layer" should be switched on too!
Friction: (Note: Not available when bridge type "pillar" has been chosen)

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Figure 5.68: The Friction tab of a bridge.

On this tab, the friction values for the bridge can be entered:

Type friction bed: This friction value represents the roughness of the bridge’s walls.
Thus, if the bridge is made of concrete, a proper hydraulic roughness value for concrete
should be entered.
Type friction ground layer: (only for bridge type "soil bed bridge")If the bridge type
"soil bed bridge" has been chosen and the "use ground layer option has been activated
on the "cross section" tab, this option becomes active. It represents the roughness value
of the ground layer that lays on the bottom of the bridge.
For more information about the various friction options, see the "Bed Friction" section from the
Technical Reference Manual.
Topology

Nodes of the type Flow - Bridge need to be attached to one of these branch types:
Flow Channel:
Flow Channel with lateral discharge
Add a Flow - Bridge node to your schematisation in the following way:

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Select the appropriate node type (Flow Bridge)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note: Before adding a bridge to your schematisation, you should have at least one of the
above Channel types present.

Flow - Calculation point (basic)
Description

Flow - Calculation point

This chapter describes the nodes of the type Flow Calculation Point, which all together form
the Calculation Grid or Computational Grid. The Flow - Calculation Point node type is one of
the most important nodes for hydrodynamic modelling as their presence determine the spatial
discretisation of the model area.

For the input options you have when creating a calculation grid: see the Flow - Calculation
grid input screens section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow Calculation point topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the "Calculation point section from the Technical Reference Manual".

The SOBEK Water Flow modules solve the model equations on this grid of ζ -calculation
points. For good model performance it is therefore important that these points are spaced
evenly. Therefore SOBEK has an option to generate the calculation grid automatically. This
can be done after the schematisation has been completed.
Flow - Calculation grid input screens
After you have chosen to create a calculation grid, by using the Set calculation grid branch or
Set calculation grid all branches buttons (

), the following screen will appear:

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Figure 5.69: Setting a calculation grid on all branches.

This tab will probably be the only one you will ever use. Here you can define how the
branch(es) should be divided into computational segments. The following options are available:

Full Vector: This option means: the branch will not be split up into computational seg

ments. Therefore no calculation points will be added to the branch. You can also use this
option to remove calculation points from an existing branch.
Split by coordinate: When using this option, the branch will receive a ζ -calculation point
on every vertex. ’Vertex’ is a GIS term for all points on a line, that define its curves. For
example: a branch may run from node A to node B, but it may have some meanders.
These meanders are defined through vertices. These also determine the actual length of
the branch. You can manually remove or add such vertices to your SOBEK branch in the
Edit Vector Layer mode.
Length: This option will split the branch(es) into computational segments of a certain
length. It does so by adding ζ -calculation points.
Equidistance: Gives you a choice of what to do with the remaining lengths while creating
the ζ -calculation grid. Suppose that your branch has a length of 1 020 m. Setting a ζ calculation grid with a length of 100 m: Equidistance = off: this will result in ten branch
segments of each 100 m and one of 20 m. Equidistance = on: this will result in ten branch
segments of each 102 m.
In use: With these check boxes you can define whether the other tabs will also be used:
- Branch- 2DGridMore information about those tabs and their options is given below.

Graphical User Interface

Figure 5.70: The Branch tab of the Calculation points window.

On this tab, you can select what type of objects you want to use as a ζ -calculation point
(besides their original purpose). When a certain node type has been selected, it will keep its
original purpose, but in addition it will work as a ζ -calculation point and will show water levels
in the simulation results. Select the node types with the > and buttons.
Do not forget to activate the "Branch" checkbox on the "General" tab. Otherwise this option
will not be active!
Important Note: If you select a node type that’s usually invisible in the "Results in Maps"
mode (for instance the Flow - Cross Section node type), you’ll have to make it visible first in
order to view the results on these nodes.
Tab 2D Grid:

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Figure 5.71: The 2D Grid tab of the Calculation points window.

This tab is necessary to couple a 1D branch with a 2D grid. When the option "Connect Cells
to branch" is activated, for every 2D grid cell that the 1D branch crosses, a ζ -calculation point
is created and linked with the ζ -calculation point of that particular cell.
Do not forget to activate the "2DGrid" checkbox on the "General" tab. Otherwise this option
will not be active!
Topology

Nodes of the type Flow - Calculation point need to be attached to one of these branch types:
Flow Channel:

Flow Channel with lateral discharge

Unlike structure and cross section nodes, ζ -calculation points are usually not placed in a
schematisation one by one. SOBEK provides an option to automatically generate a grid of
ζ -calculation points for all branches or for one branch at a time:

Switch to the "edit network" mode in NETTER
Open the "Branch" toolbar and choose one of the following options: 1. click the button

and click on the desired branch.

2. click the button
Choose an appropriate grid spacing distance. The best value depends on various things,
but to give you an impression: for most channel systems 50 to 100 meters is a good
value. For slow rivers that show little changes in bed shape and bed level 500 meters is

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appropriate. See the chapter: Flow - Calculation Grid input screens from the Functional
Reference Manual for a detailed information on the various options.
It is also possible to add calculation points manually. This may be desirable when two structures are located closely to each other. Between two structures or lateral discharges there
should always be a calculation point.

The image below shows an example of a valid schematisation that contains calculation points.
Notice that between the weir and the lateral discharge node at least one calculation point
should be present.

Figure 5.72: An example of a schematisation that contains calculation points.

Flow - Fixed Calculation point
Description

In this chapter, the Flow - Fixed Calculation Point is described.

This type of calculation point is equal to the normal calculation points, except that it will not
be automatically removed when you decide to re-generate a calculation grid. This might, for
example, be a useful feature for locations where you desire to compare measured water levels
with computed water levels.

For a detailed description of this node’s possible network configurations: see the "topology" section from the Reference Manual
Topology

Nodes of the type Flow - Fixed Calculation Point need to be attached to one of these branch
types:
Flow Channel:
Flow Channel with lateral discharge
Add a Flow - Fixed Calculation Point node to your schematisation in the following way:

Select the appropriate node type (Flow - Fixed Calculation Point)

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Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note: Before adding a structure to your schematisation, you should have at least one of the
above Channel types present in it.
Flow - Compound Structure

This chapter describes the Flow - Compound Structure node type. A compound structure can
combine two or more different type of structures into one node. It considers these structures
to lay parallel to each-other within the same water course.

For a detailed description of this node’s input parameters: see the "Flow - Compound

Structure node input screens" section from the Technical Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow Compound Structure node topology" section from the Technical Reference Manual
Structure types that can join in a Compound Structure node as a compound member are:

River Weir (discharge computed on basis of energy-levels)
Advanced weir (discharge computed on basis of energy levels)
General Structure (discharge computed on basis of energy-levels)
River Pump (discharge computed on basis of water levels)
Database Structure (discharge computed on basis of water levels)

Please note that the above structure types are also available as single structures (respectively:
;

Input screens
When starting the model data editor for an Flow - Compound Structure node type, the following tabs will be available for input:
Compound Structure Tab:

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You can use the default value for structure inertia damping factor as defined in Setting, Tab
– numerical parameters, or you can define a value for structure inertia damping factor for
each compound structure member separately. For meaning of structure inertia damping
factor see Numerical parameter.
Under the "Member definitions" section, one can define the structures that become part
of the Compound Structure. Type a name of a new member in the field, and click on the
button. For explanation on the other sections of this tab, see the Functional
Reference Manual for the coresponding member as single structure.
All other tabs are identical to the tabs as for the coresponding member as single structure.
See that chapter in the Functional Reference Manual for a detailed explanation.
Definitions tab:

The definition tab will look differently, depending on the type of structure you are editing.
Please refer to the chapters named "input screens" in the "Reference Manual’ for the specific
structure types that you can edit there:

River Weir
Advanced weir
General Structure
River Pump
Database Structure

Controllers & Triggers tabs:
see section 5.8.
Topology

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Figure 5.73: Branches connected to Flow connection nodes

Nodes of the type Flow - Compound Structure need to be attached to one of these branch
types:
Flow Channel:

Flow Channel with lateral discharge

Add a Flow - Compound Structure node to your schematisation in the following way:

Select the appropriate node type (Flow - Compound Structure)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note:
1. Before adding a compound structure to your schematisation, you should have at least one
of the above Channel types present in it.
2. SOBEK by default places a computational point 0.5 m upstream and 0.5 m downstream
of the compound structure location. Hence the compound structure is default located on a
branch having a length of 1 m.
5.3.4

Different types of Flow - Connection nodes
The following types of Flow - Connection nodes are available:

Flow - Connection node
Flow - Connection node with Lateral Flow
Flow - Connection node with Storage and Lateral Flow
For each type of connection node yields that one or more branches can be connected to each
other (see Figure 5.73). A connected branch might either a pipe or a Flow - Channel.

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Figure 5.74: Interpolating data over Branch 1 and 2 at a Flow - Connection Node

Flow - Connection node

At a Flow - Connection node it is possible to interpolate data (see definition and restrictions
hereafter) between two adjacent Flow – Channels. For these two Flow - Channels should yield
that one ends at (i.e. the so-called First Branch), while the one starts from (i.e. the so-called
Second Branch) the concerning “Flow - Connection node” (see Figure 5.74).
A left mouse click on a Flow - Connection Node opens the Data Edit for Node Form. In a
scroll box you can define here the branches for which data is to be interpolated over the Flow
- Connection Node.
Definition of data interpolation over a Flow - Connection Node

For the open channel part from cross-section R1_Crs_A to cross-section R2_Crs_B (see
Figure 5.74), interpolating data over the Flow - Connection Node means:

Bathymetrical data:

The bathymetry of the cross-section at the Flow – Connection Node is obtained by linear
interpolation between the nearest cross-section on the “First Branch” (e.g. R1_Crs_A and
the nearest cross-section on “Second Branch” (e.g. R2_Crs_B). In hydraulic calculations,
this interpolated cross-section is respectively placed at the end of the “First Branch” and
at the beginning of the “Second Branch”.
Friction data

Interpolation of friction data for “Y-Z” and “Asymmetrical Trapezium” profiles only.
For Y-Z and Asymmetrical Trapezium profiles yields that friction is defined per crosssection. Firstly, for each cross-section a conveyance table is constructed on basis
of its defined roughness and cross-sectional profile. For each h- and u-point lying
in between two cross-sections, a tabulated type of cross-sectional profile is obtained
by linear interpolation. For each u-point, conveyance tables are obtained by linear
interpolating between the conveyance tables available at its adjacent cross-sections.
No interpolation of friction data for profiles that are not Y-Z and Asymmetrical Trapez-

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ium profiles. For profiles other than Y-Z and Asymmetrical Trapezium profiles, the
friction applied for the interpolated cross-section located at the “First Branch” and the
“Second Branch” are respectively obtained from the user-defined friction at the “First
Branch” and the “Second Branch”.

Diffusive lateral discharges:
Data with respect to diffusive lateral inflows is not interpolated over a “Flow - Connection
node”.

Flow - Connection node with Lateral Flow

Restrictions for data interpolation over a Flow - Connection Node:
Table 5.4 in section 5.6.1 provides an overview of the various available different types of crosssections. Cross-section types that may lay on the same branch are given in Table 5.3. With
respect to data interpolation over a Flow - Connection Node yields that interpolation is only
allowed between cross-sections that may lay on the same channel branch (see Table 5.3).

Definition and Restrictions for data interpolation over a Flow - Connection Node with
Lateral Flow :
A Flow - Connection Node with Lateral Flow has the same functionality with respect to interpolating cross-sections as a Flow - Connection Node. For more information reference is made
to section 5.3.4.1.
A Flow - Connection Node with Lateral Flow has the same lateral flow functionalities as a
Flow - Connection Node with Storage and Lateral Flow. No storage is, however, availabe at a
Flow - Connection Node with Lateral Flow. For the flow functionalities of a Flow - Connection
Node with Lateral Flow reference is made to section 5.3.4.3.
5.3.4.3

Flow - Connection node with Storage and Lateral Flow
Description

In this chapter, the Flow - Connection node with storage and lateral flow is described.

For a detailed description of this node’s input parameters: see the "Flow - Connection node
with Storage and Lateral Flow node input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow Connection node topology" section from the Reference Manual
Definition and Restrictions for data interpolation over a Flow - Connection Node with
Storage and Lateral Flow :
A Flow - Connection Node with Storage and Lateral Flow has the same functionality with
respect to interpolating cross-sections as a Flow - Connection Node. For more information
reference is made to section 5.3.4.1.
This type of node is very similar to the normal Flow - Connection node, apart from the fact
that it has some extra features:

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It gives the opportunity to add lateral discharge. This option is often used to submit known
discharges from industry or smaller rivers that have not been included in the schematisation.
It can bear additional storage area. This option is often used to include the area that is
represented by small water courses which have not been included as Flow - Branches in
the schematisation. For non-stationary simulations, the storage capacity of such smaller
watercourses may be of importance.
Location of Lateral Flow:
The location of the lateral inflow or lateral outflow coincides with the location of the Flow Connection Node with Storage and Lateral Flow.

Input screens
When starting the model data editor for a Flow - Connection node with Storage and Lateral
Flow type, the following tabs will be available for input:

Figure 5.75: The Bottom level tab of a Flow - Connection node with Storage and Lateral
Flow.

On this tab, the storage capacity of the node should be entered.

Bed Level: Represents the level where the additional storage area starts. This may be
higher than the bed level of the channel itself. For example: if the storage on this node
should represent small watercourses that are connected to the main channel, the bed
level of those watercourses should be entered here: not the bed level of the main channel.

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Storage Area: Here, the storage area for this node should be entered. For example: if the
storage capacity of this node should represent a secondary ditch of 200 m long and 2 m
wide that has not been schematised as a branch, the area should be 400 m2 .Optionally,
the storage area can be entered as a function of level. Use the option "variable" to do so.

Figure 5.76: The Lateral flow tab of a Flow - Connection node with Storage and Lateral
Flow.

On this tab, the lateral inflow can be entered. It gives three options:

Constant: Use this option if a constant amount of water flows into or out of the model.
(plus = in, minus = out)
5.3.5

Flow - Cross Section
Description

In this chapter, the Flow - Cross Section node is described. This is one of the most important
node types when creating a hydrodynamic model. It defines the dimensions of the channels/rivers that you want to model.

For a detailed description of this node’s input parameters: see the "Flow - Cross Section
node input screens" section from the Reference Manual;

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For a detailed description of this node’s possible network configurations: see the "Flow Cross section node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations and the applied interpolation methods, see the "Cross Section" section from the Technical Reference
Manual".
The discharges through a river or channel are greatly determined by the shape of the river
bed. To obtain a proper schematisation, it is therefore important to supply it with a sufficient
amount of cross section data. This is done by adding nodes of the Flow - Cross Section node
type to the schematisation.

From the cross section data, the bed levels and hydraulic radiuses are interpolated towards
the calculation points, for which every time step water levels are calculated.
Input screens
When starting the model data editor for an Flow - Cross Section node type, the following tabs
will be available for input:

Figure 5.77: The Location tab of a Flow - Cross Section node type.

On this tab, you can define the bed level and surface level for the particular cross section.

Bed level or cross-section level shift: For some cross-sections a bed level, or lowest
point of the cross-section, can be entered. Examples of cross-sections with a bed level
are the Trapezium, Round and Egg-Shape types.For other cross-sections, a cross-section

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level shift can be entered. The defined cross-section level shift is added to all the levels
defined in the cross-section definition. Examples of cross-sections with a cross-section
level shift are the Y-Z, River Profile and Tabulated types.
Surface level: The value you enter here represents the level of the embankments at this
cross section. This value will become visible in the results as follows: — in Sideview as
the green line — in results at nodes it will be used to calculate the freeboard. Note: In
the hydrodynamics calculations the value that you fill in for surface level will not be used.

Figure 5.78: The Cross section tab of a Flow - Cross Section node of the Y-Z Profile type.

On this tab, you should define the shape of the cross section. Notice you should first type
a name for the cross section shape that you want to define. Then later this shape can be
re-used on other Flow - Cross Section nodes! This prevents double work.

Select Cross Section: If you had already created several cross section definitions for
the chosen type, you can choose one here. If not, you can define a cross section shape
by typing a name in this field and clicking the button.Dependent
on the cross section type you chose, various buttons will become active where you can
define the shape of the cross section. For each type of cross section, a separate chapter
is available in the "Functional Reference Manual" - "Channel Flow module" - "Flow - Cross
section node" section: - Trapezium type- Round type- Egg-shape type- Tabulated typeRectangle type- Y-Z profile type- Trapezium type- Asymmetrical trapezium type- Elliptical
type- Arch type- Cunette type- Steel cunette type

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Friction:
Three different friction input screens are available when using the model data editor.

Figure 5.79: Y-Z and Asymmetrical Trapezium friction input screen.

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Figure 5.80: River profile friction input screen.

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Figure 5.81: Friction input screen for the remaining profile types.

For all cross-sections except Y-Z and Asymmetrical Trapezium profiles, the friction value that
you define will count for the entire branch on which it is located. For every branch, therefore
only the friction value of one of its cross sections needs to be edited.
For the Y-Z and Asymmetrical Trapezium profiles it is possible to define different friction values per cross-section lying on a branch. For river profiles it is possible to define friction as
f (x), f (h, x) and f (Q, x). More information is available in the chapter 1D hydraulic friction
concepts.

Use local value for this cross section You have the opportunity to choose between a

local friction value or a global friction value for the cross section. Global means that you
have a global (or model-wide)friction value that will apply to all branches for which you did
not define "use local friction values for this cross-section". To edit and apply the global
value, do the following:
switch off the "use local value" checkbox
select in the "Show:" combo box "Global value(s)".
Change the friction value according to your wishes.

Note that if you change the global value, the friction value for all branches that refer to this
value is changed too!To edit and apply the local value, do the following:
switch on the "use local value" checkbox
select in the "Show" combo box "Local value(s)"
Change the friction value according to your wishes.

Type friction: Various friction formulas are available. Choose the one of your wishes.

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More information about the various friction types is available in the "Bed Friction" section
from the Technical Reference Manual.
Topology

Nodes of the type Flow - Cross Section need to be attached to one of these branch types:
Flow Channel:

Flow Channel with lateral discharge
Add a Flow - Cross Section node to your schematisation in the following way:

Select the appropriate node type (Flow Cross Section)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note: Before adding a cross section to your schematisation, you should have at least one of
the above Channel types present in it.
Example of a valid network configuration containing a cross section:

Figure 5.82: Example of a valid network configuration containing a cross section.

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Flow - Culvert node
Description

In this chapter, the Flow - Culvert node is described.

For a detailed description of this node’s input parameters: see the "Flow - Culvert node
input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow Culvert node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the "Culvert section from the Technical Reference Manual".

Definition of a culvert:
A culvert is a sleeve-shaped structure (with usually a freely moving water level) which connects two water courses with each other (Dutch Hydrological Society, 2002).
In SOBEK, a culvert can be modelled by a Flow - Culvert node. For this node, a cross section,
bed levels on both sides, length and some other parameters should be defined.

Note: It is best to use this node type only for rather short culverts (up to several tens of
meters). If you would model a long culvert with this node type, the amount of storage in your
water system would be over-estimated. The reason is that adding a Flow - Culvert node does
not automatically reduce the storage capacity on the branch according to the culvert’s length.
The branch will still assume that its cross sections remain valid over the entire branch; which
is not the case because you just added a long culvert. So in case of a long culvert, where the
storage capacity of the channel/river is an important factor, it is best to simulate it by creating
a branch of its length and applying cross section to it that’s equal to the culvert’s dimensions.
Input screens
When starting the model data editor for an Flow - Culvert node type, the following tabs will be
available for input:
Culvert:

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Figure 5.83: The Culvert tab of a Flow - Culvert node.

On this tab, the general dimensions of the culvert can be defined:

Type: Here you can choose what kind of culvert it will be:- Culvert- Syphon- Inverted
Syphon

Bed level: These parameters define the bed levels of both sides (upstream and down

stream) of the culvert.Left means: the "upstream" side with relation to the defined branch
direction.Right means: the "downstream" side with relation to the defined branch direction.
Length: This parameter defines the length of the culvert. See the "Culvert" section from
the Technical Reference Manual for more details on the application of this parameter within
the structure equations.
Inlet loss coefficient: This parameter represents the energy loss due to the contraction
of the water when it has to enter the culvert. See the "Culvert" section from the Technical
Reference Manual for more details on the application of this parameter within the structure
equations.
Outlet loss coefficient: This parameter represents the energy loss of water when it
leaves the culvert. See the "Culvert" section from the Technical Reference Manual for
more details on the application of this parameter within the structure equations.
Valve: If the culvert also includes an internal valve, this option should be switched on.
Then also the tab "Controller" will become active. The valve should have an initial opening
height for the first time step of the simulation. For every next time step, the defined controller will operate the valve. In the table for "Loss coefficients", an energy loss factor has
to be defined for various opening heights.
Possible flow direction: This parameter defines in which direction(s) water can flow
through the orifice. The directions are defined with relation to the defined branch direction. Positive means: in the same direction as the defined branch direction; negative

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means: in the opposite direction than the defined branch direction. If you don’t know the
defined direction of the branch, read the Flow - Branch topology section of the Functional
Reference Manual.

Figure 5.84: The Cross section tab of a Flow - Culvert node.

On this tab the cross sectional shape of the culvert should be defined. This is done by means
of cross section definitions, very similar to the ones you define for the shape of a river bed.
The only real difference is that the number of cross section types is limited to eight:

Round
Egg-shape
Table-form
Rectangle
Elliptical
Arch
Cunette
Steel cunette

For a detailed description of all available cross section types and their input parameter, see
the "Functional Reference Manual" - "Channel Flow module" - "Cross section types" section.
Friction:

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Figure 5.85: The Friction tab of a Flow - Culvert node.

On this tab, the friction values for the culvert can be entered:

Type friction (bed):This friction value represents the roughness of the culvert’s walls.
Thus, if the culvert is made of concrete, a proper hydraulic roughness value for concrete
should be entered.
Type friction (ground layer):If the option "use ground layer" had been activated on the
"cross section" tab, this option becomes active. It represents the roughness value of the
ground layer that lays on the bottom of the culvert.
For more information about the various friction options, see the "Bed Friction" section from the
Technical Reference Manual.
Controller:

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Figure 5.86: The Controller tab of a Flow - Culvert node.

This option is only activated when the "valve" option on the "Culvert" tab has been switched
on. The valve can be operated by a controller. A controller will overrule your general settings
for the valve’s opening height and apply the chosen controlling rules to it. Read more about
them in the Controller section of the Technical Reference Manual.
Note that three of the four available controller options only become available after you have
defined a Flow - Measurement station within the schematisation and saved that schematisation.
Topology

Nodes of the type Flow - Culvert need to be attached to one of these branch types:
Flow Channel:
Flow Channel with lateral discharge
Add a Flow - Culvert node to your schematisation in the following way:

Select the appropriate node type (Flow Culvert)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.

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If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note: Before adding a culvert to your schematisation, you should have at least one of the
above Channel types present.
Flow - Database structure
Description

World-wide various different types of weirs have been constructed in rivers and channels.
Although the most common types of weirs are available in SOBEK, definitely not all type of
weirs (e.g. crump weir) are available in SOBEK. For this reason the Flow-Database structure
was implemented in SOBEK.
Crest levels of a Flow-Database structure cannot vary in height along the weir. The discharge
over any structure can be defined as a relationship between upstream and downstream water
level. The Database structure allows you to define this relationship is in a tabulated form
(e.g. database). For more information on how discharges are computed from a user-defined
database, reference is made to section 6.1.16.5.

Although not advised (see section 6.1.16.5), the crest level of a Database structure can be
varied by a controller. A structure inertia damping factor (see Numerical parameters) can be
defined for each Database structure.
Input screens
When starting the model data editor for a Flow - Database structure node type, the following
tabs will be available for input:
Database structure tab:

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Figure 5.87: The Database Structure tab of a Flow - Database structure node.

On this tab, you can select a previously defined structure definition. If there is no definition
available yet, go to the "definitions" tab first, to create one.
Also, you can select the controllers that apply to this structure. If there are no controllers
available to be selected yet, go to the "controller" tab first to create them.
You can use the default value for structure inertia damping factor as defined in Setting, Tab –
numerical parameters, or you can define a value for structure inertia damping factor for this
particular Database structure. For meaning of structure inertia damping factor see Numerical
parameters.
Definitions tab:

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Figure 5.88: The Definitions tab of a Flow - Database structure node.

On this tab, you can define the properties of your database structure. Select an existing definition from the drop-down box or create one by typing an appropriate name in the "definition"
field and then clicking .
Then you can:

Define the crest level of the structure
Choose whether the discharge is a function of:

- difference between upstream water level & crest level and- difference between downstream water level & crest level or
- difference between upstream water level & crest level and- difference between upstream
& downstream water level
Create a table which contains the data for the type of function you chose. Click the Edit
button to open the "Structure database window"

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Figure 5.89: The Structure Database window of a Flow - Database structure node.

You can add rows or columns by activating the "Row" or "Column" radio button respectively
and subsequently clicking . First you will be asked how many rows/columns you want
to add, then you will be asked to enter the row/column titles (values) one by one.Note that the
title (value) of the first row and column should be equal!The table can be checked by clicking
the button. If everything is fine, the OK button will become active.
Controllers & Triggers tabs: see section 5.8.
5.3.8

Flow - Extra Resistance
Description

Placing a Flow - Extra Resistance Node on a branch segment, means that an additional term
(describing the influence of the Extra Resistance) is added to the momentum equation, which
is solved for this specific branch segment (see section 6.1.1.2). More precisely, it means
that an additional water level difference is invoked over this branch segment equal to ξQ|Q|,
where ξ is the Extra Resistance coefficient and Q the discharge flowing through the branch
segment. The additional water level difference is added to the upstream located water level
point.
Note: In case of an Extra Resistance Node an additional term is added to the momentum
equation. For a structure located on a branch segment yields that the momentum equation
is replaced by the structure equation. Hence, an Extra Resistance can not be considered to
be a structure. Nevertheless, in the task blocks "Results in Maps" and "Results in Charts",

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the output of an Extra Resistance Node is provided under "Results at Structures and Extra
Resistances"’.
Following restrictions yields for Flow - Extra Resistance Nodes:

Flow - Extra Resistance Nodes are only allowed on a "Flow - Channel" and a "Flow Channel with lateral discharge".

Only 1 (one) Flow - Extra Resistance Node is allowed per branch segment
A Flow - Extra Resistance Node may not be located on a "Flow - Calculation point", a

"Flow - Fixed Calculation Point", a "Flow - Connection Node" and a "Flow - Boundary
Node.
A Flow - Extra Resistance Node may not be located on a branch segment adjacing a "Flow
- Boundary Node".
A Flow - Extra Resistance Node may not be located on a branch segment on which a
structure is located".

Input screens
Selecting a Flow - Extra Resistance Node and left mouse click opens the Extra Resistance
input screen (see Figure 5.90). Clicking on the button opens a table, where
Extra resistance coefficients (ξ ) can be defined as function of water level (see Figure 5.91)

Figure 5.90: The Extra Resistance tab of a Flow - Extra Resistance node.

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Figure 5.91: Input Table for Extra Resistance coefficients of a Flow - Extra Resistance
node.

Flow - Boundary
Description

In this chapter, the Flow - Boundary node is described.

For a detailed description of this node’s input parameters: see the "Flow - Boundary node
input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow Boundary node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the
"Boundary section from the Technical Reference Manual".

Nodes of this type mark the outer edges of a hydraulic schematisation. In short, these nodes
represent the geographical locations where a model has been cut out of the real world. Therefore their interaction with the world outside the model should be applied in terms of hydraulic
boundary conditions. The following options are available:

Flow boundary condition: the user submits a constant or alternating discharge that flows
into or out of the model (positive values mean in, negative mean out). Example: the
upstream edge of a river model where the model receives water from the upstream river
branches should be given such a condition;
Water Level boundary condition: the user submits a constant or alternating water level at

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the edge of the model’s area. Example: a river’s mouth, where tidal movement forms the
downstream boundary condition for the model;
A Q-H boundary condition: the user submits a relationship between water level and discharge. This type of condition is commonly used on the downstream edge of a river
model.
Note:

1 one should always place his or her boundary nodes at a sufficient distance from the area
that is to be modelled. The flow conditions that you apply to artificial boundary conditions
should never be allowed to influence the hydraulic results in the area of interest!
2 In case more than one branch is connected to a 1D h-boundary node, only a water level
boundary can be defined at this particular boundary condition. Further on the user-defined
water level boundary condition is applied to each and every branch that is connected to
this particular water level boundary.
3 Commonly, nodes of the Flow - Connection node type are also used as boundary nodes
for hydraulic schematisation. This too is allowed, as these nodes are similar to Flow Boundary nodes with a Q = 0 boundary condition.
Input screens
When starting the model data editor for a Flow - Boundary node, the following tabs will be
available for input:
The Boundary condition tab:

Figure 5.92: The Boundary condition tab of a Flow - Boundary node.

Graphical User Interface

On this tab, the following data can be entered:

A fixed or alternating water level as boundary condition By choosing the type "water

level (h)", the user can apply a fixed or alternating water level as a hydraulic boundary
condition to this node. This type of boundary condition is commonly used on the downstream edges of river models that end in a lake or sea. The option "Function of time" can
be used when the water levels at the downstream boundary alter in time (i.e. tidal waves)
More information about the tables for alternating boundary conditions can be found in the
chapter section 5.13.4..
A fixed or alternating discharge as boundary condition By choosing the type "flow
(Q)" the user can apply a fixed or alternating discharge as a hydraulic boundary condition
to this node. This type of boundary condition is commonly used on upstream edges of
river models, as these receive a certain discharge from upstream branches.
Note: although it is also possible to apply a discharge-boundary to a downstream node,
we advice you NOT to do so.
The reason is rather simple: in reality the discharge through a downstream boundary is
affected by the water levels in the area of interest. By enforcing a downstream discharge,
this relationship is discarded, thus leading to fake results. On downstream nodes therefore
we recommend the usage of "water level" or "Q-H" boundary conditions.
More information about the tables for alternating boundary conditions can be found in the
chapter section 5.13.4..
A Q-H relation as boundary condition By choosing the type "Q-H relation", the user
can define how the water levels and discharge at the boundary are related. This type of
boundary condition is commonly used for downstream boundaries in river models, when
the downstream boundary node lies somewhere in the middle of a river.
The Q-H relationship consists of a table that relates water levels and discharges to eachother. It is not easy to determine a proper Q-H relation for a river. Globally, there are two
ways to determine it: — measure it in the river — estimate it by calculating the hydraulic
radius at various water levels and applying the Chézy formula.
Topology

Nodes of the Flow - Boundary node type serve as the end- or starting point for a Flow - Branch
or a Sewer Pipe. Do not place nodes of this type just as loose objects in the schematisation
or on top of an existing branch. Flow Boundary nodes should always be part of a branch
themselves. A correct working method is:

Switch to the "edit network" mode in NETTER
Select the node type Flow - Boundary

Select the "add node" option
Place the node in the schematisation by clicking
Select the appropriate branch type (Flow Branch or Sewer Pipe)

Select the "connect nodes" option
Connect the boundary node that you just added to another node by clicking and dragging.
Some examples of valid methods to apply Flow-Boundary nodes:

SOBEK, User Manual

Figure 5.93: Examples of valid configurations with Flow - Boundary nodes

Note: when you attach more than one Flow - Branch to one Flow - Boundary node, you
can only apply a water level boundary condition to it. The reason for this is that in case of
a discharge condition, it would not be clear how to divide the discharge over the connected
branches.
5.3.10

Flow - General Structure
Description

In this chapter, the Flow - General structure node is described. The general structure combines weir and gate flow in one structure type. It offers you much freedom in defining geometry and dimensions of the structure. Discharges through a general structure are computed
on basis of upstream and downstream energy levels. The crest level, crest width and gate
lower edge level [m AD] can be varied by a controller. A structure inertia damping factor (see
Numerical parameters) can be defined for each General structure.

For a detailed description of this node’s input parameters: see the "input screens" section
from the Reference Manual;
For a detailed description of this node’s possible network configurations: see the "topology" section from the Reference Manual
For a detailed description of this node’s underlying mathematical equations: see the "General structure" section in the "Technical Reference Manual.
Input screens
When starting the model data editor for an Flow - General Structure node type, the following
tabs will be available for input:

Graphical User Interface

General structure tab:

Figure 5.94: Data Edit window, General Structure tab

On this tab, you can select a previously defined structure definition. If there is no definition
available yet, go to the "definitions" tab first, to create one.
Also, you can select the controllers that apply to this structure. If there are no controllers
available to be selected yet, go to the "controller" tab first to create them.
You can use the defined value for structure inertia damping factor as defined in Setting, Tab
– numerical parameters, or you can define a value for structure inertia damping factor for this
particular General structure. For meaning of structure inertia damping factor see Numerical
parameters.
Definitions tab:

SOBEK, User Manual

Figure 5.95: Data Edit window, Definitions tab

You must enter five dimensions for the flow width along the structure, plus five bed elevations
and the gate lower edge level (Zgle) See for the use and meaning of each dimension see the
Technical Reference Manual, Flow modules, General Structure.
You can use the default value for Extra resistance as defined in Setting, Tab – numerical
parameters, or you can define a value for Extra resistance for this particular General structure.
For meaning of Extra resistance see Numerical parameters.

Graphical User Interface

Figure 5.96: Cross-sectional view on general structure; definitions of vertical distances

Figure 5.97: Top view on general structure; definitions of width distances

Depending on the downstream water level free or drowned (submerged) flow can occur for
the weir or for the gate. For each of these conditions you must specify a reduction factor; if
you wish you can also enter values for the condition of reverse flow. The reduction factors
are used in the formulas given in the last part of the description in the Technical Reference
Manual.

Free gate flow cgf
Drowned gate flow cgd
Free weir flow cwf
Drowned weir flow cwd
Zgle Gate lower edge: the lower crest level of the gate.

SOBEK, User Manual

The default value for each coefficient is 1.00. Finally you must enter a contraction coefficient
for gate flow.
Controllers & Triggers tabs: see section 5.8.
Topology

Nodes of the type Flow - General Structure need to be attached to one of these branch types:
Flow Channel:

Flow Channel with lateral discharge
Add a Flow - General Structure node to your schematisation in the following way:

Select the appropriate node type (Flow - General Structure)
Use the "add node" button to add it to the schematisation. When clicking, SOBEK will

automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"
Note:

1 Before adding a general structure to your schematisation, you should have at least one of
the above Channel types present in it.
2 SOBEK by default places a computational point 0.5 m upstream and 0.5 m downstream of
the general structure location. Hence the general structure is default located on a branch
having a length of 1 m.
5.3.11

Flow - Lateral Flow
Description

A "Flow - Lateral Flow Node" can be used to model the lateral inflow (positive values) of water
and/or the lateral outflow (negative values) of water in a branch. For how lateral discharges
are assigned to a particular calculation point, reference is made to section 6.1.11.2.
Input screens
When starting the model data editor for an Flow - Lateral Flow node type, the following tab
will be available for input:

Graphical User Interface

Figure 5.98: Data Edit window, Lateral flow tab

Here, the lateral discharge can be specified.

Constant discharge When choosing this option, a constant lateral discharge is applied.
A positive value means inflow of water, a negative value means outflow of water.

Function of time Here a lateral inflow and or outflow as function of time can be specified.
Clicking the Table button opens a window like the one depicted below:

SOBEK, User Manual

Figure 5.99: Change Table window

In this table, the modeller can submit lateral discharges as function of time. More information about the input options of such tables can be found in the following chapter:
section 5.13.4.
Area based method The Area based method calculates lateral discharges based on the
runoff area, design factor, rainfall, seepage and/or infiltration (see Equation (6.14)). When
choosing the Area based method, the input window looks like this:

Graphical User Interface

Figure 5.100: Data Edit window, Lateral flow tab

Model-Wide Unit: Either Standard units or Hydrological units can be selected. In case
of Standard units: the runoff area is to be given in [square metres]; while seepage,
infiltration and constant rainfall are to be given in [milimetres/seconds]. In case of
Hydrological units: the runoff area is to be given in [hectares]; while seepage, infiltration and constant rainfall are to be given in [liters/second/hectares]. Please note that
selecting the option "Rainfall from Meteo Station" means that irrespective of the selected unit (Standard or Hydrological), the unit of the rainfall equals the unit defined
for the concerning Meteo station. Please further note that changing the selected unit
(f.i. from Standard unit into Hydrological unit) at a specific "Flow - Lateral Flow Node",
means that you change the unit for all lateral flows in your entire model schematization
that are computed using the Area based method .
Runoff Area: represents the surface area of the catchment, that is assigned to the
Lateral Flow node. For the unit of runoff area, see item "Model-Wide unit" above.
Seepage/Infiltration: Only constant Seepage (positive value, inflow) or or constant Infiltration (negative value, outflow) can be defined. For the unit of seepage and infiltration,
see item "Model-Wide unit" above.
Constant Rainfall: Here you can define a constant rainfall. For the unit of constant
rainfall, see item "Model-Wide unit" above.
Rainfall from Meteo Station: Here you can define that the rainfall (including unit) from
a particular Meteo station, defined in the Meteorological Task Block, is to be used.

Nodes of the type Flow - Lateral Flow need to be attached to one of these branch types:

SOBEK, User Manual

Flow Channel with lateral discharge

Add a Flow - Lateral Flow node to your schematisation in the following way:

Select the appropriate node type (Flow - Lateral Flow)
Use the add node
button to add it to the schematisation. When clicking, SOBEK will
automatically find the nearest channel to attach it to.
another branch by using the "move node"

If desired, the node may later-on be moved to other locations on the branch, or even to
button.

Example of how a network could contain a Lateral Flow node:

Figure 5.101: Example of network with a Lateral Flow node

5.3.12
5.3.12.1

Flow - Flow manhole

Flow - Flow manhole (basic)
Flow Manhole description

This chapter describes the Flow - Manhole node. These nodes form a basic modelling element for all urban schematisations. Manholes can be interconnected by Flow-Pipes and/or
internal structures. At Flow-Manholes the Water levels are calculated. On Flow-Pipes, discharges are calculated.

For a detailed description of this nodes input parameters, see the "Flow - manhole input
screens" section from the Reference Manual.
Flow Manhole input screens
When starting the model data editor for an Flow - Manhole node type, the following tabs will
be available for input:
Storage tab:

Graphical User Interface

Figure 5.102: Data Edit window, Storage tab

On this tab, the following data can be entered:

The bottom level level and storage area of the manhole.

A manhole is in fact a small reservoir that interconnects two or more sewer pipes. Therefore, it has a certain storage volume. This volume is defined by the bottom level, the
surface level and the area of the manhole. (Surface level - Bottom level)*surface area =
total storage capacity of the manhole.
On this tab, the modeller can also choose between three manhole types:

SOBEK, User Manual

Figure 5.103: The difference between Flow-manholes of the type "closed", "reservoir"
and "loss"

The difference between Flow-manholes of the type "closed", "reservoir" and "loss"
Three manhole types that can be chosen. Note: In case the ’loss’ type is chosen, all water
that exceeds the surface level, will be removed from the model. However, if you connect it
with a 2D grid (Overland Flow module), it will exchange water with the grid.

Reservoir In case the manhole type "Reservoir" is chosen, there will be an open connection between the manhole and the street surface. This means that, if the water level in the
manhole exceeds the street level, it will inundate the ’storage area’ that can be entered
in the section below.Choosing the type ’reservoir’ is useful if you desire to connect your
sewer model with a 2D grid (Overland Flow module). That will allow interaction between
flow in the pipes (1D) and flow over the land (2D).
Closed Choosing a manholes of the type "Closed" means that you have selected a manhole that has a lid at street level, thus there will be no interaction between the water within
the manhole and the street surface.
Loss Manholes of the type "Loss" will have all water that exceeds the entered street level
flow out.Thus, you might want to use this manhole type if you need to connect it to a 2D
grid (Overland Flow module). Water that exceeds the street level will then start flowing
over the 2D grid.
5.3.12.2

Flow - Flow manhole with level measurement
Measurement stations
Measurement stations represent locations where structure controllers get the required hydraulic information. Flow-Measurement Pipes are Flow-Pipes with a discharge measurement
station. These branches have a length, a cross section and a resistance. Flow-Manholes with
Level Measurement are Flow-Manholes with a water level measurement station. Before you
can specify a controller you must define a measurement location in the schematisation.

Graphical User Interface

Flow - Flow manhole with runoff
Flow-manhole with runoff - description

This chapter describes the Flow - Manhole with Runoff.
Basically, these nodes are equal to Flow - Manholes. The only difference is that Flow manholes with runoff have an extra option to transfer rainfall into a discharge into the pipes
(rainfall-runoff).

For a detailed description of this node’s input parameters defining its physical dimensions
(Sewer Flow), see the "Flow - manhole input screens" section from the Reference Manual.

For a detailed description of this node’s Rainfall-Runoff input parameters defining the

catchment dimensions, see the "Module - Rainfall runoff section of the Reference Manual"

For a detailed description of this node’s possible network configurations: see the "Flow Manhole topology" section from the Reference Manual
Flow - Measurement station

In this chapter, the Flow Measurement station node is described.

Measurement stations represent the locations from where structure controllers get their required hydraulic information. Before you can specify a controller you must place at least one
measurement station in the schematisation.

For a detailed description of this node’s possible network configurations: see the "Measurement station node topology" section from the Reference Manual
Note that, after placement of a measurement station, your schematisation needs to be saved
before a structure will know that it exists! After saving, you’ll notice that when editing model
data for structures, various controlling options become available under the "controller" tab.
Topology
Nodes of the type ’Measurement Station’ need to be placed on a Flow Branch. Do this by
using the

(add node) button.

Figure 5.104: Placement of a Flow Measurement Station node

Note: the measurement station will derive information about the water level from the nearest
ζ -calculation point.

SOBEK, User Manual

Flow - Orifice node
Description

In this chapter, the Flow - Orifice node is described.
With a Flow - Orifice node you can simulate rectangle-shaped gates through which water
within a channel or river is led. Orifices are used to regulate the water flow through or towards
a channel or river. For a detailed description of this node’s underlying mathematical equations:
see section 6.1.16.8.
Some applications are:

In rivers: used to regulate the division of flows over an upstream split-point.
In deltas: to protect the delta against storms on the coast (the orifices close during a
In smaller channels: to allow water to flow into an area in periods of drought.

Input screens
When starting the model data editor for an Flow - Orifice node type, the following tabs will be
available for input:
Orifice:

Figure 5.105: Data Edit window, Orifice tab

Graphical User Interface

On this tab, you can fill in the general dimensions and parameters for the orifice:

Width: This parameter represents the width of the gate through which the water will flow.
Crest level: This parameter represents the bottom crest level of the gate.
Initial openings height: Here you can enter the vertical dimension of the gate for the

start of the simulation. For orifices it is common to apply a controller, which will define
the gate height during the simulation. If you don’t define a controller, the initial openings
height will remain valid throughout the entire simulation.
Contraction coefficient µ: This parameter represents the energy loss that is caused by
contraction of the flow towards the orifice. This phenomenon generally occurs when the
weir’s crest is less wide than the channel. See the Technical Reference Manual for the
exact mathematical implementation of this parameter.
Lateral Contraction Cw : This parameter represents the energy loss that is caused by
contraction of the flow towards the orifice. This phenomenon generally occurs when the
weir’s crest is less wide than the channel. See the Technical Reference Manual for the
exact mathematical implementation of this parameter.
Possible flow directions: This parameter defines in which direction(s) water can flow
through the orifice. The directions are defined with relation to the defined branch direction. Positive means: in the same direction as the defined branch direction; negative
means: in the opposite direction than the defined branch direction. If you don’t know the
defined direction of the branch, read the Flow - Branch topology section of the Functional
Reference Manual. In addition to defining the flow directions, you can also define a maximum flow through the gate for each flow direction. To do so, activate the check boxes next
to the word "Max. flow" and enter a value.
Controller:

Figure 5.106: Data Edit window, Controller tab

SOBEK, User Manual

On this tab, you can define a controller for your orifice. A controller will overrule your general
settings for the orifice’s opening height and apply the chosen controlling rules to it. Read
more about them in section 6.4.1.
Note that three of the four available controller options only become available after you have
defined a Flow - Measurement station within the schematisation and saved that schematisation.
Topology

Nodes of the type Flow - Orifice need to be attached to one of these branch types:

Flow Channel:
Flow Channel with lateral discharge

Add a Flow - Orifice node to your schematisation in the following way:

Select the appropriate node type (Flow Orifice)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note: Before adding an orifice to your schematisation, you should have at least one of the
above Channel types present.
5.3.15

Flow - Pump station node

A Flow - Pump station can be used to remove excess water or to supply water for drought
prevention. In the section Topology it is explained how to place a Flow - Pump station on
a network. The data input screens are described in the section Data input screens. See
section 6.1.16.9 for detailed information on:

Pump discharge direction with respect to the positive x-direction along the branch,
Pump stages,
Controller options at a Pump station,
Capacity reduction table,
Pump station output parameters,
Dead-band triggering algorithm,
Conventions for switch-on and switch-off levels.

Nodes of the type Flow - Pump Station need to be attached to one of these branch types:
Flow Channel:

Graphical User Interface

Flow Channel with lateral discharge

Add a Flow - Pump Station node to your schematisation in the following way:

Select the appropriate node type (Flow Pump Station)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
button.

another branch by using the "move node"

Note: Before adding a pump station to your schematisation, you should have at least one of
the above Channel types present in it.

Figure 5.107: Example of a valid network configuration containing a pump station.

SOBEK, User Manual

Figure 5.108: Example of the application of a Flow - Pump Station. If you would define
a "positive pump direction", here node #1 would be the suction side and
node #2 would be the pressure side.

Data input screens

After starting the model data editor for an Flow - Pump Station node type, the Pump tab (see
Figure 5.109) becomes available. On the Pump tab two separate windows can be opened,
respectively the reduction table window (see Figure 5.110) and the pump data window (see
Figure 5.111) For detailed information on the various pump station input parameters, reference is made to section 6.1.16.9.

Following pump characteristics can be defined on the Pump tab (see Figure 5.109):

Number of different pump stages
Reduction factors on pump discharge capacity (see also Figure 5.110)
Unit of the specified pump discharge capacity
Location of dead-band triggers (Suction-side only, Delivery-side only, both Suction-side
and Delivery-side)
Pump stage data (see also Figure 5.111)

Graphical User Interface

Figure 5.109: Data Edit window, Pump tab

In the capacity reduction window (see Figure 5.110), the capacity reduction factor can be
defined as function of pump head (e.g. water level at delivery-side minus water level at the
suction-side).

SOBEK, User Manual

Figure 5.110: Data Edit window, Capacity Reduction Table tab

In the Pump data window (see Figure 5.111), for each pump stage following parameters can
be defined:

Pump stage capacity
Switch-on-level at the Suction-side (if applicable)
Switch-on-level at the Delivery-side (if applicable)
Switch-off-level at the Suction-side (if applicable)
Switch-off-level at the Delivery-side (if applicable)

Graphical User Interface

Figure 5.111: Data Edit window, Capacity Reduction Table tab

Flow - River Advanced Weir
Description

In this chapter, the Flow - Advanced Weir node is described.

The advanced weir requires entry of values for crest level, (net) sill width and number of piers.
Discharges through an Advanced weir are computed on basis of upstream and downstream
energy-levels. The crest level can be varied by a controller. A structure inertia damping factor
(see Numerical parameters) can be defined for each Advanced weir.

For a detailed description of this node’s input parameters: see the "input screens" section
from the Reference Manual;
For a detailed description of this node’s possible network configurations: see the "topology" section from the Reference Manual
For a detailed description of this node’s underlying mathematical equations: see the "Advanced weir" section in the "Technical Reference Manual".
Input screens
When starting the model data editor for an Flow - Advanced Weir node type, the following
tabs will be available for input:
Advanced weir tab:

SOBEK, User Manual

Figure 5.112: Data Edit window, Advanced Weir tab

On this tab, you can select a previously defined structure definition. If there is no definition
available yet, go to the "definitions" tab first, to create one.
Also, you can select the controllers that apply to this structure. If there are no controllers
available to be selected yet, go to the "controller" tab first to create them.
You can use the default value for structure inertia damping factor as defined in Setting, Tab –
numerical parameters, or you can define a value for structure inertia damping factor for this
particular Advanced weir. For the mening of structure inertia damping factor see Numerical
parameters.
Definitions tab:

Graphical User Interface

Figure 5.113: Data Edit window, Definitions tab

The advanced weir requires entry of values for crest level, (net) sill width and number of piers.
The crest level can be varied by a controller. For the following parameters you get default
values in the corresponding data fields, which you may adapt to your particular situation.
1 Upstream face height The height of the weir relative to the bed level at the upstream
sideA default value of 10 m is available, but you should enter the actual value.
2 Design head The head for which the structure was designed. A default value of 3 m is
available, but you should enter the actual value.
3 Pier contraction The contraction coefficient represents the net sill-width reduction due to
the presence of piers. It depends on the shape of the piers. Default value is 0.01.
4 Abutment contraction The contraction coefficient represents the net total flow width reduction due to the presence of abutments. It depends on the shape of the abutments.
Default value is 0.10. If reverse flow may occur you can adapt the values for that condition
as well.
Controllers & Triggers tabs: see section 5.8.
Topology

Nodes of the type Flow - Advanced Weir need to be attached to one of these branch types:
Flow Channel:
Flow Channel with lateral discharge
Add a Flow - Advanced Weir node to your schematisation in the following way:

SOBEK, User Manual

Select the appropriate node type (Flow - Advanced Weir)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK will
automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Flow - River Pump

A Flow - River Pump can be used to remove excess water or to supply water for drought
prevention. Controllers can not be assigned to a River pump. In the section Topology it
is explained how to place a Flow - River Pump on a network. The data input screens are
described in the section Data input screens. See section 6.1.16.11 for detailed information
on:

Note:
1. Before adding an Advanced weir to your schematisation, you should have at least one of
the above Channel types present in it.
2. SOBEK by default places a computational point 0.5 m upstream and 0.5 m downstream of
the Advanced weir location. Hence the Advanced weir is default located on a branch having
a length of 1 m.

Pump discharge direction with respect to the positive x-direction along the branch,
Pump stage,
Constant Reduction Factor,
Reduction Factor F(Pump Head),
Pump station output parameters,
Dead-band triggering algorithm,
Comparison of a River Pump and a Pump station.

Nodes of the type Flow - River Pump need to be attached to one of these branch types:
Flow Channel:

Flow Channel with lateral discharge

Add a Flow - River Pump node to your schematisation in the following way:

Select the appropriate node type (Flow - River Pump)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK will
automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Note:
1 Before adding a river pump to your schematisation, you should have at least one of the

Graphical User Interface

above Channel types present in it.
2 SOBEK by default places a computation point 0.5 m upstream and 0.5 m downstream of
the River pump location. Hence the River pump is default located on a branch segment
having a length of 1 m.
Data input screens

After starting the model data editor for an Flow - River Pump node type, the River Pump
tab (see Figure 5.114) becomes available. On the River Pump tab you can select a previously defined River Pump definition. Various River Pumps definitions can be specified on the
Definition tab (see Figure 5.115).

Figure 5.114: Data Edit window, River Pump tab

On the Definition tab of a River Pump (see Figure 5.115) following parameters can be defined:

Control direction,
Capacity,
Start level,
Stop level,
A Constant Reduction Factor or a Reduction Factor F(Pump Head),

For detailed information on these various River Pump input parameters, reference is made to
section 6.1.16.11.

SOBEK, User Manual

Figure 5.115: Data Edit window, Definition tab

Flow - River Weir
Description

Different crest shapes (broad crested, triangular, round or sharp) can be defined for a Flow
- River Weir by selecting a particular "drowned reduction curve" (see Figure 6.38 in section 6.1.16.12). Crest levels of a Flow - River Weir cannot vary in height along the weir.
Discharges through a Flow - River Weir are computed on basis of upstream and downstream
energy-level. For the applied mathematical equations, reference is made to section 6.1.16.12.
The crest level and crest width of a river weir can be varied by a controller. A structure inertia
damping factor (see Numerical parameters) can be defined to each River weir.
Input screens
When starting the model date editor for an Flow - River Weir node type, the following tabs will
be available for input:
River weir tab:

Graphical User Interface

Figure 5.116: Data Edit window, River Weir tab

On this tab, you can select a previously defined structure definition. If there is no definition
available yet, go to the "definitions" tab first, to create one.
Also, you can select the controllers that apply to this structure. If there are no controllers
available to be selected yet, go to the "controller" tab first to create them.
Definitions tab:

SOBEK, User Manual

Figure 5.117: Data Edit window, Definitions tab

On this tab, you can define the properties of your River Weir structure. Select an existing definition from the drop-down box or create one by typing an appropriate name in the "definition"
field and then clicking .
Then you can:

Define the crest level of the weir
Define the crest width of the weir
Define the crest’s shape: choose between (broad, triangular, sharp and round)Note that
changing the crest’s shape will change the default flow coefficients.

Define a correction coefficient: For flow in the positive direction of the branch or in the
opposite direction, default correction coefficients cw are proposed by SOBEK for each
crest shape (see also Technical Reference Manual, Flow Modules, River Weir). If you
wish, you can replace them by other values.
Define the submerge flow coefficient. If the tail water level affects the weir flow, drowned
(submerged) flow occurs. Whether this happens is determined by the submergence (or
modular) limit. For each crest shape a default value is presented. If the submergence
factor Sf ((H2-Zs)/(H1-Zs)) is above the submergence limit, the flow is multiplied by a
corresponding drowned reduction factor, which is also a function of the crest shape. The
default values are shown in the Technical Reference Manual, Flow Modules, River Weir. If
you wish to apply other factors you can enter them in a table, accessible through Edit. A
similar table is available for reduction factors applying to the reverse flow condition
Controllers & Triggers tabs: see section 5.8.
Topology

Graphical User Interface

Nodes of the type Flow - River Weir need to be attached to one of these branch types:
Flow Channel:
Flow Channel with lateral discharge
Add a Flow - River Weir node to your schematisation in the following way:

Select the appropriate node type (Flow - River Weir)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK will
automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to

another branch by using the "move node"

1 Before adding a River weir to your schematisation, you should have at least one of the
above Channel types present in it.
2 SOBEK by default places a computational point 0.5 m upstream and 0.5 m downstream
of the River weir location. Hence the River weir is default located on a branch having a
length of 1m.
Flow - Universal Weir
Description

The Flow - Universal Weir is a broad crested weir. Crest levels may vary in height along the
weir. For the assumptions made in the parameterization of the Flow - Universal Weir as well
as for the applied mathematical equations, reference is made to section 6.1.16.14
Input screens
When starting the model data editor for an Flow - Universal Weir node type, the following tabs
will be available for input:
Universal Weir:

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Figure 5.118: Data Edit window, Universal Weir tab

On this tab, the general dimensions of the weir can be defined:

Crest Level: This value represents the lowest part of the weir’s crest. On the cross
section tab, later on the exact shape of the crest can be defined.

Discharge coefficient Ce: This parameter represents the discharge coefficient for the
weir, as present in the formula that applies to this type of structure. See the "Universal Weir" section in the Technical Reference Manual for the exact implementation of this
parameter.
Possible flow direction: This parameter defines in which direction(s) water can flow over
the weir. The directions are defined with relation to the defined branch direction. Positive
means: in the same direction as the defined branch direction; negative means: opposite
of the defined branch direction. If you don’t know the defined direction of the branch, read
more about it in the Flow - Branch topology section of the Functional Reference Manual.
Cross Section:

Graphical User Interface

Figure 5.119: Data Edit window, Cross section tab

On this tab, the actual shape of the weir’s crest should be defined. This is done by means of
cross section definitions, very similar to the ones you define for the shape of a river bed.
The only real difference is that the number of cross section types is limited to two:

Y-Z profile
Asymmetrical Trapezium

For a detailed description of both cross section types and their input parameter, see the "Functional Reference Manual" - "Channel Flow module" - "Cross section types" section.
5.3.20

The Flow - Weir is a broad crested weir. Crest levels cannot vary in height along the weir. For
the applied mathematical equations, reference is made to section section 6.1.16.16.
Input screens
When starting the model data editor for an Flow - Weir node type, the following tabs will be
available for input:
Weir:

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Figure 5.120: Data Edit window, Weir tab

On this tab, the weir’s general dimensions can be filled in:

Width This parameter represents the width of the crest over which the water will flow.
Crest level This parameter represents the level (with relation to reference level) of the
weir’s crest. Note that the value you fill in here may be overruled by a controller, if you
desire.
Discharge coefficient Ce This parameter represents the discharge coefficient that is
used for calculation of the discharge. See the Technical Reference Manual for the exact
mathematical implementation of this parameter.
Lateral contraction coefficient Cw This parameter represents the energy loss that is
caused by contraction of the flow towards the weir. This phenomenon generally occurs
when the weir’s crest is less wide than the channel. See the Technical Reference Manual
for the exact mathematical implementation of this parameter.
Possible flow direction This parameter defines in which direction(s) water can flow over
the weir. The directions are defined with relation to the defined branch direction. Positive
means: in the same direction as the defined branch direction; negative means: in the
opposite direction than the defined branch direction. If you don’t know the defined direction of the branch, read the Flow - Branch topology section of the Functional Reference
Manual.
Controller:

Graphical User Interface

Figure 5.121: Data Edit window, Controller tab

On this tab, you can define a controller for your weir. A controller will overrule your general
settings for the weir’s crest level and apply the chosen controlling rules to it. Read more about
them in the Controller section of the Technical Reference Manual.
Note that three of the four available controller options only become available after you have
defined a Flow - Measurement station within the schematisation and saved that schematisation.
5.3.21

Flow - 2D-Boundary
Description

General description:
The 2D - boundary node works more or less the same as its counterpart in the 1D-channel
flow module. The boundary condition is either a water level or a discharge, both of which can
be either constant or varying in time.
Important: the grid cell on which a 2D-Boundary node is placed, should be given the no-data
value! (often -9999) If not, this object will not work.

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How the 2D-boundary node works:

Any 2D grid cell can discharge into any of the four cells directly surrounding it. However, a
2D cell containing a boundary can only discharge into (any) ONE of these cells! By default, it
discharges into the cell directly to the right of it. The flow direction can be controlled by defining
no-data values in the surrounding cells to which the boundary cell should NOT discharge. This
way, if you define 3 no-data values out of 4 surrounding cells, the boundary cell will discharge
into the remaining cell (see example Figure 5.122).

Figure 5.122: Possible configuration of a 2D boundary node. Note: the white (transparent) cells contain no-data values

In case of a 2D h(t) boundary condition, the water level is directly imposed at the active
grid cell that lies in front of the concerning 2D boundary grid cell. Hence there is no water
movement over the concerning 2D boundary grid cell.
In case of a 2D Q(t) or 2D Q-h boundary, an artificial 1D link is created from the concerning
2D boundary grid cell towards the active 2D grid cell that lies in front of this 2D boundary grid
cell. The hydraulic properties of this artificial 1D link are based on the properties of the active
2D grid cell lying in front of the 2D boundary grid cell. This implies that in case of a 2D Q(t)
or 2D Q-h boundary water movement over the 2D boundary grid cell is taken into account.
Suggestions for the user:

If you decide to use a Discharge boundary condition as part of the 2D schematisation, it is
wise to define an initial water level point in the 2D grid cell into which the cell containing the
boundary condition should flow. The reason for the initial water level point in this case is
purely a numerical one, as sometimes no water will flow at all from the discharge boundary.
The water depth can be very small, for example one centimeter.
The initial water level node will (instantly) fill up all surrounding 2D grid cells with water, until
cells which have a higher terrain level are branched, or if the edge of the grid is branched.
This can be a problem when using a discharge boundary condition on a high point in the grid:
an initial water level used for numerical reasons may fill a large part of the grid! This problem
can be solved by lowering the terrain level of the 2D grid containing the initial water level point
slightly below the level of the surrounding cells.

Graphical User Interface

One more rule to remember when using this node is that the 2D grid cell containing the node
should be defined manually as ’no-data value’!. This can be done in ’edit model data’ mode,
under the properties of the 2D grid.
Finally, it is not possible to add this type of node to a grid cell that already contains a 1Dboundary node.
2D-Boundary nodes are normally used in situations where the dam break is modelled starting
in the 2D schematisation, as opposite to starting in the 1D-schematisation.

Editing 2D-Boundary data

After selecting any 2D-boundary node in the edit model data mode and pressing Edit, the data
edit window for this node type pops up. The first tab ’location’ displays the (non-editable) id
and location of node.

Under tab ’boundary condition’, the user can specify the boundary condition. See Figure 5.123.
There is a choice between a Water level boundary condition or a Flow boundary condition.
Both of these can be given either a constant value or a value changing in time.

Figure 5.123: 2D-boundary edit window - boundary condition tab

A variable water level or flow in time can ben entered by pressing table. . . and filling in the
table, as shown in the example in Figure 5.124:

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Figure 5.124: Change table window

Please note that the water level is defined relative to the reference level (positive above the
reference level), and that it is not possible to enter a water depth as a boundary condition.
Also note that a positive value for the flow means input into the system, while a negative value
means output.
2D Q-h tabulated boundary condition

Functionality:
The 2D Q-h tabulated boundary condition enables the user to apply a Q-h relationship as
the (downstream) boundary condition of a 2D grid. A Q-h relationship is to be defined as
discharges as function of water levels Q = f (h). Presently a 2D Q-h tabulated boundary
condition may not pass over nested grids and should be parallel to either the x-axis or y -axis
of the 2D grid. Further on a 2D Q-h tabulated boundary condition is supposed not to pass
over a 1D channel flow schematisation.
How to define:

Double click the ‘Schematisation’ task block and thereafter click the Edit Model button on
the Schematisation window.

Click the Zoom in button and go to the location where you want to place the 2D Q-h
Tabulated boundary condition.

Click the Edit Network button.
Click the Nodes button, pull-down the menu and click the Overland Flow Model/ 41, 2D Corner node.

Graphical User Interface

Click the Branch button, pull-down the menu and click the Overland Flow Model/ 16, 2D Line Boundary.

Click the Edit action button, pull-down the menu and click on Nodes/Add Nodes. Go to

the location where you want to place the first 2D Corner node of the 2D Q-h Tabulated
Boundary Condition and click with your left mouse button. Place the second 2D Corner
node in the same way.
Click the Edit action button, pull-down the menu and click on Connection/Connect nodes.
Click with the left mouse button on your first 2D Corner node. While pressing down the
left mouse button drag a line to your second 2D Corner node and release your left mouse
button.
Click the button to end the network editing activities.
Click on the 2D Q-h Tabulated Boundary Condition and thereafter click with your right
mouse button, and click on Model data/ Overland Flow Model. The ‘Data Edit’ window
should appear on your screen.
Click the ‘Q-h relation’ check-box in the ‘Boundary condition’ Tab of the ‘Data Edit’ window.
Click on the button in the ‘Data Edit’ window to enter your Tabulated Q-h relation
in the ‘Change Table’ window.
Close both the ‘Change Table’ and the ‘Data Edit’ windows by clicking OK.
Click the Save Network button for saving your defined 2D Q-h Tabulated Boundary Condition.

Figure 5.125: Data Edit window, Boundary condition tab

How to retrieve information:
Under the ‘Results in Maps’ Task block

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Double click the ‘Results in Maps’ task block.
Click in the main menu on File/Open Data/Overland Flow Module Result at history stations
(i.e. in the ‘Select item’ window)

In the ‘View Data’ window select for instance the hydraulic parameters "Water level" and
Abs.Disch [m3 /s]’.
Click the 2D Q-h Tabulated Boundary Condition and then click with right mouse and then
on show graph or click on the button in the ‘View Data’ window.
Under the ‘Results in Charts’ Task block

Double click the ‘Results in Charts’ task block.
Double click on Overland Flow Module/ Results at history stations (in the ‘Results in
Charts’ window).

In the ‘ODS-View’ window select under parameters Water level and Abs Disch [m3 /s],

under location select location l_x (where l stands for link and x for the ID of the 2D Qh Tabulated boundary condition), under time-steps select the required time-period. Now
click on the Graph button or Export button to respectively view a graph or export to the
data to a particular file.
2D Refined Q boundary condition
Functionality:

In effect the 2D refined Q-boundary condition refers to an improvement of the existing 2D
Q-line boundary condition. In the past imposed discharges were equally distributed over
the number of concerning 2D grid cells. Nowadays imposed discharges are distributed in
accordance with the conveyance capacity of the concerning 2D grid cells.
5.3.22

Flow - 2D-Breaking Dam
Description

Dike bbranches can be modeled either in 1D (see Branch – Flow Dam Break) or in 2D using
a 2D Breaking - Dam Node (see Figure below). You have two options for controlling the bed
level of the 2D grid cell that lies underneath a 2D Breaking – Dam:

Using the Decrease in Height Time Table,
Using a controller that can be overruled by RTC or RTC-Matlab. For more information see
Module – SOBEK Real Time Control (RTC).

For information on how to use these control options, see Editing Node 2D Breaking Dam.

Figure 5.126: Example of 2D- Breaking Dams located on 2D grid cells

Graphical User Interface

Remark:
A 2D breaking dam node may not lay on an active 2D grid cell that is surrounded by a
boundary condition cell.
Editing 2D-Breaking Dam data

The 2D-Breaking Dam enables you to control the bed level of its underneath lying 2D grid cell.
Following control options are available:

see Module – SOBEK Real Time Control (RTC).

Option 1: The Decrease in Height Time Table,
Option 2: A controller that can be overruled by RTC or RTC-Matlab. For more information

You can select either option 1 or option 2 by checking its corresponding radio bullet (see
Figure 5.127 below).

Figure 5.127: Example of selecting the controller option for a 2D Breaking - Dam

Option 1: The Decrease in Height Time Table
Check the “Decrease in Height Time Table” radio bullet and click on the Table button. You can
now specify the lowering of the 2D grid cell lying beneath your 2D Breaking – Dam as function
of time (see Figure 5.128).

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1 You specify the lowering with respect to the start level (or initial bed level) defined in your
2D bed level grid (i.e. <*.asc> file). Positive and negative values respectively mean that
your grid cell will moved downwards or upwards,
2 SOBEK applies linear interpolation in the Decrease in Height Time Table,
3 In case the actual computational time is before the first time or after the last time specified
in your Table, SOBEK will respectively apply the value on the first row or the value on the
last row of your Time Table.

Figure 5.128: Example of a Decrease in Height Time Table available at a 2D Breaking –
Dam

Option 2: A controller
Firstly you have to define a controller. Thereafter you can select this controller as the one
providing set points for the bed level of the 2D grid cell lying beneath your 2D Breaking –

Graphical User Interface

Dam.
Defining a controller for a 2D Breaking – Dam:
Click on the “Controllers” Tab (see Figure 5.129) and type a name in the “Definition” scroll
box. Now click the Define button and specify your controller. Don’t forget to click the Save
button in order to save your controller definition.

Remarks:
Presently only a Time Controller providing bottom(bed) levels as set point for a 2D
Breaking – Dam can be defined,
Update frequency=1, means that the set point of controller is updated after each hydrodynamic time step, defined in Settings; Update frequency=10, means that the set point
of the controller is updated every 10 hydrodynamic time steps,
dValue/dt=0.002 m/s, means a maximum speed for the change in bed level (either positive or negative) of 0.002 m/s. Hence in one minute a maximum bed level change of
0.12 m (=0.002 m/s * 60 s) is allowed,
Click on the Time Controller Table button for specifying your set points.

Figure 5.129: Example defining a controller for a 2D Breaking – Dam

Assigning a controller at a 2D Breaking – Dam:
Click on the 2D Breaking – Dam Tab and check the “Controller” radio button. Now select your
previously defined controller in the “Controllers” scroll box (see Figure 5.129 above).
Remark:
In the “Controller” scroll-box you can only select so-called 2D Flow controllers. Hence
you cannot select a 1D Flow controller or a RR controller.

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Flow - 2D-Grid
2D-Grid node

This is one of the most important building blocks for the modelling of 2D systems, and the
one you would usually start with. It is referred to in the user interface as a ’node’ which at first
sounds confusing, as this node actually represents a whole grid.
A grid can be either imported from a GIS system, or defined within SOBEK as a new grid.

Importing a ’2D grid’ is possible by selecting the ’import 2D grid’ option, an option which
has been added to the standard SOBEK edit network menu (see Figure 5.130). Note that this
option is only available after you have selected the ’2D grid’ node as a building block.

Figure 5.130: Edit network menu, Import 2D-Grid... menu

Edit network menu

After you have selected this option, you need to select the -file that contains the grid
information you want import. As mentioned before, this -file is a standard grid definition file, which can be generated as output by for example ARCView (see appendix for an
example). The file contains the following information about the grid:

the number of columns
the number of rows
x-coordinate of the bottom left corner of the grid
y-coordinate of the bottom left corner of the grid
cell size of the grid elements (same for x and y size)
the no_data value (’missing value’), usually -999 or -9999
For every cell the terrain level.

Graphical User Interface

In theory, you can select the file from any given path, for example .
However, we strongly recommend using the default directory for these filenames, which is the
directory. This makes it easier to make a copy of an existing project
and give it to somebody else.
After you have successfully imported the grid, it should appear on the map at the coordinates
specified in the file. You can then visualise the terrain levels of all grid cells by turning on
the active legend (under options) and activate the z-data (model data) from the legend panel.
The active legend will be explained later on.

Most of the time, grids will (need to) be imported from GIS based programs. It is however also
possible to define the 2D grids by hand, by selecting the ’define 2D grid’ option from the edit
network menu (see Figure 5.131). This means that the user will not only have to define the
exact location and size of the grid, but also the terrain level for every grid element. In theory,
one can place the grid at any given location and make it any given size. However, the way the
grids are defined have a major impact on the accuracy of the results, so accurate definition of
2D grids is very important. There are a number of considerations important in this matter:

The number of grids and the number of elements determine the simulation time. The less

elements there are, the shorter the simulation takes.

The smaller the grid elements are, the more accurate the results can be. It is therefore a
good idea to choose a coarse grid in (most) places where accuracy is not required, and a
more fine grid in places where results are critical, for example close to the inlet point/ dam
break point. Another option is to choose the resolution of the grid in the same order as the
resolution of the available terrain level input data.
The grid elements containing a no-data value don’t participate in the calculations; they are
used to specify the barrier around the area of interest, and possibly as no-flow locations
within the area of interest.
Grid properties

For every grid you need to specify a number of properties, some of which need to be specified
immediately, while others can be defined later in the ’model data’ mode.
Figure 5.131 shows the properties that need to be defined.

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Figure 5.131: Grid properties

Selected point information

The ’X’ and ’Y’ coordinates are the coordinates of the map position you selected by pressing
the mouse button just before entering this menu. They represent a (any) corner of the 2D
grid you are about to define. If you are not satisfied with the coordinates, you can alter them
manually here.
The Position represents which of the four corners should appear at the X-Y coordinate you
defined. By default it’s the left-bottom corner.
Filename

The default location for putting the .asc files is the directory. Make
sure you select a path before saving the grid file.
2D grid definition

Name If you want to, you can specify a unique grid name. This is not absolutely necessary,
as a default name will be defined for you if you don’t specify a name here.
Columns/Rows Every grid is rectangular in shape, the size of which is determined by the
number of rows and columns. The area of interest is inside the rectangular grid, which is
filled up with the no-data values.
Width/Height [m] The width and height of every cell are uniform for the whole grid, so it’s
not possible to specify varying grid size elements throughout one grid. However, different
grids within one schematisation can have different grid sizes.
Level [m] (above OR below reference level, dependent on your definition in SETTINGS)
When using the define 2d grid option, it is only possible to define one uniform terrain level.

Graphical User Interface

Later on, in the edit model data mode, there is the possibility to change terrain levels for
single grid elements.
X0/Y0 This is the same coordinate as specified under selected point.
Parent 2D-grid
This option is only relevant when using multiple grids that are either overlapping or nested.

If you select the align to parent option, the child grid will be replaced according to the parent
grid. If you select Fix parent, the position of the parent grid will be changed according to the
position of the child grid. Note that the position of the top left corner of the grid selected will
be changed, and not the number of rows or columns. So, make sure to check both the top
left and bottom right corner of the child grid afterwards to check the alignment. It may be
necessary to adjust the size (columns/ rows) of the child grid manually.
Note: due to an error in the options ’align to parent’ and ’fix parent’, these options should not
be used at the moment!

Edit 2D-grid. . .

This option is available under the edit network menu (see Figure 5.130). Opening the grid
properties window (see Figure 5.131), it gives the user the possibility to change grid properties, after the grid has been defined. If you decide to resize the grid (number of columns and/
or rows, don’t forget to edit the terrain levels in the -file accordingly.
Before you can edit the properties of any grid, you will first have to select the node that
represents the grid. And in order to be able to select this type of node, they first have to be
made visible. This can be done by selecting options → network options → nodes. . . select
the 2D grid node and turn on visibility (see Figure 5.132). The 2D-grid nodes should now be
visible in the schematisation.

Figure 5.132: Node settings

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Change 2D-grid order. . .

After selecting this option from the edit network menu, Figure 5.133 appears:

Figure 5.133: 2D Grid Order Window

Here you can change the order of nested grids according to the rules specified in the FAQ on
multiple grids. In short, the child grid (in Figure 5.133 the small green grid, grid 25) should be
’on top of’ the parent grid (the blue grid, grid 18).
This means that in the table on the left, the parent grid should be mentioned BEFORE the
child grid. If the grid order is wrong (clearly visible in the 2D grid order window because the
child grid is hidden behind the parent grid), the simulation will stop. By default, the grid order
is defined by the order in which the grids are defined in the first place. So if you first define
the parent grid, and then the child, the grid order will be correct. If you first define the child,
and the parent, the order needs to be changed using this option.
So, it is very important to always check this option after defining new grids!
Editing 2D-Grid data

After a 2D grid node has been selected for editing, window Figure 5.134 appears:

Graphical User Interface

Figure 5.134: Grid data window - 2D Grid location tab

This tab displays general information about the selected grid, which was already defined during the edit network mode. If you want to change any of the data specified here, you need to
go back to the edit network mode and use the ’Edit 2D grid settings’ option.
The next tab contains the terrain levels for all 2D grid elements:

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Figure 5.135: Grid data window - Grid Cell Bottom Depth tab

In this window, two aspects are of interest:

The terrain levels in this window can be displayed as either bottom levels (m above ref.lev.)
or bottom depths (m below ref.lev.), whichever one the user prefers. The option selected
here does not influence the simulation in any way, nor the way the results are displayed.
The table contains terrain levels (either depth or height) for all grid-cells. Cell (1,1) represents the top-left corner of the grid. The user is free to alter any of these values. When
the user presses OK after anything has been changed, the changed .ASC file containing
the terrain levels can be saved under the same name or another. Please verify that the
file is written to the correct directory (preferably ), and when you enter
a new filename, don’t forget to add the extension.
The next tab contains the friction values for all grid cells:

Graphical User Interface

Figure 5.136: Grid data window - Friction tab

The user can choose between three types of friction formulations, Chézy, Manning or WhiteColebrook. Only one type of friction can be selected per grid. The user can either define one
(uniform) friction value for the whole grid, or select a -file containing friction values
for all 2D grid elements as a way to model distributed friction. This -file should have
exactly the same format (including number of columns and rows) as the height definition file.
It is possible, however, to have no-data values in 2D grid cells in the height -file where
there ARE values in the friction -file. The other way around is not possible.
Note: that in the user interface, the number on the horizontal axis have been replaced by
letters, ranging from ’A’ to ’XX’.
The next tab, grid cell friction, displays a table with all friction values. This tab is only available
when a distributed friction file has been selected first. It is not possible to modify any of the
values seen here. If the user want to change any of these values, he/she will have to edit the
friction -file directly (outside SOBEK).

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Figure 5.137: Grid data window - Grid Cell Friction tab

The last tab, defaults, gives the user the possibility to save or load certain grid-related parameters as default. For example, if you save the ’friction’ as default (only with uniform friction!),
the next grid you define will have the same friction as the current grid.
5.3.24

Flow - 2D-History

The 2D-history node is a special type of object which can be used to specify (in the Schematisation Taskblock) those 2D grid cells for which output is to be provided. After the simulation
has finished, the output will be available as “Results at history stations” in the Result in Maps
Taskblock.
In case a 2D-History node is located on a 2D grid cell that has a missing value for the bed elevation, no output for such 2D-History node will available, meaning that all output parameters
(see below) will have missing values only. The same yields if a 2D-History node is located on
a 2D grid cell of a nested grid that has a missing value, while the underlying parent 2D grid
might have a real value for its bed elevation.
Following output is provided for each 2D-History node:

Bottom, the bed elevation of its underlying 2D grid cell in m.
Waterdepth, the water depth above its underlying 2D grid cell in m.
Waterlevel, the water level in m.

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U-Velocity, the average flow velocity (u) in x-direction in m/s (u = (u1 + u2 )/2; see figure
below).

V-Velocity, the average flow velocity (v ) in y -direction in m/s (v = (v1 + v2 )/2; see figure
below)
√
Abs Velocity, the resulting none-directional flow velocity (C ) in m/s (C = u2 + v 2 ).
Specific U-Discharge, the discharge per meter length (i.e. in m2 /s) flowing in x-direction

through the eastern side (green line in figure below) of the underlying 2D grid cell. More
precisely, the specific U-Discharge equals the water depth times the u2 -flow velocity at
the eastern side of the underlying 2D grid cell.
Specific V-Discharge, the discharge per meter length (i.e. in m2 /s) flowing in y -direction
through the northern side (brown line in figure below) of the underlying 2D grid cell. More
precisely, the specific V-Discharge equals the water depth times the v2 -flow velocity at the
northern side of the underlying 2D grid cell.

Flow - 2D initial water level point
Description

This node can be used to create an initial water level in a part of the grid. This is useful in two
cases:

Initially there really is water in part of the 2D system, for example a lake.
A discharge boundary condition is used as part of the 2D schematisation. In this case, it

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is best to define an initial water level point somewhere to make sure that the 2D grid cell
adjacent to the cell containing the boundary condition is not initially dry. So, the reason
for the initial water level point in this case is purely a numerical one, as sometimes no
water will flow at all from the discharge boundary. The water depth can be very small, for
example 1 cm.

Editing 2D-Initial Water level point data

The initial water level node will (instantly) fill up all surrounding 2D grid cells with water, until
cells are branched that have a higher terrain level, or the edge of the grid is branched. This
can be a problem when using a discharge boundary condition on a high point in the grid: an
initial water level used for numerical reasons may fill a large part of the grid! This problem
can be solved by lowering the terrain level of the 2D grid containing the initial water level point
slightly below the level of the surrounding cells.

The only variable that needs to be specified for this node type is the initial water level, relative
to the reference level. Note that a positive value means above the reference level, as opposite
to terrain levels, which are defined as positive in downward direction.
Node description (Rainfall-Runoff)
RR - Boundary

RR RR - Boundary node

In this chapter, the RR boundary node is described. This node type is used to define boundary
conditions for a Rainfall-Runoff schematisation.

For a detailed description of this node’s input parameters: see the "boundary node input
screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "boundary node topology" section from the Reference Manual

What does an RR boundary node do?
RR boundary nodes hold a certain water level, which will form a boundary condition for the
schematisation. This boundary condition is then used to calculate the interaction with the
other RR nodes that are connected to it. For example: if an RR unpaved node is directly
connected to an RR boundary node, on every time step the outflow of the unpaved area
towards that boundary depends on the groundwater level and the boundary value.
Input screens for the RR - Boundary node type
When starting the model data editor for an RR - boundary node, the following tab will be
available for input:

Graphical User Interface

Figure 5.138: Data Edit for Boundary Area window - Boundary tab

Here, the water level that applies to the model’s boundary should be entered. There are two
options:

Fixed water level: In this case, the water level on the boundary is constant.
Variable water level (from a table): With this option, the water level on the boundary
node can be given as a function of time.Notice that the option "online from flow module" is dimmed. This option is only available for types of nodes that connect the Rainfall
Runoff module with one of the Flow modules (RR on Flow connection node and the RR connection on Channel)
Boundary node topology
Nodes of the RR - boundary type can be connected to nearly all of the other RR nodes:

RR - orifice node

RR - pump station node (either applied as a pump or as an inlet)

RR - QH relation node
RR - friction node This node is considered deprecated functionality.
Use is not recommended.

RR - unpaved node
RR - paved node

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RR - greenhouse node

RR - Sacramento node

RR - industry node

RR - wastewater treatment plant node

The only node types that can not be directly connected to an RR boundary node are:

RR Connection on Channel nodes
RR Connection on Flow connection node(These
nodes actually form boundary nodes themselves)

Flow RR Open water node(If such a node would be connected
directly to a boundary, it would immediately get a water level equal to the boundary value.
Thus, that would be of no use at all)

The picture below gives some examples of how RR boundary nodes can be connected to
other node types. Note that these are only some of the possibilities.

Figure 5.139: An example of RR boundary nodes connected to other nodes

In this example you can see the following phenomena:

Upper chain: an industry node that withdraws water from the boundary (demand), and
injects water into an RR open water node

Second chain: an unpaved area that drains towards an Open Water node, which on its
turn is connected to the boundary via a weir.

Third chain: a pumping station that is used as an inlet (see the link directions) to supply
an RR open water node & unpaved area during periods of drought.
Fourth chain: a greenhouse node that drains off towards a boundary node.
Fifth chain: an unpaved area node that drains off directly towards a boundary node.

Graphical User Interface

Sixth & Seventh chain: a paved area where the sewer discharge is pumped towards the
boundary via a Waste Water Treatment Plant node, and where the sewer spills directly
towards that boundary.
RR - Flow-RR Connection on Channel node
Description

In this chapter, the Flow - RR Connection on Channel node is described. This is one of two
node types through which an RR schematisation can be linked to a CF schematisation. The
other such node type is the Flow-RR connection on Flow connection node.

The large difference between both nodes is that this node is a derivative of a normal Flow Lateral Flow node. This means that this node type should be attached to a branch by simply
using the "add node" button. The other node type is a derivative of a Flow - Connection node,
thus that one should form the start or end of a branch itself.

For a detailed description of this node’s input parameters: see the "Flow - RR Connection
on Channel node input screens" section from the Reference Manual;
For a detailed description of this node’s possible network configurations: see the "Flow RR Connection on Channel node topology" section from the Reference Manual

Input screens
When starting the model data editor for an Flow - RR connection on Channel node type, the
following tabs will be available for input:
Boundary:

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Figure 5.140: Data Edit for Boundary Area window - Boundary tab

The parameters that need to be filled in here will form the boundary condition for the Rainfall
- Runoff module. The availability of the options is dependent on your simulation settings:
The "online from flow module" option is only available when you have the RR and CF simulation settings set to "simultaneous". This can be done in the SETTINGS task block:

Graphical User Interface

Figure 5.141: Settings window

Fixed boundary: If you choose for a fixed boundary value, the Rainfall-Runoff process will
take place completely independent of the Flow processes. This means that alternating
water levels on the channel will not affect the Rainfall-Runoff process. The RR module
will have a fixed boundary condition to calculate its in- or outflow towards CF.
Variable boundary - table: Also if you choose for a table with varying boundary values,
the Rainfall-Runoff process will take place completely independent of the Channel Flow
processes. This means that alternating water levels on the channel will not affect the
Rainfall-Runoff process. The RR module will have a fixed boundary condition to calculate
its in- or outflow towards CF.
Variable boundary - online from Flow module: This option allows the Rainfall Runoff
module to receive its boundary conditions every time step from the Flow module. This
means that changing water levels in the Flow module will cause the boundary conditions
for the Rainfall- Runoff module to change too, thus influencing its in- or outflow.
Topology

Nodes of the type Flow - RR Connection on Channel need to be attached to one of the
Channel Flow branch types depicted below:
,
On the Rainfall - Runoff side, it should be linked with one of the following RR node types:

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The link with RR should be made through one of the following types:

,
Please keep in mind that the RR links should point from the RR nodes towards the Flow RR Connection on Channel node.
Add a Flow - RR Connection on Channel node to your schematisation in the following way:

Select the appropriate node type (Flow - RR Connection on Channel)
Use the "add node"

button to add it to the schematisation. When clicking, SOBEK
will automatically find the nearest channel to attach it to.
If desired, the node may later-on be moved to other locations on the branch, or even to
another branch by using the "move node"

Figure 5.142: Move node icon

Note: Before adding a Flow - RR Connection on Channel node to your schematisation, you
should have at least one of the above channel types present.

Figure 5.143: An example of a valid network

RR - Flow-RR Connection on Flow Connection node
Description

In this chapter, the Flow - RR Connection on Flow Connection node is described. This is one
of two node types through which an RR schematisation can be linked to a CF schematisation.
The other such node type is the Flow-RR Connection on Channel.
The large difference between both nodes is that this node is a derivative of a normal Flow
- Connection node. This means that this node type should not be attached to an existing
branch, but that itself it should form the start or end of a branch.
The other node (Flow-RR Connection on Channel) is a derivative of a normal Flow - Lateral
Flow node, which means that it can be attached to a branch by simply using the "add node"
button.

Graphical User Interface

For a detailed description of this node’s input parameters: see the "Flow - RR Connection
on Flow Connection node input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "Flow RR Connection on Flow Connection node topology" section from the Reference Manual
Input screens
When starting the model data editor for an Flow - RR connection on Flow connection node
node type, the following tabs will be available for input:

Figure 5.144: Data Edit for Boundary Area window - Boundary tab

The parameters that need to be filled in here will form the boundary condition for the Rainfall
- Runoff module. The availability of the options is dependent on your simulation settings:
The "online from flow module" option is only available when you have the RR and CF simulation settings set to "simultaneous". This can be done in the SETTINGS task block:

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Figure 5.145: Settings window

Fixed boundary: If you choose for a fixed boundary value, the Rainfall-Runoff process will
take place completely independent of the Flow processes. This means that alternating
water levels on the channel will not affect the Rainfall-Runoff process. The RR module
will have a fixed boundary condition to calculate its in- or outflow towards CF.
Variable boundary - table: Also if you choose for a table with varying boundary values,
the Rainfall-Runoff process will take place completely independent of the Channel Flow
processes. This means that alternating water levels on the channel will not affect the
Rainfall-Runoff process. The RR module will have a fixed boundary condition to calculate
its in- or outflow towards CF.
Variable boundary - online from Flow module: This option allows the Rainfall Runoff
module to receive its boundary conditions every time step from the Flow module. This
means that changing water levels in the Flow module will cause the boundary conditions
for the Rainfall- Runoff module to change too, thus influencing its in- or outflow.
The Storage tab depicted below is only activated when the Urban 1DFLOW (Sewer flow)
module is activated.
Storage tab:

Graphical User Interface

Figure 5.146: Data Edit for Node window - Storage tab

For a more detailed description of the Storage tab, see section 5.3.12.1 paragraph input
screens
Topology
Nodes of the type Flow - RR connection on Flow connection need to form the starting or
end point of one of the Channel Flow branch types depicted below:
,

On the Rainfall - Runoff side, it should be linked with one of the following RR node types:

The link with RR should be made through one of the following types:

,
Please keep in mind that the RR links should point from the RR nodes towards the Flow
- RR connection on Flow connection node. Remember that Flow - RR connection on Flow

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connection nodes should always be part of a branch themselves. A correct working method
is:

Switch to the "edit network" mode in NETTER
Select the node type Flow - RR connection on Flow connection
Select the "add node" option
Place the node in the schematisation by clicking
Select the appropriate branch type (Flow Branch or Sewer Pipe)

Select the "connect nodes" option
Connect the node that you just added to another one by clicking and dragging.

Figure 5.147: An example of a valid schematisation containing a Flow - RR connection
on Flow connection node

RR - Greenhouse area
Greenhouse area

A greenhouse horticulture area can be schematised with a greenhouse node.

For a detailed description of this node’s input parameters: see the "greenhouse node input
screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "greenhouse node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the "Technical Reference" manual.

What does a greenhouse node do?
The rainfall-runoff process on greenhouses is described by volume balances in two storage
reservoirs:

storage on the greenhouses; and
storage in rainwater basins.
Storage-on-greenhouses represents the storage of water on greenhouse glass surface area
(roofs). Rainfall can be stored on the roofs, before it evaporates or flows into the rainwater
storage basins above- or underground.

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The above-ground basins take in runoff-water from the glass surface as well as from direct
precipitation. The amount of water stored is reduced by evaporation, water use in greenhouses, and possible pumping to the subsoil (under ground storage). When the maximum
storage capacity is exceeded, the excess water flows into the adjacent open water. The figure
below shows the volume balance in the greenhouse areas.

Figure 5.148: Volume balance in the greenhouse areas

Representation of the rainfall-runoff process in greenhouse areas
In SOBEK the rainwater basins have been divided into ten categories, depending on their
volume per hectare of draining glass surface. SOBEK uses the lower limits of the categories.
For example: all basins with a storage between 2500 and 3000 cubic meters per hectares of
glass are considered as basins with a capacity of 2500 cubic meters per hectare of glass.
SOBEK-rr distinguishes itself from most other models with respect to the way greenhouse
areas are treated. They are considered a special area type with provisions for the way horticulture makes use of rainwater storage basins. For instance, the initial filling percentage can
be defined. Since the rainwater storage basins are usually not completely filled at the start of
a rainfall period, this possibility often leads to a more realistic description of the flow into open
water.
The (remaining) storage present in the basins at the beginning of the computation is an important variable determining whether spilling from the basins will occur or not. Therefore, SOBEK
also provides historical data about the development of the storage in basins. To that end a
separate computation has been carried out for each of the ten basin categories for the period
1951–1994, using the detailed greenhouse model of the Staring Centre-LDO. This accurate
model is based on the water usage by a standard glass culture firm. This model takes into account aspects such as the management of rainwater basins by the market gardeners, return
flow of water due to the combustion of natural gas etc. All assumptions have been rounded
conservatively, so that the remainder storage in basins are under-estimated.
Greenhouse area input screens
When starting the model data editor for an RR - Greenhouse area node type, the following
tabs will be available for input:

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Figure 5.149: Data Edit for Greenhouse, Area tab

On this tab, all data related to the area of different greenhouse types should be entered:

Surface level: Represents the surface level of the soil.
Area per greenhouse type: As explained in the Functional Reference Manual chapter
"greenhouse area description", the rainwater basins have been divided into ten categories,
depending on their volume per hectare of draining glass surface. On this tab, the surface
area for each of these categories can be entered. Of course, the sum of all areas should
correspond with the total surface of the greenhouses.
Subsoil storage:For some greenhouses, additional water can be stored in subsoil silos. Here the greenhouse area that uses such storage method should be entered. After
choosing this option, the tab "Silo" becomes active.

Graphical User Interface

Figure 5.150: Data Edit for Greenhouse, Storage tab

On the storage tab, the maximum and initial amount of water that can be stored on the roof of
the greenhouses is defined. The chosen values can be saved in a separate "storage definition"
so that the same values can easily be applied to other greenhouse nodes.
Enter the data as follows:

first type a name in the "storage definition" field
click the Define button
enter the appropriate values for maximum and initial storage;
click the Save button;
note that you can re-use this storage definition on other greenhouse nodes.

Explanation of the parameters:
Maximum storage: Equals the amount of water that can be stored on the rooftop without
being drained off. Only after the rainfall amount exceeds this amount, water starts draining
off the roofs.
Initial storage: If your simulation starts right after a wet period, it might be the case that
the storage capacity of the roof itself is already partially filled with water. That amount of
water should be entered here.

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Figure 5.151: Data Edit for Greenhouse, Silo tab

If the "subsoil storage" option on the "Area" tab has been chosen, this tab will become active.
Here the storage and pumping capacity of a subsoil silo can be entered.
Due to rainfall on the greenhouse area that is connected to this silo, the silo is filled with water.
In the meantime, water is being pumped out in order to supply the plants with water. If, due
to heavy rainfall, the silo’s storage capacity is exceeded, the excess amount will "overflow"
towards a connected RR - Open water node or boundary node.

Silo capacity:This parameter represents the storage capacity of the subsoil silo in volume
per unit of greenhouse area. When multiplying this value with the "Greenhouse area" value
on the "Area" tab, the total volume of the silo is obtained.
Pumping capacity:This parameter represents the capacity of the pumps that supply water from the silo to the plants within the greenhouse. In the model, this amount of water is
simply defined as an outflowing term.
These values too are entered as a "definition". This allows for re-using that definition on other
greenhouse nodes.
Enter the data as follows:

first type a name in the "silo definition" field
click the Define button
enter the appropriate values for maximum and initial storage
click the Save button;

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note that you can re-use this silo definition on other greenhouse nodes.
Rainfall station tab:
Here, the rainfall station that applies for this node can be selected. Rainfall stations can be
created in the "Meteorological data" task block.
Greenhouse area node topology
Nodes of the RR - Greenhouse area type may drain off towards one of the following nodes:

RR - open water node

RR - boundary node

Commonly, a greenhouse node is connected with an open water node.
RR - Industry

RR - Industry node general description

In this chapter, the RR - Industry node is described. With an RR - Industry node you can
simulate lateral discharges to and from the water system. This node type is commonly used
to simulate industrial water extraction and -return (e.g. water for process cooling).
But this node type can also be used to simulate lateral discharges (extractions and discharges)
of known amounts.

For a detailed description of this node’s input parameters: see the "RR - Industry node
input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "RR Industry node topology" section from the Reference Manual
RR - Industry node input screens

When the model data editor for an RR - Orifice node type is started, the following tabs will
become available for input:
Industry tab:

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Figure 5.152: Data Edit for Industry, Industry tab

On this tab, lateral discharges (discharges and extractions of water) can be defined. Extractions are defined as "demands" and "discharges" as "injections".

Demands: Here, the amount of water that is extracted from the system should be entered
(as a function of time). Click the button to open the table where the values should
be entered.Note that demands are always extracted from an "upstream" connected node.
See the chapter on Industrial node topology for more information.
Discharge: In this section, the amount of water that is injected into the system should be
entered (as a function of time). This can be done with two options:
1 "Use return flow factor of the demand". Using this option, the amount of injected water
will be a percentage of the amount that is extracted according to the Demands settings.
Fill the appropriate percentage in into the box next to this parameter name.
2 "Variable discharge (table)". Using this option, the amount of injected water will take
place independently of the demand, but can be defined manually as a function of time.
Click the button to open the table where the values should be entered.
Note: that discharges are always injected on a "downstream" connected node. See the
chapter on Industrial node topology for more information.

Graphical User Interface

RR - Industry node topology
The RR - Industry node requires an upstream node to extract its demands and a downstream
node to inject its discharges. Note that the arrows on the RR links indicate which nodes are
defined as "upstream" and which ones as "downstream".
RR Industry nodes can be connected to the following node types:

RR - Open Water nodes:

RR - boundary nodes:

CF RR on Flow connection nodes:

Open water node descriptions

RR - Open water

CF RR on channel connections.

In this chapter, the open water node is described. It is a commonly used modelling object
within the SOBEK Rural Rainfall-Runoff module.
What does the open water node do?
It can represent the area which is occupied by a number of water courses. Such area may
vary with the prevailing water level, due to existing bank slopes. Usually, the open water node
receives water from connected nodes of the following types:

Unpaved area node
Paved area
Greenhouse area
Industry
Waste Water Treatment Plant
Sacramento

Furthermore it can exchange water with other open water nodes, a Flow model (Channel Flow
or River Flow module) or a model boundary, via structures or a friction node.
Note: in dry periods the above described procedure can be reversed to let water in. In that
case water is deliberately led from a boundary or Flow model towards the open water node,
and finally infiltrated in the unpaved area.
Open water node input screens
When the model data editor for an RR - Open Water node type is started, the following tabs
will become available for input:
Tab Surface:

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Figure 5.153: Data Edit for Open Water, Surface tab

Note that an RR Open Water node represents a series of channels through a certain volume
of water, thus:

The area that is covered by the open water (may be dependent of the water level)
The water depth, which is calculated during every time step.
The following variables have to be specified:

Bed level: Represents the bed level of the channels/ditches that are represented by the
open water node.
Level-Area relation: In this section, the open water area (as seen from above) is entered.
It may be constant (independent of the water level; this is the case if all ditches have vertical walls) or an area that varies with the water level (if the ditches have side slopes).The
options:
1 A constant area.
Independent of the water level.
2 Interpolation from values in a table.
This option lets you fill in six water levels for which the open water area is known.
The area for other water levels is then interpolated from this table. Note: when
using this option, it is wise to include the open water area at the bottom level in the
table. Otherwise the calculation of the area at bottom level will be calculated by linear
extrapolation of the lowest two values from the table. Sometimes this may lead to
negative areas.
3 Linear.
Allows to fill in the area of open water at the target level and the percentage by which

Graphical User Interface

it increases with rising water level. You can check the interpolation table which is
generated and used in SOBEK by switching towards the "interpolation" option after
having specified your values for linear interpolation.

Tab Management:

Figure 5.154: Data Edit for Open Water, Management tab

On this tab, the hydrological management characteristics for this open water node need to be
entered:

Target Level: Generally, in second order ditches, a certain target level is being maintained
by weirs or other structures. This kind of target level needs to be filled in here. It can either
be a fixed level or variable in time.
Note: the target level value on itself will not have any effect on the water management.
The actual water levels are determined by the operation of structures (such as weirs) that
are connected to this area. You’ll need a structure to actually maintain the desired target
level. The reason to enter a value for target level here is mainly for the creation of output
files that refer to that value.
Maximum permissible level: This parameter does not have any effect on the calculations. It is only used to calculate the amount and duration by which a certain level is
exceeded.
Tab Seepage:

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Figure 5.155: Data Edit for Open Water, Seepage tab

The Seepage tab refers to the exchange of water between the top layer (all soil that’s higher
than the bottom of the ditches) and the groundwater underneath
First, enter a name for the seepage definition, then click on and enter the appropriate value. A positive value represents inflow, a negative value represents outflow.
The values can either be:

Constant
Variable (in time)
Calculated from a variable H0 value (pressure head in the underlying aquifer) and the
resistance value of a confining layer in between.
Tab Rainfall Station:

Graphical User Interface

Figure 5.156: Data Edit for Open Water, Rainfall station tab

On this tab you choose the meteorological station that will apply to the Open Water node.
Rainfall and evaporation will apply to the area open water on every time step. Wind data will
have no influence because the Open Water node is a 0-dimentional node type (point objects
without physical outstretches in the horizontal plain).
Open water node topology

An RR open water node can only be connected to other RR objects. On the upstream side, it
may be connected with:

RR Unpaved nodes
RR Paved nodes

RR Greenhouse nodes
RR Sacramento node
WWTP node
Industry node
Notice that the first four node types transfer a rainfall intensity to a certain outflow. When
connecting these nodes to an RR Open Water node, this outflow will therefore flow into the
RR Open Water node.

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On the downstream and upstream side, the RR Open Water node may be connected to RR
structures or a friction node:

RR Weir nodes
RR Orifice nodes
RR Pump station nodes
RR Friction nodes
RR QH relation nodes

Note: on their turn, these structures should be connected to another RR Open Water node
or an RR boundary node.

Optionally, one may connect an additional RR Industry node
to an RR
Open Water node in order to withdraw or inject a certain amount of water in time. Typical
schematisations covering RR Open water nodes could look like this:

Figure 5.157: Example of RR Open Water node connections.

In this example an RR Open Water node receives water from an Unpaved area, a Paved area
and a Greenhouse area. The node is connected to a Boundary node via a Weir, thus when
the water level exceeds the crest level of the weir, water is discharged to the boundary node.
Furthermore there is a connection with another Open Water node via a friction node, causing
a slight difference in water level between both Open Water nodes. The downstream Open
Water node is connected to the SOBEK Channel Flow module via a RR Pump Station (which
could have been any RR structure).

Graphical User Interface

RR - Orifice node
RR - Orifice node general description

In this chapter, the RR - Orifice node is described. With an RR - Orifice node you can simulate
a structure with a controllable gate height, through which water flows.

For a detailed description of this node’s input parameters: see the "RR - Orifice node input

screens" section from the Reference Manual;
For a detailed description of this node’s possible network configurations: see the "RR Orifice node topology" section from the Reference Manual
For a detailed description of this node’s underlying mathematical equations: see the "Orifice section from the Technical Reference Manual".
RR - Orifice node input screens
When the model data editor for an RR - Orifice node type is started, the following tabs will
become available for input:

Figure 5.158: Data Edit for Gate/Orifice, Options tab

On this tab, you can define how the orifice is to be used:

Orifice type: normalThis option means that water can flow through the orifice in both
directions.

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Orifice type: inletThis option means that water may only flow through the orifice in positive direction. The arrows on the links that connect the orifice to other objects indicate the
positive flow direction.

Figure 5.159: Data Edit for Open Water, Orifice tab

On this tab, the dimensions of the orifice should be entered:

Discharge coefficient c: See the "Orifice" section of the Technical Reference Manual for
the exact implementation of this parameter in the discharge formula of this structure type.
This is a coefficient that represents the energy loss due to
contraction of the water mass that flows through the orifice. See the "Orifice" section
of the Technical Reference Manual for the exact implementation of this parameter in the
discharge formula of this structure type.
Width B: Represents the width of the gate through which the water flows.
Crest level Z: Represents the crest level of the gate, thus the bottom of the gate opening.
Initial gate opening: This parameter represents the orifice’s gate opening. Notice that it
is called "initial" gate opening height. This name has been chosen because the opening
may eventually be overruled by a controller. If there’s no controller active for the orifice, the
gate opening will remain equal to the "initial gate opening" throughout the entire simulation.

Contraction coefficient

Controller Tab:

Graphical User Interface

Figure 5.160: Data Edit for Open Water, Controller tab

On the controller tab, the behaviour of the orifice can be controlled (optional). With a controller,
the initial opening heights, as defined on the "Orifice" tab, are overruled.For RR - Orifices, only
a so-called time controller is available. This means that the gate height can be defined as a
function of time.
RR - Orifice node topology
An RR - Orifice should always be connected to at least one RR - Open Water node, as it is
meant to let water flow in or out of an open water section.
RR - Orifices can be connected to nodes of the following types:

(available in the Flow modules only)
(available in the Flow modules only)

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Figure 5.161: An example of a network where RR Orifices are used

RR - Paved node

Paved area node; general description

In paved areas water can be stored on the surface (“on-the-street storage”) and in a sewer
system. The first one represents the storage on paved areas like roofs and roads. The second
one represents the water stored in sewer mains of separated or combined sewer systems. The
representation of the rainfall-runoff process in paved areas is shown.
The storage on the street and the sewer storage can be considered to be two reservoirs.
The rainfall-runoff module calculates a water balance of these reservoirs. When precipitation
occurs on the paved area, first the on-the-street storage reservoir is filled. If this reservoir is
full, it starts spilling into the sewer reservoir. The amount of on-the-street storage is reduced
by evaporation.
Water can enter the sewer reservoir in two ways: first by spilling from the on-the-street storage,
and second by return flow from domestic water use (dry weather flow). Depending on the type
of sewer system, the inflow from the surface and the dry weather flow are mixed in one sewer
storage reservoir, or put into separate sewer storage reservoirs.
When the sewer storage reservoir contains water, the sewer pumps are switched on, and
water is pumped from the sewer to the local open water or to a boundary representing a
waste-water treatment plant outside the system. If the sewer is full, it can also spill directly
into the open water. Flows from paved to unpaved areas and vice versa are neglected.

Graphical User Interface

Figure 5.162: The storage on the street and the sewer storage can be considered as two
reservoirs

Representation of the rainfall-runoff process in paved areas.

You can model multiple types of paved area by dividing the total area into sub-areas with
specific characteristics. In this way areas with and without sewers can be modelled. By
definition, there is no infiltration to groundwater in paved areas. When modelling urban areas,
as a rule of thumb about 50 percent of the urban area can be considered as paved area, and
50 percent can be considered as unpaved area (private gardens and public parks).
Paved area input screens

When starting the model data editor for a paved area node type, the following tabs will be
available for input:
The Area tab

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Figure 5.163: Data Edit for Paved Area window, the Area tab

On this tab, the following data can be entered:

Runoff Area: The value filled in here will represent the paved area on which rainfall from

the selected rainfall station for this node will fall. When the maximum storage capacity
of the surface (storage tab) is exceeded, the water will immediately start flowing into the
sewer system (management tab).
Surface level: Surface level equals the street level for the paved area node. If the water
level in a connected open water node will exceed this level, the water will inundate the
paved area.
Definition of Spilling:
No delay: All surface runoff branches the outflow point in the same timestep.
Use Runoff Coefficient: A runoff delay coefficient, similar to the RR-Urban runoff
model.
Use QH-Relation (Beta functionality): Limit the discharge Q (mm/s) based on the
water level H (m above datum).

For more information on these options, see section 6.5.1.24.

Graphical User Interface

The Management tab

Figure 5.164: Data Edit for Paved Area window, the Management tab

On the Management tab, one can define the operation of the sewer system into which the
intercepted rainfall flows.

Sewer Type: There are three sewer types: Mixed system, Separate system and Improved
separate system. The images below show how they work:

Figure 5.165: Sewer type: Mixed system

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Figure 5.166: Sewer type: Separate system

Figure 5.167: Sewer type: Improved separate system

Sewer pump: Here, the pumping capacities for the sewer pump[s] should be specified.
These pump will attempt to keep the systems empty. In case of a separate system, each
subsystem has its own pump.
Pump discharge to: You should also define whereto the sewer pump[s] should transport its/their discharge. This can either be an RR open water node, a boundary node or
a Waste Water Treatment Plant. If you want to have the discharge pumped towards a
Channel Flow connection, select ’boundary’. The Rainfall Runoff module sees RR-Flow
connections as boundaries.

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The Dry Wether Flow (DWF) tab

Figure 5.168: Data Edit for Paved Area window, the Dry Weather Flow tab

On this tab, you should define the amount of inhabitants and the amount of water they use
daily. Both numbers are then multiplied and simulated as an inflow towards the paved nodes
sewer system.
The Rainfall Station tab

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Figure 5.169: Data Edit for Paved Area window, the Rainfall Station tab

Select here the rainfall station that applies for this node. Rainfall stations can be created in
the "Meteorological data" task block.
The Storage tab

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Figure 5.170: Data Edit for Paved Area window, the Storage tab

On the storage tab, the maximum storage capacities of the street level and the sewer system
should be specified.
How does it work:
When the rainfall intensity exceeds the maximum storage on street, the remaining amount will
flow into the sewer system. On its turn, when that discharge exceeds the maximum storage
plus pumping capacity of the sewer, the remaining discharge is spilled (see Management tab).
The initial storage fields can be used when part of the available storage is already filled up at
the start of a simulation.
Paved area node topology

RR - Paved nodes give a choice to create one or two connections.

In case only one connection is used, both the sewer pump discharges and the sewer
overflows (spills) will flow towards the same node.

In case two connections are used, the user may, for example, choose to have the sewer
pump discharges flow towards a boundary node, and the sewer overflows towards an RR
open water node. By default, all sewer overflows (spills) flow towards open water nodes.
RR - Paved nodes can be connected to either one of the following node types:

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An RR Open Water node
An RR on channel connection
An RR on Flow connection node
An RR Boundary node
An RR Waste Water Treatment Plant node

When connecting a paved area node to one of these nodes, make sure you have selected
the RR-link connection type. Notice: the usage of an RR-Sewerage Link is optional. The
difference with a regular RR link is only for presentation purposes.

Figure 5.171: Select RR-Paved node connection

Below, some examples of typical RR Paved connections are given.

Figure 5.172: Connecting an RR Paved node to an RR open water for the sewer overflows
and surface runoff and an RR boundary for the sewerage discharge.

Figure 5.173: Connecting an RR Paved node to an RR open water for the sewer overflows and surface runoff and an RR Waste Water Treatment Plant for the
sewerage discharge. Note that the WWTP node on its turn should be connected to another node.

RR - Pump Station

Graphical User Interface

RR - Pump station node general description

In this chapter, the RR - Pump station node is described. With an RR - Pump station node
you can simulate a pump that is activated or deactivated through changing water levels. RR Pump stations can either be applied to withdraw excess water or to supply water in periods of
shortage.

For a detailed description of this node’s input parameters: see the "RR - Pump station

RR - Pump station node input screens

node input screens" section from the Reference Manual;
For a detailed description of this node’s possible network configurations: see the "RR Pump station node topology" section from the Reference Manual

When the model data editor for an RR - Pump Station node type is started, the following tabs
will become available for input:

Figure 5.174: Data Edit for Pump, the Options tab

On the "Pump" tab, one can define how the pump will be used:

Normal: The pump will operate as a normal pump that starts extracting water when the
water level on the upstream side (suction side) exceeds the switch-on level. It will then

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continue pumping until the water level drops below the switch-off level. In this case, the
switch-on level will be higher than the switch-off level.
Inlet: The pump will supply water to prevent water shortage in the downstream area
(pressure side) when the water level there drops below the switch-on level. It will then
continue pumping until the water exceeds the switch-off level again. In this case, the
switch-on level will be lower than the switch-off level. Note: look at the direction of the
arrows on the RR-links to find out which side of the pump is defined as the pressure side,
and which one as the suction side. You may need to reverse the directions in order to
make the pump work the way you want it to.

Figure 5.175: Data Edit for Pump, the Pump tab

On this tab, pump capacities and switch-on and -off levels should be entered. Two pump
capacities can be entered. For each pump capacity, the corresponding switch-on and switchoff values for day- and nighttime should be entered.
The distinction between day- and night is made because the usage of electricity is cheaper
during nighttime. During nighttime, pumps are usually switched on earlier and switched off
later. The night- and day hours can be specified in the SETTINGS task block for the RainfallRunoff module.
Notice that, when both capacities are active at the same time, both values are summed up in
order to get the total capacity of that moment.

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Controller tab:
On this tab, a time controller can be applied. With a time controller the pumping capacity can
be defined as a function of time, and the capacities according to the values on the "Pump" tab
are overruled.
******************* IMPORTANT ***************************************
The controller will only adjust the pump capacity. Not its status of active or inactive. The
status of active or inactive is controlled by the values on the "Pump" tab.

In other words: if the pump would be inactive judging from the settings on the "Pump" tab, it
cannot be re-activated by the controller! Therefore, make sure that, if you want the controller
to be active all the time, your pumping station should also be active according to the settings
on the "Pump" tab. Only then, the controller will be able to adjust the capacity to your desired
values in time.
**********************************************************************

RR - Pump station node topology

An RR - pump station should always be connected to at least one RR - Open Water node, as
it is meant to let water flow in or out of an open water section.
RR - pump station can be connected to nodes of the following types:

(available in the Flow modules only)
(available in the Flow modules only)

RR - QH relation node

RR-QH Relation node general description

In this chapter, the RR-QH Relation node is described. If the relationship between the water
levels in an area and the discharges from that area is known, such knowledge may be applied
to a QH-Relation node.
In fact one can simulate any structure type by using a RR-QH Relation node. In hydraulic
river models (1D flow) QH-relations are commonly used to define downstream boundary conditions.

For a detailed description of this node’s input parameters: see "RR-QH Relation node
input screens";
For a detailed description of this node’s possible network configurations: see "RR-QH
Relation node topology"
For a detailed description of this node’s underlying mathematical equations: see QHrelation.
RR-QH Relation input screens

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When the model data editor for an RR-QH Relation node type is started, the following tabs
will become available for input:

Q-h relation tab:

Figure 5.176: Data Edit for Q-H relation window, Q-h relation tab

In the table, the relationship between water levels in the area and the discharge through the
"structure" should be entered. For six representative water levels (or level differences), a
corresponding discharge should be entered.
There are three options for the RR-QH Relation. The options can be chosen in the Unit-h
section of this tab.
1 Discharge related to upstream water level only If this option is chosen, the calculated
discharge will only depend on the upstream water level.
2 Discharge related to downstream water level only If this option is chosen, the calculated discharge will only depend on the downstream water level.
3 Discharge related to water level difference If this option is chosen, the calculated discharge will depend on the water level difference between the upstream and downstream
RR nodes.
RR-QH Relation topology
Like any other RR structure type, an RR-QH Relation should always be connected to at least
one RR - Open Water node, as it is meant to let water flow in or out of an open water section.
RR-QH Relations can be connected to nodes of the following types:

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(available in the Flow modules only)

RR - Sacramento node
Sacramento node general description

In this chapter, the Sacramento node is described. Nodes of this type host the Sacramento
Rainfall-Runoff modelling concept, which has been implemented in the SOBEK RR module.

(available in the Flow modules only)

Figure 5.177: The rainfall-runoff processes that are included in the Sacramento concept.

What is Sacramento?
Sacramento is a concept for rainfall-runoff modelling. It has originally been derived from the
Stanford Watershed model, and designed for the Sacramento river system, United States.
Today, it is one of the most popular rainfall-runoff modelling concepts. It describes the mathematical equation that count for each process within the transformation of rainfall into an outflow
towards a river.

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Figure 5.178: Flowchart of the processes that are covered by the Sacramento concept.

For a detailed description of this node’s input parameters: see the Sacramento node input
screens section from the Reference Manual;

For a manual on the Sacramento rainfall-runoff model concept: see the Technical Reference Manual for the Rainfall Runoff module.
For guidelines on Sacramento parameters: see the document on Estimation of Sacramento segment parameters in the Technical Reference Manual for Rainfall Runoff
The application of the Sacramento model in the way it has been integrated in SOBEK is
based on a semi-distributed approach. It implies that a catchment is divided into a number of
segments, which are interconnected by channel branches as shown in the figure below:

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Figure 5.179: Catchment divided into a number of segments

In each segment, rainfall is transformed into runoff towards the main river system. Within each
segment, areal homogeneity of rainfall input and basin characteristics is assumed. The contributions of the segments may be linked to a SOBEK Channel Flow or River Flow schematisation.
Note: to apply hydrodynamics to your schematisation, link the Sacramento nodes to your
SOBEK Flow schematisations by using RR connection on Flow connection nodes, or RR
connection on channel nodes.
Sacramento node input screens
When starting the model data editor for a Sacramento node type, the following tabs will be
available for input:
Area tab:

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Figure 5.180: Data Edit for Sacramento node window, Area tab

Here, the following parameters can be specified:

Surface Enter the total surface , i.e. pervious and impervious area.
Parameter set definition You may want to apply a unique combination of parameter values for multiple nodes. For that reason, such a combination can be saved as a parameter
set. Enter a name for the set in the drop down box, and click the Define button. Then,
enter the appropriate parameter values. Finally click Save, and the set can be selected for
any Sacramento node by choosing it from the drop down box.
ZPERC The proportional increase in percolation from saturated to dry condition is expressed by the term ZPERC. The value of ZPERC is best determined through computer
trials. The initial estimate can be derived by sequentially running one or two months containing significant hydrograph response following a dry period. The value of ZPERC should
be initially established so that a reasonable determination of the initial run-off conditions
is possible.
REXP The exponent in the percolation equation which determines the rate at which percolation demand changes from the dry condition, (ZPERC + 1) * PBASE, to the wet condition, PBASE. Figure VIII.3.4 illustrates how different values of the exponent affects the
infiltration rate. It is recommended that an initial estimate of this exponent is made from
the same record which is used in determining an initial estimate of ZPERC. The interaction between PBASE, ZPERC and REXP may require a shift of all three terms whenever
it becomes clear that a single term should be changed. Visualising the percolation curve
generated by these three terms helps to ascertain the necessary changes. The observed
range of REXP is usually between 1.0 and 3.0. Generally a value of about 1.8 is an
effective starting condition.
PFREE Fraction of the percolated water which is transmitted directly to the lower zone free

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water aquifers. Its magnitude cannot generally be determined from hydrograph analysis.
An initial value of 0.20 is suggested. Generally, values will range between 0 and 0.40. The
analysis of early season baseflow allows an effective determination of PFREE.
RSERV Fraction of the lower zone free water which is unavailable for transpiration purposes. Generally this value is between zero and 0.40 with 0.30 being the most common
value. This factor has very low sensitivity.
PCTIM Permanently impervious fraction of the basin contiguous with stream channels. It
can be determined from small storms after a significant period of dry weather. Then the
volume of direct runoff (= observed runoff - baseflow) divided by the volume of rain gives
the percentage impervious fraction of the basin. PCTIM should not be close to 1!
ADIMP Fraction of the basin which becomes impervious as all tension water requirements
are met. It can be estimated from small storms after a very wet period. As before, the
volume of direct runoff divided by the volume of rain gives the total percentage of impervious area. The estimate for ADIMP follows from:ADIMP = Total Percentage Impervious PCTIM
SARVA Fraction of the basin covered by streams, lakes, and riparian vegetation, under
normal circumstances. The SARVA area is considered to be the same as or less than
PCTIM. Detailed maps may be referred to in order to estimate the extent of paved areas
which drain directly to the streams so that differences between PCTIM and SARVA can
be approximated. Generally, SARVA appears to range between 40 % and 100 % of the
PCTIM value.
SSOUT The sub-surface outflow along the stream channel which must be provided by
the stream before water is available for surface discharge. This volume expressed in
mm/time interval is generally near zero. It is recommended that the value of zero be
utilised, and SSOUT is applied only if the log Q vs time plot requires a constant addition
in order to achieve a valid recession characteristic. If constant volumes of flow are added
to observed stream flow, the slope of the discharge plot will be altered. That value, which
is required to linearize the primary recession, is the appropriate value of SSOUT. It should
be realised that where SSOUT is required, an effective determination of lower zone free
water storages and discharge rates will require inclusion of the SSOUT value.
PM, PT1, PT2 Time interval increment parameter (PM) and rainfall thresholds (lower rainfall threshold PT1 and upper rainfall threshold PT2).The model simulates the rainfall-runoff
process with a time step which is smaller than the time interval of the basic data (usually
one day). The number of increments in the time interval is derived from:N t = 1 + PM *
(UZFWC * F + Peff)where:F = 1 : for Peff < PT1F = (Peff/PT2)0.5 : for PT1 <= Peff <=
PT2F = 1-PT2/Peff : for Peff > PT2 If the input time interval equals an hour, this option is
internally skipped.

Unit Hydrograph tab:

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Figure 5.181: Data Edit for Sacramento node window, Unit Hydrograph tab

About the Unit Hydrograph:
On this tab, a Unit Hydrograph can be defined. It is used to transform the runoff from impervious areas (direct runoff), the surface runoff and the interflow into an adapted time distribution
of these flow rates. Before the runoff from the impervious areas (direct runoff), the surface
runoff and the interflow branches the channel, they may be transformed according to a Unit
Hydrograph.

The unit hydrograph (UH) runs for hourly and daily intervals only. Hence, only one hour
UH or one day UH’s can be entered. At maximum 36 (non-zero) UH-ordinates can be
entered, together with a step size. The units with which the UH are to be entered are
not of importance; they should only be mutually consistent. First the given ordinates (with
given step-size) are interpolated down to ordinates at one hour intervals. Then the sum of
the ordinates is computed and all ordinates are subsequently divided by the sum, so the
sum of the adjusted ordinates will always be 1.
To test the behaviour of the UH for surface runoff, a run can be made with all storages
initially filled and with UZK and LZSK e.g. = 10−5 . The only reservoir that is depleted then
will be the Lower Zone Primary reservoir = LZPWC * LZPK. Note that LZPK, LZSK and
UZK are to be given as fraction of runoff per day. To get the hourly value the daily value
is internally adjusted as follows:UZK(hr)=(1-(1-UZK(day))1/24), etc. for the other linear
reservoirs.
Example:
1 Given unit hydrograph components : 2. 4. 3. 2. 1. . . . . . . . .
2 Step size = 2
3 Computed unit hydrograph components:

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0.042 0.083 0.125 0.167 0.146 0.125 0.104 0.083 0.063 0.042 0.021
4 Given the 5 (non-zero) ordinates at 2 hour intervals a time base of 12 hours is considered.
The ordinates at two hourly intervals first are converted to ordinates at 1 hour intervals:
1, 2, 3, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5. Its sum is 24. Dividing the 1 hour ordinates by 24
results in the above shown computed components.
Note:

In the SOBEK Sacramento node the UH is available to transform the direct runoff + surface

The Capacities tab:

runoff + interflow as described above.
The original Sacramento model concept offers some methods to transform the total inflow
hydrograph (i.e. direct runoff + surface runoff + interflow + 2 baseflow components). These
methods are the Standard Muskingum method or the Clark method. Note: The latter is
not available in the SOBEK Sacramento node.
Instead of using routing methods like Muskingum, one can use SOBEK-Channel flow for
routing the inflow hydrograph from a SOBEK Sacramento node.

Figure 5.182: Data Edit for Sacramento node window, Capacities tab

Here, one can define the storage capacity of the five reservoir types (see the figure in the
chapter Sacramento node general description) These types are: Upper zone, tension water
Upper zone, free water Lower zone, tension water Lower zone, supplemental free watero
Lower zone, primary free water

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Initial Content Initial content of the reservoirs, thus the amount of storage capacity that is
already occupied at the start of a simulation.

Drainage rate Upper zone free watero Lower zone, supplemental free watero Lower zone,
primary free water
Rainfall Station tab:
Select here the rainfall station that applies to this node. Note: rainfall stations and rainfall data
can be specified in the Meteorological Data task block.

An RR Open Water node
An RR on channel connection

An RR on Flow connection node

Sacramento node topology
Nodes of the Sacramento type can be placed in a network in exactly the same way as RRunpaved nodes. They can be connected to either of the following three node types:

When connecting a Sacramento area node to one of these nodes, make sure you have selected the RR-link connection type:

Figure 5.183: Showing the RR-Link connection type

The images below show how the Sacramento area node can be connected to the three nodes
mentioned.

Figure 5.184: Connecting an RR Sacramento node to an RR Open Water node. Notice
the defined link directions.

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Figure 5.185: Two ways to connect an RR Sacramento node to a channel (only available
if you have a license for the flow module).

General description of the unpaved area node

RR - Unpaved node

In this chapter, the unpaved area node is described. It is by far the most important modelling
object within the SOBEK-Rural Rainfall-Runoff module.

For a detailed description of this node’s input parameters: see the "unpaved area input
screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "unpaved
area node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the "Technical Reference" manual.

What does the unpaved area node do?
This node type transforms rainfall that falls on a parcel of land into an outflow towards open
water. In order to do so, it catches rainfall, which infiltrates in the soil and/or is stored on
the land. The infiltrated water fills up the groundwater, so that the groundwater level will rise.
Through different soil layers, each covering its own drainage capacity it will then flow out of
the soil towards the connected open water. Also evaporation, infiltration and percolation can
be modelled. If desired, unsaturated zone processes can be included in the calculations.
Because the SOBEK Rainfall-Runoff module is a so-called zero-dimensional model, an unpaved node can be seen as a container where water flows in (rainfall and seepage), water is
stored (change in groundwater table & unsaturated zone) and water flows out, (evaporation,
runoff, surface runoff and infiltration). The picture below gives an impression of the various
terms which apply to the unpaved area node.

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Figure 5.186: Representation of the rainfall-runoff process in unpaved areas

In addition, the user can choose whether to use the above described definition of modelling
the transport processes in the unpaved area, or to use a more detailed description. In that
case the unsaturated zone is modelled by means of root zone reservoir.
The unsaturated zone is modelled as vertically oriented 1-D model using the steady-state
approach. The 1-D column model consists of a reservoir representing the root zone and
the subsoil. The equilibrium moisture storage in the root zone is defined as the amount of
moisture corresponding with a steady-state situation with no-flow conditions to or from the
root zone. If the equilibrium moisture storage for the root zone is exceeded, excess water will
percolate to the saturated zone. If the moisture storage is less than the equilibrium moisture
storage, upward flow from the saturated zone is simulated through capillary rise. The height
of the phreatic surface is calculated from the water balance of the subsoil, using a storage
coefficient which is dependent on the depth of the groundwater table.
The root zone reservoir is used for calculations of evapotranspiration. The subsoil reservoir is
used to calculate the saturated storage coefficient.
Evapotranspiration is determined by the crop and the moisture content in the root zone. For
these calculations, recorded values of precipitation and potential evapotranspiration of a reference crop and woodland must be available. The potential evapotranspiration for other crops
or vegetation types are derived from the values for the reference crop by conversion.
Some important characteristics of the unsaturated zone, i.e. upward flux, storage coefficient

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and equilibrium moisture storage of the root zone, are calculated from the soil moisture
retention-, and hydraulic conductivity curves using the CAPSIM model which is based on
the assumption of steady state soil moisture flow (Wesseling, 1991). For more than twenty
different soil types, sets of pre-defined tables are provided with SOBEK.
Input screens for the unpaved area node type
When starting the model data editor for an unpaved area node type, the following tabs will be
available for input:

Figure 5.187: Data for UnPaved Area window, Area tab

Here, the following data can be entered:

Area per crop: Every crop type has it’s own evaporation characteristics. Therefore it is
important to define which crops are grown on the area you want to model. The sum of all
crop-areas should be equal to the total area you want to model with this unpaved node.
Use different area for groundwater computations: Sometimes, a part of the area you
want to model might be paved, having it’s own runoff system. Such areas do not contribute
to the rainfall-runoff process for your unpaved area. However, the soil underneath the
paved area will. For such cases this variable can be used. Example: an area of 10 000
m2 has 2 000 m2 of paved area, which has it’s own runoff system. The rest is unpaved
area where grass is grown. Only 8 000 m2 of the area will therefore catch rainfall, actually
contributing to the rainfall-runoff process. However, the rainfall on these 8 000 m2 will
apply to the groundwater of a 10 000 m2 large area, because there is a soil underneath
the paved area. In this case, we fill in: 8 000 m2 for the Area per crop, type grass, 10 000
m2 for the total area (for groundwater computations).
Surface level: Here, the surface level for the area should be filled in. The surface level is
important for several processes within the calculations:

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1 When the unsaturated zone module "CAPSIM" is not active, the initial groundwater
depth (= surface level - initial groundwater level) will be used to calculate the soil
storage coefficient. Note: CAPSIM can be switched on in the SETTINGS task block
for the RR module.
2 When the groundwater level branches the surface level, excess water will be stored on
land or run off over land
3 When the water level in a connected node exceeds the unpaved area surface level,
the area will be inundated.
The surface level can be entered as ’constant’ or ’variable’. When using the ’variable’ type,
for various levels the percentage of land laying below it can be filled in, thus creating an
S-curve. Important: when using the variable surface level type, the value you previously
filled in for the constant value, will still be used for calculation of the soil storage coefficient!

Figure 5.188: Data for UnPaved Area window, Soil tab

On the Soil tab, the following variables can be filled in:

Soil type: Choosing a certain soil type, actually implies choosing the soil storage coeffi-

cients that will be used during the calculations. These coefficients determine how quickly
the groundwater table will rise due to recharge.
Note: is important to know whether the unsaturated zone module CAPSIM is active or
inactive. You can activate CAPSIM in the SETTINGS task block for the RR module.
If CAPSIM is inactive:
At the start of each simulation, SOBEK will determine for all unpaved nodes:— the
soil type — the initial groundwater depth (in cm below surface)SOBEK will then search
for an appropriate storage coefficient in the file <\SOBEK\FIXED\3B\BERGCOEF>.

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The coefficient it finds there, will then be applied to the corresponding unpaved node
during the entire simulation. The deeper the initial groundwater level lies, the higher
the storage coefficient will be.
If CAPSIM is active:
soil storage coefficient will be calculated on every time step. It will depend on:- soil
type- actual groundwater level

Thickness groundwater layer: This parameter is only of importance when salinity cal-

culations are done. For calculation of salinity, the water volume of each object should
be known. Therefore a groundwater depth should be given (soil volume = surface area *
depth)
Maximum allowed groundwater level: This parameter is not used in the calculation itself, but it may be very usable for output. In the post processing phase, one can determine
whether, and for how long the maximum allowed groundwater level has been exceeded.
This is suitable for the calculation of the damage of floodings to crops.
Initial groundwater level: Unless you’re using a restart file for the initialisation of your
simulation, the initial groundwater level is the groundwater level which is applied during
the first time step of the simulation. Furthermore, it is used to determine the soil storage
coefficient (see the points above). Notice that the initial groundwater level is defined in
[meters below surface level]. When choosing the initial groundwater level as a function of
time, you can have a rainfall events in summertime starting with different initial groundwater levels than rainfall events in wintertime.
The Storage tab

Figure 5.189: Data for UnPaved Area window, Storage tab

On the Storage tab, values for the initial and maximum storage on land can be filled in. These
values can then be saved in a "Storage definition" so that you can re-use them on other nodes.

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The storage on land determines how long it takes before surface runoff will occur. Surface
runoff will start when the rainfall intensity is so high that the sum of the infiltration capacity and
the maximum storage on land is exceeded. To define the storage parameters, type a name of
the storage definition and click Define. Then fill in the values for maximum and initial storage
on land. Finally click Save. On other unpaved area nodes you can select your previously
defined values or create a new set.

The Infiltration Tab

Figure 5.190: Data for UnPaved Area window, Infiltration tab

On the Infiltration tab, one may enter values for the infiltration capacity of the soil. If the
rainfall exceeds the infiltration capacity, water will be stored on land. To define the infiltration
parameters, type a name for the infiltration definition and click . Then fill in the value
infiltration capacity. Finally click . On other unpaved area nodes you can then select
your previously defined values or create a new set.
The Drainage tab

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Figure 5.191: Data for UnPaved Area window, Drainage tab

This tab is one of the most important ones. Here the drainage resistance values for different
soil layers are filled in. The groundwater outflow is determined by:
1
2
3
4

groundwater level
drainage resistance values
soil storage coefficient
downstream water level

Computation option for drainage: Three drainage formulas are available:
1 De Zeeuw - Hellinga,
2 Ernst and
3 Krayenhoff van de Leur

Note:
If you are using CAPSIM for calculation of the unsaturated zone, you are advised to use
the ERNST drainage formula.
Definition: The values that you fill in for a certain node, may be re-used on other nodes.
Therefore, they can be stored in a "definition". Define a name for the set of values you enter and save it. On the other nodes you can then refer to this previously defined definition.
The values to be entered: The name of the section where the values should be entered
varies with the chosen computation method.
surface runoff: the drainage resistance (Ernst) or reaction factor (Zeeuw-Hellinga) for
the surface-runoff process (usually a very quick process, so low drainage resistance
or high reaction factor)
horizontal inflow: the values for water flowing backwards from surface water into the
soil.
drainage levels: for different soil layers, different values may apply.

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All levels are defined as from x meters below surface level to y meters below surface level.

The Seepage tab

Figure 5.192: Data for UnPaved Area window, Seepage tab

Besides rainfall and evaporation, also seepage and infiltration are input/output terms for unpaved area nodes. On the Seepage tab, one can define the flux from or towards deep aquifers.
Various options are available:

Constant: A negative value means that the amount of water will be withdrawn from the
unpaved area node; a positive values means that the amount of water is supplied to the
node.
Variable (table): The seepage and infiltration can be entered as a function of time
Variable (H0-table): The seepage and infiltration is calculated as a function of: - groundwater table in the unconfined aquifer (as calculated by SOBEK) - groundwater head in the
aquifer below (entered as a constant or function of time) - hydraulic resistance value of the
aquitard between the unconfined and confined aquifer.
Future option: from Modflow: In this future option, SOBEK RR and the groundwater
software Modflow will be able to run simultaneously. Modflow will then supply SOBEK
every time step with values for the groundwater head, so that the seepage/infiltration can
be calculated according to the difference between phreatic and piezometric head.
The Meteo tab
On the Meteo tab, one selects the rainfall station that applies for the unpaved area node.
Rainfall stations and - values can be created in the Meteorological Data Task block.

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Unpaved area node topology
Nodes of the unpaved area type can be connected to four types of nodes:

An RR Open Water node
An RR on channel connection
An RR on Flow connection node
An RR boundary node

When connecting an unpaved area node to one of these nodes, make sure you have selected
the RR-link connection type:

Figure 5.193: RR-link connection type

The images below show how the Unpaved area node can be connected to the three nodes
mentioned.

Figure 5.194: Connecting an RR Unpaved node to an RR Open Water node. Notice the
defined link directions.

Figure 5.195: Two ways to connect an RR Unpaved node to a channel (only available if
you have a license for the flow module).

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D-NAM Input Screens
Hereunder the D-NAM rainfall-runoff model input screens are described. For more information
on the various input parameters, reference is made to section 6.5.3.

The D-NAM Tab (see Figure 5.196): On this tab, the catchment area can be defined. To

be selected on this tab are a Soil definition, an Initial value definition, a Surface runoff
definition, a Base flow definition and a Groundwater pump definition. These definitions
can respectively be specified and deleted on the Soil&Soil2 tab, the Initial tab, the Runoff
tab, the Base flow tab and the GW Pump tab.

Figure 5.196: The D-NAM Tab of the "Data for D-NAM Node" Form

The Meteo Stations Tab (see Figure 5.197): The meteo (rainfall) station of the D-NAM
rainfall-runoff model is specified on this tab. In addition, an area adjustment factor is
defined, being a multiplication factor applied on rainfall only. Please note that rainfall and
evapotranspiration data of meteo stations are defined in the Meteo Task Block.

Figure 5.197: The Meteo Stations Tab of the "Data for D-NAM Node" Form

Graphical User Interface

The Soil Tab (see Figure 5.198): On this tab are specified the maximum soil infiltration

rate of water contained in the surface storage [mm/hr], the field capacity of the root zone
layer [-], the specific yield of the root zone layer [-] and the specific yield of the subsoil
layer [-].
For information only are shown the maximum water depth in the lower zone storage [mm],
the maximum water depth in the root zone part of the groundwater storage [mm], the maximum water depth in the subsoil part of the groundwater storage [mm] and the maximum
water depth in the groundwater storage [mm]. These maximum water depths are computed using the field capacity and specific yields defined on this tab as well as the values
defined on the intial tab for the surface level, the bed level of the root zone layer and the
bed level of the subsoil layer.

Figure 5.198: The Soil Tab of the "Data for D-NAM Node" Form

The Soil2 Tab (see Figure 5.199): On this tab are defined the potential maximum capillary rise [mm/day] and the potential maximum percolation capacity [mm/day] either as a
constant or as function of the groundwater table depth.

Figure 5.199: The Soil2 Tab of the "Data for D-NAM Node" Form

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The Initial Tab (see Figure 5.200): On this tab are defined the surface level of the catch-

ment area [m above datum], the bed level of the root zone layer [m above datum], the bed
level of the subsoil layer [m above datum], the initial water depth in the surface storage
[mm], the initial water depth in the lower zone storage [mm] and the initial water depth in
the groundwater storage [mm].
Please note that the resulting initial water depth in the root zone part of the groundwater
storage (GW SDi,rz ) is computed and shown for information only. If GW SDi,rz > 0
while the initial water depth in the lower zone storage (Li ) is less than its maximum water
depth (Lmax ), means that there is water contained in the root zone part of the groundwater storage that can be retained against gravity. In such case a form pops up (see
Figure 5.200) informing on the amount of water depth in the root zone part of the groundwater storage that should be transferred to the lower zone storage. By clicking on the
button, the initial water depth in the lower zone storage (Li ) and the initial water
depth in the groundwater storage (GW SDi ) are adapted in such way that the root zone
part of the groundwater storage does not contain any water that can be retained against
gravity.

Figure 5.200: The Initial Tab of the "Data for D-NAM Node" Form

The Runoff Tab (see Figure 5.201): On this tab are defined the catchment length in
drainage direction [m], the surface slope [-], the Manning roughness of the catchment landuse [s/m1/3 ], the surface-storage-threshold for overland flow [mm], the interflow reservoir
coefficient [days], the surface-storage-threshold for interflow [mm] and the lower-zonestorage threshold for interflow [mm].

Graphical User Interface

Figure 5.201: The Runoff Tab of the "Data for D-NAM Node" Form

The Base Flow Tab (see Figure 5.202): On this are defined the fast base flow reservoir
coefficient [days], the slow base flow reservoir coeffient [days], the external (ground)water
inflow reservoir coeffient [days], the lower-zone-storage threshold for percolation [mm], the
groundwater-storage threshold for fast base flow [m above datum] and the groundwaterstorage threshold for slow base flow [m above datum].

Figure 5.202: The Base Flow Tab of the "Data for D-NAM Node" Form

The GW Pump Tab (see Figure 5.203): On this tab the discharge of the groundwater
pump [m3 /s] is defined either as a constant or as function of time. Please note that
a positive groundwater pump discharge means that water is to be abstracted, while a
negative groundwater pump discharge means that water is to be supplied.

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Figure 5.203: The GW Pump Tab of the "Data for D-NAM Node" Form

RR - Wastewater Treatment Plant
RR - WWTP node description

A WWTP node can be used when there is measured data available for the discharges from a
waste water treatment plant towards a boundary or an open water node that is connected on
the downstream side.

For a detailed description of this node’s input parameters: see the "RR - WWTP node
input screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "RR WWTP node topology" section from the Reference Manual
RR - WWTP node input screens

When the model data editor for an RR - Orifice node type is started, the following tabs will
become available for input:
WWTP Tab:

Graphical User Interface

Figure 5.204: Data for WWTP window, WWTP tab

Here, the discharges from the Waste Water Treatment Plant to a boundary or Open Water
node can be entered. There are two options:

No measured data available: With this option, the discharges from the WWTP node
towards a downstream side connected Boundary or Open Water node will be derived
directly from the combined actual flows of all RR - Paved area nodes that are connected
on the upstream side.
Measured data available: If this option is active, discharges from the WWTP node towards a Boundary node or Open Water node can be entered as a function of time.
Note: : the specified WWTP discharges only apply for the flow from the WWTP node
towards a downstream Boundary or Open Water node. Not for the flow from the RR paved
nodes towards the WWTP. For that flow, the summed up sewer pump discharges apply.
The difference between the flow towards and from the WWTP will become visible as a
storage change in the results for the WWTP.

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RR - WWTP node topology
A WWTP node always forms an interconnection between two nodes:
On the upstream side:

(multiple nodes of this type are allowed)

On the downstream side:

(available in the Flow modules only)

(available in the Flow modules only)

Figure 5.205: Typical example of a schematisation that contains a WWTP node

In this example, the upper paved node will pump its sewer discharge towards the WWTP
node. The sewer overflows from that paved node will flow directly towards a boundary node.
The lower paved node also pumps its sewer discharge towards the WWTP, but sewer overflows will take place on an RR Open Water node.
On the WWTP node, the modeller now has the option of applying measured data for the flow
towards the boundary, or to apply the sewer discharges from the connected paved nodes
directly to the WWTP.
5.4.15

Graphical User Interface

Description of the RR - Weir node type

In this chapter, the RR - Weir node is described. With an RR - Weir node you can simulate
a structure over which water flows. Nodes of this type therefore can represent three types of
weirs: broad crested weirs (rectangular), v-notch weirs or 2-stage weirs.

For a detailed description of this node’s input parameters: see the "RR - Weir node input
screens" section from the Reference Manual;

For a detailed description of this node’s possible network configurations: see the "RR Weir node topology" section from the Reference Manual

For a detailed description of this node’s underlying mathematical equations: see the "Weir

Definition of a Weir (barrage):

section from the Technical Reference Manual".

A weir is a fixed or movable structure that aims to control a certain water level on its upstream
side (Dutch Hydrological Society, 2002).

Figure 5.206: Example of a broad crested weir. Photo: Dutch waterboard "Peel and
Maasvallei"

RR - Weir node input screens

When the model data editor for an RR - Weir node type is started, the following tabs will
become available for input:
Options Tab:

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Figure 5.207: Data for Weir window, Options tab

On this tab, you can define how the weir is to be used:

Weir type: normal This option means that water is allowed to flow over the weir in both
directions.

Weir type: inlet This option means that water may only flow over the weir in positive
direction. The arrows on the links that connect the weir to other objects indicate the
positive flow direction.
Weir tab (normal type):

Graphical User Interface

Figure 5.208: Data for a normal RR-Weir window, Weir tab

On the "Weir" tab, the shape and crest level of the weir is defined. In the "Weir type" combo
box can choose between three types of weirs:
Rectangular weir (broad crest):

Figure 5.209: Example of a broad crested weir. Photo: South African Department of
Water Affairs

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This weir type requires the following input parameters:

discharge coefficient: See the "Weir" section of the Technical Reference Manual for the
exact implementation of this parameter in the discharge formula of this structure type.

Width: Represents the width of the weir’s crest. See the "Weir" section of the Technical
Reference Manual for the exact implementation of this parameter in the discharge formula.

Initial Crest level: This parameter represents the weir’s crest level. Notice that it is called
"initial" crest level. This name has been chosen because the crest level may be overruled
in certain cases:

1 by a controller. If there’s no controller active for the weir, the crest level will remain
equal to the "initial crest level" throughout the entire simulation.
2 if the option "adjust weir setting automatically to <= upstream target level" in the "Settings" task block has been activated.

Figure 5.210: Example of a V-notch weir. Photo: South African Department of Water
Affairs

If the V-notch type is selected for the weir, there will be some other parameters required than
in case of a rectangular one:

Discharge coefficient: See the "Weir" section of the Technical Reference Manual for the
exact implementation of this parameter in the discharge formula of this structure type.

Slope: Represents the tangent of the weir’s side slopes. Thus a value of 2 results in a
steep V-shape (1 horizontally -> 2 vertically)
Initial Crest level: This parameter represents the weir’s crest level. Notice that it is called
"initial" crest level. This name has been chosen because the crest level may be overruled
in case the option "adjust weir setting automatically to <= upstream target level" has been
activated in the "Settings" task block .
2-stage weir:

Graphical User Interface

Figure 5.211: Example of a multiple-stage weir. Photo: South African Department of
Water Affairs

Weirs of this type are a variety of the broad crested type. In stead of one crest level they
have two: at the lowest point there is a small crest which is meant to maintain sufficient flow
velocities over the weir in periods of low discharge. A little higher, the crest becomes broad.
This is meant to allow enough water to flow over the weir in cases of high discharges.
The following parameters are required for this weir type:

Discharge coefficient: See the "Weir" section of the Technical Reference Manual for the
exact implementation of this parameter in the discharge formula of this structure type.

Width: Represents the width of the crest at its narrowest point.
Additional width 2nd stage: Represents the amount by which the weir broadens at the
crest level of the 2nd stage.
Crest level 2nd stage: Represents the crest level for the second stage; thus the crest
level for the broad part of the weir. Naturally this value should be higher than the crest
level for the 1st (narrow) stage.
Initial Crest level: This parameter represents the weir’s crest level. Notice that it is called
"initial" crest level. This name has been chosen because the crest level may be overruled
in two cases:
1 by a controller. If there’s no controller active for the weir, the crest level will remain
equal to the "initial crest level" throughout the entire simulation. Note that only the
crest for the first stage can be controlled:

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2 if the option "adjust weir setting automatically to <= upstream target level" in the "Settings" task block has been activated.

Weir tab (Inlet type):

Figure 5.212: Data Edit for Weir window, Weir tab

If the option Inlet is selected in the "Options" tab, the "Weir" tab will allow the user to set two
additional parameters:

Minimum flushing flow: This is the minimum amount of flow when the inlet is active.
Switch on-off levels: The inlet will open according to the switch on-off levels (relative to
the downstream target level).
Controller tab:

Graphical User Interface

Figure 5.213: Data Edit for RR - Weir window, controller tab

On the controller tab, the behaviour of the weir can be controlled (optional). With a controller,
the initial crest levels, as defined on the "Weir" tab, are overruled. For more details on the
available controllers and their function, see the Controller section of the RR Technical Reference Manual.
RR - Weir node topology

An RR - Weir should always be connected to at least one RR - Open Water node, as it is
meant to control the water level on an open water node.
RR - Weirs can be connected to nodes of the following types:

(available in the Flow modules only)
(available in the Flow modules only)

An example of a network where RR Weirs are used is given below:

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Branch description
Branch - Channel

Figure 5.214: Example of a network with RR Weirs

In this chapter, the Flow - Channel branch is described. This type of object forms the basis for
any River or Channel. With a branch you can define the course of the river or channel that you
want to schematise. A branch is always interconnecting two nodes; these may be boundary
nodes, or connection nodes. On top of the branch, you may later add other objects, such as
weirs, pumping stations etc.

This branch has no input parameters for itself.
For a detailed description of this branch’s possible network configurations: see the "Flow
- Channel branch topology" section from the Reference Manual

This branch type has no underlying mathematical equations for itself. Its length, the
boundary nodes and other objects attached to it determine the flow through branches
of this type.
In SOBEK-Rural Water Flow channels are represented by branches of the type ‘Flow - Channel’. In contrast to the branches in SOBEK-Rural Rainfall-Runoff, the so-called RR-Links, the
lengths of these branches have a physical meaning. Furthermore, they can have objects attached to the, such as cross sections, ζ -calculation points and structures. The cross section
is defined per branch by a cross section node. Various branches can be connected by connection nodes which can comprise extra storage capacity and lateral inflow. The connection
of the modelled area with the outside world (which can also be a sobek-Rural Rainfall-Runoff
schematisation) is represented by the boundary condition nodes.
Topology
The direction of a branch is defined when you create it:

If you create a branch by starting at node A and drawing the mouse to node B, the branch
direction is from A to B.

If you create a branch by starting at node B and drawing the mouse to node A, the branch
direction is from B to A.

Graphical User Interface

If you don’t know the branch direction, do the following:

Click the Menu "Options" - "Network Data" - "Links"- Select the option "Defined" under the
"show direction" section.
Click OK
You should now see an arrow that indicates the branch direction.

If you still don’t see it, zoom in on the branch.

Figure 5.215: Visualising the defined direction of a branch.

The branch direction can be reversed with the "reverse branch direction" button
5.5.2

Branch - Flow 1D Dam Break branch and the Once Hydraulic Trigger

This section describes the "Flow 1D Dam Break branch", including the "Once Hydraulic Trigger":

Application examples of the "Flow 1D Dam Break branch" are given in section 5.5.2.1.
The method of modelling bbranching and the available bbranch growth options/formulae
are discussed in section 5.5.2.2.
Options for specifying the point-in-time that bbranching should start (e.g. at an absolute
point-in-time or at the point-in-time that a specific hydraulic event occurs) are discussed in
section 5.5.2.3.
The "Flow 1D Dam Break branch" input screens are discussed in section 5.5.2.4.
The output parameters available at a "Flow 1D Dam Break branch" are explained in section 5.5.2.5.
For detailed information on the Verheij-vdKnaap(2002) bbranch growth formula and the vdKnaap(2000) bbranch growth formula both available at "Flow 1D Dam Break branch", reference is respectively made to section 6.3.3.1 and section 6.3.3.2.
5.5.2.1

Application examples of the Flow 1D Dam Break Branch
The "Flow 1D Dam Break Branch" can be used to model the hydraulic consequences of a
dam break or dike failure. Possible applications are:

The bbranching of a dike in a 2D model (see Figure 5.216). The dike is represented
by elevated 2D grid cells. The "Flow 1D Dam Break Branch" is located between two

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Connection Nodes, that are respectively located at the west-side and east-side of the
dike. Due to bbranching, water flows though the "Flow 1D Dam Break Branch" from the
west-side towards the east-side of the dike. Please note that if the water at the east-side
is higher than the elevation of the 2D dike cells, in addition to 1D flow through the "Flow
1D Dam Break Branch" also 2D water will flow over the 2D dike grid cells from west to
east.
The bbranching of a river levee (see Figure 5.217). The river is modelled as 1D flow.
The left and right river levees are represented by elevated 2D grid cells. The "Flow 1D
Dam Break Branch" connects the 1D river with a connection node located on the 2D grid
part, representing the left flood plain of the river. Due to bbranching, river water will flow
through "Flow 1D Dam Break Branch" into the left flood plain.
Bbranching of a 1D river dam (see Figure 5.218). A "Flow 1D Dam Break Branch"
can be incorporated into a 1D river model to represent a river dam. Due to bbranching,
reservoir water stored upstream of the river dam will flow through the "Flow 1D Dam Break
Branch" towards the downstream located river sections.

Note: In the application examples give above, the point-in-time that bbranching should start
can be specified either as an absolute point-in-time or as the point-in-time that a specific
hydraulic event occurs (for instance: the exceedance of water level upstream of the "Flow 1D
Dam Break Branch"). For more information, see section 5.5.2.3).

Figure 5.216: Bbranching of a dike in a 2D model using a "Flow 1D Dam Break Branch"

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Figure 5.217: Bbranching of a river levee using a "Flow 1D Dam Break Branch"

Figure 5.218: Bbranching of a 1D river dam using a "Flow 1D Dam Break Branch"

Method of modelling bbranching and Bbranch growth options/formulae
In this section three topics are discussed:

Method of modelling bbranching.
Bbranch growth options/formulae.
Controller table, defining the development of the bbranch area in time.

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Method of modelling bbranching
Bbranching (e.g. development of a bbranch, resulting in a dam break or dike failure) is modelled by lowering the crest level and increasing the crest width of a weir, accommodated in the
"Flow 1D Dam Break Branch". The discharge over this weir is computed in accordance with
the formulae given in section 6.1.16.16, where for the "Flow 1D Dam Break Branch" yields
that the dimensionless lateral contraction coefficient (cw ) is set equal to 1.
Two phases are discerned in the development of a bbranch (see Figure 5.219):

Phase 1: At the on-start of the bbranching process, the initial crest level of the weir is
set equal to the user-defined initial crest level (Z0 , supposed to coincide with the crown

height of the dike) and the initial crest width of the weir is set equal to the user-defined
initial bbranch width (B0 ). In phase 1 for a constant crest width equal to B0 , the crest level
of the weir is lowered from Z0 to the user-defined lowest crest level (Zmin ). Please note
that for vdKnaap(2000) yields that Zmin is equal to Z0 minus the user-defined maximum
bbranching depth.
Phase 2: After phase 1 is completed, the bbranch only grows in width (e.g. crest width of
the weir increases). Hence, in phase 2 the crest level of the weir remains equal to Zmin .
Note: If the "Flow 1D Dam Break Branch" is connected by means of a Connection node to a
2D grid cell, the elevation of this 2D grid cell will be set equal to the user-defined lowest crest
level (Zmin ).

Figure 5.219: Development of a bbranch in a "Flow 1D Dam Break Branch"

Bbranch growth options/formulae

Three bbranch growth options/formula are available at a "Flow 1D Dam Break Branch", viz:

The Verheij-vdKnaap(2002) formula: The bbranch width growth in phase 2 (see Figure 5.219) depends on the actual flow velocity in the bbranch (e.g. the average flow velocity
over the weir, accommodated in the "Flow 1D Dam Break Branch"). For more information
on the Verheij-vdKnaap(2002) formula, reference is made to section 6.3.3.1.
The vdKnaap(2000) formula. The bbranch width growth in phase 2 (see Figure 5.219)
is independent of the actual flow velocity in the bbranch. For more information on the
vdKnaap(2000) formula, reference is made to section 6.3.3.2).
User defined bbranch development: You can define your own bbranch development independent of the actual flow velocity in the bbranch by manually editting the controller
table, that is generated by applying the vdKnaap(2000) formula (see section 5.5.2.4).
Hereunder, in paragraph "Controller table, defining the development of the bbranch area

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in time" it is explained how the controller table defines the development of the bbranch.
Note: For all bbranch growth options/formula yields that the final bbranch width may become
larger than the 2D grid cell size.
Controller table, defining the development of the bbranch area in time
During the bbranching process, SOBEK obtains the crest level and crest width of the weir,
accomodated in the "Flow 1D Dam Break Branch" from a controller table (see Controller Tab
description in section 5.5.2.4), that specifies the bbranch area [m2 ] as function of (relative)
time.

Verheij-vdKnaap(2002): The controller table describes only phase 1 of the bbranch development and comprise of two rows only. First row [start-time of phase 1 (T0 ); 0])
and second row [end-time of phase 1 (T1 ); Bbranch area at the end of phase 1 (A1 )],
where A1 = Initial bbranch width(B0 ) * (Initial Crest level(Z0 ) - Lowest Crest Level(Zmin )).

During phase 1 the actual crest level is determined by linear interpolation in the controller table (e.g. crest level equals Z0 minus bbranch area divided by B0 ). Please note
that the bbranch width growth (e.g. crest widths) in phase 2 follows from the VerheijvdKnaap(2002) formula (see section 6.3.3.1) taking into account the actual hydraulic conditions in the bbranch.
vdKnaap(2000) and User defined bbranch development: The controller table describes
both phase 1 and phase 2 of the bbranch development and may comprise of several rows.
The first row [start-time of phase 1 (T0 ); 0] and the last row [end-time of phase 2 (T2 );
Bbranch area at the end of phase 2 (A2 )]. For intermediate rows yields [0 button. After changing vdKnaap(2000) input data, click on the button for updating the controller table.
Notice that by checking the "Once Hydraulic Trigger (see section 5.5.2.3)" check-box the
"Start bbranch growth" input fields disappear in both Figure 5.221 and Figure 5.222.

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Figure 5.221: "Flow 1D Dam Break Branch"; the Verheij-vdKnaap(2002) Dam Break Tab

Figure 5.222: "Flow 1D Dam Break Branch"; the vdKnaap(2000) Dam Break Tab

The Controller Tab: The defined bbranch development of the "Flow 1D Dam Break
Branch" can be inspected on the Controller Tab. There are four options: 1) VerheijvdKnaap(2002) formula with "Once Hydraulic Trigger (see section 5.5.2.3)"; 2) VerheijvdKnaap(2002) formula without "Once Hydraulic Trigger"; 3) vdKnaap(2000) formula with
"Once Hydraulic Trigger"; and 4) Verheij-vdKnaap(2000) formula without "Once Hydraulic
Trigger".
Option 1 is shown in Figure 5.223. Since the Verhey-vdKnaap(2002) formula is selected,
the controller table contains only two rows, defining the bbranch development of phase 1

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only (see section 5.5.2.2 and paragraph "Controller table, defining the development of the
bbranch area in time"). Using an "Once Hydraulic Trigger" implies a "relative-time controller table (see section 5.5.2.3)" with times in seconds.
Option 4 is shown in Figure 5.224. Since the vdKnaap(2000) formula is selected, the controller table comprises of several rows, defining the bbranch development of phase 1 and
phase 2 (see section 5.5.2.2 and paragraph "Controller table, defining the development
of the bbranch area in time"). Not using an "Once Hydraulic Trigger" implies a controller
table with absolute times (dd-mm-yyyy hh:mm:ss).

Note: The controller table cannot be edited in case the Verheij-vdKnaap(2002) formula
is selected. However, the controller table can be edited if the vdKnaap(2000) formula
is selected, which allows for defining an "User defined bbranch development (see section 5.5.2.2)". Please note that clicking on the button on the Dam Break
Tab (see Figure 5.222) will overwrite your edited controller table.

Figure 5.223: "Flow 1D Dam Break Branch"; Option 1", Controller Tab for the VerheijvdKnaap(2002) formula with an "Once Hydraulic Trigger"

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Figure 5.224: "Flow 1D Dam Break Branch"; Option 4, Controller Tab for the vdKnaap(2000) formula and without an "Once Hydraulic Trigger"

The Triggers Tab: The Triggers Tab is only available if the "Once Hydraulic Trigger" is
selected on the Dam Break Tab. At the Triggers Tab (see Figure 5.225) only a trigger
of the type "Once Hydraulic Trigger" can be selected in the Trigger Type scroll-box. By
typing a Name in the Definition scroll-box a "Once Hydraulic Trigger" can be added and
specified. An existing "Once Hydraulic Trigger" can be selected in the Definition scroll-box,
and thereafter been edited or deleted. Optional hydraulic parameters are the water level
or discharge at a 1D measuring station; the head difference, force difference, crest level,
crest width or gate lower edge level of a 1D structure (see Parameter scroll-box). In the
Measurement Location scroll-box the ID of the 1D measuring station or 1D structure is to
be selected.
The Trigger table (see Figure 5.226) can be obtained by clicking on the
button. A trigger table is interpreted as a blocked function. In Figure 5.226 it can be seen
that the trigger condition of the "Once Hydraulic Trigger" becomes "True": a) if from 0101-2014 00:00:00 onwards up to 01-01-2014 03:00:00 minus the computational time-step
(∆t), the water level at the measuring station becomes above 1.00 m; b) if from 01-012014 03:00:00 onwards till the end of the computation, the water level at the measuring
station becomes above 1.5 m. Trigger condition is "True" means that the status of the
"Once Hydraulic Trigger" is set to "On", that the relative controller table is made absolute
and the bbranching starts (for more details, see section 5.5.2.3).

Graphical User Interface

Figure 5.225: The Triggers Tab of the "Flow 1D Dam Break Branch"

Figure 5.226: "Flow 1D Dam Break Branch"; Trigger Table of the "Once Hydraulic Trigger"

Output available at a Flow 1D Dam Break Branch
Output parameters available at a Flow 1D Dam Break Branch are in effect structure output
parameters, hence:

Firstly, in the "Settings" Task block, click on the button of the "1DFLOW" module.
Thereafter select the "Output options" Tab and click on the "Structure Tab" available in
the "Output parameters" window. Now select your Flow 1D Dam Break Branch output
parameters.

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After a computation, these output parameters can be viewed in the "Results in Maps"
Tasblock (e.g. at a Flow 1D Dam Break branch) as well as in the "Results in Charts" Task
block (e.g. under "Results at Structures and Extra Resistance")
The Flow 1D Dam Break Branch output parameters comprise off:

Discharge, the discharge through the "Flow 1D Dam break branch" (e.g. discharge
through the bbranch) [m3 /s].
Water Level Up, water level at the ζ -calculation point having the lowest x-coordinate along
the "Flow 1D Dam break branch" [m].
Water Level Down, water level at the ζ -calculation point having the highest x-coordinate
along the "Flow 1D Dam break branch" [m].
Head, the head (=upstream water level minus downstream water level) of the "Flow 1D
Dam break branch" (e.g. head over the bbranch) [m].
Velocity, the velocity over the weir, accommodated in the "Flow 1D Dam break branch"
(e.g. velocity through the bbranch) [m/s].
Crest Level, crest level of the weir, accommodated in the "Flow 1D Dam break branch".

The crest level represents the bed level of the bbranch (see section 5.5.2.2 and Figure 5.219) [m].
Structure Flow Area, flow area above the crest level of the weir, accommodated in the
"Flow 1D Dam break branch" [m2 ].
Crest Width, crest width of the weir, accommodated in the "Flow 1D Dam break branch".
The crest width represents the width of the bbranch (see section 5.5.2.2 and Figure 5.219)
[m].
Note: The bbranch area at a particular point-in-time is equal to the actual crest width times
the difference between the initial crest level and the actual crest level.
5.5.3

Branch - Flow pipe

Pipes
In SOBEK-Urban Water Flow pipes are represented by branches of the type ‘Flow-Pipe’. The
Flow-Pipe with Runoff is considered equal to the Flow-Pipe by the Sewer flow module. These
branches have a length, a cross section and a resistance. The cross section is defined per
branch. Various branches can be connected by various types of Flow-Manholes which can
comprise extra storage capacity and lateral inflow.
5.5.4

Flap Gates available for specific type of Pipes

An example of a flap gate is at a tidal outlet; where water can flow into the sea as long as
water levels in the pipe are above the sea-level; and where by a hinged flap gate, sea-water
is prevented from flowing into the pipe if sea-levels are higher than the water level in the pipe.
A Flap Gate can be accommodated in the following type of pipes only:

Flow - Dry Weather Pipe
Flow - Flow Measurement Pipe
Flow - Pipe
Flow - Pipe with Runoff
Flow - Rain Pipe

On the "Flap Gate" Tab (see Figure 5.227), the user can specify the allowable flow direction(s)
in a pipe. Following options are available:

Graphical User Interface

None, Flow in Both Directions, meaning no restriction regarding the flow direction in this
pipe (e.g. no flap gate present).

Only Positive Flow, meaning that only positive flow is allowed in this pipe. Flow is positive
if flowing in pipe-direction (e.g. flowing from the beginning towards the end of the pipe).

Only Negative Flow, meaning that only negative flow is allowed in this pipe. Flow is negative if flowing in opposite pipe-direction (e.g. flowing from the end towards the beginning
of the pipe).

Note: If a "Pipe with Flap Gate" is located adjacent to a 1D Boundary Node, then only a
"water level (h)" boundary condition is allowed. Hence, in such case no "flow (Q)" or "Q-h
relation" is allowed as boundary condition.

Figure 5.227: The Flap Gate input screen, that is available for specific type of pipes

Branch - 1D-2D Internal Boundary Condition

Description
Functionality:
The 1D-2D internal boundary condition enables the user to connect several 2D grid cells to
the end of a 1D channel (see picture below). The 1D channel outflow is distributed over the
concerning 2D grid cells in accordance with their conveyance capacity. The flow in the 2D grid
cells is transferred to the 1D channel. At a 1D-2D Internal boundary condition only 1(one) 1D
channel can/may be connected to a particular 2D grid.
Note: At present, a 1D-2D internal boundary condition may not pass over nested grids and
should be parallel to either the x-axis or y -axis.

SOBEK, User Manual

Figure 5.228: Placing a 1D-2D internal boundary in a model

Doubleclick the ‘Schematisation’ task block and thereafter click the Edit Model button on
the Schematisation window.

Click the Zoom in button and go to the location where you want to place the 1D-2D Internal

boundary condition.
Click the Edit Network button.
Take care that the end node of the 1D Channel, that you like to connect to the 2D grid is a
type 36: Flow - 1D2D Internal Boundary Node.
Click the Nodes button, pull-down the menu and click the Overland Flow Model/ 41, 2D Corner node.
Click the Branch button, pull-down the menu and click the Overland Flow Model/ 15, 2D Line 1D2D Internal Boundary.
Click the Edit action button, pull-down the menu and click on Nodes/Add Nodes. Go to the
location where you want to place the first 2D Corner node of the 1D-2D Internal boundary
condition and click with your left mouse button. Place the second 2D- Corner node in the
same way. Take care that the two 2D - Corner nodes are located: 1) on either a horizontal
or vertical line; 2) on 2D grid cells not having missing values; and 3) that the 2D grid cells
lying directly in front of the line through the two 2D Corner nodes are active 2D grid cells
(i.e. having no missing value)
Click the Edit action button, pull-down the menu and click on Connection/Connect nodes.
Click with the left mouse button on a 2D Corner node. While pressing down the left mouse
button drag a line to the other 2D Corner node and release your left mouse button.
It is advised to locate the end node of the 1D Channel on a 2D grid cell, that is part of
the 2D grid cells lying under the line connecting the 2D Corner nodes. For moving the
end node of the 1D Channel, click the Edit action button, pull-down the menu and click on
Node/Move Node Click, thereafter click with the left mouse button on the end node and
drag it to its new position.
Click the Edit Network button to end the network editing activities.
Click on the 1D-2D Internal boundary condition and thereafter click with your right mouse
button, and click on Model data/ Overland Flow Model. The ‘Data Edit’ window should

Graphical User Interface

appear on your screen.
Click under Type the 1D2D connection ’ check-box’ in the ‘Boundary condition’ Tab of the
‘Data Edit’ window.
Pull down the list-box left of 1D2D Boundary Connection Node and select the ID of the
end node of the 1D Channel that you wish to connect to the 2D grid (see Figure below).
The ID of a particular node can be obtained by clicking on it, right mouse click, show info.
Click the Save Network button for saving your defined 2D Q-h Tabulated Boundary Condition.

Figure 5.229: Data Edit, Boundary condition tab

How to retrieve information:

Under the ‘Results in Maps’ Task block

Double click the ‘Results in Maps’ task block.
Click in the main menu on File/Open Data/Overland Flow Module Result at history stations
(i.e. in the ‘Select item’ window)
In the View Data window select the hydraulic parameters "Water level" and "Abs. Disch
[m3 /s]".
Click the 1D-2D Internal boundary condition and then click with right mouse and then on
show graph or click on the graph button in the ‘View Data’ window.
Remarks:
the shown water level is the same as the one at the 1D2D boundary connection
node, that is connected to this particular 1D-2D Internal boundary condition;
the discharge is given as an absolute discharge, hence only the magnitude but not
the direction of the flow is given,

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the direction of the discharge can either be seen from the concerning 1D Channel
branch or by providing a discharge-measuring-section on the 2D grid near the 1D2D Internal boundary condition
Under the ‘Results in Charts’ Task block

Double click the ‘Results in Charts’ task block.
Double click on Overland Flow Module/ Results at history stations (in the ‘Results in

Branch - 2D Line discharge measurement
Description
Functionality:

Charts’ window).
In the ‘ODS-View’ window select under parameters Water level and Abs Disch [m3 /s],
under locations select the location l_x (where l stands for link and x for the ID of the 1D2D Internal boundary condition), under time-steps select the required time-period. Now
click on the Graph button or Export button to respectively view a graph or export to the
data to a particular file.

The 2D Line discharge measurement provides the user with information on both the direction and magnitude of the 2D flow passing through the 2D Line discharge measurement as
function of time. Using 2D Path, the 2D grid cells that are lying under the 2D Line discharge
measurements can be shown. These 2D grid cells are used for determining the actual 2D
flow that is passing the 2D Line discharge measurement. From a 2D Line discharge measurement one can obtain the 2D discharge in U direction (i.e. U-Discharge [m3 /s]) and the
2D discharge in V direction (i.e. V-Discharge [m3 /s]) passing through the 2D Line discharge
measurement. Discharges in U and V-direction are positive when the flow is respectively
flowing in the positive x- and y -direction of the underlying 2D grid. In addition the 2D Line
discharge measurement provides the user with information on the direction and magnitude of
the effective 2D flow (i.e. Eff.Disch_2D [m3 /s]), passing through the 2D Line discharge measurement as function of time. The sign of this effective 2D discharge depends on the direction
in which the user has drawn the 2D Line discharge measurement (see also how to define a
2D Line discharge measurement). In dragging the 2D Line discharge measurement, it is assumed that the user defines an arrow pointing from the starting 2D Corner node towards the
ending 2D Corner node. The positive direction of the effective 2D discharge is the clock-wise
direction seen from the starting 2D Corner node. In case the effective 2D discharge passes
the 2D Line discharge measurement in clock-wise direction or in anti-clock-wise direction, the
effective 2D discharge is respectively given a positive or a negative sign (see figure below).
It is to be mentioned that at present discharge-measurement sections must lay on 1
(one) 2D grid and may not pass over nested grids. It is anticipated that in the verynear future the functionality of the discharge-measurement-section will be extended,
allowing for a 2D Line discharge measurement to pass several 2D grids (parent and
nested 2D grids) as well as areas having no 2D grid at all. In addition information on
the effective 1D discharges will be available for the user.

Graphical User Interface

Figure 5.230: Definition of the sign of the effective 2D Discharge passing a 2D Line discharge measurement

How to define a 2D Line discharge measurement:

Double click the ‘Schematisation’ task block and thereafter click the Edit Model button on
the Schematisation window.

Click the Zoom in button and go to the location where you want to place the 2D Line
discharge measurement.

Click the Edit Network button.
Click the Nodes button, pull-down the menu and click the Overland Flow Model/ 41, 2D Corner node.

Click the Branch button, pull-down the menu and click the Overland Flow Model/ 16, 2D –
Line Measurement.

Click the Edit action button, pull-down the menu and click on Nodes/Add Nodes. Go to
the locations where you want to place the 2D Corner nodes of the 2D Line discharge
measurement and click with your left mouse button.
Click the Edit action button, pull-down the menu and click on Connection/Connect nodes.
Click with the left mouse button the starting 2D Corner node. While pressing down the
left mouse button drag a line to your ending 2D Corner node and release your left mouse
button.
Click the Edit Network button to end the network editing activities.

SOBEK, User Manual

Click the Save Network button for saving your defined 2D Line discharge measurement
How to retrieve information on a 2D Line discharge measurement:
Under the Results in Maps Task block

Double click the Results in Maps task block.
Click in the main menu on File/Open Data/Overland Flow Module Result at history stations

(i.e. in the Select item window)
In the View Data window select for instance the hydraulic property "Eff. Discharge 2D
[m3 /s]"
Click the 2D Line discharge measurement and then click with right mouse and then on
show graph or click on the graph button in the View Data window.

Figure 5.231: View Data window

Under the ‘Results in Charts’ Task block

Double click the ‘Results in Charts’ task block.
Double click on Overland Flow Module/ Results at history stations (in the ‘Results in
Charts’ window).

Select the hydraulic parameter (for instance Eff. Disch 2D [m3 /s]), under locations select
location l_x (where l stands for link and x for the ID of the 2D Line discharge measurement), under time-steps select the required time-period. Now click on the Graph button or
Export button to respectively view a graph or export to the data to a particular file.
5.5.7

Branch - 2D-Line boundary
Description
The 2D-line boundary can be used instead of the 2D-boundary node when there are multiple
grid cells next to each other that have the same boundary condition (i.e. tidal boundary). The
boundary condition specified for the line boundary (in edit model data mode) is used for all
underlying 2D grid cells.
The 2D-line boundary is made up of a construction of two 2D-corner nodes and one 2Dline boundary. This construction is made by first placing the 2 nodes on the grid, and then
connecting them using the ’2D-line boundary’ branch type and the ’connect existing nodes’

Graphical User Interface

option from the edit network menu. The line boundary can be either horizontal or vertical, but
not anything else. All underlying 2D grid cells should contain no-data values, and from every
boundary cell the water should be allowed to flow to (or from) only one other cell. See the
Figure 5.232 for an example.

Figure 5.232: Possible configuration of a 2D Line boundary

Note: the 2D line boundary should not pass over a nested grid.
Editing 2D Boundary Corner and Line Boundary data

At a 2D-line boundary the user can define a water level or discharge as function of time (i.e.
h(t) or Q(t)) as an external forcing boundary condition. In case of a water level boundary
all 2D grid cells lying under the 2D-line boundary obtain the same water level. In case of a
discharge boundary condition, the inflowing discharge is distributed over the 2D grid cells lying
under the 2D-line boundary in accordance with the conveyance capacity of each individual 2D
grid cell.

Overview of available cross-sectional profiles

An overview of the cross-section types that may lay on the same branch is given in Table 5.3.
An overview of the properties of the available cross-section types is given in Table 5.4.
Table 5.3: Overview of Cross-section types that may lay on the same branch

Open Vert.Segm. Y-Z

Open Tabulated1

Open Lumped Y-Z

Closed Tabulated1

Arch
AsymTrap
Closed Lumped Y-Z
Closed Tabulated1
Cunnette

Closed Lumped Y-Z

Overview of Cross-section types that may lay on the same SOBEK branch

Asym. Trapezium

Cross Section types

SOBEK, User Manual

Table 5.3: Overview of Cross-section types that may lay on the same branch

Open Vert.Segm. Y-Z

Open Tabulated1

Open Lumped Y-Z

A Tabulated profile is closed in case the total width at its highest level is less than 20 mm

Closed Tabulated1

Egg-shape
Elliptical
Open Lumped Y-Z
Open Tabulated1
Open Vert.Segm. Y-Z
Rectangle
River Profile
Round
Steel Cunette
Trapezium

Closed Lumped Y-Z

Asym. Trapezium

Overview of Cross-section types that may lay on the same SOBEK branch

Closed
Open
Open
Open
Closed
Open

no
no
no
no
no
yes

no
no
yes
no
no
yes

Ground layer Friction def.

Elliptical
Open Lumped Y-Z
Open Tabulated
Open Vert.Segm. Y-Z
Rectangle
River Profile

lumped
V.Segm
lumped
lumped
lumped
lumped
analytic
lumped
lumped
lumped
V.Segm
lumped
lumped

Bed Friction definition

no
no
no
no
no
no

Ground layer Thickness

no
no
no
no
no
no

No. of Friction Sections

Closed
Open
Closed
Closed
Closed
Closed

Conveyance method

Arch
AsymTrap
Closed Lumped Y-Z
Closed Tabulated
Cunnette
Egg-shape

Table 5.4: Properties of available cross-section types

yes
no
no
yes
yes
yes

G&L
Crs
Crs
G&L
G&L
G&L

G&L
G&L
G&L
G&L

yes
no
yes
no
yes
no

G&L
Crs
G&L
Crs
G&L
G&L

f (x),
f (x, h),
f (x, Q)
Round

lumped
analytic
lumped

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Conveyance method

No. of Friction Sections

Ground layer Thickness

Bed Friction definition

Ground layer Friction def.

Note:
1 Open/Closed:

Table 5.4: Properties of available cross-section types

Closed means that pressurized flow occurs for water depths higher than the inner
cross-sectional height.

A tabulated profile is closed in case the total width at the highest level is less than 20
millimetres. At all levels of a closed Tabulated profile should yield that the total width
equals flow width (hence no storage allowed)

2 Method for computing conveyance (see section 6.1.20):

Lumped means that conveyance is computed using the “lumped conveyance method”
(see section 6.1.20.1)

Lumped analytical means that in computing “the lumped conveyance” use is made of
analytical formulae, giving the wetted area and the wetted perimeter as function of the
actual water depth.
V.Segm. means that conveyance is computed using “the vertically segmented conveyance method” (see section 6.1.20.2).
3 Number of Friction sections

For a River profile three different friction sections can be defined (main section, floodplain1 and floodplain2)

For a Y-Z and Asym. Trapezium profile yields that a particular friction section may not
be smaller than the width of its underlying vertical segment (W = Yi+1 − Yi )
4 Ground layer Thickness

The surface level of the ground layer equals the lowest level in the cross-sectional
profile plus the ground layer thickness.

The cross-sectional part, located below the surface level of the ground layer is omitted
in the hydraulic computations.

The “ground layer width” is the width of the cross-sectional profile at the surface level
of the ground layer.

For the “ground layer width” a roughness value can be defined that differs from the
roughness value applied to the remaining part of the wetted cross-sectional perimeter.
The roughness of the ground layer width is referred to as Ground layer friction. The
roughness value applied to the remaining part of the wetted cross-sectional perimeter
is referred to as Bed friction.
The same friction formula (Chézy, Manning etc) is applied for bed friction as well as
for ground layer friction.

SOBEK, User Manual

5 Bed and Ground layer Friction definitions

G means constant global (or model-wide) friction value.
L means for the entire branch a constant (local) friction value.
f (x), f (x, h) and f (x, Q) means that bed-friction along a branch can be defined as
function of the x-coordinate, as function of the x-coordinate and the actual water level,
or as function of the x-coordinate and the actual discharge.
Crs means that bed friction is to be defined for each and every cross-section.
Flow - Cross Section node (Arch type)
Cross sections of the Arch type are closed profiles using the tabulated lumped conveyance
approach (see section 6.1.20.1).

The input screen looks as follows:

Figure 5.233: Data Edit, Cross section tab

In the right-lower corner of the screen, an impression of the cross section shape that you enter
will be plotted. The dimensions that you filled in will be plotted next to it.
Create a cross section definition:
To start creating a cross section definition, do the following:

choose the cross section of the "Arch" type in the ’Choose Type’ box.
Create a new definition by typing a name for it in the "select cross section" field
Click the button Define Dimensions;
Enter the desired values in the parameter fields "width", "height" and "arc height";

Graphical User Interface

Optionally, turn on the "use ground layer option" and enter a value;
Click the button Save Dimensions.
Parameters:
This cross section type requires the following parameters:

Width: represents the width of the arch.
Height: represents the height of the rectangle part of the arch(from the bottom up to the

Flow - Cross Section node (Asymmetrical trapezium type)

Cross-sections of the Asymmetrical trapezium type (see Figure 5.234) are open profiles using
the vertically segmented conveyance approach (see section 6.1.20.2).

point where the curved section starts)
Arc Height: represents the height of the curved part.
Use Ground Layer: switch on if a layer of sediment lies in the cross section. An individual
roughness value may be given for the ground layer. See the ’Friction’ tab for this.
Ground layer: enter the thickness of the sediment layer that lies within the cross section.
This thickness will be made visible in the image on the right side through a red line.

Figure 5.234: Asymmetrical trapezium cross section

The bed level that you define on the Location tab becomes the lowest point of this cross
section.
There is no restriction to the number of side slopes that are chosen left and right. Of course
a trapezium cross section that is symmetrical can be modelled by using the same side slope,
heights and extra width at the left and right side of the cross section.
The maximum flow width is limited by the outer left and outer right point of this profile. These
points are the left and right bank of the profile. The surface level is equal to the highest point
of the cross-sectional profile.

SOBEK, User Manual

For the Asymmetrical trapezium profile the vertically segmented conveyance approach is applied.
Flow - Cross Section node (Closed Lumped Y-Z type)

Cross-sections of the closed Lumped Y-Z type use the tabulated lumped conveyance approach (see section 6.1.20.1). A ground-layer as well as total widths (i.e. storage) can not be
defined for a closed lumped Y-Z profile. Furthermore, only one roughness value and corresponding roughness formula can be defined, which are applied to the entire wetted perimeter. Please note that a Closed Lumped Y-Z profile is obtained by selecting the item ’Closed
Lumped’ in the ’Type of Y-Z profile’ list-box (see Figure 5.235), accomodated on the ’Crosssection’ Tab (Edit/Model data/ Flow - Cross Section).

Figure 5.235: Example of a closed Lumped Y-Z profile defined in ModelEdt

If the user defines a closed lumped Y-Z profile that is actually not closed (see Figure 5.236),
such lumped Y-Z profile will be closed by adding a (Y,Z) point at the end of the user-defined
Y-Z table. This added (Y,Z) point equals the first user-defined (Y,Z) point (see Figure 5.237).
The computational procedure is as follows. Firstly, it is verified if a valid closed lumped Y-Z
profile is defined and an error message is given if this is not the case. Thereafter, a tabulated closed lumped Y-Z table is constructed (see Figure 5.238). Next, based on the symmetrical tabulated closed lumped Y-Z profile depicted in Figure 5.238, for a particular water
level the corresponding flow area and wetted perimeter is determined. Finally, using this
information and the defined roughness, the corresponding conveyance is computed (see section 6.1.20.1).

Graphical User Interface

Figure 5.236: User defined closed Lumped Y-Z profile

Figure 5.237: SOBEK adapted closed Lumped Y-Z profile

Figure 5.238: Symmetrical tabulated closed lumped Y-Z profile

Flow - Cross Section node (Closed Tabulated type)
Cross-sections of the tabulated type use the tabulated lumped conveyance approach (see
section 6.1.20.1). A tabulated cross-section is closed if the flow width at the heighest defined
elevation is smaller than 20 millimetres, else it is an Open tabulated cross-section (see section 5.6.10). Total widths (i.e. storage) cannot be defined for a Closed tabulated cross-section.

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Flow - Cross Section node (Cunette type)
Cross sections of the Cunette type are closed profiles using the tabulated lumped conveyance
approach (see section 6.1.20.1).

The input screen looks as follows:

Figure 5.239: The Cross section tab of a cunette profile

The parameter Height is determined based on the user-defined Width. Internally, a cunette
profile is handled as a tabulated profile. When reopening a cunette profile, SOBEK will show
the converted tabulated profile based on the cunette profile as defined by the user. See
Figure 5.240. A tabulated type originating from a cunette profile is prefixed by ’c_’.

Graphical User Interface

Figure 5.240: The corresponding tabulated profile data of the cunette profile in Figure 5.239

For more information, see Cross-Section type: Steel Cunette (section 5.6.15).
5.6.7

Flow - Cross Section node (Egg-shape type)

Cross-sections of the Egg-shape type are closed profiles using analytical formulae for computing lumped conveyance as function of water depth. An egg-shaped cross section is defined
by its bed level and width. The height is by definition 3/2 times the width.
5.6.8

Flow - Cross Section node (Elliptical type)

Cross-sections of the Elliptical type are closed profiles using the tabulated lumped conveyance
approach (see section 6.1.20.1). An Elliptical cross section is defined by its maximum width
and maximum height.
5.6.9

Flow - Cross Section node (Open Lumped Y-Z type)

Cross-sections of the open Lumped Y-Z type use the tabulated lumped conveyance approach
(see section 6.1.20.1). A ground-layer as well as total widths (i.e. storage) can not be defined
for an open lumped Y-Z profile. Furthermore, only one roughness value and corresponding
roughness formula can be defined, which are applied to the entire wetted perimeter. Please
note that an Open Lumped Y-Z profile is obtained by selecting the item ’Open Lumped’ in
the ’Type of Y-Z profile’ list-box (see Figure 5.241), accomodated on the ’Cross-section’ Tab
(Edit/Model data/ Flow - Cross Section).

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Figure 5.241: Example of an Open Lumped Y-Z profile defined in ModelEdt

The algorithm in SOBEK does not allow for open lumped Y-Z profiles, having ’Y-Z line-segments’
that can be wetted from both sides. See for instance the ’Y-Z line-segment’ from (Y,Z) points
(25,3) to (5,4) in Figure 5.242, that is intersected by a water level of 3.5 metres. Hence a
part of this ’Y-Z line-segment is at a water level of 3.5 metres wetted at its left-side as well
as at its right-side. To avoid wetting from both sides. If the Z-value of the first user-defined
(Y,Z) point is below the maximum Z-value (Zmax) in the user defined open lumped Y-Z profile,
a (Y,Z) point is added at the beginning of the user-defined Y-Z table for which yields that its
Y-value equals the Y-value of the first user-defined (Y,Z) point and its Z-value equals Zmax.
The same applies when the Z-value of the last user-defined (Y,Z) point is below Zmax. In
such case a (Y,Z) point is added at the end of the user-defined Y-Z table for which yields that
its Y-value equals the Y-value of the last user-defined (Y,Z) point and its Z-value equals Zmax.
In Figure 5.243 it can be seen that two additional (Y,Z) points are added by SOBEK to the Y-Z
table of the open lumped Y-Z profile, that is depicted in Figure 5.242.
The computational procedure is as follows. Firstly, it is verified if a valid open lumped Y-Z
profile is defined and an error message is given if this is not the case. Thereafter, a tabulated
open lumped Y-Z table is constructed (see Figure 5.244). Next, based on the symmetrical
tabulated open lumped Y-Z profile depicted in Figure 5.244, for a particular water level the
corresponding flow area and wetted perimeter is determined. Finally, using this information
and the defined roughness,the corresponding conveyance is computed (see section 6.1.20.1).

Graphical User Interface

Figure 5.242: User defined open Lumped Y-Z profile

Figure 5.243: SOBEK adapted open Lumped Y-Z profile

Figure 5.244: Symmetrical tabulated open lumped Y-Z profile

Flow - Cross Section node (Open Tabulated type)
Cross-sections of the tabulated type use the tabulated lumped conveyance approach (see
section 6.1.20.1). A tabulated cross-section is open if the flow width at the heighest defined
elevation is greater or equal than 20 millimetres, else it is a closed tabulated cross-section (see
section 5.6.5). Total widths (i.e. storage) can be defined for open tabulated cross-sections.

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Flow - Cross Section node (Open vertically segmented Y-Z type)
Cross-sections of the open vertically segmented Y-Z profile type use the vertically segmented
conveyance approach (see section 6.1.20.2). Please note that an Open vertically segmented
Y-Z profile is obtained by selecting the item ’Open Vertically Segmented’ in the ’Type of Y-Z
profile’ list-box (see Figure 5.245), accomodated on the ’Cross-section’ Tab (Edit/Model data/
Flow - Cross Section).
Open vertically segmented Y-Z profiles are often used when river bed loadings (bathymetry
measurements) are available. The Y-Z table corresponding to Figure 5.245 is given in Table 5.5.
Table 5.5: Cross Section - Y-Z table

Z
level of the river bed

0
15
30
45
60
75
90
105
120
135

16.4
15.2
13.8
11.4
10.6
11.0
12.5
14.0
14.8
16.4

Y
distance along measuring-section

Cross section tab:

Figure 5.245: Example of an Open Vertically Segmented Y-Z profile defined in ModelEdt

Create a cross section definition:

Graphical User Interface

To start creating a cross section definition, do the following:
1
2
3
4
5
6
7

Choose the cross section of the "Y-Z profile" type in the ’Choose Type’ box;
Create a new definition by typing a name for it in the "select cross section" field
Select option "Open Vertically Segmented" in the "Type of Y-Z profile" frame
Click the button Define Dimensions and subsequently Edit Table;
Enter the desired values in the parameter columns Y and Z;
Leave the table editor again by clicking OK
Click the button Save Dimensions.

Figure 5.246: Data Edit, Friction tab, Open vertically segmented YZ profile

The conveyance of an open vertically segmented Y-Z profile is computed based on the vertically segmented conveyance approach. You can define subsections along the Y-Z profile,
having different friction values. For instance, the main gully may have a lower friction value
than the area near the embankments. In the above figure, this principle is shown.
You can change the number of subsections by clicking the arrow keys next to the ’Number of
sections’ field. Subsequently, you’ll have to assign the distances from the shore where the
change in friction will occur. Do that in the ’to Y’ fields.

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Flow - Cross Section node (Rectangle type)
Cross-sections of the Rectangular type are closed profiles using the tabulated lumped conveyance approach (see section 6.1.20.1). The rectangular cross-section is defined by its bed
level, its width and its height.
Flow - Cross Section node (River Profile type) (beta functionality)
Cross-sections of the River Profile type are open profiles using the tabulated lumped conveyance approach (see section 6.1.20.1).

The Cross Section tab

The "River Profile" cross section type becomes available when selecting the River Flow module in the Settings task block. In this chapter the options for this cross section type are discussed in more detail.

The river profile is a cross section type that can be used to model river sections. It comes
available by selecting the ‘River Profile’ cross section type in the second tab of the properties
of a cross section. Once selected, the user can start to define the properties. Figure 5.247
shows an example of a profile:

Figure 5.247: Example of a ’river profile’ type cross section

The user has the option to differentiate between flow width and storage width. This is a useful
option when part of the cross section, i.e. the sections between groynes, does not participate
in the conveyance of the water, but does contribute to the river’s storage capacity. The picture

Graphical User Interface

of the cross section will show the flow width as a green line, and the total width with a blue
line.

The level-width table is entered in the table window, which is opened by pressing the edit table
button:

Figure 5.248: Table where a cross section’s dimensions are defined.

The levels in the cross-section should be entered in ascending order. At each next level
both the flow width and the total width (flow width) are to be specified. The entire (total)
cross-section is divided into a flow part and a storage part. As a consequence, the terms
storage width and storage area refer to the storage part of the cross-section and the terms
total width and total area are used when the entire cross-section is meant. In view of the
applied numerical solution method, it is important not to specify widths that change too rapidly
with increasing level. Remark that such rapidly varying widths should also be avoided because
of reasons of accuracy. A maximum relative increase of about a factor of 5 over 1 cm (or a
factor of 50 over 10 cm, etc.) is recommended, i.e.

Wi+1 /Wi
= O(5/cm)
zi+1 − zi

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with Wi and Wi+1 the cross-sectional widths specified at the two consecutive levels Zi and
Zi+1 (this applies to both flow width and storage width). So for example, when the storage
width at a certain level measures 85 m, the storage width to be specified at a level that is 1
cm (5 cm) higher should not be much larger than 425 m (2 125 m), i.e., the bank slope should
not be smaller than about 0.0025 m/100 m in this particular case.

Both the total width and the flowing width can be entered here as a function of the vertical
level. The total width should always be equal to or larger than the flow width. When you
choose to use a summer dike, you can enter the necessary information by selecting the ‘edit
summer dikes’ option and switching on the ‘use summer dike’ option. See Figure 5.249.

Figure 5.249: Activating the ’summer dike’ option

The transition height for summer dikes should be defined in the ’Advanced Settings’ Tab in the
SOBEK-River section on the SETTINGS task block from the Case Manager. This transition
height will act on all summer dikes defined in the model.

Graphical User Interface

Figure 5.250: The advanced settings tab for the SOBEK-River settings.

When a flood plain is separated from the river by a summer dike, the cross section profile
including the floodplain does not increase monotonously in height. In this case, it is possible
to include summer dikes in the schematisation.
The Friction Tab

The friction type and value can be specified per subsection of the flowing part of the cross
section. There are three different subsections: (i) the main river, (ii) floodplain 1 (fp1 ) and
(iii) floodplain 2 (fp2 ). For every section the flow width can be chosen. The width of the three
sections combined is always equal to the total flow width specified in the level-width table.
The following friction types can be applied:

Chézy
Manning
Strickler (kn )
Strickler (ks )
White-Colebrook
Engelund

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Figure 5.251: Defining subsections for unique friction values on different sections

By default, the friction value is the same for river flow in positive direction (defined branch
direction) and in negative direction. The user can choose to change this by pressing the
corresponding button in the ‘bed friction column in Figure 5.251. As a result, the form depicted
in Figure 5.252 pops up.

Figure 5.252: Window for friction settings of the main profile section.

Graphical User Interface

Finally, the Chézy, Nikuradse, Manning or Strickler coefficients may be defined as

a constant;
spatially varying along the river branch (F (X));
a tabulated function of both the water level (h) and the x-axis (F (h)) or both the total
discharge (Q) and the x-axis (F (Q)).

The last two options are only available for local friction definitions (when also local values have
been selected), not for global definitions. All options are available for all three sections of the
flowing part of the river. Figure 5.253 shows the empty table that can be filled in for friction
values dependent on water levels and location.

Figure 5.253: Entering friction values as a function of water levels and location

First of all, the locations for which the friction is a known variable should be filled in. This is
done by adding columns (locations), and giving them the numerical value of the distance along
the branch from the start of the branch to the location itself. In Figure 5.254, two locations
have been added at 1 200 m and 2 400 m from the beginning, respectively. Next, the number
of rows needs to match the number of water levels for which there is data. In the example

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below, two levels have been added to make a total of four levels available. Finally, the friction
values as a function of f (X, h) can be entered.

Figure 5.254: Locations for which the friction values are known, added to the table.

Flow - Cross Section node (Round type)

Cross-sections of the Round type are closed profiles using analytical formulae for computing
lumped conveyance as function of water depth.
The input screen looks as follows:

Graphical User Interface

Figure 5.255: Data Edit, Cross section tab, Round type

In the right-lower corner of the screen, an impression of the cross section shape that you enter
will be plotted. The dimensions that you filled in will be plotted next to it.
Create a cross section definition:
To start creating a cross section definition, do the following:
1
2
3
4
5
6

choose the cross section of the "Round" type in the ’Choose Type’ box;
Create a new definition by typing a name for it in the "select cross section" field
Click the button Define Dimension;
Enter the desired value in the parameter fields "diameter";
Optionally, turn on the "use ground layer option" and enter a value;
Click the button Save Dimensions.

Parameters:
This cross section type requires the following parameters:

Diameter: represents the diameter the cross section.
Use Ground Layer: switch this on if a layer of sediment lies in the cross section. An
individual roughness value may be given for the ground layer. See the ’Friction’ tab for
this.
Ground layer: enter the thickness of the sediment layer that lies within the cross section.
This thickness will be made visible in the image on the right side through a red line.

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Flow - Cross Section node (Steel Cunette type)
Cross sections of the Steel Cunette type are closed profiles using the tabulated lumped conveyance approach (see section 6.1.20.1).

The input screen looks as follows:

Figure 5.256: Steel Cunette type Cross section input screen.

In the right-lower corner of the screen, an impression of the cross-section shape that you
enter will be plotted. The dimensions that you filled in will be plotted next to it.
Create a Steel Cunette cross section definition (see Figure 5.256):
To start creating a cross-section definition do the following:

Choose the cross section of the “Steel Cunette” type in the ‘Choose Type’ box;
Create a new definition by typing a name (e.g. Steel Cunette Type 2) for it in the “Cross

section” field
Click the button Define Dimensions;
Enter the desired values in the parameter fields “Height, Radius r, Radius r1, Radius r2,
Radius r3, Angle a, and Angle a1. To define a coherent set of these parameters, see the
section Types of Steel Cunette Cross-section hereafter;
Optionally, turn on the “use ground layer option” and enter a value;
Click the button Save Dimension

Note:
That the prefix “s_” has been added in front of your defined Cross-section name, indicating that
the Steel Cunette Cross-section is stored as Tabulated Cross-section, the entered parameters
are not stored.
Editing a defined Steel Cunette cross-section (see Figure 5.257):

Graphical User Interface

Once a Steel Cunette Cross-section has been saved, its dimensions can be changed in the
following manner:

Choose the cross section of the “Tabulated” type in the ‘Choose Type’ box;
Open the scroll box available in the “Cross section” field and select the “s_Steel Cunette
Type 2” cross-section;
Click the button Define Dimensions.
Optionally, turn on the “use ground layer option” and enter a value;
Optionally, check the option “Different flow and storage width”;
Click the button Edit Table for making changes in the [Level, Total width, Flow width] table,
Click the button Save Dimension for saving your changes

Figure 5.257: Editing an existing Steel Cunette profile.

Types of Steel Cunette Cross-sections:
Steel Cunette Cross-sections are symmetric w.r.t. the vertical axis through the centre of the
profile. A Steel Cunette Cross-section may comprise of either three or four different circle
segments.
Steel Cunette Cross-section comprising of three different circle segments:
A Steel Cunette comprising of three different circle segments is depicted in Figure 5.258. For
obtaining a realistic cross-sectional profile the user-defined values for the parameters: Height,
Angle a, Angle a1, Radius r, Radius r1, Radius r2 and Radius r3 should be mutually consistent
(see Figure 5.258):

Create the first circle segment (i.e. AB) with Radius r by starting at point A (located anywhere on the vertical symmetry axis) with centre point M (located on the vertical symmetry
axis at a distance of Radius r below point A) and rotate over an angle of half the Angle a.
In this way point B is obtained,
Create the second circle segment (i.e. BC) with Radius r2 by starting at point B with centre
point M2 (located at a distance of Radius r2 from point B on the line through points B and

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M) and rotate over a particular angle in order to obtain point C,
Create the third circle segment (i.e. CD) with Radius r1 by starting at point C with centre
point M1 (located at the intersection of the vertical symmetry axis and the line through
points C and M2) and rotate up to the intersection with the vertical symmetry axis and
obtain point D.
Parameter Height is the vertical distance between points D and A. Parameters Angle a, Radius
r, Radius r1 and Radius r2 follow from the three circle segments. Parameters Angle a1 and
Radius r3 are equal to zero.

Remarks:
In case the user-defined Angle a = 120 degrees; Angle a is used to compute the crosssectional profile, including its actual height that is used instead of the user-defined
height.
In case Angle a < 120 degrees, the user-defined Angle a is ignored and the actual
applied Angle a is computed using the formula below (see Figure 5.258). Using this
computed Angle a, the cross-sectional profile is computed including its actual height,
that is used instead of the user-defined height.

1
2
2
2
a = arccos lM,M
+ lM,M
− lM
/(2lM,M1 lM,M2 )
1
2
1 ,M2
2
lM,M1 = r1 − H + r
lM,M2 = r − r2
lM1 ,M2 = r1 − r2

(5.3)
(5.4)
(5.5)
(5.6)

Steel Cunette Cross-section comprising of four different circle segments:
A Steel Cunette comprising of four different circle segments is depicted in Figure 5.259. For
obtaining a realistic cross-sectional profile the user-defined values for the parameters: Height,
Angle a, Angle a1, Radius r, Radius r1, Radius r2 and Radius r3 should be mutually consistent
(see Figure 5.259):

Create the first circle segment (i.e. AB) with Radius r by starting at point A (located anywhere on the vertical symmetry axis) with centre point M (located on the vertical symmetry
axis at a distance of Radius r below point A) and rotate over an angle of half the Angle a.
In this way point B is obtained,
Create the second circle segment (i.e. BC) with Radius r3 by starting at point B with centre
point M3 (located at a distance of Radius r3 from point B on the line through points B and
M) and rotate over Angle a1 in order to obtain point C.
Create the third circle segment (i.e. CD) with Radius r2 by starting at point C with centre
point M2 (located at a distance of Radius r2 from point C on the line through points C and
M3) and rotate over a particular angle in order to obtain point D,
Create the fourth circle segment (i.e. DE) with Radius r1 by starting at point D with centre
point M1 (located at the intersection of the vertical symmetry axis and the line through
points D and M2) and rotate up to the intersection with the vertical symmetry axis and
obtain point E.
Parameter Height is the vertical distance between points E and A. Parameters Angle a, Angle
a1, Radius r, Radius r1, Radius r2 and Radius r3 follow from the four circle segments.

Graphical User Interface

Figure 5.258: Construction of a Steel Cunette Cross-section comprising of three circle
Segments (i.e. Type 3, see Table 5.6 for examples of Steel Cunette Crosssections)

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Figure 5.259: Construction of a Steel Cunette Cross-section comprising of four circle
Segments (i.e. Type 4, see Table 5.6 for examples of Steel Cunette Crosssections)

Examples of Steel Cunette Cross-sections:
In Table 5.6 four examples of Steel Cunette Cross-sections are given. Type 1 to 3 are based
on three circle segments only, while Type 4 is based on four circle segments. For Type 1 the
actual height is smaller than the user-defined height.
Table 5.6: Examples of Steel Cunette Cross-sections

Type 1
(three circles)

Type 2
(three circles)

Type 3
(three circles)

Type 4
(four circles)

Graphical User Interface

Flow - Cross Section node (Trapezium type)
Cross-sections of the Trapezium type are open profiles using the tabulated lumped conveyance approach (see section 6.1.20.1).

The input screen looks as follows:

Figure 5.260: Data Edit, Cross section tab, Trapezium

In the right-lower corner of the screen, an impression of the cross section shape that you enter
will be plotted. The dimensions that you filled in will be plotted next to it.
Create a cross section definition:
To start creating a cross section definition, do the following:

Choose the cross section of the "Trapezium" type in the ’Choose Type’ box.
Create a new definition by typing a name for it in the "select cross section" field.
Click the button Define Dimensions.
Enter the desired values in the parameter fields "Slope", "Bottom Width" and "Maximum
Flow width".
Optionally, turn on the "use ground layer option" and enter a value.
Click the button Save Dimensions.

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Parameters:
This cross section type requires the following parameters:

Bottom width B
Maximum Flow width

Use Ground Layer

represents the side slopes of the channel or pipe. Note that this
value represents Horizontal/Vertical. Thus values < 0 represent
steep side slopes.
represents the with at the bed level of the cross section;
the final term that is needed to define the shape of a trapezium,
though not really a physical realistic parameter in case of Cross Sections. Make sure that you choose a maximum flow width so that the
channel’s shape is correctly described from bed level to surface level.
The surface level that you filled in on the "location" tab is visible here
as a green line. It is best if the top of the trapezium lies higher than
that line.
switch on if a layer of sediment lies in the cross section. An individual
roughness value may be given for the ground layer. See the ’Friction’
tab for this.
enter the thickness of the sediment layer that lies within the cross
section. This thickness will be made visible in the image on the right
side through a red line.

Connecting the Rainfall-Runoff module to the 1DFLOW module
You can connect a SOBEK Rainfall-Runoff module to a SOBEK Channel Flow or River Flow
schematisation by using either of the following node types:

The Flow-RR Connection on Channel is an object that should be placed on an existing Flow
branch. A Flow-RR Connection on Flow Connection node is an equivalent for a normal Flow
Connection node. That node type should therefore form the start or the end of a branch.
To both node types, an RR schematisation can be connected. The nodes will then form the
boundary for the Rainfall-Runoff schematisation.
Tips ’n Tricks
Calculate water levels on other model objects, such as cross sections or structures
Besides the node type "calculation point" it is also possible to use other model objects for
the calculation of water levels. One can, for instance, use cross sections as if they were
calculation points. For every cross section in the model, the resulting water level will then be
written to the result-files.
Here’s how to include model objects such as cross sections in the calculation grid:

Go to the Edit Network mode of SOBEK;
Open the "Branch" toolbar and click the "Calculation Grid All branches" button
The following screen will then pop up:

Graphical User Interface

Figure 5.261: Calculation points, General tab

Activate the "Use Branch" option and go to the "Branch" tab:

Figure 5.262: Calculation points, Branch tab

Move the objects that you want to use as calculation points to the right side by using the
buttons in the middle of the screen.

Click OK
After you run the model, output data will also be available on the type of objects you
selected above.

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IMPORTANT NOTE: the type of objects you chose to use as calculation points will probably
NOT be visible in the "Results in Maps" yet. Make them visible by clicking "Options" - "Network
Options" - "Nodes" , selecting the node type, and activating the "visible" checkbox".

Features SOBEK-Urban 1DFLOW

Uses the complete de Saint Venant Equations, thus including backwater and transient flow

phenomena
Models a wide variety of cross sections and manhole shapes (including user-defined ones)
and allows you to build up your own cross section and manhole database
Specially designed to handle large and complex sewer networks on an ordinary PC, where
the computation time is only linear with the size of the network and independent of its
complexity
Has an automatic drying and pressurised procedure and handles real super critical flow
and is always 100% mass conservative
Self-selecting time step so your computer won’t crash and accuracy is guaranteed
All possible boundary conditions can be specified by you or are automatically applied
You can specify virtually any type of hydraulic structure, such as single or multiple stage
pumps, weirs of any shape, rectangular and circular gates, culverts and basins. All structures handle free, submerged and transient flow conditions
Real-time control options, including PID control, are available for all structures and is ideal
for complex centralised control systems using rainfall predictions
Sediment transport computation shows where sediment might be deposited; interfaces
completely with the SOBEK-Rural product line to provide an integrated model of the urban
water system and its environment

SOBEK-Urban 1DFLOW (Sewer Flow)

Water flow
The Water Flow module of SOBEK-Urban allows you to analyse the hydrodynamic behaviour
of a sewer network under different hydrological conditions and different management operation strategies. An example of an application is the analysis of the management of a sewer
network discharging the inflow of runoff under high rainfall conditions. Such an application
focuses on preventing high water levels at specific locations by taking measures such as creating additional storage, increasing the discharge capacity of the network, or adaptation of the
operation rules.
In SOBEK-Urban Water Flow sewer systems can be modelled by the following branch elements:

Flow-Pipe ;
Flow-Pipe with Runoff ;
Flow-Pipe with Infiltration ;
Flow-Flow Measurement Pipe ;
Flow-Internal Weir ;
Flow-Internal Orifice ;
Flow-Internal Pump Station ;

In SOBEK-Urban Water Flow sewer systems can be modelled by the following node elements:

Flow-Manhole;
Flow-Manhole with Level Measurement ;
Flow-Manhole with Runoff;

Graphical User Interface

Flow-Manhole with Lateral Flow;
Flow-External Weir ;
Flow-External Orifice ;
Flow-External Pump Station ;

With these node and branch types a wide range of networks can be represented. Consult the
Technical Reference for detailed information about the topics mentioned.
5.7.2

Flow - Pipe with Infiltration

A pipe with infiltration refers to a drainage pipe fully located inside a trench (see Figure 5.263).
Although the drainage pipe is porous it still can get pressurized. The trench is filled with
material (for instance gravel) having a certain porosity.

A pipe with infiltration allows for the exchange of water in the pipe towards the trench (positive
sign) and vice versa as well as for the exchange of water in the trench towards the groundwater
(negative sign) and vice versa. Hence, a pipe with infiltration can be seen as a pipe having a
diffusive lateral discharge option (e.g. infiltration of water in the pipe towards the trench and
exfiltration of water in the trench towards the pipe). For more information on the infiltration and
exfiltration process, reference is made to Ellis and Bertrand-Krajewski (2010), Rutsch et al.
(2008) and Karpf et al. (2008). For more information on the computational procedure of a
Pipe with Infiltration reference is made to Section 6.1.11.5.

Figure 5.263: Pipe with Infiltration (e.g. a drainage pipe located in a trench); Allowing for
the exchange of water in the pipe towards the trench (positive sign) and
vice versa; Allowing for the exchange of water from the trench towards the
groundwater (negative sign) and vice versa

Input screens of the Flow - Pipe with Infiltration

The Pipe with Infiltration input screens comprise of:

The Location Tab (see Figure 5.264): On this tab, the ID and Name of the Pipe with
Infiltration are shown. Furthermore, the invert level at the beginning of the pipe (e.g.
upstream side) and the invert level at the end of the pipe (e.g. downstream side) can be
defined.

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Figure 5.264: The Location Tab of the Pipe with Infiltration

The Cross-section Tab (see Figure 5.265): On this tab, the pipe cross-section can be
defined. Notice that in the "Type scroll box" only a Round, Egg-Shape or Rectangle closed
cross-section type can be selected. Provide a name in the window, standing next to
Cross sections, then click on the button and enter the cross-section
dimensions. Now click on the button to save your cross-sectional
profile.

Figure 5.265: The Cross Section Tab of the Pipe with Infiltration

Graphical User Interface

The Friction Tab (see Figure 5.266): On this tab, the friction formula and friction value to

applied for computing the 1D flow through the Pipe part of the Pipe with Infiltration can be
defined.

Figure 5.266: The Friction Tab of the Pipe with Infiltration

The Trench Profile Tab (see Figure 5.267): On this tab, the trench profile can be defined.
In the "Type scroll box" only a Trapezium or a Rectangle trench profile can be selected.
Please notice that both the trapezium and rectangle trench profiles are open profiles.
Hence, the water level in the trench may rise above the highest elevation, defined for such
trench profile. Dimensions of the trench profile can be specified in the same manner as
explained for the Cross-section Tab. In the picture, shown on the Trench profile Tab, it can
be verified if the cross-sectional area of the pipe is fully located inside the trench profile.
If this is not the case, a simulation will be terminated with a message in the SOBEK.log
file.

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Figure 5.267: The Trench Profile Tab of the Pipe with Infiltration

The Trench Data Tab (see Figure 5.267): On this tab in the trench window, the resistance
of the interface between the Pipe and Trench, the porosity of the trench material (notice
that porosity = 1, for trench water level above the top level of the trench or water on
street) and the initial water level in the trench (e.g. user-defined value, equal to initial 1D
water level or equal to groundwater level) can be defined. In the Groundwater window,
the permeability of the ground/soil (e.g. permeable or impermeable), the resistance of the
interface between the Trench and the Groundwater (only possible if the option permeable
is selected) and groundwater levels (only possible if the option permeable is selected)
can be defined. For more information on the background of the various input parameters,
reference is made to Section 6.1.11.5.

Graphical User Interface

Figure 5.268: The Trench Data Tab of the Pipe with Infiltration

Additional Output available for Flow - Pipe with Infiltration

The "Settings for 1DFLOW module" Form (see Figure 5.269) becomes available after clicking
on the 1D Flow buttton in the Settings Task block. Additional output parameters for a
Flow - Pipe with Infiltration become available by checking "Results from Infiltration Pipes" in
the output parameter-box, located on the Output options Tab (see Figure 5.269). After a computation, these additional output parameters can be viewed at a Flow - Pipe with Infiltration
in the "Results in Maps" Task block or under "Results at Branch Segments" in the "Results in
Charts" Task block. The additional "Flow - Pipe with Infiltration" output parameters comprise
of:

Groundwater level at trench: The groundwater level boundary condition applied for the
Flow - Pipe with Infiltration. [m above datum]

Groundw. to trench lat. flow: Exchange of water between the external groundwater

reservoir and the trench. Positive if water flows from the groundwater reservoir towards
the trench. Negative if water flows from the trench towards the groundwater reservoir.
[m3 /s]
Pipe to trench lat. flow: Exchange of water between the pipe and the trench. Positive
if water flows from the pipe towards the trench. Negative if water flows from the trench
towards the pipe. [m3 /s]
Volume in trench: The volume of water stored in the trench [m3 ].
Water depth in trench: The water depth in the trench of the Flow - Pipe with Infiltration.
[m]
Water level in trench: The water level in the trench of the Flow - Pipe with Infiltration.
[m above datum]

Note: If there is no water in the trench, a water level equal to the bed level of the trench is
provided as output.

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Figure 5.269: The "Settings for 1DFLOW module Form" available in the Settings
Taskblock

Especially for sewer systems it is useful to determine the storage in the pipe system. Therefore
you can use the Storage Graph tool. This tool can be used from the Tools menu in the network
editor.

Figure 5.270: To start the storage graph

Once the program has been started the user has the option to determine the storage for the
whole network, or for a part of the network, that must be selected already.

Graphical User Interface

Figure 5.271: Definition of storage graph options

The next options are available (see Figure 5.271:

Use storage in nodes If selected, both the storage in the pipes and the nodes are taken
into account. If not selected, only the storage in the pipes are included.

Use the storage at the street
Determine storage in mm related to the defined runoff area If you select this option, the
storage is not only determined in cubic metres, but also related to the runoff area that is
defined in the selected network.
To perform the calculation of the storage, you have to press the Process button. The calculation might take a few seconds and finally the graph pops up as shown in Figure 5.272

SOBEK, User Manual

Figure 5.272: Storage graph result

The left part of the window contains a table with the surface area [m2 ] and storage (m3 ) as
function of the level. The table starts at the lowest part in the network and runs with a step of
1 cm to the highest level.
The right part of the window shows the graph. It is possible to print the graph and to copy
the graph to the clipboard. Next to that also the contents of the table can be copied to the
clipboard by pressing the button Copy Data.
5.7.4

Coupling with other modules

Coupling a Sewer Flow manhole with the Overland Flow module (2D grid)
If you desire to create an interaction between the Sewer Flow module and the Overland Flow
module, you may want to couple a Flow - Manhole with the 2D-grid. You can either choose to
use a manhole of the type "reservoir" or the type "loss".
Manhole of the type "closed":
If a Flow-manhole of the type "closed" is placed on a 2D grid cell, there will be no exchange
of water between the 2D grid and the manhole.
Manhole of the type loss:
If you choose place a Flow-Manhole of the type loss on a 2D grid cell, the street level for that
manhole is overruled by the level of the connected 2D grid cell:

Graphical User Interface

Figure 5.273: Coupling a manhole ot the type loss with a 2D grid cell

Manhole of the type reservoir:
If you choose a Flow-manhole of the type reservoir, and place it on top of a 2D grid cell, two
situations may occur. See the picture below.

SOBEK, User Manual

Figure 5.274: Coupling a manhole ot the type reservoir with a 2D grid cell

Connecting the Rainfall-Runoff module to the 1DFLOW module

You can connect a SOBEK Rainfall-Runoff module to a SOBEK Channel Flow or River Flow
schematisation by using either of the following node types:

The Flow-RR Connection on Channel is an object that should be placed on an existing Flow
branch. A Flow-RR Connection on Flow Connection node is an equivalent for a normal Flow
Connection node. That node type should therefore form the start or the end of a branch.
To both node types, an RR schematisation can be connected. The nodes will then form the
boundary for the Rainfall-Runoff schematisation.

Graphical User Interface

River Flow controllers and triggers
In this section the so called River Flow controllers and triggers are discussed. These controllers and triggers can be assigned to compound structure members (excluding River Pump),
a Database structure, a General structure, an Advanced weir and a River weir.

The Controllers tab:

Figure 5.275: Data Edit, Controllers tab

Each above mentioned structure can be operated by a combination of controllers (max. 4).
There are six possible controllers that can be applied:

Time Controller
Hydraulic Controller
Interval Controller
PID Controller
Relative from Time controller
Relative from Value controller

A detailed description of the parameters for these controller types is given in the Technical
Reference Manual. For further detailed explanation on controller functionalities, reference is
made to Appendix River Flow controller options.
Defining a controller:A new controller can be defined as follows:

Type an appropriate name for the controller in the "Definition" field.
Click the button
Choose the appropriate controller type from the "Type" drop-down box.
Enter the parameter values for the chosen controller.

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If necessary, let the controller be activated and deactivated by a trigger. Do this by appointing the appropriate trigger on the button. Triggers can be defined
on the "Triggers" tab.

Don’t forget to activate the controller. Do this on the tab "Structure"

Figure 5.276: Data Edit, Triggers tab

A certain controller can be activated or deactivated by using a trigger. A trigger can be programmed so that it is activated under certain circumstances. We distinguish three types of
triggers:

Time triggers: a time table defines when the trigger is active and when it is inactive.
Hydraulic triggers: the trigger is activated or inactivated under specific hydraulic circumstances at a measurement location.

Time & Hydraulic triggers: this refers to a combined of a Time trigger and Hydraulic trigger.
Defining a trigger:

Type an appropriate name for the trigger in the "Definition" field.
Click the button
Choose the appropriate trigger type from the "Trigger Type" drop-down box.
Enter the parameter values for the chosen trigger.

Don’t forget to let your controller know that it should ’listen’ to this trigger. Do this by clicking
the button on the "Controllers" tab. For an example see Figure below,
where you can see that Time Trigger no 1 is used to activate and de-activate Time Controller
no 1. Note that clicking on the controller data button in the Figure below, provides information

Graphical User Interface

on the controller data of Time Controller no 1. Thereafter clicking one of the ’Trigger used’
buttons (see two figures above) provides information on the triggers used (i.e. figure below is
obtained again).

Figure 5.277: Data Edit, Controllers tab

SOBEK-Rural/Urban/River Overland Flow (2D)
Introduction

In January 1998, RWS|DWW and WL | Delft Hydraulics branched an agreement to work together on a project to combine the functions of Delft-FLS and the SOBEK-Rural 1DFLOW
module. The goal was to create a single computer model that could be used to model combined 1D and 2D flow for different scenarios, like for example a dike-bbranch. The agreement
resulted in a number of projects which had as a goal to improve and expand the possibilities
of the program. Many refinements were added, among which the concept of multiple grids.
The resulting functionality is known as ’1D2D functionality. This functionality is available in
case a 1DFLOW module and the Overland Flow (2D) module are selected.
Definitions
This chapter gives an overview of various terms used in this manual to describe the Overland
Flow module.
ArcView
ArcView is a desktop-GIS application, that gives the user the possibility to solve GIS related
problems in a very user-friendly environment.
Delft-FLS
Purely 2D hydrodynamical flood modelling system.

SOBEK, User Manual

DEM
Digital Elevation Model. A DEM is a representation of terrain heights in grid format. Also
called DTM (Digital Terrain Model)
GIS:
Geographic Information System. Geographically oriented database used to analyze and
present spatially distributed data.
NETTER:
A GIS- tool from the Delft-Tools family. It is used within SOBEK to view and edit schematisations, and to visualize results from simulations.

Viewing 2D Grid Info

Using the 2D Grid Info option, information can be obtained on:

individual 2D grid cells, or
on a path of 2D grid cells.

Note: all units used in this manual and in SOBEK are metric (S.I. standard).

The user can add the information of various individual 2D grid cells to one and the same
graph. A path of 2D grid cells can cross at any angle over a 2D grid. At present the path of
2D grid cells can not pass over nested grids (i.e. parent grid and child grid) in such way that
only the active parent and child 2D grid cells are being selected.
Further on a distinction is to be made between static values and dynamic values. Static values
refers to the values on the underlying 2D grid (for instance a bed elevation) or underlying
map file (for instance maximum water depths). Dynamic values refers to time-dependent
computation results (for instance incremental water depths).
How to make a 2D path:

Both in the ‘Schematisation’ and ‘Results in Maps’ Task blocks.

In the main menu, click on Select/2D-Grid cell info
Click on the 2D grid cell at which you like to start your 2D path (i.e. starting 2D grid cell).
Note that in the ‘Path2D-Grid Info’ window, the column and row number of the starting 2D
grid cell are given in the two boxes in front of the Path check-box.

Click the Path check-box,
While pressing on the Shift key, place the mouse-pointer on the 2D grid cell at which you
like to end your 2D path (i.e. the end 2D grid cell). Releasing the Shift key will result in the
selection of the end 2D grid cell. The column- and row number of the end 2D grid cell are
now filled in the two boxes behind the Path check-box.
Click on the button in the ‘2D-Grid info’ window to visualise the 2D grid cells
contained in your 2D Path.
Remark: In case you have more than 1(one) 2D grid (for instance in case of nested grids), the
2D grid cell of the 2D grid that lies on top will be selected. Using the Next Grid button the grid
cell on the underlying 2D grid will be selected. Note that in this case the Grid ID will change.
How to retrieve 2D Grid Info:

Under the ‘Schematisation’ Task block only information on static values of the 2D grid

Graphical User Interface

cells are available. In case the 2D path option is not used, the static value of the selected
2D grid cell is depicted on the one most last line in the ‘2D-Grid Info’ window (Note that
dynamic values are not available under the ‘Schematisation Task’ block). In case a 2D
path is selected, the static values of the concerning 2D grid cells can be obtained by
clicking the Graph button. Note that in the main menu of this graph the x-axis can be
changed to either value (distances) or labels (column and row number of the 2D grid).
Under the ‘Results in Maps’ Task block, information on both static- and dynamic values
of the 2D grid cells are available. In case the 2D path option is not used, the static- and
actual dynamic value of the selected 2D grid cell is depicted on the last two lines in the
‘2D-Grid Info’ window. Please note that static values are displayed in grey. Clicking the
most left Graph button, provides a graph of dynamic values of each selected 2D grid cell
as function of time. Please note that by clicking on another 2D grid cell and sequentially
clicking on this Graph button again, the user can add the dynamic results of various 2D
grid cells in one and the same graph. In case a 2D path was selected, clicking on the
most left Graph button results in a graph of the dynamic values of the starting 2D grid cell
of the 2D path. Clicking the most right Graph button provides a graph, showing for all 2D
grid cells lying on the 2D path, its static value as well as its dynamic values for a particular
point-in-time.
Note:
1 the x-axis of this graph can be plotted as function of value (distance) or labels (column
or row number);
2 dynamic values are only available in case they are selected beforehand (Click in main
menu on File→Open Data→Depth Incremental (in the Select Item window));
3 using the ‘View Data’ window dynamic values can be added to the graph; and
4 using the forward and backward buttons in the ‘View Data’ window, the point-in-time
for which the dynamic values are shown under the most right Graph button can be
changed.

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Figure 5.278: Example of a 2D Path under a particular user defined line

Coupling with other modules

General Aspects of a 1D2D model
The figure below depicts the currently available building blocks (called ’nodes’ in SOBEK). For
now, two groups of nodes are available, namely the flow nodes and the 2D nodes. The flow
nodes are the ones used to build 1D schematisations, please refer to the SOBEK Channelflow manual. The 2D nodes are the elements that have been added to SOBEK for the modelling of 2D systems. Together they make up the 1D-2D schematisation.
One important 2D building block that is not included in Figure 5.279 is the flow - dam break
branch. This is a branch type, and not a node, which means that it can be found with the
branches.

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Figure 5.279: Available node types for the Overland Flow & Channel Flow modules

A very important aspect to consider when using this type of schematisation is the interaction
between the 1D and the 2D system. The theory behind this interaction was explained in
chapter 2, and the FAQ-section contains an example of a dike-bbranch modelled in 1D.
When building a 2D schematisation, there are a number of rules that need to be obeyed.
One of the first rules is that every 2D-schematistion needs to contain al least one 1D-branch,
even when the schematisation is purely 2D. In this case, the 1D-branch is referred to as a
’dummy-branch’. Usually, this branch would be placed somewhere outside of the grid, and it’s
properties would be as simple as possible. The figure below shows an example:

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Figure 5.280: Example of a 1D dummy branch

The second rule is that it is not possible to put more than one object in one 2D grid cell. The
only exception to this rule is the 2D- history node, which can be combined with any other type
of 2D node.
One also needs to take care when combining 1D and 2D schematisations. Some combinations of elements will not be possible because of the (automatic) links made between the two
models. As explained in chapter 2, links with the 2D grid are only possible starting from a 1D
connection node or a 1D calculation point, and not from any other type of 1D node, like a 1D
boundary. Because there can be only one 1D node connected to a 2D grid cell, it is a good
idea to have exactly One, no more and no less, 1D calculation point (or connection node)
defined per 2D grid cell.
Finally, the last important fact to remember is that SOBEK internally removes all outside grid
cells from the grid, before starting the simulation! So the grid used for calculation will be 2
columns and 2 rows smaller. Knowing this, it is also not possible to define any 2D nodes in
any of the outer grid cells. If you do so anyway, SOBEK can stop the simulation with an error
message.
Coupling a Sewer Flow manhole with the Overland Flow module (2D grid)
If you desire to create an interaction between the Sewer Flow module and the Overland Flow
module, you may want to couple a Flow - Manhole with the 2D-grid. You can either choose to
use a manhole of the type "reservoir" or the type "loss".
Manhole of the type "closed":
If a Flow-manhole of the type "closed" is placed on a 2D grid cell, there will be no exchange
of water between the 2D grid and the manhole.
Manhole of the type loss:
If you choose place a Flow-Manhole of the type loss on a 2D grid cell, the street level for that
manhole is overruled by the level of the connected 2D grid cell:

Graphical User Interface

Figure 5.281: Coupling a manhole ot the type loss with a 2D grid cell

Manhole of the type reservoir:
If you choose a Flow-manhole of the type reservoir, and place it on top of a 2D grid cell, two
situations may occur. See the picture below.

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Figure 5.282: Coupling a manhole ot the type reservoir with a 2D grid cell

SOBEK-Rural RR (Rainfall-Runoff)

Features SOBEK-Rural Rainfall-Runoff
Models rainfall run-off and other hydrological processes in rural areas and urban areas
Catchment areas can easily be modelled in a lumped or detail manner, with no restriction
to the number of catchment areas
Catchment areas can be modelled in any detail using land elevation curves, soil characteristics, land cultivation, drainage characteristics etc.
Distinguishes between various rainfall run-off processes such as surface run-off, sub-soil
drainage and storage in saturated and unsaturated areas, taking into account crop evaporation and capillary rise
Uses separate storm events or long time series of meteorological data for statistical analysis
You can input your own rainfall patterns or use historical data, and model any number of
rainfall gauges taking into account the spatial variation
Model both flood events and dry spells
Module can be used in combination with the flow module and real-time control module
Can also be used as a stand-alone, using reservoir approach for open water flow

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Connecting the Rainfall-Runoff module to the 1DFLOW module
You can connect a SOBEK Rainfall-Runoff module to a SOBEK Channel Flow or River Flow
schematisation by using either of the following node types:

The Flow-RR Connection on Channel is an object that should be placed on an existing Flow
branch. A Flow-RR Connection on Flow Connection node is an equivalent for a normal Flow
Connection node. That node type should therefore form the start or the end of a branch.

Selecting a subset period of a rainfall event

This page explains how to select a subset period of a rainfall event for running the Flow
module, while running the full period for the rainfall-runoff module.

To both node types, an RR schematisation can be connected. The nodes will then form the
boundary for the Rainfall-Runoff schematisation.

For combined Rainfall-Runoff and Flow schematisations, it is possible to run the Flow simulations for a subset of the Rainfall-Runoff simulation period. Usually, the simulation period of
the Rainfall-Runoff model is determined by the rainfall file as indicated in the following figure.

Figure 5.283: Definition of simulation period for Rainfall-Runoff model.

The Channel or Sewer Flow module simulation period is specified using a similar screen.

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As an additional option, when both the RR and CF/SF simulation periods are derived from the
meteorological data, there is the option to specify the interaction period for the RR and CF/SF
modules. This is done in the Settings screens of the Rainfall-Runoff module. Of course, the
interaction period should be a subset of the period covered by the meteorological data.

Figure 5.284: Interactions of Rainfall-Runoff module with Flow module.

In the example shown in the figure, the Rainfall-runoff module will use the full precipitation
event (from 1995-01-01 0 o’clock to 2 o’clock) while the Flow module covers the period from
00:15 to 01:55 o’clock.
5.11
5.11.1

SOBEK-Urban RR (Rainfall-Runoff)

Features SOBEK-Urban RR (Rainfall-Runoff) module
Models dry weather flows and the rainfall run-off processes for various types of paved
areas, such as streets, roofs and parking lots
Extended possibilities for unpaved areas and groundwater using the fully integrated link
with the Rainfall Run-off module of the SOBEK-Rural product line
Urban catchment areas can be easily modelled in a lumped or detailed manner with no
limit to the number of catchments
You can input your own time and spatially varied rainfall pattern or use historical data of
storm events and long time series with or without dry periods
Links two directionally to the hydrological database program HYMOS
Infiltration is specified as a time-dependent process following the HORTON eqation

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The SOBEK-Urban RR (Rainfall-Runoff) concept
The inflow towards the sewer system consists of runoff from rainfall and dry weather flow. The
Runoff model of Flow-Manhole and Flow-Pipe, also called NWRW model, Nationale Werkgroep Riolering en Waterkwaliteit (NLingenieurs, 1978), describes the dry weather flow and
the transformation in time of rainfall into runoff entering the sewer system. The Runoff model
is based on the guidelines. The processes included are:

moistening and puddle forming;
infiltration;
runoff delay.

It is illustrated that the rainfall-runoff process with netto rainfall is the same as the runoff
towards the sewer system and is equal to the rainfall minus evaporation minus infiltration
minus the change of storage.

Figure 5.285: Illustration of rainfall-runoff process

The rainfall-runoff process
As a result of moistening and puddle forming, part of the rainfall will be stored temporarily on
the surface. This storage is called surface storage. This storage is reduced by evaporation
as well as infiltration. Different types of surfaces can be distinguished, depending on surface
characteristics and slope. The model distinguishes four types of surfaces (closed paved,
open paved, roof, unpaved) and three types of slopes (area with a slope, flat, stretched flat),
thus twelve different area types. The slope of the surface and the infiltration capacity largely
influence the rainfall-runoff process.
The infiltration of rainfall takes place in the open paved areas and unpaved areas. The infiltra-

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tion capacity depends mostly on the type of surface and moisture condition. Other factors may
also play an important role. For example, the infiltration capacity of brick paths depends on the
condition of the openings between the bricks. The infiltration capacity of the unpaved areas
depends on the vegetation, the kind of soil and the percentage of moisture in the subsurface.
The description of the infiltration of the Runoff model is based on the formula of Horton (See
also Technical Reference).
The delay of runoff depends on the average distance to the inflow location in sewer system,
the slope and the geometry of the catchment. The formula which describes the runoff to the
sewer system is the formula of the rational method (See also section 6.5.4).

SOBEK-Urban RR (Rainfall-Runoff) input screens

Figure 5.286: Data Edit for Sewerage Inflow, Surface tab

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Figure 5.287: Data Edit for Sewerage Inflow, DWF tab

Figure 5.288: Data Edit for Sewerage Inflow, Rainfall station tab

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Figure 5.289: Data Edit for Sewerage Inflow, Runoff tab

Figure 5.290: Data Edit for Sewerage Inflow, Storage tab

Graphical User Interface

Figure 5.291: Data Edit for Sewerage Inflow, Infiltration tab

For NWRW nodes (Urban rainfall-runoff model), there are two infiltration options available in
the user interface:

Infiltration from depressions;
Infiltration from runoff;

Figure 5.298 illustrates the NWRW modelling concept.

The infiltration from depressions indicates the infiltration from water that is stored in depressions. The surface storage in depressions is typically a few mm. When the surface (depression) storage exceeds the defined threshold, runoff is computed.
However, the runoff may take some time to branch the outflow point (for urban sewer systems:
the point where the runoff flows into the sewer system). The option ’infiltration from runoff’
can be used to simulate infiltration from the runoff dynamic storage. The same set of Horton infiltration parameters are used for both infiltration from depressions and infiltration from
runoff.
Default only the infiltration from depressions is switched on. Switching on the infiltration from
runoff will result in some additional infiltration losses and less inflow in the sewer system.

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Figure 5.292: Concept of Urban runoff model

SOBEK-Rural/Urban/River RTC (Real Time Control)
Why a separate RTC (Real-time Control) module

Real-time Control is a separate module within SOBEK. One could ask for the reason for this.
In a SOBEK-Urban 1DFLOW, a SOBEK-Rural 1DFLOW, a SOBEK-River 1DFLOW and a RR
schematisation, controllers can be defined for operating the available structures. So real-time
control options are already available within these modules. The reasons for having a separate
Real-time Control (RTC) module are:

the controllers in the SOBEK-Urban 1DFLOW, SOBEK-Rural 1DFLOW and SOBEK-River

1DFLOW modules are local controllers, looking at 1 (one) water level or flow in the hydrodynamic schematisation. Using Real-time Control, it is possible to take into account more
than 1 location: you can control the structure looking at any linear combination of values
at different locations;
in Real-time Control, it is possible to define a measure (or RTC controller) for a (previously
defined) controller in the Flow or Rainfall-Runoff schematisation. Such RTC measure can
consist of several different type of decision rules, where each decision rule has its own
priority. If defined active, such RTC measure will overrule its associated active controller
in the Flow or Rainfall-Runoff schematisation. In case the associated controller is notactive (i.e. not triggered), the setpoint provided by the RTC measure will be neglected
(see for more details RTC does not overrule Flow Triggers).
most important, using Real-time Control it is possible to take into account information from
different SOBEK modules. One can define the operation of a pump in Rainfall-Runoff
based on results of the Flow modules (or hydrodynamic computational results), or define
the operation of a weir or pump in a Flow module based on computed runoff by the rainfallrunoff module, or based on available rainfall and wind data, or on other data (e.g. water
quality). This gives many more possibilities than just using local controllers in a Flow or
Rainfall-Runoff schematisation.
SOBEK RTC is equiped with a special reservoir module, allowing operation of reservoirs
or ponds with multiple outlets using a set of rule curves.
Further on the Real-time Control (RTC) module can be online coupled with a Matlab com-

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putation, allowing for any type of controller to be applied.
5.12.2

Condition
A Real-time Control measure usually involves a logical condition. Only if that condition is
satisfied, the measure will be active.
A condition is of the following form:
‘value of decision parameter’ ‘check’ ‘check value’
The check can be ‘<’, ‘=’ or ‘>’.

Data locations in RTC

The check value can either be a constant input value, or the value of another decision parameter.

Data locations in Real-time Control (RTC) represent, as the name suggests, those locations
at which data can be defined. Using the data defined at data locations, so-called decision
parameters can be defined. In RTC so-called measures can be defined. A measure consists
of a number of decision rules. These decision rules can be formulated using the defined decision parameters. In case a measure is defined active, the corresponding decision rules will be
evaluated and will result in a setpoint for the associated Flow or RR controller, that is assigned
to a particular structure[s] located in either the Flow or Rainfall-Runoff schematisation.
In Real-time Control five different types of data locations can be defined:

1DFLOW Data; computed hydrodynamic parameters at specific locations in the SOBEK

Urban 1DFLOW, SOBEK-Rural 1DFLOW and SOBEK-River 1DFLOW schematisations
2DFLOW Data; computed hydrodynamic parameters at specific locations in the Overland
Flow schematisation
RR Data; computed parameters at specific locations in the Rainfall-Runoff schematisation
Precipitation Data; user-defined rainfall data
Wind Data; user-defined wind data (i.e. wind velocities and wind directions)
External Data - His Files; user-defined External Data (can be data, that is not used or
computed by any SOBEK module)

Data measurement location

The data measurement locations represent, as the name suggests, those locations at which
data is available for Real-time Control. At the moment, 4 types of data measurement locations
are available. These are:

locations in the Water Flow module (Water Flow locations)
locations in the Rainfall-Runoff module (Rainfall-Runoff locations)
rainfall prediction locations
other locations (also called external locations); at the moment these locations are used for
wind predictions and for data from external HIS files.

SOBEK, User Manual

Figure 5.293: RTC Flow data locations input screen

The available data (measurements) at Water Flow locations are given in the following list:

water level + RefL [m];
flow [m3 /s];
surface area [m2 ];
water depth [m];
crest level [m];
crest width [m];
gate lower edge [m];
gate opening height [m];
structure flow area [m2 ];
discharge at the structure [m3 /s];
flow velocity at the structure [m/s];
water level up [m];
water level down [m];
head over structure [m];
pressure difference over structure;
pump capacity [m3 /s].

Data availability depends on the type of location (a node, a branchsegment, a flow measurement location, or a structure) and type of structure. For instance, for a weir, no pump capacity
is available.
The available data at Rainfall-Runoff locations are:

open water level (m + RefL);

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groundwater level (m + RefL);
The available data at rainfall prediction locations are:

rainfall prediction at time step t+1 (mm/time step);
rainfall prediction at time step t+2 (mm/time step);
rainfall prediction at time step t+3, etc.
The available data for wind prediction are:
wind direction prediction at time step t+1 (degrees);
wind direction prediction at time step t+2; etc. and
wind velocity prediction at time step t+1 [m/s];
wind velocity prediction at time step t+2, etc.

The available data for external locations related to a SOBEK HIS file are taken from the external HIS file and indicated by the user.
Decision Parameters in RTC

In Real-time Control (RTC), decision parameters can be defined on basis of the data available
at earlier defined Data locations. Decision parameters are used in defining measures (or RTC
controllers), that determine how a particular structure is to be operated.
Real-time Control allows to define a wide range of decision parameters. Examples of decision
parameters are:

The water level or discharge at a particular location in a 1DFLOW schematisation,
The waterlevel or abs. velocity at particular location in an Overland Flow schematization,
The outflow discharge from a Rainfall-Runoff schematisation,
The predicted area weighted average rainfall of all rainfall stations,
The predicted wind velocity

In RTC following type of decision parameters are discerned (see Figure below):

Function (decision) parameters,
Time (decision) parameters, and
Reservoir (decision) parameters.

Please note that Interpolation Tables are not decision parameters. Interpolation Tables are
used in defining so-called Interpolation Function decision parameter (see mathematical manipulations available for function decision parameters hereafter).

SOBEK, User Manual

Figure 5.294: Example of RTC input screen for Function (decision) parameters

Function (decision) parameters:
The actual time-dependent value of a Function decision parameter can result from a mathematical manipulation:

on the corresponding value of a single data series, or
on the corresponding values of a set of data series.

Mathematical manipulations available for single data series are: None, Sin, Cos, Tan, ArcSin,
ArcCos, ArcTan, Sinh, Cosh, Tanh, Interpolate, Floor, Ceil, Nint, Exp, Log, Log10, Square and
Sqrt.
Remarks:
None means that no mathematical manipulation is carried out on the data series,
Interpolate; for each independent value, a corresponding dependent value (or Interpolate Function Decision parameter) is determined by linear interpolation in an Interpolation Table (first column: independent variable in ascending order; second column:
dependent variable). If an independent variable is smaller than the value on the first
row, the dependent variable will be set equal to its value on the first row. If an independent variable is larger than the value on the last row, the dependent variable will be set
equal to its value on the last row.
Floor(12.8)=12.0; Ceil(12.2)=13.0;
Nint (Nearest INTeger), Nint(12.1)=12, Nint(12.5)=13, Nint(-12.5)=-13
Mathematical manipulations available for a set of data series are: Add, Subtract, Multiply,
Divide, Max, Min, Average and Power (for more information, see Table 5.7)

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Table 5.7: Mathematical manipulations available for a set of data series

Values (V) of data series

Function Decision Parameter value

V1, V2, V3, . . . . . . Vn

V1 + V2 + V3 . . . + Vn

V1, V2, V3, . . . . . . Vn

V1 - V2 - V3 . . . - Vn

V1, V2, V3, . . . . . . Vn

V1 * V2 * V3 . . . * Vn

V1, V2, V3, . . . . . . Vn

V1 / V2 / V3 . . . / Vn

V1, V2, V3, . . . . . . Vn

Max (V1, V2, V3, . . . , Vn)

V1, V2, V3, . . . . . . Vn

Min (V1, V2, V3, . . . , Vn)

V1, V2, V3, . . . . . . Vn

(V1 + V2 + V3 + . . . + Vn) / n

V1, V2, V3, . . . . . . Vn

(((V1ˆV2)ˆV3)ˆV4) . . . ˆVn)

Mathematical manipulation

Note: V1 is the value of the data series defined on the first row and Vn is the value of the
data series defined on the last row (see Figure above).
A data series is defined by its:

1 Data Type, Data location, and Variable Type,
2 Multiplication factor A, Off-set B, and RTC Time shift n.
Ad 1) Data Type, Data location, and Variable Type:
Presently the following data types are supported:

Data Type=1D Flow location: Computed 1D Flow data at “1D Flow Data locations” previously defined on the “1D Flow Data” Tab (see 1D Flow Data in RTC),

Data Type=2D Flow location: Computed 2D Flow data at “2D Flow Data locations” previously defined on the “2D Flow Data” Tab (see 2D Flow Data in RTC),

Data Type=External: Available data locations are the “External Data locations” previously
defined on the “External Data – His File” Tab (see External Data – His File in RTC),
Data Type=Decision parameter: Available data locations are the previously defined Function/Time/Reservoir (decision) parameters,
Data Type=Date/Time: Data source is the RTC computational point-in-time; Available data
locations are: Year, Month, Day, Hour, Minute, Second, Date, Time, Date+Time, Day of
Week and CompTimestep; Variable follows from the actual RTC computational point-intime (for more information, see Table below)
Ad 2) Multiplication factor A, Off-set B, and RTC Time shift n:
Each data series can be a linear function of the actual value of a specific variable at a particular
data location. The linear function is defined as: Data series value = A * Variable(t+n*dt)
+ B, where: A = Constant multiplication factor, t = actual RTC computational point-in-time,
n=number of timesteps, dt= time step defined in RTC Settings, and B = Constant off-set
value.

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Resuming:
Say that a Function (decision) parameter should be the 1D water levels, computed at Rotterdam at a point-in-time that is 2 RTC time steps earlier than the actual RTC computational time.
This Function (decision) parameter should comprise of only one data series with mathematical manipulation “None”. This data series is to be defined as: Data type=1D Flow location,
Data location=Rotterdam (defined at the 1D Flow Data Tab), Variable=water level, A=1, B=0
and n=-2.
Table 5.8: Data Type=Date/Time (yyyy-mm-dd; hh:mm:ss)

RTC “Date/Time”

Integer value = “yyyy”

RTC “Date/Time”

Integer value = “mm”

RTC “Date/Time”

Integer value = “dd”

RTC “Date/Time”

Integer value = “hh”

RTC “Date/Time”

Integer value = “mm”

RTC “Date/Time”

Integer value = “ss”

RTC “Date/Time”

Integer value = “yyyymmdd”

RTC “Date/Time”

Integer value = “hhmmss”

RTC “Date/Time”

Real value = “yyyymmdd.hhmmss”

RTC “Date/Time”

Integer value = day no.

RTC “Date/Time”

RTC timestep in seconds

Remarks:
Say that: the RTC time-step=10 seconds; the actual RTC “Date/Time” is Tuesday,
March 29th, 2005 at 12:10:50 (2005-03-29; 12:10:50); A=2; B=-4; and n=96. Than
if:

Data location=Year; resulting value = 2*[2005-03-29; 12:10:50 – 96*10s]-4= 2*yyyy

4=4006
Data location=Minute; resulting value = 2*[2005-03-29; 12:10:50 – 96*10s]-4= 2*mm4= 104
Data location=Date; resulting value = 2*[2005-03-29; 12:10:50 – 96*10s]-4= 2*hhmmss4= 230896
Data location=Date+Time; resulting value = 2*[2005-03-29; 12:10:50 – 96*10s]-4=
2*yyyymmdd.hhmmss-4= 40100654.230900
Data location=Day of week; resulting value = 2*[2005-03-29; 12:10:50 – 96*10s]-4=
2*Day_of_week -4= 0

Day_of_week(Sunday)=0; Day_of_week(Monday)=1; and Day_of_week(Saturday)=6
Please note that resulting values follow from a mathematic expression only, and might
become negative integer values or negative real values.

Graphical User Interface

Time (decision) parameters:
A Time decision parameter can be a user-defined function of time.
5.12.6

Decision rules in RTC - General
In Real-time Control (RTC), Measures can be defined consisting of a set of so-called Decision
rules. For each decision rule, the user has to define its priority and its decision rule type. A
decision rule might consist of a number of criteria. Each criteria has the following form:
“Value of decision parameter” “Check” “Check value”
Note:
point-in-time.

The value of a decision parameter is the value that corresponds to the RTC computational
The “Check” can be ‘<’, ‘=’ or ‘>’
“Check value” can be a constant or a user-defined decision parameter

In case for a decision rule all its criteria are “True”, than the evaluation of such decision rule is
“True”. Else the evaluation of such decision rule is “False”.

In case the evaluation of more than one decision rule is “True”, than the setpoint for the
Measure will be equal to the set-point of the decision rule having the highest priority (e.g.
lowest integer number)
In case the evaluation of more than 1 (one) decision rule having the highest defined priority
are “True”, than the set-point for the Measure will be equal to the set-point of the decision
rule that is the closest to end of the drop-down list.
In case not one of the defined decision rules is “True”, than the set-point of the Measure
will be kept equal to the set-point determined in the previous RTC time-step.
For more information on the type of decision rules available for RTC Flow Measures, see Flow
Measures in RTC.
5.12.7

External Data - His File in RTC

On the External Data – His File Tab available under the Data locations Tab in Real-time Control
(RTC), data contained in a so-called His file (.his) can be selected. This His file can
be placed at any location/folder at your computer and should be available at the start of the
computation. A His file may contain any kind of data (for instance number of crocodiles lying
on a river bank). In addition a His file can contain different type of data for a large number of
locations.

SOBEK, User Manual

Example of a MATLAB M-file
The example program below shows the use of some SOBEK output variables, the conversion of the SOBEKTime string to numerical values and the passing of setpoints computed by
Matlab back to SOBEK.

if (SOBEKFirst == 1)
SOBEKC_Matlab1=1;
Sinitial=1;
end
SOBEKS_Matlab1=Sinitial;
Level_measurementlocation1=SOBEKH_2_4;
Level_measurementlocation2=SOBEKH_6;
Flow_measurementlocation1=SOBEKQ_2_4;
Flow_measurementlocation2=SOBEKQ_4;
Crestlevel=SOBEKCL_17;
Crestwidth=SOBEKCW_17;
DeltaHStructure=SOBEKDH_17;
TimeControllerSetpoint=1.;
temp_time=str2num(SOBEKTime);
Hour=round(floor(temp_time/1000000));
temp=temp_time-Hour*1 000 000;
Minute = round(floor(temp/10000));
if (temp_time < 6000000)
TimeControllerSetpoint=1.;
elseif (temp_time < 10000000)
TimeControllerSetpoint=0.9;
elseif (temp_time < 12000000)
TimeControllerSetpoint=1.;
elseif (temp_time < 15000000)
NrMinutes=(Hour-12)*60 + Minute
TimeControllerSetpoint=1. + (NrMinutes)/180 * 0.4;
elseif (temp_time < 20000000)
NrMinutes=(Hour-15)*60 + Minute
TimeControllerSetpoint=1.4 - (NrMinutes)/300 * 0.4;
end
if (Flow_measurementlocation1 > 1.0)
SOBEKS_Matlab1 = TimeControllerSetpoint;
end

Example m-file
Note:

1 In Matlab, you can on-line check the values of the variables in your program. You can
request which variables are available by using the who command. The value of a variable
can be requested by simply typing the name of the variable and pressing Enter. Note that
Matlab is case-sensitive, so carefully check the variable names used in your m-file and the
SOBEK-ids.
2 Matlab declarations must not be written to the screen, so must always end with a semicolon (;), e.g. SOBEKC_0_65=1;
3 When using Matlab 6.1., errors in the Matlab m-file (e.g. an undefined variable is used;

Graphical User Interface

since Matlab is case-sensitive this may just be a typing error) , will be heard by regular
beeps whenever the m-file is executed (each time step in the RTC-Matlab coupling). Older
Matlab versions do not give this indication of error!
The M-FILE that is selected in the [Matlab Options] tab, must produce the following variables
for the Flow controllers which are controlled by Matlab:

SOBEKC_ (optional)Indication if Matlab controls the SOBEK controller. For
example with: SOBEKC_0_65 for the controller ’0-65’. This identifier corresponds with the
identifier following keyword id in the inputfile . The result has value
1 (=central control by Matlab) or 0 (=local control in the hydrodynamic model).

SOBEKS_Setpoint for local controller or the controlled parameter of a con-

troller. For example with: SOBEKS_0_65 for identifier ’0-65’. This identifier corresponds
with the identifier following keyword id in the input file .
The M-FILE that is selected in the [Matlab Options] tab, must produce the following variables
for the RR structures which are controlled by Matlab:

RRC_ (optional) Indication if Matlab controls the RR structure. For example with: RRC_0_65 for the structure ’0-65’. This identifier corresponds with the identifier
following keyword ‘id’ in the inputfile 3B_MEAS.RTC. The result has value 1 (=central control by Matlab) or 0 (=local control in the rainfall-runoff model).

RRSlowon_ Switch on level low capacity pump for RR structure with id
as defined in the inputfile <3B_MEAS.RTC>.
RRSlowoff_ Switch off level low capacity pump for RR structure with id
as defined in the inputfile <3B_MEAS.RTC>.
RRShighon_ Switch on level low capacity pump for RR structure with id
as defined in the inputfile <3B_MEAS.RTC>.
RRShighoff_ Switch off level low capacity pump for RR structure with id
as defined in the inputfile <3B_MEAS.RTC>.
Note:

1 The old variables with flow structure parameters: SOBEKP_=X are not supported anymore. The old SOBEKP parameter contained different types of parameters as
function of the type of corresponding structure.
2 The new version of RTC communicates structure parameters in more detail using different
variables mentioned above, e.g. SOBEKCL_=X to get the crest level of a
weir, or SOBEKPC_=X to get the pump capacity of a SOBEK pump.

SOBEK, User Manual

Flow Measures in RTC

Features Real-time Control
Real-time control often saves money in the construction, operation and management of
the water system infrastructure. The RTC module shows to what extent the existing infrastructure can be used in a better way
Allows you to simulate complex real-time control of all structures in the canal network
Allows the system to react optimally to actual water levels, discharges, (forecasted) rainfall,
by controlling gates, weirs, sluices and pumps
The Real-Time Control module can also be linked to Matlab, the industrial standard for
control engineers, and even allows you to define your complete control system in Matlab
Enables you to intervene in events taking place within your water system
Helps you make informed choices about automation and the best water control strategy
All standard irrigation automation concepts can be handled with this module

On the Flow Measures Tab in Real-time Control (RTC), you can create a so-called “Flow
Measure (or RTC Flow controller)” for any type of Controller defined in a Flow schematisation.
This is done by clicking on the “Create RTC Controller” check-box. In case the “Create RTC
Controller” check-box is not checked, there exists no Flow Measure for the selected Controller
in the Flow schematisation. In other words, there will be no Flow Measure data what-so-ever
stored in the SOBEK Model Database for the selected Controller in the Flow schematisation
(see Figure below). A Flow-measure can be defined active by clicking on the “Active” checkbox (see Figure below). A Flow Measure, when defined active, will overrule its associated
active (see below) Flow Controller, that can be assigned to a structure located in a Flow
schematisation. In the user-interface a Flow Measure can be linked to a particular Controller
in the Flow schematisaton based on the Controller ID or the Controller Name (see Figure
below). Internally, the Flow Measure identification is based on the Controller ID.

It is explicitly mentioned that RTC does not overrule Triggers, that might be assigned to Flow
controllers. This means that in case a particular Flow controller is not triggered (i.e. not
activated) at a certain point-in-time, this Flow controller will not be overruled by its associated
Flow Measure (or RTC Flow controller). Hence, the setpoint of a not-triggered Flow controller
will be equal to the setpoint of the last point-in-time for which it was triggered. Further on
please note that in case no triggers are defined for a Flow controller, this means that such
Flow controller will be activated during the entire computation.
Note:

1 For SOBEK-Urban 1DFLOW and SOBEK-Rural 1DFLOW structures; the Controller ID is
identical to the structure ID given when the structure is defined. Later on the structure ID
can be changed. However, the controller ID cannot be changed. Controller Names are
user-defined and not related to the Structure Name,
2 For single and compound River structures (i.e. River Weir, Advanced Weir, General Structure, River Pump and Database Structure only) both Controller ID’s and Names are not
related to structure ID’s and Names, and Controller Names are user-defined. The same
applies for controllers assigned to 2D Breaking – Dams in the Overland Flow module.
Warnings:
Suppose that you defined a Flow Measure for a Flow controller assigned to a particular
structure, and that you later-on delete this structure in the Flow schematisation. The
Real-time Control (RTC) module is not aware that the structure has been deleted and
will determine a setpoint for the Flow Measure and provide this setpoint to the Flow controller. You should be aware that this setpoint will be ignored in the hydrodynamic (Flow)

Graphical User Interface

computation. Hence, to make things transparent, it is advised to either delete such Flow
Measure or make it inactive. The same applies for Rainfall-Runoff RR measures.
River Flow controllers may be assigned to various different type of single and compound
River structures. You should be aware that a RTC Flow Measure associated to a River
Flow controller might affect the operation of more that one structure. The same applies
for controllers assigned to 2D Breaking – Dams in the Overland Flow module.

Figure 5.295: Definition of RTC Flow Measures

RTC Flow measures can overrule all six different type of Flow Controllers. The output (or setpoint) of a RTC Flow Measure depends on the type of overruled Flow Controller (see Table
below).
Table 5.9: Output (or set-point) of RTC Flow Measure as function of overruled Controller
type

Flow Controller Type
Time controller
Relative-time controller
Relative-from-value
(time) controller
Hydraulic controller
Interval controller
PID controller

Output of RTC Flow Measure
set point for controlled structure parameter
set point for controlled structure parameter
set point for controlled structure parameter
set point for controlled structure parameter
set point for controlled water level or discharge
set point for controlled water level or discharge

SOBEK, User Manual

Remark:
If the RTC Flow Measure is defined active, it means:

for a Time controller, a Relative-time controller, a Relative-from-value (time) controller, and a hydraulic controller, that the associated Flow controller is not active
anymore, and
for a Interval controller and a PID controller, that only the set point (steer value) is
provided by RTC, but that the controlling mechanisms of these controllers as such
are still active.
For each Flow Measure, the user has to define its initial/default value. This initial/default
value will be provided as setpoint in case:

1 an initial setpoint is not available for whatsoever reason;
2 in case the defined RTC decision rules do not result in the determination of a setpoint. A Flow Measure may be composed of several so-called “Decision rules”.

For each Decision rule, you have to define its priority and its decision rule type. For decision
rules comprising of criteria (see Decision rules in RTC – General):

The evaluation of a decision rule can either be “true” or “false”. In case the evaluation
of more than one decision rule is “true”, the set-point for the RTC Flow Measure will be
equal to the set-point of the decision rule having the highest priority (e.g. lowest integer
number).
In case the evaluation of more than 1 (one) decision rule having the highest defined priority
are “true”, the set-point for the RTC Flow Measure will be equal to the set-point of the
decision rule that is the closest to end of the drop-down list.
In case not one of the defined “Decision rules is “True”, than the set-point of the Flow
Measure will be equal to the set-point determined in the previous RTC time-step.
Eight different type of decision rules are available for RTC Flow Measures:

Type A: Setpoint f (t) from user-defined Interpolation Table (Internal Type 2)The user has

to select a previously defined decision parameter and a so-called Interpolation Table, with
in the first column a value for the selected decision parameter and in the second column the corresponding set point. During the computation on basis of the actual decision
parameter value, the set point value for the next computation RTC point-in-time will be
determined from the Interpolation Table.
Type B1: n criteria, Constant Check Values, Constant Setpoint (Internal Type 5)The user
can define a number of criteria, that check if previously defined decision parameters are
“<”, “=” or “>” than an user-defined constant check-value. The evaluation of the decision
rule is only “true” in case all defined criteria are “true”, else the evaluation of the decision
rule is “false”. In case the evaluation of the decision rule is “true”, the setpoint will become
equal to the user-defined constant set point. In case the evaluation of the decision rule is
“false”, the set point will be equal to the set-point determined in the previous RTC timestep.
Type B2: n criteria, Constant Check Values, Set point f(t) (Internal Type 6)Same as Type
B1, with the exception that if all defined criteria are “true”, the setpoint will be equal to the
actual (time) value of a user-defined decision parameter.
Type B3: n criteria, Check Values f(t), Constant Set point (Internal Type 7) Same at Type
B1, with the exception that for check-values previously defined decision parameters can
be applied, meaning that these check-values are a function of the actual computational
time.
Type B4: n criteria, Check Values f(t), Set point f(t) (Internal Type 8)Same at Type B3, with

Graphical User Interface

the exception that if all defined criteria are “true”, the setpoint will be equal to the actual
(time) value of a user-defined decision parameter.
Type B5: Unconditional Setpoint f(t) (Internal Type 10)Set points will be the values of the
specified decision parameter.
Type C1: Set point from Matlab simulation (Internal Type 9)The value for the set point will
be retrieved from a Matlab computation. The user has to define a Matlab ID, which will be
linked to ID of the selected Controller in the Flow schematisation. In addition the user has
to define a “Default value”. The RTC set point will be taken equal to this “Default value”
in case during a computation no set-point is provided by Matlab (i.e. SOBEKC_ = 0) For further information on the use of Matlab, reference is made to the topics:
RTC Wind/Rain/Matlab/Reservoir Control options in Settings, RTC-Matlab communication
– General, Flow structure parameters in RTC and Matlab and Example of a Matlab m-file.
Type C2: Set point from external TCN measure (Internal Type 12)The value for the set
point will be retrieved from a TCN (TeleControlNet) computation. The user has to define
an ID, which will be linked to ID of the selected Controller in the Flow schematisation.
In addition the user has to define a “Default value”. The RTC set point will be taken
equal to this “Default value” in case during a computation no set-point is provided by
TCN. For further information on the use of TCN, reference is made to the topics: RTC
Wind/Rain/Matlab/Reservoir Control options in Settings (see section 5.12.24).
It is to be mentioned that from the v2.10 SOBEK version onwards, the old decision rule Types
1, 3 and 4 are not anymore available, since they are special cases of respectively Type B1
to B4. When opening a model created in a previous SOBEK version (i.e. < v2.10), the old
decision rule Types 1, 3 and 4 will be automatically be updated to the new B1, B2, B3 and B4
ones. The same applies for the old decision rule Types 2, 5, 6, 7 and 8.
5.12.11

Flow structure parameters in RTC and Matlab

The type of data series, available at (Flow) Structures on the 1D Flow Data Tab and 2D Flow
Data Tab under Data locations in RTC, depend on the type of structure. These data series
can be transferred by RTC to Matlab. In the Table below an overview is given of available
data per structure type, including its Matlab string (see also RTC Matlab Communication –
General, Example of a MATLAB m-file).
Table 5.10: Data per structure type for RTC Matlab communication

Available Parameters

String in Matlab m-file

“Flow - External
Weir”

1.
2.
3.
4.
5.
6.
7.
8.

1.
2.
3.
4.
5.
6.
7.
8.

Crest level
Structure flow area
Discharge structure
Structure velocity
Water level Up
Water level Down
Head
Pressure difference

SOBEKCL_=X
SOBEKFA_=X
SOBEKQS_=X
SOBEKVS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X

SOBEK, User Manual

Table 5.10: Data per structure type for RTC Matlab communication

Available Parameters

String in Matlab m-file

“Flow - External
Orifice”

1.
2.
3.
4.
5.
6.
7.
8.

Opening height
Structure flow area
Discharge structure
Structure velocity
Water level Up
Water level Down
Head
Pressure difference

1.
2.
3.
4.
5.
6.
7.
8.

SOBEKGO_=X
SOBEKFA_=X
SOBEKQS_=X
SOBEKVS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X

“Flow - External
Culvert”

1.
2.
3.
4.
5.
6.
7.

Gate lower edge level
Structure flow area
Discharge structure
Structure velocity
Water level Up
Water level Down
Head

1.
2.
3.
4.
5.
6.
7.

SOBEKGL_=X
SOBEKFA_=X
SOBEKQS_=X
SOBEKVS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X

“Flow - External
Pump station”

Pump capacity
Pump structure
Water level Up
Water level Down
Head

SOBEKPC_=X
SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X

“Flow - Internal
Weir”

see External Weir

see External Weir

“Flow - Internal
Orifice”

see External Orifice

see External Orifice

“Flow - Internal
Culvert”

see External Culvert

see External Culvert

“Flow - Internal
Pump station”

see External Pump station

see External Pump station

“Flow - Weir”

see External Weir

see External Weir

“Flow - Orifice”

see External Orifice

see External Orifice

“Flow - Culvert”

see External Culvert

see External Culvert

“Flow station”

see External Pump station

see External Pump station

“Flow - Universal
weir”

Discharge structure
Water level Up
Water level Down
Head

SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X

Graphical User Interface

Table 5.10: Data per structure type for RTC Matlab communication

Available Parameters

String in Matlab m-file

“Flow - Bridge”

Discharge structure
Water level Up
Water level Down
Head

SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X

“Flow
weir”

1.
2.
3.
4.
5.
6.
7.
8.
9.

Crest level
Crest width
Structure flow area
Discharge structure
Structure velocity
Water level Up
Water level Down
Head
Pressure difference

1.
2.
3.
4.
5.
6.
7.
8.
9.

SOBEKCL_=X
SOBEKCW_=X
SOBEKFA_=X
SOBEKQS_=X
SOBEKVS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X

“Flow - Advanced
weir”

1.
2.
3.
4.
5.
6.

Crest level
Discharge structure
Water level Up
Water level Down
Head
Pressure difference

1.
2.
3.
4.
5.
6.

SOBEKCL_=X
SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X

“Flow - General
structure”

1. Crest level
2. Crest width
3. Gate lower edge level
4. Structure flow area
5. Discharge structure
6. Structure velocity
7. Water level Up
8. Water level Down
9. Head
10. Pressure difference

1. SOBEKCL_=X
2. SOBEKCW_=X
3. SOBEKGL_=X
4. SOBEKFA_=X
5. SOBEKQS_=X
6. SOBEKVS_=X
7. SOBEKHU_=X
8. SOBEKHD_=X
9. SOBEKDH_=X
10.
SOBEKPD_=X

“Flow - Database
structure”

1.
2.
3.
4.
5.
6.

Crest level
Discharge structure
Water level Up
Water level Down
Head
Pressure difference

1.
2.
3.
4.
5.
6.

SOBEKCL_=X
SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X

“Flow pump”

Pump capacity
Pump structure
Water level Up
Water level Down
Head

SOBEKPC_=X
SOBEKQS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X

SOBEK, User Manual

Table 5.10: Data per structure type for RTC Matlab communication

String in Matlab m-file

Compound “Flow
- River weir”
member

Compound “Flow
- Advanced weir”
member

see Advanced weir

see Advanced weir

Compound “Flow
- General structure” member

see General structure

see General structure

Compound “Flow
- Database structure” member

see Database structure

see Database structure

Compound “Flow
- River pump”
member

2D Breaking
Dam

Water level
Water depth
Bottom(bed) level
U-velocity
V-velocity
Abs.
velocity
[=sqrt(U 2 + V 2 )]

Available Parameters

1.
2.
3.
4.
5.
6.

SOBEK1D2DH_=X
SOBEK1D2DWD_=X
SOBEK1D2DBL_=X
SOBEK1D2DU_=X
SOBEK1D2DV_=X
SOBEK1D2DC_=X

Measures – general

Real-time Control allows to define measures for Water Flow and for the Rainfall-Runoff. A
measure is a decision rule using one or more decision parameters. A measure can be active
or inactive, based on the evaluation of a logical condition. When a measure is active, it can
change the set point of a structure in Water Flow or change the availability of pumps in RainfallRunoff. Several measures can apply to one object (e.g. a structure in the hydrodynamic
module Water Flow).
Measures can be complementary in the sense that one measure defines the set point of
the structure for low flow conditions, one for medium flow conditions, and one for high flow
conditions (in which the conditions are mutually exclusive, and cover all possible situations).
In this case there is always only one active measure.
But also it is possible that several measures are active at the same time. In this case the
measure with the highest priority determines the set point. In case of equal priorities, the
first/last active measure determines the set point.
The Real-Time Control module in fact adjusts the settings of a Flow controller. RTC control
can therefore only be applied on Flow-structures which are using a controller (a time controller,
hydraulic controller, interval controller or PID controller). The interpretation of the RTC results
in the Flow module is depending on the type of controller defined:

Graphical User Interface

Type of local controller in Flow module
Time controller
Hydraulic controller
Interval controller
PID controller

Interpretation of RTC result
setting of control parameter
setting of control parameter
set point
set point

So for a time controller or hydraulic controller you can directly set the weir crest level, gate
opening height or pump capacity using RTC.
For an interval controller or PID controller, you adjust the set point of the controller, i.e. the
the desired water level or discharge at the specified measurement location of the local Flow
controller. The Flow controller will than adjust the control parameter (weir crest level, gate
opening height or pump capacity) according to the local controller rules.

Real-time Control measures for Rainfall-Runoff can only be defined for all structures in RainfallRunoff, but they are typically applied for RR-pump stations. With RTC, you can temporarily
switch off the structure (i.e. set the flow to zero) in Rainfall-Runoff based on conditions outside Rainfall-Runoff. Using Matlab, for RR-pumps also the switch-on and -off levels can be
adjusted.
Precipitation Data in RTC

On the Precipitation Data Tab available under the Data locations Tab in Real-time Control
(RTC), you can select the precipitations stations available for use in RTC. It is possible to
select Precipitation data on basis of rainfall data defined for individual rainfall stations.
5.12.14

Rainfall-Runoff measure

Real-time Control measures for Rainfall-Runoff can be defined for all structures in RainfallRunoff. They are typically applied for RR-pump stations. This can be either an inlet or an
outlet pump. With RTC, you can temporarily switch off the structure (i.e. set the flow to zero)
in Rainfall-Runoff based on conditions outside Rainfall-Runoff. Using Matlab, for RR-pumps
also the switch-on and -off levels can be adjusted.
A typical application for a combined Water Flow and Rainfall-Runoff network in wet situations
is the following: in order to prevent too high water levels at the Water Flow network, outlet pumps in the Rainfall-Runoff schematisation are switched off if the water level at certain
locations in the Water Flow network is exceeding a critical maximum level.
A similar type of rule can be applied for dry situations: in that case the Rainfall-Runoff inlet
pumps are switched off if the water level in the Channel Flow network is below a critical
minimum level.
The measures for RR can be defined in the user-interface using screens like shown below.

SOBEK, User Manual

Figure 5.296: SOBEK RTC Editor window, the tab Measure → RR Measure

Figure 5.297: Definition of RR measure

Graphical User Interface

Real-time Control concepts or elements
There are three important concepts (or elements) in Real-time Control. They are:

Data locations;
Decision parameters; and
Measures;
5.12.16

RR Data in RTC
On the RR Data Tab, available under the Data locations Tab, you can define the RainfallRunoff (RR) locations for which RTC will receive data, computed by the Rainfall-Runoff module.

The following type of RR Data are available:

open water level at RR Open water nodes [m AD];
groundwater level at RR unpaved nodes [m AD];
RTC Communication-General

At present the Real-time Control (RTC) module can be used in combination with following
SOBEK modules:

The SOBEK-Urban 1DFLOW module,
The SOBEK-Rural 1DFLOW module,
The SOBEK-River 1DFLOW module,
The SOBEK-Rural RR module, and
The SOBEK-Rural 1DWAQ module (Note: 1DWAQ data can not yet be defined in the RTC
Editor)

In the RTC module use can be made of the user-defined Meteo (rainfall & wind) data as well
as user-defined external data.
Further on the RTC module can be linked to online Matlab computations, allowing for any kind
of control mechanism to be incorporated into SOBEK.
In the above mentioned options (i.e. linkage with other SOBEK modules, the use of other data
sources, and the use of Matlab, the RTC module take cares of the following data exchange:
RTC – SOBEK-Urban 1DFLOW, SOBEK-Rural 1DFLOW and SOBEK-River 1DFLOW modules:

Exchange of Flow (computational) data towards RTC,
Exchange of computed setpoints from RTC towards Flow controllers
RTC – SOBEK-Rural RR module:

Exchange of Rainfall Runofff (computational) data towards RTC,
Exchange of computed setpoints from RTC towards RR controllers
RTC – other data sources:

Transfer of other (rain, wind, external) Data towards RTC

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RTC – Matlab computation:

RTC definitions and options in Settings

The SOBEK Real-Time Control (RTC) module can be activated by checking the “Realtime
control” check-box in Settings (see Figure below). The RTC module runs simultaneously
with other SOBEK modules, since RTC may overrule controllers defined in other SOBEK
modules. In addition you might like to use data, computed by other SOBEK modules for
defining decision rules. These decision rules determine the setpoints for the controllers. At
present SOBEK modules that can run simultaneously with the RTC module are:
SOBEK-Rural RR module
SOBEK-Rural 1DFLOW module
SOBEK-Urban 1DFLOW module
SOBEK-River 1DFLOW module
SOBEK Overland Flow module
1DWAQ module (Note: 1DWAQ data can not yet be defined in the RTC Editor)

Exchange of Flow (computational) data from RTC towards Matlab
Exchange of Rainfall Runofff (computational) data from RTC towards Matlab,
Exchange of other (rain, wind, external) data from RTC towards Matlab
Exchange of by Matlab computed setpoints for RR controllers towards RTC
Exchange of by Matlab computed setpoints for Flow controllers towards RTC

By pressing the Edit button behind the Realtime control module (see Figure 5.298), following
RTC options can be specified:

RTC Time settings
RTC Wind/Rain/Matlab/Reservoir Control options
RTC Output options

Figure 5.298: Settings input screen for SOBEK-Rural 1DFLOW-RTC run

Graphical User Interface

RTC does not overrule Flow Triggers
In Real-time Control (RTC), RTC Measures (or RTC Flow controllers) can be defined. In
case a RTC Measure is defined active, this Measure will provide a setpoint for its associated
controller in either a Flow or Rainfall-Runoff schematisation. In case the associated controller
is active, the setpoint provided by the RTC Measure will be used in either the Flow or RainfallRunoff computation. Hence in such situation the RTC Measure overrules the controller.
RTC does, however, not overrule Triggers defined for River Flow controllers. The evaluation of
these triggers determine whether the controller is active or not active during the computation.
In case the controller is in-active, a setpoint provided by a RTC Measure will be neglected
and the setpoint of the in-active controller will be kept equal to the previously applied setpoint
value.

RTC - Matlab Coupling

You can use RTC together with Matlab for overruling a particular controller defined in your
Flow or Rainfall-Runoff (RR) schematisation (see also: Example of a MATLAB m-file). More
precisely this means that the setpoints of this controller are determined in a Matlab computation, and that these Matlab setpoints are transferred from Matlab to this Flow or RR controller
by RTC. For determining the setpoints in Matlab, you can make use of the data series available at the data locations that you defined in the RTC module. Hence the coupling between
RTC and Matlab consists of:

Note: that in case no triggers are defined for controllers in a model schematisation, this
means that these controllers are always active during a computation.

Transfer of data series by RTC to Matlab,
Transfer of computed setpoints by Matlab to RTC
Note:

1 Flow controllers that are not actived by their associated triggers, will not be overruled
by an active RTC-Matlab Measure (see section 5.12.19);
Flow controllers having no associated triggers will always be active and hence will
always be overruled by RTC-Matlab.
2 In order to facilitate the coupling between Matlab and RTC, installing Matlab and SOBEK
might not be enough. If RTC informs you that Matlab cannot be found, Matlab will need
to manually registered for coupling through com files. This can be done by typing this
command in your Matlab installation directory:

matlab.exe /regserver

Please use the Windows option ’Run as Administrator’ to run this command.
Ad 1) Transfer of data series by RTC to Matlab:
All data series available at the data locations (see section 5.12.3) that you defined in the RTC
module, can be used in a Matlab computation. Furthermore the RTC computational pointin-time and the RTC computational time-step can be passed to Matlab. The corresponding
“strings” to be used in a Matlab m-file are given in the Table below. An overview of the type of
data series that are available for each Flow structure is given in section 5.12.11.

SOBEK, User Manual

Table 5.11: Table: Strings in a Matlab m-file for obtaining values of data series that are
available at data locations defined in the RTC module

Indication whether this is the first simulation
timestep (X=1) or not (X=0)
Date of simulation step. The date is given as
a string of the form yyyymmdd (e.g. 20041231
is December 31st, 2004)
Time of simulation step. The time is given as
a string of the form HHmmsshh, where HH
are “hours” and hh are “seconds/100”. So
22150000 is a quarter past ten in the evening.
RTC computational time-step (as defined in
Settings) in seconds
water level
discharge

SOBEKCompTimestepSize=X

surface area
water depth
crest level of structure
crest width of structure
gate lower edge level (orifice)
opening height (orifice)
structure flow area
discharge structure
velocity at structure
water level up
water level down
head over structure
pressure difference over structure
pump capacity (pump)
2D water level
2D water depth
2D bed level
2D U-velocity
2D V-velocity

SOBEKH_=X
SOBEKQ_=X
SOBEKSA_=X
SOBEKWD_=X
SOBEKCL_=X
SOBEKCW_=X
SOBEKGL_=X
SOBEKGO_=X
SOBEKFA_=X
SOBEKQS_=X
SOBEKVS_=X
SOBEKHU_=X
SOBEKHD_=X
SOBEKDH_=X
SOBEKPD_=X
SOBEKPC_=X
SOBEK1D2DH_=X
SOBEK1D2DWD_=X
SOBEK1D2DBL_=X
SOBEK1D2DU_=X
SOBEK1D2DV_=X

String in Matlab m-file

SOBEK1D2DC_=X
RRH_=X
RainH_=X

2D Abs velocity [= U 2 + V 2 ]
RR water level or groundwater level
precipitation

Ad 2) Transfer of computed setpoints by Matlab to RTC
In a Matlab computation, the setpoints for a Flow or Rainfall-Runoff (RR) controller can be
determined. These Matlab setpoints are transferred by the RTC module to the corresponding
Flow or RR controller. The corresponding “strings” to be used in a Matlab m-file are given in
the Table below. For Flow controllers, the id in the Matlab string is the “Matlab id” defined on
the Flow Measures Tab in RTC (see decision rule Type C in Flow Measures in RTC). For RR
controllers, the id in the Matlab string is the id of the structure in the RR schematisation.

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Table 5.12: Table: Strings in a Matlab m-file for transferring computed setpoints for a
particular Flow or RR controller towards the RTC module.

String in Matlab m-file

SOBEKC_=X
SOBEKS_=X
RRSLowon=X
RRSLowoff=X
RRSHighon=X
RRSHighoff=X

optional, controlled by RTC yes(=1)/no(=0)
setpoint of SOBEK-Flow controller
RR-pump switch on level, low capacity
RR-pump switch off level, low capacity
RR-pump switch on level, high capacity
RR-pump switch off level, high capacity

Note: ID’s in Matlab can only consist of letters, digits and underscores. Matlab ID’s can
not contain dots, plus signs, minus signs, equal or not-equal signs, etc., since these are
interpreted by Matlab. However, SOBEK can handle these signs in ID’s. Therefore, in sending
data to Matlab all these characters are changed into underscores. Hence unique ID’s in
SOBEK might not be unique ID’s in Matlab, in case SOBEK ID’s contain the above mentioned
characters that are interpreted by Matlab. Also Matlab will not accept these signs in the ID’s
for which data has to be sent to SOBEK.
Example: Suppose the water level at SOBEK node with id 0-64 is 0.55 m, and this node is
specified as a data location for RTC. SOBEK-RTC will then pass the following string to Matlab:
SOBEKH_0_64=0.55
Note that the - sign in the SOBEK-id is replaced by the _ sign in the string put to Matlab.
5.12.21

RTC - TCN (Telecontrolnet) coupling

In a SOBEK computation, the real time control (RTC) module can be coupled with the external
Telecontrolnet software, which is developed by InterAct (www.telecontrolnet.nl). This coupling
is, hereafter, shortly referred to as the RTC - TCN coupling.
Using the RTC - TCN coupling, any triggered (or active, see section 5.12.19) controller in a
1D Flow schematisation can be overruled by TCN. Overruling means that the setpoint for an
overruled controller is determined by TCN. Such setpoint is determined by TCN on basis of
values of state parameters (water levels, discharges etc.) in the Flow schematisation, that are
provided by the RTC module.
Note: Overruling does not affect the algorithm applied by a controller in a Flow schematisation. Say that a PID controller has to main water levels upstream of a weir by adjusting the
crest level of this weir. Overruling this PID controller means that TCN only provides the values
for the water levels to be maintained upstream of this weir. The controller using its PID algorithm, still determines the weir crest levels required for maintaining these (by TCN provided)
water levels upstream of the weir.
Specifying a RTC -TCN coupling comprises of:
1 In the Settings task block, click on button next to RTC and open the Contol options
tab (see Figure 5.299). On the Control options tab:
1.1 Check the check-box "Use TCN-Coupling"
1.2 In the box next to "TCN Run Command:", specify the path and name of the TCN run
command (i.e. a .bat batch file, see example in Figure 5.306), which calls

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TCN at the beginning of each RTC computational time step. In a TCN call two or
three command line arguments (%1 to %3) are included:

%1: The RTC event number. A Flow - RTC computation comprises of one
(1) event only with a duration, that follows from the begin-time and end-time of
the simulation as specified in settings. For a rainfall-runoff(RR) - Flow - RTC
computation the number of events is equal to the number of rainfall events (or
storms) defined in the Meteo task block (either in the .bui file or in the
.rks file). The duration of each event is equal to the duration of its
rainfall event.
%2: The RTC time step number within the event. This is an integer, varying from
1 up to the duration of the event divided by the RTC computational time step.
%3: Firstrun. This text string is only given for the first RTC time step within a
particular event.

1.3 In the box next to "SOBEK to TCN:", specify the path of the .csv file in
which the RTC module writes the current values of all specified decision parameters
(for more information, see point 2 hereunder).

1.4 In the box next to "TCN to SOBEK:", specify the path of the .csv file in
which TCN writes the setpoints for the by TCN overruled controllers (for more information, see point 3 hereunder) and which setpoints are applied in the current RTC
computational time step.

Figure 5.299: Settings Task block, RTC settings for the RTC - TCN coupling

2 In the RTC editor (see section 5.12.5), define those decision parameters which values are
to be transferred towards TCN in a .csv file (SOBEK to TCN, see Figure 5.299)
at the beginning of each RTC computational time step. Please note that the values of all

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decision parameters are transferred to TCN.
As an illustration Figure 5.300 shows that decision parameter with id "//11/N1_mwfrtc" is
defined as the water level of the 1D water level point with id "10_292810". In Figure 5.301,
file .csv is shown in which at the beginning of a particular RTC computational
time step, the value of decision parameter with id "//11/N1_mwfrtc" is transferred towards
TCN. The first line in file .csv is a header ("id","description","value") line. Each
next line contains the information of a specific decision parameter. Please note that on
such line the id and the description are between double quotes, so better make sure that
the id and description (defined in the RTC editor) itself does not contain a double quote.

Figure 5.300: RTC editor in the Schematisation Task block. Definition of RTC decision
parameter with id "//11/N1_mwfrtc", which data is transferred towards TCN
in a .csv file (SOBEK to TCN, see Figure 5.299) at the beginning
of each RTC computational time step (see Figure 5.301).

Figure 5.301: Example file in which RTC at the beginning of each RTC
computational time step, transfers the value for decision parameter with id
"//11/N1_mwfrtc" towards TCN.

3 In the RTC editor, define a Flow Measure with decision rule type C2 (including its TCN ID)
for each controller in the 1D flow schematisation that is to be overruled by TCN (see section 5.12.10). TCN will provide setpoints for these controllers in a .csv file (TCN
to SOBEK, see Figure 5.299) which are applied by RTC in the current RTC computational
time step. How TCN determines these setpoints is beyond the scope of this manual.
As an illustration Figure 5.302 shows that 1D flow controller with id "1_751010-21_751010"

SOBEK, User Manual

is overruled by the setpoint with TCN id "//26/X1_spstrrtc", that is provided by TCN. In Figure 5.303, file .csv is shown in which TCN writes the setpoint with TCN
id "//26/X1_spstrrtc", that is used to overrule the 1D flow controller with id "1_75101021_751010". The first line in file .csv is a header ("id","value") line. Each
next line contains the information of a specific TCN setpoint. Please note that on such line
the TCN id is between double quotes, so better make sure that the TCN id (defined in the
RTC editor) itself does not contain a double quote.

Figure 5.302: RTC editor in the Schematisation Task block. Defining that 1D flow controller with id "1_751010-21_751010" is to be overruled by the TCN setpoint with TCN id "//26/X1_spstrrtc". TCN provides this setpoint in a
.csv file (TCN to SOBEK, see Figure 5.299) at the end of each
RTC computational time step (see Figure 5.303).

Figure 5.303: Example file in which TCN at the end of each
RTC computational time step, transfers the setpoint with TCN id
"//26/X1_spstrrtc", which is used by RTC to overrule 1D flow controller with
id "1_751010-21_751010".

4 Specify the communication protocol between RTC and TCN by means of:
4.1 The .ini file:
Default the SOBEKTCN.ini file is located in the \SOBEK\Programs\RTC\TCN directory. The communication program SOBEKTCN.exe as well as the \Certifi subdirectory are also located in this directory. Please note that if you have several

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projects using a RTC - TCN coupling, it is advised to copy the SOBEKTCN.exe and
the SOBEKTCN.ini file into a sub-directory under the concerning project directory.
The SOBEKTCN.ini (see Figure 5.304) is to be edited manually:

4.1.1 The data behind keywords, which are left empty (being keywords: tcndomain, user, password, client_id and client_secret) are to be filled in with
the values supplied by Interact (company that developed the Telecontrolnet
software).
4.1.2 The file names behind keyword input_file (default: Peilen.csv) and keyword
output_file (default: Streefpeilen.csv) should respectively match with the file
names specified in the box behind "SOBEK to TCN" and the box "TCN to
SOBEK" in RTC settings (see Figure 5.299). Path names are to be omitted. Please note that on the TCN website, file names are case sensitive,
while in SOBEK-RTC they are not case sensitive (since SOBEK runs under
Windows).
4.1.3 Value RTC_SYS for keyword location_code means that TCN knows that it
concerns a RTC - TCN coupling.
4.1.4 Please note that in case the duration of a TCN call lasts longer than the
number of seconds specified with keyword time_out_seconds, the current
RTC calculation is finalized using the setpoints that were provided by TCN
in the previous RTC calculation time step. In such case, following message is given in the .log file: value for parameter id not found in
ReadCsvFile and set to previous value, where id refers to the TCN ID of an
overruled controller.
4.1.5 An example of a sobektcn.log file or communication file of the RTC - TCN
coupling is given in Figure 5.305

Figure 5.304: Example of the SOBEKTCN.ini file, defining the communication protocol
between RTC and TCN in a RTC - TCN coupling.

SOBEK, User Manual

Figure 5.305: Example of a sobektcn.log file or communication file of the RTC - TCN
coupling

4.2 The .bat file
As mentioned in point 1.2 above, TCN is called at the beginning of each RTC computational time step using a .bat batch file. Such batch file not only calls
TCN by starting SOBEKTCN.exe, but may as well contain some commands, that
store the communication between SOBEK-RTC and TCN. In addition the batch file
starts SOBEKTCN.exe with the proper command line arguments (%1 to %3, see
point 1.2 above).
In Figure 5.299 TCN is called using batch file .bat. This batch file is
depicted in Figure 5.306 and does following:
4.2.1 The first line changes the working directory from the CMTWORK directory
to the directory d:\SBK216\ALMELO.lit\FIXED\TCN
4.2.2 The second line start the SobekTCN.exe, which calls TCN (i.e. starts the
RTC - TCN coupling program). The command line argument %3 denotes if
it is the first TCN call within a particular event or not (i.e. textstring is either
"firstrun" or ""). Please note that the SOBEKTCN.exe should be located in
directory d:\SBK216\ALMELO.lit\FIXED\TCN.
4.2.3 Optional. The third line stores all .log files (see Figure 5.305)
in directory d:\SBK216\ALMELO.lit\FIXED\TCN\test, including the RTC event
number (%1) and the RTC time step number within the event (%2).
4.2.4 Optional. The fourth line stores all .csv files (see Figure 5.301) in
directory d:\SBK216\ALMELO.lit\FIXED\TCN\test, including the RTC event
number (%1) and the RTC time step number within the event (%2).
4.2.5 Optional. The fifth line stores all .csv files (see Figure 5.303)
in directory d:\SBK216\ALMELO.lit\FIXED\TCN\test, including the RTC event
number (%1) and the RTC time step number within the event (%2).
4.2.6 The last row changes the working directory from d:\SBK216\ALMELO.lit\
FIXED\TCN to d:\SBK216\ALMELO.lit\CMTWORK.

Note: The third line, fourth line and fifth line described above and shown in Figure 5.306) are optional (i.e. not essential) in defining a RTC - TCN coupling. These
optional lines are, however, handy to verify if a RTC - TCN coupling is working to
satisfaction.

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Figure 5.306: Example .bat, applied to call TCN and to store all communication files .csv (SOBEK to TCN) and .csv (TCN to
SOBEK) produced in a RTC - TCN coupling.

RTC Output options in Settings

The RTC Output options Tab becomes available by clicking on the Edit button behind the RTC
module in Settings (see Figure 5.307). On this Tab, the user can define the time-step for the
RTC output data, available under the Result in Charts Task block and the Result in Maps
Task block. The RTC output time-step should be a multiple of the defined RTC computational
time-step.

Figure 5.307: RTC Output Options in Settings

RTC Time settings (Time-step) in Settings
The RTC Time settings Tab becomes available by clicking on the Edit button behind the RTC
module in Settings (see Figure below).
The time-step applied in Real-time Control (RTC) is defined in the Settings Task block (see
Figure below).
Note:

SOBEK, User Manual

The defined RTC time-step is applied for each and every RTC measure, that might be over-

ruling a controller defined in either the SOBEK-Urban 1DFLOW, SOBEK-Rural 1DFLOW,
SOBEK-River 1DFLOW, SOBEK Overland Flow or SOBEK-Rural RR schematisation.
This is also valid when the RTC setpoints are determined by a Matlab computation.
In a combined Flow-RTC computation, the RTC time-step may be larger than the Flow
time-step (i.e. time-step applied in the hydrodynamic computations), this means that the
setpoints of the Flow controllers, that are overruled by a RTC Flow measure (or RTC Flow
controller) are less frequently updated as the set points of Flow controllers that are not
overruled by RTC Flow measures
In a combined RR-RTC computation, the RTC time-step should be equal to the time-step
applied in the RR computation. The same yields for a combined Flow-RR-RTC computation.

Figure 5.308: Settings for RTC module, the Time Settings tab

RTC Wind/Rain/Matlab/Reservoir Control options in Settings

By clicking on the Edit button behind the RTC module in Settings, the RTC Control options
Tab becomes available (see Figure 5.309). By clicking on the corresponding check-box, the
following RTC options can be activated:

Use rain predictor (rain data to be defined in Meteo Task block),
Use wind predictor (rain data to be defined in Meteo Task block)
Use Matlab
Use reservoir control

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Figure 5.309: RTC Control options

Matlab is a general purpose software package, which allows you to write your own programs
(so-called m-files) using e.g. ‘fuzzy logic’ or other control features which are available in Matlab. SOBEK RTC can make use of your Matlab m-files.
In order to use Matlab, it is required to have an installation of Matlab on your own PC or an
accessible network drive. It is not necessary to specify to SOBEK where Matlab is located. If
Matlab has been properly installed and used on the PC before, SOBEK will be able to communicate with it. However, if you specify a version of Matlab which is different from the version
last used on your PC, the SOBEK RTC module will not be able to set up communication with
Matlab properly. In that case you will get a message after starting the first timestep of the
simulation, saying that there was an error starting Matlab.
To define the use of Matlab, go to the tab , switch on the use of Matlab,
and specify which version of Matlab you want to use. SOBEK supports communication with
Matlab versions 5.3, 6.0, 6.1, 6.5 and 7.0.
You also have to specify the location of your Matlab m-file.

SOBEK, User Manual

Setpoints in RTC
If defined active a RTC Measure will overrule an active controller, that is defined in a Flow or
a Rainfall-Runoff schematisation. With overruling is meant that the RTC Measure determines
the setpoint for the controller (i.e. the gate-height, crest level, water level to be controlled etc.).
Note:
1 Flow controllers that are not actived by their associated triggers, will not be overruled by
an active RTC Measure;
2 Flow controllers having no associated triggers will always be active and hence will always
be overruled by RTC. For more information, see RTC does not overrule Flow Triggers.

Type of Measures available in Real-time Control

For information on the type of set-points corresponding to each Flow controller, see Flow
Measures in RTC.

In Real-time Control following Type of Measures are available:

Flow Measures,
RR Measures,

Flow Measures (or RTC Flow controllers), when defined active, will overrule their associated
active Flow controller in the SOBEK-Urban 1DFLOW, SOBEK-Rural 1DFLOW or SOBEKRiver 1DFLOW schematisation (see Flow Measures in RTC and RTC does not overrule Flow
Triggers).
RR Measures, when defined active, will overrule their associated controller in the Rainfall
Runoff schematisation. At present RR Measures are to defined on the RR Measure Tab and
the RR Structure Measure Tab.
5.12.27

Wind Data in RTC

On the Wind Data Tab available under the Data locations Tab in Real-time Control (RTC),
you can select wind data (velocity and direction) available for use in RTC. At present only the
complete set of wind data defined in the Meteo Task block can be selected at the Wind data
Tab. Under Decision Parameters in RTC, however, it is possible to make a selection on basis
of individual wind stations defined in the Meteo Task block.
5.12.28

1D Flow Data in RTC

On the 1D Flow Data Tab, available under the Data locations Tab, you can define the 1D Flow
locations for which RTC will receive data, computed by the SOBEK 1DFLOW modules.

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Figure 5.310: RTC Flow Data input screen

For each 1D Flow Data location, the user can define its ID as well as an optional comment
string (see Figure above). Data locations can be selected on basis of their ID or user-defined
Name. Five different type of 1D Flow Data locations are discerned, viz:

Nodes:
Branch segments
Structures
Measurement locations (or stations)
Branch locations

Hint: If the “Show Name” option together with a checked “Only show Named Items” checkbox is used (see Figure above), than only those objects in the drop-down lists are shown for
which the user has defined a Name. In this way you can considerably reduce the length of the
drop-down list (and hence the time needed for finding your object).
The data availability depends on the selected 1D Flow Data type. For instance: at Nodes,
water levels and water depth are available; at Branch segment: velocities and discharges
are available. Below an overview of the available 1D Flow Data (i.e, computed hydrodynamic
parameters) is given

water level [m AD];
flow [m3 /s];
surface area [m2 ];
water depth [m];
crest level [m];
crest width [m];

SOBEK, User Manual

2D Flow Data in RTC

On the 2D Flow Data Tab, available under the Data locations Tab, you can define the 2D Flow
locations for which RTC will receive data, computed by the SOBEK Overland Flow module.

gate lower edge [m];
gate opening height [m];
structure flow area [m2 ];
discharge at the structure [m3 /s];
flow velocity at the structure [m/s];
water level up [m];
water level down [m];
head over structure [m];
pressure difference over structure;
pump capacity [m3 /s];

Figure 5.311: RTC 2D Flow Data input screen

For each 2D Flow Data location, the user can define its ID as well as an optional comment
string (see Figure 5.311). Data locations can be selected on basis of their ID or user-defined
Name. Two different type of 2D Flow Data locations are discerned, viz:

2D History stations
2D Breaking – Dams
Hint: If the “Show Name” option together with a checked “Only show Named Items” checkbox is used (see Figure above), than only those objects in the drop-down lists are shown for

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which the user has defined a Name. In this way you can considerably reduce the length of the
drop-down list (and hence the time needed for finding your object).
Following data is available at 2D History stations and 2D Breaking – Dams:

Calibration data editor

If you desire to compare measured data with computed data, you can create a "measured
data file" according to the SOBEK Output format (.his files). This file can then be imported
into the "Results in Tables" window or into the "Case Analysis Tool" for comparison with your
simulation results.

water level [m AD];
water depth [m];
bottom(bed) level [m AD];
U-velocity in [m/s];
V-velocity in [m/s
√];
Abs. velocity [= U 2 + V 2 ] in [m/s].

Creating a custom HIS file (SOBEK results file)

Go to the SOBEK Startup window
Choose "Utilities" - "Calibration data editor" from the menu. The "Edit History file" window
will appear.

Choose "File" - "new". A spreadsheet-like environment will appear:

Figure 5.312: Hisfile editor

Use the "Table" - "Add/Insert/Delete Row" options to customise the size of your table.
Add measurement locations by choosing "Table" - "Add Location" and entering the name
of the location.Note: you may decide to make this name equal to the ID of a node or
branch segment in your schematisation!
Enter the parameter name by choosing "Edit" - "Description". Choose for example the
parameter name "water levels measured"
You can copy and paste data from Excel into the fields. Important: the "date format"
and "time format" of your cells in Excel must be equal to the format as indicated in the
Hisfile editor: dd/mm/yyyy. You can change this format in Excel by selecting the cells,
right-clicking your mouse, and selecting "format cells".
When your file is ready, choose "File" - "Save as", and type a name for your HIS file.
Using your custom HIS file

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You can open this file in the Case Analysis Tool to compare it with your simulation results.
You can also add this file to the "results in charts". In order to do so, open your simulation

results and choose "File" - "add file" from the "Ods_view" window:

Figure 5.313: ODS view

Your measurement results will then appear as an extra parameter, but with the same
location ID in the list of results:

Figure 5.314: ODS View, parameter list

Online Visualisation (SOBEK-1D2D)
Sometimes it may be useful to visualise simulation results during computation on a detailed
level. In Online Visualisation it is possible to click on waterlevel points (nodes) or on velocity
points (links) and show the printed values of selected parameters.
To use Online Visualisation
Online Visualisation is available in SOBEK version 2.12.002 and upwards.

After starting SOBEK, click on the menu item: "Options".
Select the option: "SOBEK Options".
Switch on the option"Online Visualisation" in the "Simulation" tab.

Graphical User Interface

Figure 5.315: Examples of the Online Visualisation.

SOBEK, User Manual

Figure 5.316: Enabling the Online Visualisation in the SOBEK Options window.

Continue or interrupt computation

Double click the taskblock ’Simulation’ to start a simulation.
When the Online Visualisation Component appears, left mouse click on your screen.
Click to start the simulation, left mouse click to pause the simulation.
Click spacebar if you want to proceed a single timestep.

Interrogate data on nodes and links

Left mouse click either on nodes (square boxes) to display nodes values, or on links, (dots
in 1D). Flow velocity, discharge, cross-sectional area etc will be shown.

When clicking on a link, the items on both connected nodes will also be refreshed.
In the top screen line, one can select a field parameter to be displayed: e.g.
‘Display’ → ‘Node values’ → Waterlevel
When a node or link is clicked, this parameter is also printed as the last parameter in
the list, see ‘Userpar’

The left and right isoscales pertain to the requested node- and link-parameter fields.

Graphical User Interface

Figure 5.317: The Online Visualisation.

On the left side, from top tot bottom, after clicking on a link, we get the first node, the second
node and the link in between. When more links exist on the same location, click more times.
For the first node:

Node id: Corresponding to Netter id
Node nr: Internal array nr
Kcs code: 1 for 1D point, 100 for 2D point, 101 for 1D2D point
Water level: Level in [m] upward [1]
Water depth: Difference between water level and bottom level [2]
Depth: Negative value of bottom level, depth increases downward [3]
2D depth: Negative value of 2D bottom level [4]
Dike level min: Lowest level for connecting 1D and 2D [5]
Userpar: The value for the parameter specified in ‘Display’ → ‘Node values’

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Figure 5.318: Explanation of cross-section for Onlie Visualisation

For the second node: same as for left node
For the connecting link:

Link id: Corresponding to Netter id
Link nr.
Link kcu: 1=1D link, 100=2D link
Kfu: 1=wet, 0=dry
Velocity.
Discharge.
Cross sectional area: Flow carrying area
Top width.
Wet perimeter.
Bob 1: Depth (pos down) at left side of pipe or link
Bob 2: Depth (pos down) at right side of pipe or link
Cz: Chézy parameter, if applicable
Conveyance: given if applicable
Hydraulic depth
Dx, pipelength
U1/Ufriction: Velocity vs equilibrium friction velocity
Velocity Courant
Dep1: Depth of manhole or waterlevel point on left side of link
Dep2: Depth of manhole or waterlevel point on right side of link
Linev(L,1) : Internal nr
Userpar : The value for the parameter specified in ‘Display’ → ‘Link values’

Display area control
Left mouse click on the schematisation, so that the crosshair cursor appears and the coordinates of the cursor are displayed in the top right corner of the screen.
Click .

Graphical User Interface

A window will appear that can be moved around. Now you can:

Zoom in, with a left mouse click.
Zoom out, with another .
Pan by moving the zoom window until it touches the screen border.
Restore default viewing area with a right mouse click.

Press to drop an anchor, to show the distance between the cursor and the anchor
position in the upper right corner of the screen.

The size of 2D velocity vectors can be adjusted, Display, Display Parameters, Vectorsize.

Figure 5.319: Online Visualisation 2D velocity vectors.

ReaHis (Convert HIS files to ASCII)

The ReaHis command-line tool can be used to easily convert .HIS files to ASCII format. After
converting to ASCII, the output can be imported in other software packages or used in scripts.
The tool ReaHis.exe can be used after installing SOBEK. It is located in
.\SOBEK215\PROGRAMS\ReaHis\
Usage: ReaHis >
For example: ReaHis flowhis.his > flowhis.txt

SOBEK, User Manual

Time tables in SOBEK
Tables for parameters as a function of time
In many situations, one may encounter tables that have to be filled with time-dependent data.
For example lateral inflows at a Flow - Lateral Flow node, or water levels at a Flow - Boundary
node. In this chapter, the structure and the options of such tables is explained.
The general lay-out for the tables window looks like this:

Remark:
The numbers in the table below do not correspond with the graphs later on.

Figure 5.320: A generic table.

Left Column: date Here, the dates for which you want to change certain parameter
values should be entered. It is not necessary to type all values by hand: you can copy
them from a spreadsheet, such as Microsoft Excel. But note that the field format within the
spreadsheet should correspond to the format indicated by SOBEK: dd-mm-yyyy. In Excel,
the field format can be altered by right-clicking a field, choosing "format cell" - "number"
- "custom" - and type the appropriate format: dd-mm-yyyy (or dd-mm-jjjj in the Dutch

Graphical User Interface

version)
Middle Column: time Here, the times on which you want to change certain parameter
values should be entered. It is not necessary to type all values by hand: you can copy
them from a spreadsheet, such as Microsoft Excel. But note that the field format within the
spreadsheet should correspond to the format indicated by SOBEK: hh:mm:ss. In Excel,
the field format can be altered by right-clicking a field, choosing "format cell" - "number" "custom" - and type the appropriate format: hh:mm:ss (or uu:mm:ss in the Dutch version)
Right Column: parameter value This column represents the parameter that needs to be
changed in time. For example: discharges, water levels, moist content, crest levels etc.
The buttons on the right side of the window adds one or more rows to the
downside of the table adds a new row just above the one that’s currently
selected deletes the currently selected row
copies the data of the currently selected cells to the clipboard. An alternative to
this button is to press Ctrl+ C.
pastes data from the clipboard to the currently selected cells. An alternative to
this button is to press Ctrl + P. Important: make sure that the data that you want to
paste has the correct format (dd-mm-yyyy for date and hh:mm:ss for time)!
Graph plots a graph of the data in the table gives the option to import a
previously stored table gives the option to save the current table. This
table may then be used for other objects too.
Options
Block function: interprets the data from the table as a block function, thus the parameter value will be constant during the period between two data entries.
Linear function: for the calculation period between two data entries the values of both
surrounding entries will be linearly interpolated.

Periodicity: - Use periodicity: let the values in the table repeat themselves with a certain
interval (year, month, week, day, 12 hours, hour)
If the periodicity interval you chose is smaller than the time span of your table, SOBEK will
apply the periodicity procedure to the last section of the table that covers the periodicity
interval. The picture below shows how this situation is handled within SOBEK:

Figure 5.321: This picture shows which part of your table will be continuously repeated if
the periodicity timespan that you choose is shorter than the available data
in your table.

Note 2: If the periodicity interval you chose is larger than the time span of your table,

SOBEK, User Manual

SOBEK will linearly interpolate between the data in the last record of the table and the
value from the first record of the table. See the picture below for a better understanding:

Figure 5.322: In this graph you can see how SOBEK handles periodicities that exceed
the time span in your table.

The first value from the table is then assumed to occur at the end of the periodicity too, and
all values between the last value of the table and that value are then interpolated blockwise
or linearly, depending on the chosen interpolation option. The example assumes linear
interpolation has been specified.
5.14

1D Hydraulic friction concepts

The following hydraulic friction concepts can be discerned in 1D flow:

Global (or Model-wide) friction concept
Global friction refers to defining (formula & value) for Bed friction (and optional Groundlayer
friction):

Use of Global friction:
If Global friction definition is selected at cross-section X, this means that the Global friction
definition is applied for all cross-sections, that are located on the same branch as crosssection X.
Restrictions for Global friction:

Global (or Model-wide) friction concept
Local (or Branch-wise) friction concept
Cross-section friction concept
Culvert friction concept

Not available at “Y-Z” and “Asymetrical Trapezium” cross-sections.
At “River profiles” only Global Bed friction can be defined.

Graphical User Interface

Warning for Global friction:
Changing the Global friction at cross-section X, has consequences for all branches using
Global friction.
For “River profiles” two situations are to be discerned:
There are only River profiles in the model: Different global values for positive flow and
negative flow as well as friction formulations can be specified for Main section, Floodplain
1 and Floodplain 2.
There is also another type of cross-section: In case a global value and friction formulation
is defined at a non-River profile (i.e. another type of cross-section), all the information
regarding different global values and friction formulations for positive and negative flow at
Main section, Floodplain 1 and Floodplain 2 is overruled by the global value and friction
formulation defined at the non-River profile.
Local (or Branch-wise) friction concept

Local friction refers to defining (formula & value) for Bed friction (and optional Groundlayer
friction):

Use of Local Friction

If local friction definition is selected at cross-section X, this means that this specific Local
friction definition is applied for all cross-sections, located on the same branch as crosssection X
Restrictions for Local friction:
Not available at “Y-Z” and “Asymetrical Trapezium” cross-sections.
At “River profiles” only Local Bed friction can be defined.

Exception for Local friction:

Only at River Profiles, Local Bed friction can be defined as function of the branch x_coordinate
(f (x), f (Q, x) and f (h, x))
Warning for Local friction:
Changing local friction at cross-section X, has consequence for all cross-sections, that are
located on the same branch as cross-section X.
5.14.3

Cross-section friction concept

Cross-section friction means that Bed friction (formula & value) can be defined per crosssection:

Use of Cross-section friction

Only available for “Y-Z” and “Asymetrical Trapezium” cross-sections.
The cross-sectional area can be divided in (vertical) roughness sections for which a
different Bed friction (formulae & value) can be defined.

Restriction for Cross-section friction
Groundlayer friction cannot be defined
5.14.4

Culvert friction concept
Culvert friction means that Bed and optional Groundlayer friction (formula & value) can be
defined for the closed cross-section available at a Culvert:

Use of Culvert friction:
Only available for Culverts, Inverted Siphons and Siphons

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6 Conceptual description
6.1
6.1.1

Hydrodynamics D-Flow 1D
Model equations
The water flow is computed by solving the complete De Saint Venant (1871) equations for
unstaedy flow are based upon the the following series of assumptions (Cunge et al., 1980):

The flow is one-dimensional i.e. the velocity can be representated by a uniform flow over
the cross-section and the water level can be assumed to be horizontal across the section.

The streamline curvature is small and the vertical accelerations are negiglible, hence the
pressure is hydrostatic.

The effects of boundary friction and turbulence can be accounted for through resistance

laws analogous to those used for steady flow.
The average channel bed slope is small so that the cosine of the angle it makes with the
horizontal may be replace by unity.

For one dimensional flow (Channel Flow and Sewer Flow modules) the following equations
are solved

continuity equation 1D
momentum equation 1D

For two dimensional flow (Overland Flow module), three equations are solved:

continuity equation 2D
momentum equation 2D for the x-direction
momentum equation 2D for the y -direction

These equations are solved numerically using the Delft-scheme.

Note: on the 2D equations
As opposed to the shallow water equations, the described equations do not incorporate the
turbulent stress terms, accounting for the sub grid transfer of momentum in between grid
cells. These terms have been omitted because they are relatively unimportant for flood flow
computations, in order to save computational effort.
The wall friction terms have been introduced to account for the added resistance that is caused
by vertical obstacles, like houses or trees. The wall friction coefficient is based on the average
number and diameter of the obstacles per unit area and the average obstacle drag coefficient
(Cd coefficient).
6.1.1.1

Continuity equation (1D)
The 1D continuity equation reads:

∂AT
∂Q
+
= qlat
∂t
∂x

Total area (sum of flow area and storage area) [m2 ]
Discharge [m3 /s]

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Lateral discharge per unit length [m2 /s]. Positive value refers to inflow. Negative value refers to outflow.

Momentum equation (1D)
The 1D momentum equation reads:

∂Q
∂
+
∂t
∂x

∂ζ
gQ|Q|
τwind
ξQ|Q|
+ 2
− wf
+ gAF
=0
∂x C RAF
ρw
Lx

The first term describes the inertia
The second term describes the convection
The third term describes the water level gradient
The fourth term describes the bed friction
The fifth term describes the influence of the wind force
The sixth term describes the influence of extra resistance
where:

Flow area [m2 ]
Chézy value [m1/2 /s]
Acceleration due to gravity [m/s2 ]
Water level [m]
Length of branchsegment, accomodating an Extra Resistance Node [m]
Discharge [m3 /s]
Hydraulic radius [m]
Time [s]
Water surface width [m]
Distance along the channel axis [m]
Density of fresh water [kg/m3 ]
Wind shear stress [N/m2 ] (see section 6.1.7)
Extra Resistance coefficient [s2 /m5 ]

AF
C
g
ζ
Lx
Q
R
t
wf
x
ρw
τwind
ξ

Hydrodynamic definitions

Model datum/reference level

The Model datum and reference level both refer to a horizontal plane from which elevations
are defined (positive in upward direction). By default the model datum and reference level are
equal to zero.

zb
Reference level/Model datum
Figure 6.1: Definition of model datum/reference level

Note: All levels (quantities with a vertical coordinate) in SOBEK are defined with respect to
the model datum or reference level.

Conceptual description

Bed level
The bed level is defined as the lowest point in the cross section. In the definition of the cross
section an example is given of the interpolation and extrapolation of the bed levels over a
branch. The used symbol in the D-Flow 1D module is zb .
It is given relative to a reference level, for example Mean Sea Level .

Reference level/Model datum

Figure 6.2: Definition of bed level

If the water level is lower than the bed level, drying occurs.
Water depth

In the D-Flow 1D module the water depth is the distance between the water level and the bed
level. The symbol used for the water depth is h.

Reference level/Model datum

Figure 6.3: Definition of water depth h = ζ − zb

SOBEK, User Manual

Water level
The water level (ζ ) is the level of the water surface relative to the reference level or Model
datum (= reference level).
In the one-dimensional D-Flow 1D module the water level perpendicular to the flow direction
is assumed to be horizontal.

Reference level/Model datum
Figure 6.4: Definition of water level

The water level together with the discharge form the result of the D-Flow 1D module computations. Water levels are calculated at the connection nodes and the ζ -calculation points.
Note: In each D-Flow 1D, all levels are relative to the reference level
6.1.2.5

The flow area AF of a cross-section is the area through which water is actually flowing.
In a cross-section, distinction can be made between the flow area and the storage area. In
the latter part, water is stored only, see Figure 6.5.

AS = storage area

AS = storage area

Figure 6.5: Definiton of flow area (AF ) and storage area (AS )

The shape of the cross-section, and the distinction between the flow area and storage area
are defined for each cross-section by user input.
6.1.2.6

Storage area
The storage area AS of a cross-section is the area in which only water is stored i.e. the
non-conveying part of the cross-section.
In a cross-section, distinction can be made between the flow area and the storage area, see
Figure 6.5.
The shape of the cross-section, and the distinction between the flow area and storage area is
defined for each cross-section by user input.

Conceptual description

The total area AT is defined as the flow area plus the storage area.
6.1.2.7

Wetted area
The wetted area (AF [m2 ]) is the part of the cross section that is filled with water. See
Figure 6.6

Wetted perimeter
The wetted perimeter (O [m]) is the interface between the soil and the flowing water.
See Figure 6.6.

In the case of a main channel and one or two floodplains in the cross-section, a wetted perimeter is computed for each section. In that case the water interface between the sections is not
included in the wetted perimeter. See also Figure 6.6 and Figure 6.7

The wetted perimeter is used to compute the hydraulic radius, which is important for the
computation of the bed friction.

Figure 6.6: Wetted perimeter

Figure 6.7: Wetted perimeter for the main channel

Flow velocity
The flow velocity (u) is defined as the average flow velocity in the flow section of the crosssection. It is by default given in [m/s].
The average flow velocity is derived by dividing the discharge [m3 /s] by the flow area [m2 ].
Output of the overall average flow velocity, the flow velocity in the main channel, the flow

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velocity in floodplain 1 and the flow velocity in floodplain 2 is possible.

The indices 0, 1, 2 indicate the main channel, floodplain 1 and floodplain 2 respectively.
6.1.2.10

Velocity
The velocity (u) is defined as the average flow velocity in the wetted area of the cross section.
It is given in [m/s].

Note: Discharges and velocities are defined in branch segments, whereas cross sections are
defined in ζ -calculation points. For the computation of the velocities according to the above
formula. The D-Flow 1D module uses the upstream cross section
Hydraulic radius

The hydraulic radius is defined as the wetted area of the cross section divided by the wetted
perimeter.

Figure 6.8: Computation of hydraulic radius

Figure 6.9: Wetted perimeter for the main channel (Subdivision in main channel and
floodplains only in SOBEK-River)

Conceptual description

Inertia
The flow in one dimension is described by two equations: the momentum equation and the
continuity equation. The first term in the momentum equation is the inertia term:
inertia =

Discharge [m3 /s]
Time [s]

In the D-Flow 1D module an convection term is used to guarantee the conservation of momentum in a branch (between branch segments). The same holds for a connection node when
two branches are connected to this node. It that case the connection nodes could also have
been modelled as a ζ -calculation point. If there are more than two branches connected to a
connection node the convection term is set to zero.

When a branch has subsections, all subsections have an independent solution for the velocity.
The velocity that is used for the conservation of momentum over the branch is the average of
the velocities ui of the subsections in the cross section.
Convection (1D)

The flow in one dimension is described by two equations: the momentum equation and the
continuity equation. One of the terms in the momentum equation is the convection term:

∂
convection =
∂x

Discharge [m3 /s]
Flow area [m2 ]
Distance [m]

Water level gradient

The third term in the momentum equation is the water level gradient.
water level gradient = gAF

Distance [m]
Flow area [m2 ]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Water level [m] (with respect to the reference level)

This force tries to achieve a flat water surface under influence of the gravitational acceleration.
This force together with the bed friction have the greatest effect on the water movements.
6.1.7

Wind friction
The wind friction term in the momentum equation is expressed as:

τwind = −ρair Cwind u2wind cos(ϕwind − ϕchannel )

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Wind shear stress (positive if acting along the positive x-axis of an open channel) [N/m2 ]
Density of air, 1.205 kg/m3
αwind,1 + αwind,2 uwind , the wind friction coefficient. The used values are:

awind,1 = 0.50 × 10−3
awind,2 = 0.06 × 10−3
uwind
ϕchannel
ϕwind

Wind velocity [m/s]
Clock-wise angle between the positive x-axis of the 1D open channel and the
North (Nautical convention) [degrees]
Clock-wise angle between the wind direction and the North (Nautical convention) [degrees]

The wind direction that is specified in the D-Flow 1D module is the direction from which the
wind is blowing with respect to the north. So, if the wind is blowing from the north, the wind
direction is 0 degrees. Wind from the southeast has a wind direction of 135 degrees.

Figure 6.10: Wind direction

When a cross section has a top width smaller than 20 mm (circular, egg-shaped, or nearly
closed tabulated cross section) than the cross section is considered closed. In that case the
wind is neglected in the momentum equation
6.1.8

Initial conditions

The initial conditions are the water levels or depths and the discharges at the beginning of
the simulation. The initial conditions are defined over a branch (water level and depth at
the ζ -calculation points, discharges at the branch segments). Therefore the water level that
initially should be taken at connection nodes is not strictly defined. This happens when, for
example, branch 1 with initial water level 0.5 is connected by a node to branch 2 with initial
water level 0.6. In that case the water level at the connection node is set to the lowest value
of the connected branches (0.5). Because the ζ -calculation point at the end of branch 1,
the connection node and the ζ -calculation point at the beginning of branch 2 have the same
location, the water levels of these three points are set to 0.5.

Conceptual description

Boundary
A boundary can be applied at the locations where the model network ends with a boundary
node.
In order to solve the water flow equations (continuity equation and momentum equation),
information about the water flow at the model boundaries must be supplied.
At each boundary node, one condition for the water flow must be specified. The following
options are available:

discharge (constant, tabulated function of time, tabulated function of the water level)
water level (constant, tabulated function of time)

Because in the staggered grid, used by D-Flow 1D module, the discharges are defined for the
branch segments, a discharge boundary is imposed on the first branch segment next to the
boundary. Therefore the ζ -calculation point just before this first branch segment (first one in
a branch) is undefined and will not be taken into consideration during a calculation.

A water level boundary is defined in the first calculation point next to the boundary. This
ζ -calculation point actually has the same coordinates as the boundary node.
Note: In channel flow, usually, the discharge will be specified at boundaries where water is
flowing into the model, and the water level where water is flowing out of the model. In both
sewer and channel systems a dead end (or beginning) of a branch can be a connection node
at the end of a pipe or channel. In contrast to a boundary node, this node has storage.
6.1.10

The discharge Q is the amount of water passing a branch segment per unit of time. It is given
in [m3 /s].
The discharges at the branch segments together with the water levels at the ζ -calculation
points, form the results of a water flow simulation.
The D-Flow 1D module gives a positive discharge when the water flows in positive direction
with respect to the defined direction of a branch. If the water is flowing from branch end to
branch beginning, the discharge is negative.
6.1.11

Lateral discharges

A distinction is to be made between a Point and Diffusive lateral discharge.

Point lateral discharge: A point lateral discharge (Qlat , [m3 /s]) refers to the inflow or
outflow of water at a specific point/location in a model schematization.

Diffusive lateral discharge: A diffusive lateral discharge (qlat , [m2 /s]) refers to the inflow
or outflow of water along a specific branchsegment in a model schematization. A branch
segment is the distance (li , [m]) between two ζ -calculation points. A branch may consists
of several branchsegments. The total diffusive lateral discharge at a branch segment
equals qlat × li . A diffusive lateral discharge is uniform distributed along the axis of a
branch (see Figure 6.11).

SOBEK, User Manual

Figure 6.11: Diffuse lateral discharge

For both point lateral discharges and diffuse lateral discharges yields that they are assigned to
a ζ -calculation point(s). More precisely, their lateral inflow or outflow volume is accounted for
in the local water balance of such ζ -calculation point (e.g. local discretization of the continuity
equation, see section 6.1.11.1).
Two options are available for determining to which adjacent ζ -calculation point a lateral discharges is assigned (see section 6.1.11.2).

An overview of lateral discharges, available in SOBEK, is given in section 6.1.11.3. In general
lateral discharges can be defined as a constant or as a function of time. Exceptions are:

The Area Based Point lateral inflow (see section 6.1.11.4)
The Pipe with Infiltration (see section 6.1.11.5)
6.1.11.1

Incorporating Lateral discharges in the Continuity Equation

Both point lateral discharges and diffusive lateral discharges (see Figure 6.12) are included in
the third term (qlat ) of the continuity equation (see Equation (6.13)).

∂AF
∂Q
+
= qlat
∂t
∂x
AF
t
Q
x
qlat

Flow area [m2 ]
Time [s]
Discharge [m3 /s]
Distance [m]
Lateral discharge per unit length [m2 /s]

Figure 6.12: Lateral discharges:
Point lateral discharge: qlat = Qpoint /∆x; and
Diffuse lateral discharge: qlat = Qdiffuse /l

Note: A large withdrawal of water (negative lateral discharge) can cause problems when
the amount of outflowing water is larger than the storage available in a ζ -calculation point.
As a result negative volumes could be computed in the continuity equation. For that reason
the time step is temporarily reduced when the outflowing water volume is larger than half the
available volume (safety factor) in the ζ -calculation point. The time step is set to a value that

Conceptual description

allows a withdrawal of half the available volume in one time step. If the time step resulting
from this action is smaller than 0.01 second, the lateral withdrawal is set to zero.
Options for Assigning Lateral Discharges to ζ -calculation point(s)
Two different lateral discharge assignment options are available in Settings (see 1D Flow,
Simulation Settings Tab), that determine to which ζ -calculation (or water level) point(s) a particular lateral discharge is to be assigned. The two different lateral discharge assignment
options are:
Option 1: Lateral Assigned to Lowest Water Level Point,
Option 2: Lateral Assigned to Nearest Water Level Point.

Lateral discharge on a Node [m3 /s]:

Hereafter, the consequences of the two different lateral discharge assignment options are
discussed for each type of lateral discharge (see section 6.1.11.3) separately.

Irrespective of the selected lateral discharge assignment option, a lateral discharge on
a Node is assigned to its concerning Node (e.g. ζ -calculation point, Connection Node or
Manhole).
Point-lateral discharge on a Branch [m3 /s]:
A point-lateral discharge on a Branch is either assigned to one or equally distributed over
both of the ζ -calculation points, that are respectively located at the left-side and the rightside of the point-lateral discharge.
If option 1 (Lateral Assigned to Lowest Water Level Point) is selected, the point-lateral
discharge is assigned to the ζ -calculation point having the lowest bed level. If both
calculation points have the same bed level and the point-lateral discharge is located at
a u-velocity point (e.g. centre-point of the two adjacent ζ -calculation points), the pointlateral discharge is equally distributed over both adjacent calculation points. Else the
point-lateral discharge is assigned to the nearest ζ -calculation point.
If option 2 (Lateral Assigned to Nearest Water Level Point) is selected and the pointlateral discharge is located at a u-velocity point (e.g. centre-point of the two adjacent ζ calculation points), the point-lateral discharge is equally distributed over both adjacent
ζ -calculation points. Else the point-lateral discharge is assigned to the nearest ζ calculation point.

Diffusive lateral discharge along a Pipe or Branch [m2 /s]:

A diffusive lateral discharge along a Pipe or Branch is either assigned to one or equally
distributed over both of the ζ -calculation points, that are respectively located at the beginning and the end of a pipe or branchsegment, receiving a diffusive lateral discharge.

If option 1 (Lateral Assigned to Lowest Water Level Point) is selected, the diffusive
lateral discharge is assigned to the ζ -calculation point having the lowest bed level.
Else the diffusive lateral discharge is equally distributed over both adjacent calculation
points.
If option 2 (Lateral Assigned to Nearest Water Level Point) is selected, the diffusive
lateral discharge is equally distributed over both adjacent ζ -calculation points.

SOBEK, User Manual

Examples of Lateral Discharges
Three different types of lateral discharges are discerned:
1 Lateral Discharge on a Node [m3 /s]:
Examples of lateral discharges on a Node are:

Point-Lateral Discharge, that is exactly located on a ζ -calculation point,
Connection Node with Storage and Lateral Flow,
Manhole with Lateral Flow,
Manhole with Lateral Disch. and Runoff
Manhole with Runoff
Flow - RR Connection on Flow Connection Node.

Flow - Lateral Flow Node
Flow - RR Connection on Channel.

2 Point-Lateral Discharge on a Branch [m3 /s]:
Examples of a point-lateral discharge on a Branch are:

3 Diffusive Lateral Discharge along a Pipe or Branch [m2 /s]:
Examples of a diffusive lateral discharge along a Pipe or Branch are:
Flow - Pipe with Runoff,
Flow - Dry Weather Pipe,
Flow - Rain Pipe,
Flow - Pipe with Infiltration
Flow - Channel with Lateral Discharge.

Area Based Point Lateral Flow

Area based Point lateral flow is computed as:

Qlat = A(fd R + S)
Qlat
fd
R
A
S

Lateral discharge [m3 /s]
Design factor for area based lateral flow [−].
Rainfall [m/s].
The catchment runoff area [m2 ]
Seepage (positive, inflow of groundwater) or Infiltration (negative, outflow to
groundwater reservoir) [m/s].

Pipe with infiltration (having a lateral diffusive discharge option)

A pipe with infiltration refers to a drainage pipe fully located inside a trench (see Figure 6.13).
Although the drainage pipe is porous it still can get pressurized. The trench is filled with
material (for instance gravel) having a certain porosity.
A pipe with infiltration allows for the exchange of water in the pipe towards the trench (positive
sign) and vice versa as well as for the exchange of water in the trench towards the groundwater
(negative sign) and vice versa. Hence, a pipe with infiltration can be seen as a pipe having a
diffusive lateral discharge option (e.g. infiltration of water in the pipe towards the trench and
exfiltration of water in the trench towards the pipe). For more information on the infiltration and
exfiltration process, reference is made to Ellis and Bertrand-Krajewski (2010), Rutsch et al.
(2008) and Karpf et al. (2008).

Conceptual description

Figure 6.13: Pipe with Infiltration (e.g. a drainage pipe located in a trench); Allowing for
the exchange of water in the pipe towards the trench (positive sign) and
vice versa; Allowing for the exchange of water from the trench towards the
groundwater (negative sign) and vice versa

For the computational procedure of a pipe with infiltration yields:

The flow (water levels (ζp , see Figure 6.14), discharges and velocities) through a pipe

with infiltration is computed in exactly the same manner as the flow in any pipe (e.g. by
solving the one dimensional depth averaged St. Venant momentum and continuity equations), where the diffusive lateral flow along a pipe with infiltration is taken into account in
accordance with the selected lateral discharge assignment option (see section 6.1.11.2).
The exchange of water between the pipe and the trench is computed according to the
“Darcy leakage approach (see Rutsch et al. (2008) and Karpf et al. (2008))” in which it is
assumed that the rate of exchange of water between two media is a function of the resistance at the interface, the interface area and the hydraulic head over the interface. More
precisely per meter pipe length (see Figure 6.14), the rate of exchange of water between
the pipe and the trench (e.g. specific discharge qp↔tr , see Equation (6.15)) depends on
the resistance (cp−tr ), the wetted perimeter (Pp−tr ), the averaged water level in the pipe
(ζp ) and the water level in the trench (ζtr ).
Per metre pipe length, the maximum volume of water that can be stored in the trench (e.g.
fully saturated trench) equals the cross-sectional area of the trench that is filled with trench
material (Afiled with trench material ) times the porosity of the trench material (φtr , [-]). Once the
trench is fully saturated, the water level in the trench (htr , see Figure 6.14) may rise above
the top level of the trench (ztr,top ). In such case, per metre of pipe length an additional
volume of water is stored, that is equal to the top width of the trench (Wtr,top ) times the
water depth on the trench (= ζtr − ztr,top ). The top level of the trench is supposed to
coincide with the local surface level. Therefore in urban terminology, water depth on the
trench is referred to as water on street.
The exchange of water between the groundwater and the trench per metre pipe length
(e.g. specific discharge qgw↔tr ) is also computed according to the “Darcy leakage approach” (see Equation (6.16)).
The groundwater reservoir as such is not modelled. The user-defined groundwater levels
(hgw , see Figure 6.14) are used as boundary conditions only.

Note: The local surface level is supposed to coincide with the top level of the trench. From
a physical point of view, a groundwater level can not rise above the local surface level (see
Figure 6.14). Therefore, at the start of a computation it is verified if user-defined ground
water levels (hgw ) are above the top level of the trench (ztr,top ). If this is the case (e.g.
if hgw > ztr,top ), the computation is terminated with an error message denoting for which
"Pipes with Infiltration" yields that groundwater level(s) are above the top level of the trench.
Note: The thickness of a possible ground-layer in a pipe does affect the flow through a pipe
and is consequently taken into account in determining pipe flow. However, the thickness of a
possible ground-layer is neglected in the resistance factor, applied for the interface between

SOBEK, User Manual

pipe and trench. In other words, irrespective of the thickness of a possible ground-layer, the
resistance factor applied for the pipe-trench interface equals the user-defined resistance factor
(cp−tr ) (see Equation (6.15)).

Note: Selecting the option "Impermeable" in the "Permeability of Ground/Soil" scroll-box,
available on the "Trench Data" tab (see Section 5.7.2.1), means that the interface between
trench and groundwater is considered to be impermeable (e.g. no exchange of water between
trench and groundwater). More precisely, if impermeable is selected Equation (6.16) is not
considered in the computational procedure.

Figure 6.14: Pipe with infiltration: definition of variables

The specific discharge (qp↔tr ) between the pipe and the trench (see Figure 6.14) per metre
pipe length is computed according to the “Darcy leakage approach” as follows:

qp↔tr
cp−tr
ζ1
ζ2
ζp
ζtr
Pp−tr

qp↔tr
z1
z2
zp


if ζp ≤ zp and ζtr ≤ zp
0
= Pp−tr (ζp − zp )/cp−tr if ζp > zp and htr ≤ zp

Pp−tr (ζp − ζtr )/cp−tr if ζp > zp and htr > zp

resistance factor of the interface between pipe and trench [h].
water level in the pipe (may become pressurized) at the beginning of the pipe
(e.g. pipe-side with lowest x-coordinate) [m above datum].
water level in the pipe (may become pressurized) at the end of the pipe (e.g.
pipe-side with highest x-coordinate) [m above datum].
averaged water level in the pipe (e.g. (ζ1 + ζ2 )/2, may become pressurized)
[m above datum].
water level in the trench [m above datum].
wetted perimeter (e.g. length of the interface) between pipe and trench [m].
Note: If ζp ≤ zp and ζtr ≤ zp , the wetted perimeter equals zero. Else the
maximum water level (e.g. max(ζp ; ζtr )) determines the length of the wetted
perimeter.
specific discharge per metre pipe length between trench and pipe. Positive if
water flows from pipe towards the trench [m2 /h].
invert level at the beginning of the pipe (e.g. pipe-side with lowest x-coordinate)
[m above datum].
invert level at the end of the pipe (e.g. pipe-side with highest x-coordinate) [m
above datum].
averaged pipe invert level (e.g. (z1 + z2 )/2) [m above datum].

The specific discharge (qgw↔tr ) between the pipe and the trench (see Figure 6.14) per metre

Conceptual description

pipe length is computed according to the “Darcy leakage approach” as follows:

qgw↔tr
ztr,top

resistance factor of the interface between groundwater and trench [h].
groundwater level [m above datum].
water level in the trench [m above datum].
wetted perimeter (e.g. length of the interface) between groundwater and trench
[m]. Note: If ζtr ≤ ztr and hgw ≤ ztr , the wetted perimeter equals zero.
Else the water level (ζpm ) determining the length of the wetted perimeter is
∗
computed as ζpm = max(h∗tr ; h∗gw ), where: if ζtr ≥ ztr,top then hζtr
= ztr,top
∗
∗
∗
else ζtr = ζtr ; and if hgw ≥ ztr,top then hgw = ztr,top else hgw = hgw .
specific discharge per metre pipe length between groundwater and trench. Positive if ground water flows into the trench [m2 /h].
top level of the trench [m above datum]

cgw−tr
hgw
ζtr
Pgw−tr


if ζtr ≤ ztr and hgw ≤ ztr
0
= Pgw−tr (ζtr − ztr )/cgw−tr if ζtr > ztr and hgw ≤ ztr

Pgw−tr (ζtr − hgw )/cgw−tr if ζtr > ztr and hgw > ztr

The bed friction is the friction between the flowing water and the channel bed. As such, it
exerts a force on the flowing water always in the direction opposite the water flow.
In water courses, this force together with the force caused by earth gravity usually determines
the flow conditions: the other forces are far less important.
The fourth term of the momentum equation is the bed-friction term:
bed friction =

Acceleration due to gravity [m/s2 ] (≈ 9.81)
Discharge [m3 /s]
Chézy coefficient [m1/2 /s]
Hydraulic radius [m]
Wetted area [m2 ]

Note:
If the specified roughness parameter is equal to zero (Chézy=0, Manning=0, etc.), then the
bed friction term is not taken into account in the momentum equation.
The following roughness definitions can be used:
6.1.12.1,
6.1.12.2,
6.1.12.3,
6.1.12.4,
6.1.12.5,
6.1.12.6,

Bos-Bijkerk;
Chézy;
Manning;
Nikuradse;
Strickler;
White-Colebrook.

SOBEK, User Manual

Bos-Bijkerk
The bed friction formulation according to de Bos-Bijkerk describes the Manning coefficient as
a function of the water depth and a parameter. This parameter can be used to shape the
function to a certain empirical curve:

Manning roughness coefficient [m1/3 /s]
Water depth [m]
Parameter [1/s], normally between 20 and 40

C = γh1/3 R1/6
Chézy coefficient [m1/2 /s]
Hydraulic radius [m]

This formula can be rewritten to a formulation for the Chézy coefficient as a function of the
water depth
(6.19)

For every computational time step the new friction value is calculated according to the BosBijkerk formula and sequentially applied to the hydrodynamics calculations.
6.1.12.2

The D-Flow 1D module uses the Chézy bed friction value in solving the water flow equations.
The following roughness formulations are possible:

Chézy coefficient
Bos-Bijkerk friction shape parameter g , resulting in a Chézy value according to:
C = γh1/3 R1/6

Water depth [m]
Parameter [1/s], normally between 20 and 40
Chézy coefficient [m1/2 /s]
Hydraulic radius [m]
White-Colebrook, using the Nikuradse roughness coefficient kn , results in a Chézy value
according to:

Manning coefficient, nm , resulting in a Chézy coefficient according to:
C=

Strickler, using the Nikuradse kn roughness coefficient, results in a Chézy value according
to:

Conceptual description

Strickler, using the Strickler ks roughness coefficient, results in a Chézy value according
to:

Engelund-like roughness predictor (for main sections of SOBEK-River profiles only) resulting in a Chézy value according to:

For SOBEK-River, the Chézy, Nikuradse, Manning or Strickler coefficients may be

a constant
spatially varying
a tabulated function of the water level (h) or the total discharge (Q)

Different values or tables are possible for positive as well as negative flow. See also the
chapter 1D hydraulic friction concepts for information on the different friction concepts present
in the user interface.
Manning

One of the methods to define the bed roughness is using the Manning coefficient, symbol nm .
In the D-Flow 1D module, the Manning coefficient is used to compute the actual value of the
Chézy coefficient, by:

C
R
nm
6.1.12.4

Chézy coefficient [m1/2 /s]
Hydraulic radius [m]
Manning coefficient [s/m1/3 ]

One of the methods to define the bed friction is by entering an equivalent roughness according
to Nikuradse, represented by the symbol kn [m].
Values of kn for open channels with bed forms are in the same order of magnitude as the
height of the bed forms.
Using this option, the actual value of the Chézy coefficient will be computed according to the
White-Colebrook formula.
6.1.12.5

Strickler
One of the methods to define the bed roughness is by using the Strickler formula. The actual
value of the Chézy coefficient is computed using:

C = ks R1/6
Deltares

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Chézy coefficient [m1/2 /s]
Hydraulic radius [m]
Strickler roughness coefficient [m1/3 /s]

in which kn is the Nikuradse equivalent roughness, and ks is the Strickler roughness coefficient. You may select either ks or kn as input value.
The value of the hydraulic radius R is taken from the last iteration loop.
It is possible to enter the coefficients varying in space and depending on the local flow direction.
6.1.12.6

White-Colebrook

One of the methods to define the bed friction is by specifying an equivalent roughness according to Nikuradse. Using this option, the value of the Chézy coefficient will be computed
according to the White-Colebrook formula:
(6.29)

Chézy coefficient
Hydraulic radius
Nikuradse equivalent roughness

Note:
Actually, this formula is a simplification of the complete White-Colebrook formula.
6.1.13

The Froude number is defined by u/c, with u the average flow velocity and c the wave celerity.
Herein is c as follows:

Froude number = p

Velocity (u = Q/AF ) [m/s]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Wetted area [m2 ]
Flow width [m]

Remarks:
When the Froude number is less than 1, the flow is sub-critical, when it is larger than 1,
the flow is super-critical
Transitions from sub-critical to super-critical flow causes an hydraulic jump.

Conceptual description

Boussinesq
The Boussinesq coefficient is a parameter in the momentum equation for the water flow. It
accounts for the non-uniform velocity distribution in a cross-section.
The Boussinesq constant αB is multiplier to the convective term:

The definition of the coefficient αB is:

The constant of Boussinesq is computed by D-Flow 1D. The computation is based upon the
Engelund approach (Engelund and Hansen, 1967). In this approach the water level gradient
and bed-friction term are assumed to be an order of magnitude larger than the other terms in
the momentum equation. The resulting equation is:

∂h
gQ2
gAF
= 2
∂x
C RAF

in which locally a constant water level gradient is assumed. In an arbitrary cross-section the
discharge can be expressed as:

in which h is the water depth. Furthermore, it is assumed that the water level and water level
slope are the same for main and floodplains. Combining Equation (6.34) and Equation (6.35)
leads to a more accurate estimate of the Chézy coefficient based upon the average of the
local Chézy coefficients.

Now Equation (6.33) gives combined with Equation (6.34) and Equation (6.35) the following
expression for the Boussinesq coefficient:

1
αB =
AF RC 2

C 2 (y)h(y)R(y) dy

Cross-sections in D-Flow 1D may be divided in two or three parts. So the following three
options are available.
option 1:
The cross-section is not divided into sections with different roughness (only a main channel is
present). This gives for the Boussinesq coefficient:

option 2:
The cross-section is divided into two sections with different roughness for the modeling of, for
example, a cross-section with a main channel and a floodplain. During a computation this
gives two possibilities:

SOBEK, User Manual

possibility 1:
Actual water flow is in the main channel only:

possibility 2:
Actual water flow is in the main channel and the floodplain:

C02 Af0 R0 + C12 Af1 R1
C 2 RAF

The indices 0 and 1 respectively indicate the main channel and floodplain.

possibility 1:
Actual water flow is in the main channel only:

option 3:
The cross-section is divided into three sections with different roughness (main channel, floodplain 1 and floodplain 2). During a computation this gives three possibilities:

possibility 2:
Actual water flow is in the main channel and floodplain 1:

C02 Af0 R0 + C12 Af1 R1
C 2 RAF (ζ)

The indices 0 and 1 respectively indicate the main channel and floodplain.
possibility 3:
Water is actually flowing in all sections, main channel, floodplain 1 and floodplain 2:

C02 Af0 R0 + C12 Af1 R1 + C22 Af2 R2
C 2 RAF

The indices 0, 1 and 2 respectively indicate the main channel, floodplain 1 and floodplain
2.
6.1.15

Whether you are measuring in a prototype, studying water flow in a scale model or modelling
with a software system, you should always make some considerations about the accuracy of
your activities and of the results of your study.
As for the results of a mathematical model study, the following elements play a role in establishing the overall accuracy:

The reliability of the available data describing the prototype;
The accuracy of the available data describing the prototype;
The violation of certain assumptions underlying the mathematical modelling concept being
used;

The experience and skill of the modeller(s);
The overall accuracy that is required (perhaps more accurate results could be obtained
but the aim of the study may not require such accuracy or due to a lack of time you may
have to settle for less);
The accuracy of the applied numerical modelling technique.

Conceptual description

In general practice the first five items are the most important when you are using a onedimensional mathematical model for hydrodynamic flow. The numerical accuracy is in that
case normally of minor importance.
The D-Flow 1D module uses the Delft-scheme to solve the water flow equations. This scheme
is developed with robustness as the most important design aspect. It can deal with phenomena such as drying/flooding, super-critical flow and it guarantees a solution for every time
step.

The accuracy of the solution depends on the grid size; the smaller the grid sizes, the more
accurate the solution is. The time step can be chosen arbitrarily. It is reduced internally
when this is necessary to guarantee stability by means of a time step estimation procedure.
Obviously small grid sizes result in a network with more elements and therefore in a longer
simulation time.
The Delft-scheme is designed to produce a closed water balance.
Structures

In the D-Flow 1D-modules the following structure types are available:

6.1.16.1
6.1.16.2
6.1.16.3
6.1.16.4
6.1.16.5
6.1.16.6
6.1.16.7
6.1.16.8
6.1.16.9
6.1.16.10
6.1.16.11
6.1.16.12
6.1.16.13
6.1.16.14
6.1.16.15
6.1.16.16

Advanced weir
Bridge
Compound structure
Culvert
Database structure
General structure
Inverted siphon
Orifice
Pump station and Internal Pump station
External Pump station
River Pump
River Weir
Siphon
Universal Weir
Vertical obstacle friction
Weir

The flow through structures is computed based on:

Upstream water level or energy level (River weir, Advanced weir and General structure
only)

Downstream water level or energy level (River weir, Advanced weir and General structure
only)

Structure dimensions (some can be controlled: i.e. crest level, opening height, pump capacity, opening of valve)

A number of user-defined parameters, depending on the structure type (contraction coefficient, reduction factor, etc.).
The discharges and wetted areas that are computed in the structure formulas are imposed
in the branch segment where the structure is located. The formulas use the water levels of
the ζ -calculation points on either side of the branch segment. For the River weir, Advanced
weir, General structure, River pump, Database structure and Compound structure yields that

SOBEK, User Manual

SOBEK by default places a computational point 0.5 m upstream and 0.5 m downstream of the
structure location. Hence such structure is located in a branch having a default length of 1 m.
Note:
The dimensions of the structure do not contribute to the storage in the water system.
Advanced weir
Please note that the discharge through an Advanced weir is computed on basis of upstream
and downstream energy levels. Further on please note that default a computational point is
located 0.5 m in front and 0.5 m behind an Advanced weir.

Notation
The flow direction can be either positive or negative. A positive flow direction is a flow in
the direction that the branches have been specified, i.e. with increasing x-coordinates. The
upstream side, facing the beginning of the branch is denoted by the subscript 1, whereas the
downstream location facing the end of the branch is denoted with 2. The subscript s is used
for locations at the sill.
Energy level

Reference level/Model datum

Figure 6.15: Definition of energy and water level

and the energy level H is defined as:

The user must enter the following input parameters for this type of hydraulic structure:

zs
Wn
N
P
H0
Kp
Ka

Level of crest
Total net width
Number of piers
Level of upstream face
Design head of the weir
Pier contraction coefficient
Abutment contraction coefficient

The following parameters can be controlled by a hydraulic structure controller:

Width across flow section
Crest level of weir

The discharge through the structure is computed with:

p
2g(H1 − zs )3

Conceptual description

In which W is the active width and C1 and C2 are factors computed in the following way.
Note:
if ζ1 < zs then Q = 0.

W = Wk − 2(N Kp + Ka )(H1 − zs )
C1 = C0 Ck

The value of C0 is computed depending on the value of the ratio between the upstream face
and the design head:

if χ < 2 then:

ξ
C0 = (0.1256χ5 − 1.0178χ4 + 3χ3 − 3.94χ2 + 2.28χ + 1.66) √
2g

where ξ is a correction factor computed with:

ξ = −0.052χ3 + 0.145χ2 − 0.096χ + 1.01

if χ > 2 then:

2.1549008
√
2g

The value of χ is computed depending on the value of the ratio between the energy level
minus the sill level and the design head:

0.1394χ31 − 0.416χ21 + 0.488χ1 + 0.785
1.0718224

χ1 < 1.6
χ1 ≥ 1.6

The value of Ct is computed depending on the value of the ratio between the energy level
minus the downstream water level and the energy level minus the sill level:

H1 − h2
H1 − zs

(q
(1 −
Ct =
1

(χ2 −0.7)2
)
0.49

+ 27(0.7 − χ2 )4

χ2 < 0.7
χ2 ≥ 0.7

SOBEK, User Manual

Bridge
A bridge is one of the structure types that can be included in the SOBEK-Flow-module. The
following types of bridges can be modelled:

Pillar bridge
Abutment bridge
Fixed bed bridge
Soil bed bridge

The general description of the discharge through a bridge is given by:

p
2g(ζ1 − ζ2 )

Discharge through bridge [m3 /s]
Discharge coefficient derived from loss-coefficients [−]
Wetted area [m2 ] of flow through bridge at upstream side
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]

Q
µ
Af
g
ζ1
ζ2

Note: For numerical reasons (e.g. validity of structure Equation (6.56)) the discharge coefficient (µ) is limited to a maximum of 1.0. In other words if the discharge coefficient (µ)
according to Equation (6.57) (Pilar bridge) or Equation (6.59) (Abutment bridge, Fixed bed
bridge or Soil bed bridge) becomes larger than 1.0, the actual applied discharge coefficient in
Equation (6.56) is limited to 1.0. This means that for a given discharge, the water level difference over such bridge might be larger than anticipated, when considering the defined friction
loss coefficients. In such case it is advised to apply the Extra Resistance Node for modelling this particular bridge. An Extra Resistance Node (see section 5.3.8 and section 6.1.1.2)
adds additional(extra) resistance to the St. Venant momemtum equation. Hence no structure
equation is solved at an Extra Resistance Node.
Pillar bridge

A pillar bridge has one or more pillars that affect the discharge through the bridge with the
following definition for the discharge coefficient (µ)

1
µ= p
ξy
ξy

Pillar loss coefficient, defined as

Parameter [−] depending on shape of pillar[s] (shape factor). Normally between 0.22 and 1.56
Wetted area [m2 ] of flow through bridge at upstream side
Area [m2 ] of wetted part of pillar [s] perpendicular to the flow direction, considered at upstream side

Figure 6.16: Pillar bridge

Conceptual description

Note: For numerical reasons the discharge coefficient (µ) is limited to a maximum of 1.0. For
more information, see the note below Equation (6.56).
The plate of the bridge is always so high that it does not effect the flow through the bridge. So
the cross section is considered as open.
Note:
Pillar bridges are not allowed in closed cross-sections.
Abutment bridge
For the abutment bridge the overall loss coefficient is defined as:

1
µ= p
ξi + ξf + ξo

Entrance loss coefficient (in). Constant
Friction loss coefficient
Exit loss coefficient (out).

Note: For numerical reasons the discharge coefficient (µ) is limited to a maximum of 1.0. For
more information, see the note below Equation (6.56).
The ξo coefficient is defined as:

2
Af
ξo = k 1 −
A f2

Constant exit loss coefficient
Wetted area [m2 ] of flow through bridge at upstream side
Wetted area [m2 ] of flow in branch at downstream side of bridge

The ξf coefficient is defined as:

Acceleration due to gravity [m/s2 ] (≈ 9.81)
Length of bridge [m]
Chézy coefficient [m1/2 /s]
Hydraulic radius [m]

Figure 6.17: A suspension bridge with abutments

Here, the plate of the bridge can effect the flow through the bridge. The cross section is closed

SOBEK, User Manual

Note:
The definition of this bridge is similar to the definition of a culvert.
Fixed bed bridge
This bridge has the same formulation as the abutment bridge except it has a rectangular
profile.

Figure 6.18: Fixed bed bridge

Soil bed bridge

This bridge has the same formulation as the fixed bed bridge including the rectangular profile.
In addition to this it has a ground layer with a different friction formulation. This ground layer
can have a zero thickness.

Figure 6.19: Soil bed bridge

Compound structure

A compound structure consists of several hydraulic structures parallel to each other at one
location. These hydraulic structures may be of the same type or of different types. Presently
following structure types can be placed as a member in a compound structure, viz.: General
structure, Database structure, Advanced weir, River weir and River pump.
Please note that a value for structure inertia damping factor can be defined for each individual
member of the compound structure.
Each member of the compound structure has its own triggers and controllers.
6.1.16.4

A culvert is one of the structure types that can be included in the SOBEK-Flow-module. A
culvert is an underground structure that normally connects two open channels. The flow
through a culvert is affected by its upstream and downstream invert levels, the size and shape
of its closed cross section, its ground layer thickness, its entrance loss, its friction loss, its
valve loss and its exit loss.
Figure 6.20 shows a side view of a culvert.

Conceptual description

L
Figure 6.20: Side view of a culvert

Two flow conditions can occur:

p
2g(ζ1 − (zc2 + hc2 ))

Submerged flow when ζ2 ≥ zc2 + hc2 :

Q
µ
Af c
g
ζ1
ζ2
zc2
hc2
T2

Free flow when ζ2 < zc2 + hc2

p
2g(ζ1 − ζ2 )

Discharge through culvert [m3 /s]
Discharge coefficient, derived from loss-coefficients [−]
Discharge culvert flow area min(Af c1 , Af cgate ) [m2 ]
Af c1 : Flow area in the culvert at its upstream side [m2 ]
Af cgate : Flow area under the culvert gate [m2 ]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]
Downstream culvert invert level [m]
p
Critical culvert depth at the downstream side, 3 Q2 /(gT22 ) [m]
Surface width in the culvert at its downstream side [m]

For numerical reasons the discharge coefficient (µ) is limited to a maximum of 1.0. The
discharge coefficient (µ) is computed as follows:

1
µ= p
ξi + ξf + ξv + ξo

ξi
ξf
ξv
ξo

Entrance loss coefficient [−]
Friction loss coefficient [−]
Valve loss coefficient [−]
Exit loss coefficient [−]

The entrance loss coefficient (ξi ) can be defined as a constant value only.
The friction loss coefficient (ξf ) is computed as follows:

ξf =
L
C1
Deltares

Length of the culvert [m]
Chézy coefficient in the culvert at its upstream side [m1/2 /s]

SOBEK, User Manual

Hydraulic radius [m]

R=
hgate
Rc1
Rgate
zc1

ζ1 ≥ zc1 + hgate
ζ1 < zc1 + hgate

Gate height opening [m]
Hydraulic radius in the culvert at its upstream side [m]
Hydraulic radius based on actual gate height opening [m]
Upstream culvert invert level [m]

The valve loss coefficient (ξv ) can be defined as a constant value or as a function of the ratio
of the “Gate height opening” and the “maximum inner culvert height”.

In case the valve loss coefficient (ξv ) is not a constant, in computations the actual valve
loss coefficient (ξv ) is derived from the user defined table, while using the ratio of the
“actual gate height opening and the “actual maximum inner culvert height”.

In case the ground layer thickness is greater than zero, both the “actual gate height open-

ing” and the “actual maximum inner culvert height” will differ from the values as defined in
the user interface (see next paragraph)
The exit loss coefficient (ξo ) is computed as follows:
Submerged flow (ζ2 = zc2 + hc2 ):

Af c
ξo = k 1 −
Af r2
k
Af r2
Af c

User defined constant exit loss coefficient [−]
Flow area in the branch, adjacent to the downstream culvert side [m2 ]
Culvert flow area [m2 ]

hgate
zc1
Afcgate
Afc1

h1 ≥ zc1 + hgate
h1 < zc1 + hgate

Gate height opening [m]
Upstream culvert invert level [m]
Flow area under the culvert gate [m2 ]
Flow area in the culvert at its upstream side [m2 ]

Free flow (ζ2 < zc2 + hc2 ):

Culvert cross-sections, bed friction and ground layer
For a culvert all available closed cross-section types can be used. In a culvert, a ground
layer with constant thickness can be defined. Culvert friction and ground layer friction can be
specified, using any of the available bed friction formulations.
Defining a ground layer thickness > 0 implies that in culvert computations:

Defined invert levels are raised with the ground layer thickness,
504 of 900

Conceptual description

Gate height openings are reduced with the ground layer thickness,
Maximum inner height of the culvert is reduced with the ground layer thickness,
Cross-sectional parameters (such as: flow areas, hydraulic radius and so on) are computed based on a cross-sectional profile, that is reduced by the ground layer thickness.
Culvert, Good modelling practice aspects
It is advised to avoid that the bed level of a cross-section in front of a Culvert, Inverted Siphon
or Siphon is above the ground-layer level (= invert level + ground-layer thickness), since such
situation can result in very small computational time-steps (e.g. long required wall-clock times)
or even in a termination of the simulation.

This is explained as follows. Consider the situation depicted in Figure 6.40 were the bed level
in front of a Culvert (Inverted Siphon or Siphon) is 0.60 m above the ground-layer level. This
means that at small upstream water depths, water will be sucked into the culvert (Inverted
Siphon or Siphon), resulting in large flow velocities. For the computational time-step (∆t)
yields that ∆t ≤ ∆x/U , where U is the local flow velocity and ∆x is distance between two
water level computational points (or ζ -points). At very low discharges even negative water
depths may be computed, leading to a termination of the simulation.
The situation explained above can be avoided by making the bed level in front of the Culvert
(Inverted Siphon or Siphon) equal to the ground-layer level. In other words by defining a
bed level slope from ζ -point ζ2 to ζ3 as depicted in Figure 6.40. Providing for the parameter
"Maximum Lowering of Cross-section Bed Level at Culvert" a value greater or equal to 0.60 m
means that before the computation starts, the bed level at ζ -point ζ3 is set equal to the groundlayer level. In Figure 5.15 it is shown how to provide a value for parameter "Maximum Lowering
of Cross-section Bed Level at Culvert".

Figure 6.21: Good modelling practice, Culvert, Inverted Siphon and Siphon

SOBEK, User Manual

Database structure
Please note that default a computational point is located 0.5 m before and 0.5 m behind a
Database structure. In a hydraulic structure the discharge through the structure depends on
upstream and downstream water levels and structure parameters that define the dimension
of the structure etc. In other words the hydraulic behaviour of a structure can be defined in
the structure equation as a relationship between upstream and dowstream water level. In the
database structure however, this relationship is defined in a tabulated form which is stored in
a database. The user has to define this database.
The database consists in fact of a matrix of discharges. At every point of the matrix a discharge (Q) is defined as a function of two corresponding water levels: one facing the beginning of the branch (ζ1 ) and one facing the end (ζ2 ), are defined. There are two ways to define
the relation:

a function of both water levels Q = Q(ζ1 − zs , ζ2 − zs ), to be used for structures with
relatively high head differences; zs = crest level w.r.t. datum
a function of the water level and the water level difference Q = Q(ζ1 −zs , ∆ζ = ζ1 −ζ2 ),

to be used for structures with relatively small water level differences combined with large
water level variations; zs = crest level w.r.t. datum
All discharges in a row correspond to the same water level (ζ1 ) facing the beginning of the
branch segment. All discharges in a column correspond either to the same water level (ζ2 )
facing the end of the branch segment or to the water level difference (∆ζ = ζ1 − ζ2 ). The
water levels that are part of the database are defined with respect to a user defined datum.
During a simulation, discharges at any point in the domain of the matrix will be obtained by
interpolation. In most cases this will be a linear interpolation in two directions. However when
the discharge is requested at a water level that lies within 10 percent of a water level defined
in the matrix, cubic interpolation takes place for that water level.
Warning:
The crest level can be adjusted by a controller. This implies the assumption that the
discharge head relation is independent of the level of the crest. This is not completely
correct. The user should be aware of this.
6.1.16.6

General structure

Please note that default a computational point is located 0.5 m in front and 0.5 m behind
a general structure. In the general structure type in sobek weir and gate flow is combined
in one structure type. In addition, the general structure gives more freedom in defining the
dimensions and the geometry of the hydraulic structure. The geometrical shape is given in
Figure 6.22 and Figure 6.23. See section 5.3.10 for the definition of input parameters. Please
note that the discharge through a General structure is computed on basis of upstream and
downstream energy levels. Please note as well that a structural inertia damping factor can be
defined for each individual General structure.

Conceptual description

Figure 6.22: General structure, side view

Figure 6.23: General structure, top view

Flow across the general structure can be of the following types: drowned weir flow, free weir
flow, drowned gate flow, and free gate flow, depending on the dimensions of the structure and
the flow conditions.
When salt intrusion is modelled, the density difference of the water over the structure is incorporated in the impulse balance (this is not the case with the other structure types).
In the solution method for the general structure particular attention has been given to the
modelling of the transition between free- and submerged flow.
For this purpose, the water level at the sill (ζs ) is computed by applying an impulse balance
instead of taking it equal to the water level further downstream.
As a result the general structure is especially attractive for those who want to simulate the
shifting conditions from free- to submerged gate flow accurately and of course in case of
important density-differences over the structure.

SOBEK, User Manual

Computation of downstream water level
In case of drowned gate flow or drowned weir flow the water level at the sill or downstream of
the gate is required. This level is computed by application of the impulse balance.

drowned gate-flow

Figure 6.24: Drowned gate flow

The water depth hs can be described by a second order algebraic equation:

Aw h2s + Bw hs + Cw = 0
with:

Wsd W2
Ag = (1 + ρ )
+ (1 − ρ )
+
(6.71)
4
12

Wsd W2
Wsd
∗
Bg = (1 + ρ ) (∆S1 + ∆S2 − h2 )
+
+ (2∆S1 + h2 )
+
3
6
6

W2
(∆S1 + 2h2 )
+
6

Wsd
Wsd + W2
∗
+ (1 − ρ ) ∆S1
+ (∆S1 + h2 )
+
3
6
4ρ∗ c2gd µ2gd d2g Ws2
λ
+
(1 + ) − 4cgd µgd dg Ws
(6.72)
W2 h2
d2

Wsd
W2
Cg = (1 + ρ∗ )(∆S1 + ∆S2 − h2 ) 2∆S1 + h2 )
+ (∆S1 + 2h2 )
+
6
6

Wsd + W2
∗
2 Wsd
+ (1 − ρ ) (∆S1 )
+ (∆S1 + h2 )
+
6
12
4ρ∗ c2gd µ2gd d2g Ws2 Hs1
λ
−
(1 + ) + 4cgd µgd dg Ws Hs1
(6.73)
W2 h2
h2
∗

Conceptual description

Equation (6.70) leads to:

p 2
Bg − 4Ag Cg
2Ag

drowned weir-flow

Figure 6.25: Drowned weir-flow

The water depth at the sill hs is described by a third order algebraic equation:

Dw h3s + Aw h2s + Bw hs + Cw = 0

4ρ∗ c2wd Ws2
λ
Dw =
(1 + )
(6.76)
W2 h2
h2

Wsd W2
Wsd W2
Aw = (1 + ρ∗ )
+
+ (1 − ρ∗ )
+
+
3
6
4
12
4ρ∗ c2wd Ws2 Hs1
λ
−
(1 + ) + 4cwd Ws
(6.77)
W2 h2
h2

Wsd W2
Wsd
Bw = (1 + ρ∗ ) (∆S1 + ∆S2 − h2 )
+
+ (2∆S1 + h2 )
+
3
6
6

W2
(∆S1 + 2h2 )W2
+
6

Wf d
Wf d + W2
∗
+ (1 − ρ ) ∆S1
+ (∆S1 + h2 )
+ 4Cwd Ws Hs1
(6.78)
3
6

Wsd
W2
∗
+ (∆S1 + 2h2 )
+
Cw = (1 + ρ )(∆S1 + ∆S2 − h2 ) (2∆S1 + h2 )
6
6

Wsd + W2
∗
2 Wsd
+ (1 − ρ ) (∆S1 )
+ (∆S1 + h2 )
(6.79)
6
12

A direct method is applied to calculate hs from equation Equation (6.75).

SOBEK, User Manual

Please note that:
The relative density ρ∗ is given by the expression:

relative density [−]
density of the water at the upstream side of the General structure [kg/m3 ]
density of the water at the downstream side of the General structure [kg/m3 ]

The extra resistance parameter λ relates to the friction force in the impulse balance, that
in case of drowned gate flow or drowned weir flow is solved for the water movement at the
downstream side of the General structure. The extra resistance parameter λ is given by the
expression:
(6.81)

Extra resistance parameter [m]
Length of the expansion zone at the downstream side of the General structure
[m]
Acceleration due to gravity [m/s2 ]
Chézy value, representing the friction-roughness at the downstream side of the
General structure [m1/2 /s]

Discharge equations

The following discharge equations are applied during the computations.

Free gate flow:

2g(H1 − (zs + µgf dg ))

q
Q = us Af = µgf cgf Ws dg 2g(H1 − (zs + µgf dg ))

(6.82)
(6.83)
(6.84)

Drowned gate flow:

us = µgd cgd
Af = Ws dg

2g(H1 − (zs + ds ))

p
Q = us Af = µgd cgd Ws dg 2g(H1 − (zs + ds ))

(6.85)
(6.86)
(6.87)
(6.88)

Free weir flow:
r
us = cwf

2
g(H1 − zs )
3

2
(H1 − zs )
3
r
2 2
Q = us Af = cwf Ws
g(H1 − zs )3/2
3 3

(6.89)
(6.90)
(6.91)

Conceptual description

Drowned weir flow:
p
us = cwd 2g(H1 − (zs + ds ))
Af = Ws ds
p
Q = us Af = cwd Ws ds 2g(H1 − (zs + ds ))

(6.92)
(6.93)
(6.94)

where:
contraction coefficient for free gate flow
contraction coefficient for drowned gate flow (µgd = µgf )
correction coefficient for free gate flow
correction coefficient for drowned gate flow
correction coefficient for free weir flow
correction coefficient for drowned weir flow

µgf
µgd
cgf
cgd
cwf
cwd

Note:
The contraction coefficient has a maximum value µ = 1.0. In case the user specifies a higher
value, a warning will be generated

Criteria for flow types

First it is assumed that it is weir flow. Then the water level at the sill ζs and the critical depth
hc = 32 (H1 − zs ) are calculated.
The criteria are:

ζs > hc and dg > ζs drowned weir flow
ζs < hc and dg > ζs free weir flow
otherwise gate flow.

In the latter case the water level at the sill ζs is recalculated using the gate flow conditions.
The critical depth hc is now defined as µgf dg .
The criteria are.

ζs > hc drowned gate flow
ζs < hc free gate flow
ζs imaginary free gate flow (i.e. downstream water level below crest level)
Note:
In case upstream water level is above gate lower edge level, there can still be drowned weir
flow if ζs > hc and dg > ζs or free weir flow if ζs < hc and dg > ζs .
6.1.16.7

Inverted siphon
An inverted siphon is one of the structure types, that can be included in the D-Flow 1D-module.
An inverted siphon is a structure that normally connects two open channels, that are separated by a particular infrastructural work (e.g. dike, railroad). The inverted siphon makes an
underground connection through such infrastructural work. An inverted siphon is assumed to
be fully filled with water at its deepest point. In case this does not yield for your stucture, you
can consider to use a culvert. The flow through an inverted siphon is affected by its upstream
and downstream invert level, the size and shape of its closed cross section, its ground layer
thickness, its entrance loss, friction loss, its valve loss, losses due to its bends (bend loss),
and its exit loss.

SOBEK, User Manual

Figure 6.26: Side view of an inverted siphon

Two flow conditions can occur:

1 Free flow when ζ2 < zc2 + dc2

p
2g(ζ1 − (zc2 + dc2 )

2 Submerged flow when ζ2 ≥ zc2 + dc2 :

Q
µ
Af is
Af crs

p
2g(ζ1 − ζ2 )

Af isgate
g
ζ1
ζ2
zc2
dc2

Discharge through inverted siphon [m3 /s]
Discharge coefficient, derived from loss-coefficients [−]
Discharge inverted siphon flow area (= min(Af crs , Af isgate )) [m2 ]
Cross-sectional area of the inverted siphon. At its deepest point the inverted
siphon is considered to be completely filled with water [m2 ]
Flow area under the inverted siphon gate [m2 ]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]
Downstream inverted siphon invert level [m]
Critical inverted siphon depth at the downstream side

q
3
2
2
dc2 = Q /(gT2 )

Surface width in the inverted siphon at its downstream side [m]

For numerical reasons the discharge coefficient (µ) is limited to a maximum of 1.0. The
discharge coefficient (µ) is computed as follows:

1
µ= p
ξi + ξf + ξv + ξb + ξo

Entrance loss coefficient [−]
Friction loss coefficient [−]
Valve loss coefficient [−]
Bend loss coefficient [−]
Exit loss coefficient [−]

ξi
ξf
ξv
ξb
ξo

The entrance loss coefficient (ξi ) can be defined as a constant value only.
The friction loss coefficient (ξf ) is computed as follows:

Conceptual description

Length of the inverted siphon [m]
Chézy coefficient for fuly water filled inverted siphon [m1/2 /s]
Hydraulic radius [m]
If GHO < MIISH; R = Rgate
If GHO ≥ MIISH; R= Rinverted siphon
GHO
Gate height opening [m]
MIISH
Maximum inner inverted siphon height [m]
Rinverted siphon Hydraulic radius based on a fully water filled inverted siphon [m]
Rgate
Hydraulic radius based on actual gate height opening [m]

The valve loss coefficient (ξv ) can be defined as a constant value or as a function of the ratio
of the “Gate height opening” and the “maximum inner inverted siphon height”.

In case the valve loss coefficient (ξv ) is not a constant, in computations the actual valve
loss coefficient (ξv ) is derived from the user defined table, while using the ratio of the
“actual gate height opening and the “actual maximum inner inverted siphon height”.

In case the ground layer thickness is greater than zero, both the “actual gate height open-

ing” and the “actual maximum inner inverted siphon height” will differ from the values as
defined in the user interface.
The exit loss coefficient (ξo ) is computed as follows:
Submerged flow (ζ2 = zc2 + dc2 ):

Af is
ξo = k 1 −
Af r2

Afisgate
Ainverted

User defined constant exit loss coefficient [−]
Flow area in the branch, adjacent to the downstream inverted siphon side [m2 ]
Inverted siphon flow area [m2 ]
If GHO ≤ MIISH; Af is = Afisgate
If GHO > MIISH; Af is = Ainverted siphon
Gate height opening [m]
Maximum inner inverted siphon height [m]
Flow area under the inverted siphon gate [m2 ]
2
siphon Flow area based on a fully water filled inverted siphon [m ]

Free flow (ζ2 < zc2 + dc2 ):

Inverted siphon cross-sections, bed friction and ground layer:
For an inverted siphon all available closed cross-section types can be used. In an inverted
siphon, a ground layer width constant thickness can be defined. Inverted siphon friction and
ground layer friction can be specified, using any of the available bed friction formulations.
Defining a ground layer thickness > 0 implies that in inverted siphon computations:

Defined invert levels are raised with the ground layer thickness,
Gate height openings are reduced with the ground layer thickness,
Maximum inner height of the inverted siphon is reduced with the ground layer thickness,

SOBEK, User Manual

Cross-sectional parameters (such as: flow areas, hydraulic radius and so on) are computed based on a cross-sectional profile, that is reduced by the ground layer thickness.
Inverted Siphon, Good modelling practice aspects
It is advised to avoid that the bed level of a cross-section in front of a Culvert, Inverted Siphon
or Siphon is above the ground-layer level (= invert level + ground-layer thickness), since such
situation can result in very small computational time-steps (e.g. long required wall-clock times)
or even in a termination of the simulation.

This is explained as follows. Consider the situation depicted in Figure 6.40 were the bed level
in front of a Culvert (Inverted Siphon or Siphon) is 0.60 m above the ground-layer level. This
means that at small upstream water depths, water will be sucked into the culvert (Inverted
Siphon or Siphon), resulting in large flow velocities. For the computational time-step (∆t)
yields that ∆t ≤ ∆x/U , where U is the local flow velocity and ∆x is distance between two
water level computational points (or ζ -points). At very low discharges even negative water
depths may be computed, leading to a termination of the simulation.

The situation explained above can be avoided by making the bed level in front of the Culvert
(Inverted Siphon or Siphon) equal to the ground-layer level. In other words by defining a
bed level slope from ζ -point ζ2 to ζ3 as depicted in Figure 6.40. Providing for the parameter
"Maximum Lowering of Cross-section Bed Level at Culvert" a value greater or equal to 0.60 m
means that before the computation starts, the bed level at ζ -point ζ3 is set equal to the groundlayer level. In Figure 5.15 it is shown how to provide a value for parameter "Maximum Lowering
of Cross-section Bed Level at Culvert".

Figure 6.27: Good modelling practice, Culvert, Inverted Siphon and Siphon

Conceptual description

Orifice
The geometrical shape of an orifice is given in Figure 6.28. Four different types of orifice flow
can be discerned, viz: free weir flow, submerged weir flow, free gate flow and submerged gate
flow. No discharge flows through the orifice if its gate is closed, if the upstream water level
equals the downstream water level or if both the upstream water level and the downstream
water level are below the crest level.

Reference level/Model datum

Figure 6.28: Orifice

The following four discharge equations are applied:
1 Free weir flow:

2
(ζ1 − zs )
3 r
2 2
Q = cw Ws
g (ζ1 − zs )3/2
3 3

(6.102)
(6.103)

2 Submerged weir flow:

us 2
Af = Ws ζ1 − zs −
2g

us 2 p
Q = ce cw Ws ζ1 − zs −
2g(ζ1 − ζ2 )
2g

(6.104)
(6.105)

3 Free gate flow:

q
Q = cw Ws µdg 2g(ζ1 − (zs + µ dg ))

(6.106)
(6.107)

4 Submerged gate flow:

Af = Ws µ dg
p
Q = cw Ws µ dg 2g(ζ1 − ζ2 )
Q
AF
µ
cw
ce
Ws
Deltares

(6.108)
(6.109)

Discharge across orifice [m3 /s]
Flow area [m2 ]
Contraction coefficient [−] Normally 0.63
Lateral contraction coefficient [−]
Discharge coefficient [−]
Crest width [m]

SOBEK, User Manual

dg
g
ζ1
ζ2
zs
us

Opening height [m] (gate lower edge level minus crest level)
Gravity acceleration [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]
Crest level [m]
Velocity over crest [m/s]

The different formulas are applied when the following conditions are met

Free weir flow:
3
ζ1 − zs < dg and ζ1 − zs > 3/2(ζ2 − zs )
2

Submerged weir flow:

Free gate flow:

3
ζ1 − zs ≥ dg and ζ2 ≤ zs + dg
2

3
3
ζ1 − zs < dg and ζ1 − zs ≤ (ζ2 − zs )
2
2

Submerged gate flow:

3
ζ1 − zs ≥ dg and ζ2 > zs + dg
2

Pump station and Internal Pump station

The functionality of a Pump station and an Internal Pump station is identical. The only difference comprises the fact that:

Pump station: A Pump station is located on an open channel branch. The pump discharge
is determined using the water levels at the nearest ζ -calculation points, respectively located at the upstream-side and downstream-side of the Pump station.

Internal Pump station: An Internal Pump station is accommodated in a pipe. The pump
discharge is determined using the water levels (or hydrostatic pressure heads) at the
upstream side of the pipe and at the downstream side of the pipe.
Here after, both the Pump station and the Internal Pump station are referred to as the Pump
station. Please note that:

When activated, water is always pumped from the suction-side towards the delivery-side,
A Pump station cannot be placed in a compound structure,
A Time Controller, Hydraulic controller, a PID controller or an Interval controller can overrule the pump capacity of a Pump station.

Pump station output parameters becomes available by checking the Pump Data check-box
on the 1DFLOW/Output options/Structures Tab in Settings.
Pump direction
Positive pump direction means that the pump discharge is flowing in the positive x-direction
along a branch (see Figure 6.29). Hence, water is pumped in downstream direction towards the pump-side with the highest x-coordinate.
Negative pump direction means that the pump discharge is flowing in the negative xdirection along a branch (see Figure 6.30). Hence, water is pumped in upstream direction
towards the pump-side with the lowest x-coordinate.

Conceptual description

Figure 6.29: Pump station with positive pump direction and two pump stages

Figure 6.30: Pump station with negative pump direction and two pump stages

SOBEK, User Manual

Six possible pump stages
A Pump station comprises of one (1) pump only, which can have up to six different pump
stages (1, 2, 3, 4, 5 or 6). Each pump stage can have a different pump capacity. At each
point-in-time, the pump can be in one (1) particular pump stage only.
The actual pump stage

The actual pump stage is determined using dead-band triggers, defined either at the suctionside only, at the delivery-side only or both at the suction-side and the delivery-side of the
pump. At the beginning of each time-step for all pump stages, the status [On/Off] of their
dead-band trigger at the suction-side (if defined) and their dead-band trigger at the deliveryside (if defined) are evaluated. This evaluation is done on basis of actual water levels and the
Switch-on and Switch-off levels, defined for the concerning pump stage. For more details, see
dead-band trigger algorithm. For more information on how to define Switch-on and Switch-off
levels at the suction-side and the delivery-side of the pump, see Conventions for switch-on and
switch-off levels. The actual pump stage, applied in the time-step from t = t to t = t + ∆t,
is the number of the highest pump stage (1, 2, 3, 4, 5 or 6) that is triggered at t = t, meaning
that all its dead-band triggers have the status [On]. If not any pump stage is triggered, the
pump becomes inactive (pump discharge is zero) and the actual pump stage is set to 0. If the
pump is overruled by a controller, the actual pump stage is set to -1.
Controllers

A Time-controller, a Hydraulic-controller, a PID controller or an Interval controller can be assigned to a pump station. A controller is only active in case the pump is triggered in accordance with the Switch-on and Switch-off levels, defined for stage 1. An active controller
overrules the pump capacity of the triggered pump stage, while the actual pump stage is set
to -1. Please note that capacity reduction factors are applied to the pump capacities set by a
controller. Advice: In using a controller at a pump station, define only one (1) pump stage and
take care that its dead-band trigger is always [On].
Capacity reduction table

A capacity reduction table can be defined, which is applied to all pump stages as well as
to pump capacities, that are set by a controller. In the capacity reduction table a capacity
reduction factor can be given as function of the pump head (e.g. water level at delivery-side
minus water level at suction-side). Pump heads (first column) in a capacity reduction table
should be in increasing order. Capacity reduction factors should be equal or larger than 0.
The pump discharge equals the pump capacity times the capacity reduction factor. If no
capacity reduction table is defined in effect a capacity reduction factor equal to 1 is applied.
Please note that the pump head at t = t is used to determine the capacity reduction factor to
be applied in the time-step from t = t to t = t + ∆t.

Conceptual description

Pump station output parameters
Pump station output parameters can be viewed in Result in Charts (Pump.his file) by checking
the Pump Data check-box on the 1DFLOW/Output options/Structures Tab in Settings. Available pump station output parameters as function of time are:

Suction-Side level: Water level at the suction-side of the pump.
Delivery-Side level: Water level at the delivery-side of the pump.
Pump Head: The water level at the delivery-side of the pump minus the water level at the
suction-side of the pump.

Actual Pump Stage: Equal to -1 if pump is overruled by a controller; equal to 0 if pump is

inactive; or equal to 1, 2, 3, 4, 5 or 6 depending on the actual pump stage that is triggered
(see Dead-band triggering algorithm).
Pump Capacity: The pump capacity is either defined by its controller; equal to zero if
pump is inactive; or equal to the pump capacity defined for the actual pump stage.
Reduction Factor: The reduction factor follows from the pump head and the capacity reduction table.
Pump Discharge: The pump discharge is equal to the pump capacity times the reduction
factor.
Dead-band triggering algoritm

A distinction is to be made between evaluating the status [On/Off] of dead-band triggers defined at the suction-side of the pump and dead-band triggers defined at the delivery-side of
the pump:

Dead-band triggering at the Suction-side of the pump

Parameters used in determining the status [On/Off] of a suction-side dead-band trigger are
hSuction (water level at the suction-side), hOn,Suction (switch-on-level) and hOf f,Suction (switchoff-level), where hOn,Suction > hOf f,Suction . Two booleans are used (e.g. SOn,Suction and
SOf f,Suction ):

If hSuction > hOn,Suction
If hSuction < hOf f,suction

⇒ SOn,Suction = T rue; Else SOn,Suction = F alse
⇒ SOf f,Suction = T rue; Else SOf f,Suction = F alse

If at the start of a computation yields that hOf f,Suction ≤ hSuction ≤ hOn,Suction the deadband trigger is set [On]. During a computation the dead-band trigger is set [On] or [Off]
according to the following rules:

If (SOn,Suction = T rue and SOf f,Suction = F alse)
If (SOn,Suction = F alse and SOf f,Suction = T rue)
If (SOn,Suction = F alse and SOf f,Suction = F alse)

⇒ T rigger = [On]
⇒ T rigger = [Of f ]
⇒ T rigger obtains the

status determined in the previous computational time step.

SOBEK, User Manual

Dead-band triggering at the Delivery-side of the pump
Parameters used in determining the status [On/Off] of a delivery-side dead-band trigger are
hDelivery (water level at the delivery-side), hOn,Delivery (switch-on-level), hOf f,Delivery (switchoff-level), where hOf f,Delivery > hOn,Delivery . Two booleans are used (e.g. SOn,Delivery and
SOf f,delivery ):

If hDelivery < hOn,Delivery ⇒ SOn,Delivery = T rue; Else SOn,Delivery = F alse
If hDelivery > hOf f,Delivery ⇒ SOf f,Delivery = T rue; Else SOf f,Delivery =
F alse
If at the start of a computation yields that hOn,Delivery ≤ hDelivery ≤ hOf f,Delivery the
dead-band trigger is set [On]. During a computation the dead-band trigger is set [On] or [Off]
according to the following rules:

T rigger = [On]
T rigger = [Of f ]
T rigger obtains the

If (SOn,Delivery = T rue and SOf f,Delivery = F alse)
If (SOn,Delivery = F alse and SOf f,Delivery = T rue)
If (SOn,Delivery = F alse and SOf f,Delivery = F alse)

status determined in the previous computational time step
Conventions for switch-on and switch-off levels

A distinction is to be made between switch-on-levels and switch-off-levels, defined at the
suction-side and defined at the delivery-side of the pump (see Table 6.1).

Suction-side: The switch-on level should increase with increasing stage number. For each
stage, its switch-off-level should be lower than its switch-on-level. The switch-off-level
should increase with increasing stage number.
Delivery-side: The switch-on-level should decrease with increasing stage number. For
each stage, its switch-off-level should be higher than its switch-on-level. The switch-offlevel should decrease with increasing stage number.
Table 6.1: Example of switch-on-levels and switch-off-levels at the suction-side and the
delivery-side of a pump station

Switchoff-level

Switchoff-level

0.1
0.2
0.3
0.4
0.5
0.6

0.80
0.90
1.00
1.10
1.20
1.30

0.10
0.20
0.30
0.40
0.50
0.60

0.80
0.70
0.60
0.50
0.40
0.30

1.90
1.80
1.70
1.60
1.50
1.40

Conceptual description

External Pump station
An External Pump station is to located at the end of an open channel branch or at the end of
a (closed) pipe. The end of an open channel branch can either have the highest x-coordinate
or an x-coordinate equal to zero. The same applies for a pipe. The pump discharge is either
determined using the boundary water level and the water level at the branch-side of the pump
or determined using the boundary water level and the water level (or hydrostatic pressure
head) at the pipe-side of the pump. Please note that:

When activated, water is always pumped from the suction-side towards the delivery-side.
Water can be stored at an External Pump station, for more information see Storage options
at an External Pump station.

The ”External Pump station” cannot be placed in a compound structure,
A Time Controller, Hydraulic controller, a PID controller or an Interval controller can overrule the pump capacity of an External Pump station.

External Pump station output parameters becomes available by checking the Pump Data
check-box on the 1DFLOW/Output options/Structures Tab in Settings.

External Pump direction:
Pump direction IN means that (see Figure 6.31):

Water is pumped into the model or flows towards the branch/pipe-side (or upstreamside) of the pump,
The pump discharge has a negative sign, this is irrespective of the x-direction along
the branch (or pipe).

Pump direction OUT means that (see Figure 6.32):

Water is pumped out off the model or flows towards the boundary-side (or downstreamside) of the pump ,
The pump discharge has a postive sign, this is irrespective of the x-direction along the
branch (or pipe).

SOBEK, User Manual

Figure 6.31: External pump station with pump direction IN and two pump stages

Figure 6.32: External pump station with pump direction OUT and two pump stages

Conceptual description

Six possible External Pump stages
An External Pump station comprises of one (1) pump only, which can have up to six different
pump stages (1, 2, 3, 4, 5 or 6). Each pump stage can have a different pump capacity. At
each point-in-time, the pump can be in one (1) particular pump stage only.
The actual pump stage

The actual pump stage is determined using dead-band triggers, defined either at the suctionside only, at the delivery-side only or both at the suction-side and the delivery-side of the
pump. At the beginning of each time-step for all pump stages, the status [On/Off] of their
dead-band trigger at the suction-side (if defined) and their dead-band trigger at the deliveryside (if defined) are evaluated. This evaluation is done on basis of actual water levels and the
Switch-on and Switch-off levels, defined for the concerning pump stage. For more details, see
dead-band trigger algorithm. For more information on how to define Switch-on and Switch-off
levels at the suction-side and the delivery-side of the External Pump station, see Conventions
for switch-on and switch-off levels. The actual pump stage, applied in the time-step from t=t
to t=t+dt, is the number of the highest pump stage (1, 2, 3, 4, 5 or 6) that is triggered at
t=t, meaning that all its dead-band triggers have the status [On]. If not any pump stage is
triggered, the pump becomes inactive (pump discharge is zero) and the actual pump stage is
set to 0. If the pump is overruled by a controller, the actual pump stage is set to -1.
Controllers

A Time-controller, a Hydraulic-controller, a PID controller or an Interval controller can be assigned to an External Pump station. A controller is only active in case the pump is triggered in
accordance with the Switch-on and Switch-off levels, defined for stage 1. An active controller
overrules the pump capacity of the triggered pump stage, while the actual pump stage is set
to -1. Please note that capacity reduction factors are applied to the pump capacities set by a
controller. Advice: In using a controller at an External Pump station, define only one (1) pump
stage and take care that its dead-band trigger is always [On].
Capacity reduction table

A capacity reduction table can be defined, which is applied to all pump stages as well as
to pump capacities, that are set by a controller. In the capacity reduction table a capacity
reduction factor can be given as function of the pump head (e.g. water level at delivery-side
minus water level at suction-side). Pump heads (first column) in a capacity reduction table
should be in increasing order. Capacity reduction factors should be equal or larger than 0.
The pump discharge equals the pump capacity times the capacity reduction factor. If no
capacity reduction table is defined in effect a capacity reduction factor equal to 1 is applied.
Please note that the pump head at t = t is used to determine the capacity reduction factor to
be applied in the time-step from t = t to t = t + ∆t.

SOBEK, User Manual

External Pump station output parameters
External Pump station output parameters can be viewed in Result in Charts (Pump.his file)
by checking the Pump Data check-box on the 1DFLOW/Output options/Structures Tab in Settings. Available External pump station output parameters as function of time are:

Suction-Side level: Water level at the suction-side of the pump.
Delivery-Side level: Water level at the delivery-side of the pump.
Pump Head: The water level at the delivery-side of the pump minus the water level at the
suction-side of the pump.

Actual Pump Stage: Equal to -1 if pump is overruled by a controller; equal to 0 if pump is

inactive; or equal to 1, 2, 3, 4, 5 or 6 depending on the actual pump stage that is triggered
(see Dead-band triggering algorithm).
Pump Capacity: The pump capacity is either defined by its controller; equal to zero if
pump is inactive; or equal to the pump capacity defined for the actual pump stage.
Reduction Factor: The reduction factor follows from the pump head and the capacity reduction table.
Pump Discharge: The pump discharge is equal to the pump capacity times the reduction
factor.
Dead-band triggering algoritm

A distinction is to be made between evaluating the status [On/Off] of dead-band triggers defined at the suction-side of the External Pump station and dead-band triggers defined at the
delivery-side of the External Pump station:
Dead-band triggering at the Suction-side of the External Pump station:

Parameters used in determining the status [On/Off] of a suction-side dead-band trigger are
hSuction (water level at the suction-side), hOn,Suction (switch-on-level) and hOf f,Suction (switchoff-level), where hOn,Suction > hOf f,Suction . Two booleans are used (e.g. SOn,Suction and
SOf f,Suction ):

If hSuction > hOn,Suction
If hSuction < hOf f,suction

⇒ SOn,Suction = T rue; Else SOn,Suction = F alse
⇒ SOf f,Suction = T rue; Else SOf f,Suction = F alse

If at the start of a computation yields that hOf f,Suction ≤ hSuction ≤ hOn,Suction the deadband trigger is set [On]. During a computation the dead-band trigger is set [On] or [Off]
according to the following rules:

If (SOn,Suction = T rue and SOf f,Suction = F alse)
If (SOn,Suction = F alse and SOf f,Suction = T rue)
If (SOn,Suction = F alse and SOf f,Suction = F alse)

⇒ T rigger = [On]
⇒ T rigger = [Of f ]
⇒ T rigger obtains the

status determined in the previous computational time step.

Dead-band triggering at the Delivery-side of the External Pump station:
Parameters used in determining the status [On/Off] of a delivery-side dead-band trigger are
hDelivery (water level at the delivery-side), hOn,Delivery (switch-on-level), hOf f,Delivery (switchoff-level), where hOf f,Delivery > hOn,Delivery . Two booleans are used (e.g. SOn,Delivery and
SOf f,delivery ):

Conceptual description

If hDelivery < hOn,Delivery ⇒ SOn,Delivery = T rue; Else SOn,Delivery = F alse
If hDelivery > hOf f,Delivery ⇒ SOf f,Delivery = T rue; Else SOf f,Delivery =
F alse
If at the start of a computation yields that hOn,Delivery ≤ hDelivery ≤ hOf f,Delivery the
dead-band trigger is set [On]. During a computation the dead-band trigger is set [On] or [Off]
according to the following rules:

If (SOn,Delivery = T rue and SOf f,Delivery = F alse)
If (SOn,Delivery = F alse and SOf f,Delivery = T rue)
If (SOn,Delivery = F alse and SOf f,Delivery = F alse)

T rigger = [On]
T rigger = [Of f ]
T rigger obtains the

status determined in the previous computational time step

Conventions for switch-on and switch-off levels
A distinction is to be made between switch-on-levels and switch-off-levels, defined at the
suction-side and defined at the delivery-side of the External Pump station (see Table 6.2).

Suction-side: The switch-on level should increase with increasing stage number. For each

stage, its switch-off-level should be lower than its switch-on-level. The switch-off-level
should increase with increasing stage number.
Delivery-side: The switch-on-level should decrease with increasing stage number. For
each stage, its switch-off-level should be higher than its switch-on-level. The switch-offlevel should decrease with increasing stage number.
Table 6.2: Example of switch-on-levels and switch-off-levels at the suction-side and the
delivery-side of an external pump station

Switchoff-level

Switchoff-level

1.1
2.2
3.3
4.4
5.5
6.6

1.80
1.90
2.00
2.10
2.20
2.30

1.10
1.20
1.30
1.40
1.50
1.60

2.80
2.70
2.60
2.50
2.40
2.30

3.90
3.80
3.70
3.60
3.50
3.40

SOBEK, User Manual

Storage options at an External Pump station
Water can be stored at the site, accommodating an external pump station. In SOBEK a
distinction is made between water stored below and above a certain design level, hereafter
referred to as street level.

Below street level: At water levels below street level, water is considered to be stored in a
so-called bottom-storage-reservoir.

Water is stored in a street-level-reservoir, having a bed level equal to street level and
walls that cannot be overtopped;
Water cannot be stored (e.g. closed pump station), hence water levels inside the pump
station may become pressurized; and
Water leaves the external pump station (e.g. loss of water) by flowing towards low lying
areas, while the water level inside the pump station is considered to remain at street
level.

Above street level: For water levels above street level, there are three options:

The River Pump is to be located on an open channel branch. Please note that:

When activated, water is always pumped from the suction-side towards the delivery-side.
The River – Pump can be placed in a compound structure.
Controllers cannot be assigned to a River - Pump,
Flow - ζ -calculation points are default located 0.5 m in front and 0.5 m behind a River Pump.
River pump output parameters becomes available by checking the Pump Data check-box
on the 1DFLOW/Output options/Structures Tab in Settings.
Control direction determines location of trigger-water level (htrig ) of a River pump:
The control direction of the River pump defines the location of the so-called trigger-water level
(htrig ):

Upward control direction means that the trigger water level (htrig ) is located upward, e.g.
at the pump-side with the lowest x-coordinate along the branch.
Downward control direction means that the trigger water level (htrig ) is located downward,
e.g. at the pump-side with the highest x-coordinate along the branch.
Start-level and stop-level determine location of the suction-side and the delivery-side:
The elevation of the start-level (hstart ) and the elevation of the stop-level (hstop ) define the
location of the suction-side and the delivery-side of a river pump as follows:

If start-level is above stop-level: water is pumped away from the trigger-water level side of
the pump (e.g. trigger-water level side coincides with the suction-side of the pump).

If stop-level is above start-level: water is pumped towards the trigger-water level side of
the pump (e.g. trigger-water level side coincides with the delivery-side of the pump).

Conceptual description

Discharge direction of a River pump:
The discharge direction of a river pump with respect to the positive x-direction along the
branch is defined by the control direction and the elevations of the start-level and the stoplevel. Four different situations can be discerned:
Upward control and start-level above stop-level (see Figure 6.33),
Upward control and stop-level above start-level (see Figure 6.34),
Downward control and start-level above stop-level (see Figure 6.35),
Downward control and stop-level below start-level (see Figure 6.36),

Figure 6.33: River pump with Upward control and start-level above stop-level

SOBEK, User Manual

Figure 6.34: River pump with Upward control and stop-level above start-level

Figure 6.35: River pump with Downward control and start-level above stop-level

Conceptual description

Figure 6.36: River pump with Downward control and stop-level above start-level

River pump stages

A River pump has only one pump stage, hence only one pump capacity can be defined.
Constant Reduction Factor or Reduction Factor F(Pump Head)
Constant Reduction Factor: WARNING: This means that irrespective of the pump head,
the actual pump capacity always equals the defined pump capacity times the constant
reduction factor. Say you defined a pump capacity of 100 m3 /s and constant reduction
factor of 0.7. This means that the pump will have a capacity of 70 (=0.7*100) m3 /s for
both positive and negative pump heads.
Reduction Factor F(Pump Head): With this option you define a capacity reduction factor
as function of the pump head (e.g. water level at the delivery-side minus the water level
at the suction-side). The capacity reduction factor may vary between 0 and 1. The first
row in the F (PumpHead ) table should read 0,1 (pump head, capacity reduction factor).
For positive pump-heads, the pump discharge equals the pump capacity times the capacity reduction factor. For negative pump-heads a capacity reduction factor equal to 1
is applied. Please note that the pump head at t = tn is used to determine the capacity
reduction factor to be applied in the time-step from t = tn to t = tn + ∆t.

SOBEK, User Manual

River pump output parameters
River pump output parameters can be viewed in Result in Charts ( file) by checking the Pump Data check-box on the 1DFLOW/Output options/Structures Tab in Settings.
Available River pump output parameters as function of time are:

Suction-Side level: Water level at the suction-side of the pump.
Delivery-Side level: Water level at the delivery-side of the pump.
Pump Head: The water level at the delivery-side of the pump minus the water level at the
suction-side of the pump.

Actual Pump Stage: Equal to 0 if pump is inactive; or equal to 1 if the pump is triggered
(Please note that a river pump has one pump stage only).

Pump Capacity: The pump capacity is either equal to zero if pump is inactive; or equal to
its defined pump capacity.

Reduction Factor: The reduction factor is either a constant or follows from the F(Pump

Pump Discharge: The pump discharge is equal to the pump capacity times the reduction
factor.

Dead-band triggering algorithm

A dead-band trigger [On/Off] determines if the River Pump should pump (e.g. actual pump
stage = 1) or not pump (e.g. pump discharge is zero; actual pump stage = 0). The actual status
[On/Off] of the dead-band trigger is determined as follows. Firstly, the value of two Booleans
(Son and Sof f ) is determined. In case of triggering at the suction-side of the pump, or in
other words if the start-level (hStart ) is above the stop-level (hStop ) yields (see Figure 6.33
and Figure 6.35):

If htrig > hStart
If htrig < hStop

⇒ Son = T rue;
⇒ Sof f = T rue;

Son = F alse
Sof f = F alse

In case of triggering at the delivery-side of the pump, or in other words if the stop-level (hStop)
is above the start-level (hStart) yields (see Figure 6.34 and Figure 6.36):

If htrig < hStart
If htrig > hStop

⇒ Son = T rue;
⇒ Sof f = T rue;

Son = F alse
Sof f = F alse

If at the start of a computation yields that hstop ≤ htrig ≤ hof f , the dead-band trigger is set
[On]. During a computation the dead-band trigger is set [On] or [Off] according to the following
algorithm

If (Son = T rue and Sof f = F alse) ⇒
If (Son = F alse and Sof f = T rue) ⇒
If (Son = F alse and Sof f = F alse) ⇒

T rigger = [On]
T rigger = [Of f ]
T rigger obtains the status determined

in the previous computational time step
Comparing a River Pump and a Pump station:

From a pump direction point of view the Pump station covers the options available at a
River Pump (see Table 6.3).

Advantage of the River Pump over a Pump station is the fact that it can be placed in a
compound structure

Limitations of the River Pump with respect to the Pump station:
No controllers can be assigned,
Only one (1) pump stage can be defined,

Conceptual description

Only one (1) dead-band trigger can be defined at a River Pump, hence it is not possible
to operate the pump on basis of water levels at both its suction-side and its deliveryside.
Table 6.3: Flow-Pump station covers the options of a River pump with respect to the pump
direction

River pump
Start-level (hstart )
Stop-level (hstop )

Upward
Upward
Downward
Downward

hstart > hstop
hstop > hstart
hstart > hstop
hstop > hstart

Positive
Negative
Negative
Positive

Suction-side
Delivery-side
Suction-side
Delivery-side

Control
Direction

Please note that discharges are computed on basis of upstream and downstream energy
levels. Further on please note that default a computational point is located 0.5 m in front
and 0.5 m behind a River weir. A structure inertia damping factor can be defined for each
individual River weir.
Two types of flow conditions can occur in the case of weir flow. These are free (modular) flow
and drowned (submerged) flow. If high tail water conditions do affect the flow, the weir is said
to be drowned. These conditions may then be computed by applying a reduction factor to the
modular function, i.e. to the equation applied if the weir or flume is not drowned (Ackers et al.,
1978; Schmidt, 1955; Bos, 1989).

Figure 6.37: Free and drowned weir flow

The discharge through the weir is computed with:

2
Q = cw f Ws
3

2
g (H1 − zs )3/2
3

cw
Ws
H1
Deltares

correction coefficient
width across flow section
upstream energy level

SOBEK, User Manual

drowned flow reduction factor
crest or sill level of weir

The submergence factor of the weir is defined as:

H2 − zs
H1 − zs

submergence factor
downstream energy level

For a weir the user must specify:

level of crest or crest height
crest width across flow section
crest shape (broad, triangular, round, or sharp)

If the actual submergence factor exceeds the submergence limit, drowned flow occurs. In all
other cases modular flow occurs and a drowned flow reduction factor equal to 1.0 should be
applied. The submergence limit depends on the crest shape (see Table 6.4).

Depending on the crest shape the following parameters are used (Table 6.4), which can be
adjusted by the user:

correction coefficient (default see Table 6.4)
submergence limit (default see Table 6.4)
drowned flow reduction curve (default see Table 6.4)

Table 6.4: Crest shape and coefficients for simple weir structure (default values)

Correction coef.

Submergence limit

Reduction curve
(Figure 6.38)

broad
triangular
round
sharp

1.0
1.05
1.1
1.2

0.82
0.67
0.3
0.01

If only one flow direction has been specified, the coefficients for that flow direction are
used as default coefficients for the other flow direction.

The default drowned flow reduction curve depends on the submergence limit.
The drowned flow reduction curve is stored in tabulated format.

Conceptual description

Figure 6.38: Drowned flow reduction curves

A siphon (see Figure 6.39) can only transport water from its upstream defined side to its
downstream defined side. Hence, only positive flow is possible.
A switch-on-level and a switch-off-level at its downstream side determine if the siphon may or
may not discharge water. If the downstream water level drops below the switch-on-level, the
siphon start discharging water. If the downstream water level rises above the switch-off-level,
the siphon stops discharging water. If the downstream water level is in between the switch-onlevel and the switch-off-level (e.g. in between its dead-band), the siphon remains in its present
state of operation. In case the downstream water level is in its dead-band at the onstart of a
computation, the siphon will start discharging water.
Discharge can only flow through a siphon if its upstream cross-sectional area is fully filled with
water, meaning that the upstream water level is above the obvert level (invert level + inner
cross-sectional height) of the siphon. If the upstream cross-sectional area is not fully filled
with water, air will be contained in het upper part of the siphon, this air will prevent the siphon
from discharging water.

zc1
zc2
Figure 6.39: Siphon

Two flow conditions can occur:

SOBEK, User Manual

Free flow when ζ2 < zc2 + dc2

p
2g(ζ1 − (zc2 + dc2 )

Submerged flow when ζ2 ≥ zc2 + dc2 :

Discharge through siphon [m3 /s]
Discharge coefficient, derived from loss-coefficients [−]
Discharge siphon flow area (= min(Afcrs , Afsgate )) [m2 ]
Cross-sectional area of the siphon. At its highest point the siphon is considered
to be completely filled with water [m2 ]
Flow area under the siphon gate [m2 ]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]
Downstream siphon invert level [m]
Critical siphon depth at the downstream side

Afsgate
g
ζ1
ζ2
zc2
dc2

p
2g(ζ1 − ζ2 )

q
(= 3 Q2 /(gT22 ))

Surface width in the siphon at its downstream side [m]

For numerical reasons the discharge coefficient (µ) is limited to a maximum of 1.0. The
discharge coefficient (µ) is computed as follows:

1
µ= p
ξi + ξf + ξv + ξb + ξo

Entrance loss coefficient [−]
Friction loss coefficient [−]
Valve loss coefficient [−]
Bend loss coefficient [−]
Exit loss coefficient [−]

ξi
ξf
ξv
ξb
ξo

The entrance loss coefficient (ξi ) can be defined as a constant value only.
The friction loss coefficient (ξf ) is computed as follows:

ξf =
L
C
R
GHO
MIISH

Length of the siphon [m]
Chézy coefficient for fuly water filled siphon [m1/2 /s]
Hydraulic radius [m]
If GHO < MIISH; R = Rgate
If GHO ≥ MIISH; R= Rsiphon
Gate height opening [m]
Maximum inner inverted siphon height [m]
Hydraulic radius based on a fully water filled siphon [m]
Hydraulic radius based on actual gate height opening [m]

Conceptual description

The valve loss coefficient (ξv ) can be defined as a constant value or as a function of the ratio
of the “Gate height opening” and the “maximum inner siphon height”.
Note:

In case the valve loss coefficient (ξv ) is not a constant, in computations the actual valve
loss coefficient (ξv ) is derived from the user defined table, while using the ratio of the
“actual gate height opening and the “actual maximum inner siphon height”.

In case the ground layer thickness is greater than zero, both the “actual gate height open-

The exit loss coefficient (ξo ) is computed as follows:
Submerged flow (ζ2 = zc2 + dc2 ):

Af s
ξo = k 1 −
Af r2

ing” and the “actual maximum inner siphon height” will differ from the values as defined
in the user interface (see the paragraph "Siphon cross-sections, bed friction and ground
layer" below)

Afsgate
Asiphon

User defined constant exit loss coefficient [−]
Flow area in the branch, adjacent to the downstream siphon side [m2 ]
Siphon flow area [m2 ]
If GHO ≤ MISH; Af s = Afsgate
If GHO > MISH; Af s = Asiphon
Gate height opening [m]
Maximum inner siphon height [m]
Flow area under the siphon gate [m2 ]
Flow area based on a fully water filled siphon [m2 ]

Free flow (ζ2 < zc2 + dc2 ):

Siphon cross-sections, bed friction and ground layer:

For a siphon all available closed cross-section types can be used. In a siphon, a ground
layer with constant thickness can be defined. Siphon friction and ground layer friction can be
specified, using any of the available bed friction formulations.
Defining a ground layer thickness > 0 implies that in siphon computations:

Defined invert levels are raised with the ground layer thickness,
Gate height openings are reduced with the ground layer thickness,
Maximum inner height of the siphon is reduced with the ground layer thickness,
Cross-sectional parameters (such as: flow areas, hydraulic radius and so on) are computed based on a cross-sectional profile, that is reduced by the ground layer thickness.

Siphon, Good modelling practice aspects
It is advised to avoid that the bed level of a cross-section in front of a Culvert, Inverted Siphon
or Siphon is above the ground-layer level (= invert level + ground-layer thickness), since such

SOBEK, User Manual

situation can result in very small computational time-steps (e.g. long required wall-clock times)
or even in a termination of the simulation.
This is explained as follows. Consider the situation depicted in Figure 6.40 were the bed level
in front of a Culvert (Inverted Siphon or Siphon) is 0.60 m above the ground-layer level. This
means that at small upstream water depths, water will be sucked into the culvert (Inverted
Siphon or Siphon), resulting in large flow velocities. For the computational time-step (∆t)
yields that ∆t ≤ ∆x/U , where U is the local flow velocity and ∆x is distance between two
water level computational points (or ζ -points). At very low discharges even negative water
depths may be computed, leading to a termination of the simulation.

The situation explained above can be avoided by making the bed level in front of the Culvert
(Inverted Siphon or Siphon) equal to the ground-layer level. In other words by defining a
bed level slope from ζ -point ζ2 to ζ3 as depicted in Figure 6.40. Providing for the parameter
"Maximum Lowering of Cross-section Bed Level at Culvert" a value greater or equal to 0.60 m
means that before the computation starts, the bed level at ζ -point ζ3 is set equal to the groundlayer level. In Figure 5.15 it is shown how to provide a value for parameter "Maximum Lowering
of Cross-section Bed Level at Culvert".

Figure 6.40: Good modelling practice, Culvert, Inverted Siphon and Siphon

Crest levels of a universal weir (see Figure 6.41) can be defined as a Y-Z profile. The crest
level profile of a universal weir is divided into rectangular weir sections having a horizontal
bed and triangular weir sections having a sloping bed. It is assumed that the discharge
over an universal weir is the summation of the discharges over each individual weir section.
Rectangular weir sections are considered as a broad-crested weir. Triangular weir sections
are considered as (the half of) a broad-crested weir with truncated triangular control section
(Bos, 1989).

Conceptual description

Parameters depicted in Figure 6.41 are:

Flow area of section i [m2 ]
Width of weir section i [m]
Elevation at the left side of weir section i [mAD ]
Elevation at the right side of weir section i [mAD ]
Crest level of the Universal weir (output parameter only), equal to the lowest
elevation of its crest level profile [mAD ]
Water level [mAD ]

Ai
Wi
zi,lef t
zi,right
zCrest

Figure 6.41: Crest level (Y-Z) profile of a Universal weir, divided into three rectangular
weir sections (2, 4 and 6) and four triangular weir sections (1, 3, 5 and 7)

Following equations yield for a universal weir:

N
N
X
X
(ui Ai ) =
Qi
i
N
X

Ustructure = Q/A

A
Ai
N
Q
Qi
ui
Ustructure

Flow area of the universal weir [m2 ]
Flow area of weir section i [m2 ]
Number of weir sections i [−]
Discharge over the universal weir [m3 /s]
Discharge over weir section i [m3 /s]
Flow velocity in weir section i [m/s]
Average flow velocity over the universal weir [m/s]

Following equations yield for a rectangular weir section i:

zi,crest = min(zi,lef t , zi,right )

SOBEK, User Manual

mlrectangular ,i = 2/3

i,crest
≤ mlrectangular ,i
Free rectangular weir flow if ζ12 −zi,crest
r
2 p
u i = ce
g ζ1 − zi,crest
3
2
Ai = Wi (ζ1 − zi,crest )
3
r
2 2
Qi = ui Ai = ce
g Wi (ζ1 − zi,crest )3/2
3 3

ζ2 −zi,crest
Submerged rectangular weir flow if ζ1 −zi,crest > mlrectangular ,i
p
ui = ce 2g(ζ1 − ζ2 )
Ai = Wi (ζ2 − zi,crest )
p
Qi = ui Ai = ce Wi (ζ2 − zi,crest ) 2g(ζ1 − ζ2 )

(6.128)
(6.129)

(6.131)
(6.132)
(6.133)

Following equations yield for a triangular weir section i:

zi,crest = min(zi,lef t , zi,right )

dzi = |zi,lef t − zi,right |

mltriangular ,i =

if (ζ1 − zi,crest )) ≤ 1.25 dzi

dzi
1
6 (ζ1 −zi,crest )

if (ζ1 − zi,crest )) > 1.25 dzi

ζ −z
≤ mltriangular ,i
Free triangular weir flow if ζ21 −zi,crest
i,crest
q
ui = ce 2g(1 − mltriangular ,i )(ζ1 − zi,crest )

(mltriangular ,i (ζ1 −zi,crest ))2

if
W

i
2 dzi


ζ1 −zi,crest
1/mltriangular ,i

ζ1 −zi,crest
1/mltriangular ,i

ζ1 −zi,crest
1/mltriangular ,i

Submerged triangular weir flow if
p
ui = ce 2g(ζ1 − ζ2 )

ζ2 −zi,crest
ζ1 −zi,crest

Wi (ζ2 − zi,crest −

≤ dzi
(6.138)

> mltriangular ,i
(6.140)


(ζ2 −zi,crest )2

W
 i
2 dzi



if ζ2 − zi,crest ≤ dzi
(6.141)
dzi
)
2

ζ2 − zi,crest > dzi
(6.142)

Conceptual description

where:
Flow area of weir section i [m2 ]
Discharge coefficient, applicable to all rectangular weir sections as well as to all
triangular weir sections of a universal weir [−]
dzi
Vertical distance between the elevation at the left side and the right side of a
triangular weir section i [m]
g
Acceleration due to gravity [m/s2 ] (≈ 9.814)
mlrectangular ,i Water-level-based modular limit of a rectangular weir section i. Its value is
always equal to 2/3 [−]
mltriangular ,i Water-level-based modular limit of a triangular weir section i. Its value depends on the actual water depth. [−]
Qi
Discharge over weir section i [m3 /s]
ui
Velocity in weir section i [m/s]
Wi
Width of weir section i [m]
zi,crest
Crest level of weir section i [mAD ]
zi,lef t
Elevation at the left side of weir section i [mAD ]
zi,right
Elevation at the right side of weir section i [mAD ]
ζ1
Water level at the upstream side of the universal weir [mAD ]
ζ2
Water level at the downstream side of the universal weir [mAD ]
6.1.16.15

Vertical obstacle friction

The vertical obstacle friction terms have been introduced to account for the added resistance
that is caused by vertical obstacles, like houses or trees. The vertical obstacle friction coefficient is based on the number of obstacles, their diameter and drag coefficient. This spatial
coefficient can be prescribed in a ARC-INFO grid file, like the bathymetry.
The vertical obstacle friction coefficient a is specified as the summation of the product of
obstacle width and drag coefficient over the number of obstacles per unit area.
N

1X
Di Cdi
a=
A i=1

Vertical obstacle friction coefficient [1/m]
Number of obstacles in unit area [−]
Unit area [m2 ]
Diameter of obstacle i [m]
Drag coefficient of obstacle i [−]

For round pillars, Cd is usually 1.0. In this formulation it is assumed that the obstacle height
will always be larger than the waterdepth. In case the obstacles do become submerged, a
more advanced option is the Depth-Dependent Vegetation Roughness.

SOBEK, User Manual

Weir
Three types of flow conditions can occur in the case of weir flow. These are free (modular)
flow, submerged flow and no flow (water levels below crest level). If high tail water conditions
do affect the flow, the weir is said to be submerged.
Energy level

Figure 6.42: Weir

Reference level/Model datum

The discharge and wetted area through the weir is computed with the following formulas:

Free weir flow:

2 p
g ζ1 − zs
3
2
Af = cw Ws (ζ1 − zs )
3
r
2 2
Q = us Af = ce cw Ws
g(ζ1 − zs )3/2
3 3
us = ce

(6.144)
(6.145)
(6.146)

Submerged weir flow:

p
us = ce 2g(ζ1 − ζ2 )
Af = cw Ws (ζ2 − zs )

p
Q = us Af = ce cw Ws 2g(ζ1 − ζ2 )(ζ2 − zs )
Q
Af
ce
cw
Ws
g
ζ1
ζ2
zs
us

(6.147)
(6.148)
(6.149)

Discharge across weir [m3 /s]
Wetted area [m2 ]
Discharge coefficient [−]
Lateral contraction coefficient [−]
Crest width [m]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Upstream water level [m]
Downstream water level [m]
Crest level [m]
Velocity over crest [m/s]

The different formulas are applied when the following conditions occur
Free weir flow:

3
ζ1 − zs > (ζ2 − zs )
2

Conceptual description

Submerged weir flow:

3
ζ1 − zs ≤ (ζ2 − zs )
2

Note:
Broad weirs can cause oscillations, because the discharge calculated with the broad crest
move a lot of water at a time step. This large discharge can lower the upstream water level
significantly resulting in a discharge with a reverse flow direction at the next time step. The
following (rather conservative) rule-of-thumb can be used to avoid oscillations:

Staggered grid; ζ - and u-calculation points at different locations

A SOBEK-Flow-model consists of a network of branches connected to each other at connection nodes. The SOBEK-Flow-model uses a staggered grid. On a staggered grid the water
level points (e.g. ζ -calculation points) and velocity points (e.g. u-calculation points) are at
different locations (see Figure 6.43). Water levels are computed at the ζ -calculation points,
while velocities are computed half way between the ζ -calculation points, on the so called ucalculation points. Please note that Connection Nodes and Boundary Nodes are ζ -calculation
points.

Storage area upstream of the structure [m2 ]
Crest width [m]

In each branch a number of ζ -calculation points can be defined. These ζ -calculation points
represent the spatial numerical grid used in the simulation. The momentum equation is solved
between ζ -calculation points, while the continuity equation is solved between the u-calculation
points.
The location of each ζ -calculation point should be selected on various criteria:

the distance between two neighbouring ζ -calculation points should not be too large (for
accuracy and proper representation of the physical processes)
the distance between two neighbouring ζ -calculation points should not be too small because of increasing simulation time. The default minimum distance SOBEK uses during a
simulation is 1 meter.
the location of the ζ -calculation points may be non-equidistant.

SOBEK, User Manual

u-calculation points

ζ -calculation points

Figure 6.43: Staggered grid, ζ - and u-calculation points at different locations

Construction of the numerical bathymetry on basis of user-defined cross-sections

Cross-sections (e.g. bathymetrical data) may be defined at arbitrary locations in a model,
provided that for each branch at least one cross-section is specified. An overview of the
available type of cross-sections is given in section 5.6.1.
This section explains how the numerical bathymetry of a SOBEK model is constructed on
basis of the user-defined cross-sections. With numerical bathymetry is referred to the bathymetrical information, that depending on the cross-section type is available at ζ -calculation
points only or available at both ζ - and u-calcuation points. Water levels and discharges are
computed using this numerical bathymetrical information. For more information on ζ - and
u-calculation points, reference is made to section 6.1.17.
In constructing the numerical bathymetry a distinction is to be made between"’

The Y-Z type of profiles (e.g. Open Vertical Segmented Y-Z profile, Asymmetrical Trapezium profile, Open Lumped Y-Z profile and Closed Lumped Y-Z profile).

All cross-section types except for the Y-Z type of profiles.
6.1.18.1

The Y-Z type of profiles

With the Y-Z type of profiles is referred to the Open Vertical Segmented Y-Z profile, the Asymmetrical Trapezium profile, the Open Lumped Y-Z profile and the Closed Lumped Y-Z profile
(for more information, see section 5.6.1).
For the Y-Z type of profiles yields that numerical bathymetrical information is made available
at both ζ - and u-calculation points by interpolating (see section 6.1.19) between the userdefined cross-sectional profiles. The construction of the numerical bathymetrical information
for Y-Z type of profiles is depicted in Figure 6.44.

Conceptual description

Figure 6.44: Construction of the numerical bathymetrical information for Y-Z type of profiles; Blue coloured objects are the user-defined cross-sections; Green
coloured objects are the interpolated numerical bathymetrical information;
Open circle are ζ -calculation points; Small vertical lines are u-calculation
points

Note: If only one cross-section is specified for a branch, the bathymetrical information of
each ζ -calculation point and each u-calculation point located on this branch will be identical
to this specified cross-section.
All cross-section types except for the Y-Z type of profiles

With the Y-Z type of profiles is referred to the Open Vertical Segmented Y-Z profile, the Asymmetrical Trapezium profile, the Open Lumped Y-Z profile and the Closed Lumped Y-Z profile
(for more information, see Section 5.6.1).
For all cross-section types except for the Y-Z type of profiles yields that numerical bathymetrical information is made available at ζ -calculation points only by interpolating (see section 6.1.19) between user-defined cross-sectional profiles. The construction of the numerical
bathymetrical information for all cross-section types except the Y-Z type of profiles is depicted
in Figure 6.45.

Figure 6.45: Construction of the numerical bathymetrical information for all cross-section
types except for the Y-Z type of profiles; Blue coloured objects are the userdefined cross-sections; Green coloured objects are the interpolated numerical bathymetrical information; Open circle are ζ -calculation points; Small
vertical lines are u-calculation points

Note: If only one cross-section is specified for a branch, the numerical bathymetrical information for each ζ -calculation point located on this branch will be identical to this specified
cross-section.
6.1.19

Method of interpolating between user-defined cross-sections
This section explains the method of interpolating between user-defined cross-sections. An
overview of the available type of cross-sections is given in section 5.6.1. Following distinction
between cross-sections types is to be made:

Round and Egg-shape (see section 6.1.19.1).
Open Vertical Segmented Y-Z profile and Asymmetrical Trapezium profile (see section 6.1.19.2).
Cross-sections not being a Round, Egg-shape, Open Vertical Segmented Y-Z profile or
Asymmetrical Trapezium profile (see section 6.1.19.3).

SOBEK, User Manual

Method of Interpolating between Round cross-sections and between Egg-shape
cross-sections
A Round is specified by an invert level, a diameter and the elevation of a ground-layer surface.
Interpolating between two Round cross-sections refers to the linear interpolation along the
branch of invert level, diameter and the elevation of the ground-layer surface.
An Egg-shape is specified by an invert level, a height, a width and the elevation of a groundlayer surface. Interpolating between two Egg-shape cross-sections refers to the linear interpolation along the branch of invert level, height, width and the elevation of the ground-layer
surface.
Method of Interpolating between Open Vertical Segmented Y-Z profiles and between
Asymmetrical Trapezium profiles

For both an Open Vertical Segmented Y-Z profile and an Asymmetrical Trapezium profile
yields that first from the user-defined cross-sectional information so-called conveyance tables are constructed. In a conveyance table the width, area and conveyance as function of
water level are given. Interpolation between two of these type of profile refers to the linear
interpolation along the branch of their respective conveyance tables.
Method of Interpolating between Cross-sections not being a Round, Egg-shape, Open
Vertical Segmented Y-Z profile or Asymmetrical Trapezium profile
For all cross-sections not being a Round, Egg-shape, Open Vertical Segmented Y-Z profile or
Asymmetrical Trapezium profile yields that the cross-sectional profile is defined in a Table.
Before interpolation starts it is taken care of that the concerning two cross-sections contain
exactly the same vertical spacing for flow and total widths. In this context vertical spacing
means the level at which a certain width in one of the two cross-sections is defined minus the
bed level (lowest point) of the concerning cross-section. Afterwards, for each vertical spacing
the flow width and total width of an intermediate constructed cross-section is determined by
linear interpolation along the branch. The ground-layer surface of an intermediate constructed
cross-section is determined by linear interpolation along the branch as well.
Note: In case of a River profile, the properties of a summer dike (e.g. Flow area, Total area,
Dike crest level and Flood plain base level) are linear interpolated along the branch. The same
applies for the width of the main section, the width of floodplain 1 and the width of flood plain
2.
Note: The height of a cross-section is the maximum level at which a width is defined minus
the bed level (lowest point) of this cross-section. For open cross-sectional profiles yields that
in case two cross-sections have different heights, the height of the lowest cross-section will be
vertically extended with a width equal to the width defined at its maximum level. This is done
to obtain in the lowest cross-section exactly the same vertical spacing as in the highest crosssection. Please note that the same procedure is applied for closed cross-sections, with the
exception that the width of the lowest cross-section above its obvert level (maximum defined
level) becomes equal to zero.

Conceptual description

Methods for computing conveyance
Conveyance is computed for each u-calculation point (or velocity calculation point). A ucalculation point is located in the centre point of its two adjacent ζ -calculation points (or water
level calculation points). A distinction is to be made between:

The lumped conveyance approach (see section 6.1.20.1),
Analytical formulae for computing lumped conveyance, and
The vertically segmented conveyance approach (see section 6.1.20.2).

Lumped conveyance approach

In the lumped conveyance approach, it is assumed that there is an uniform flow velocity (U )
in the cross-sectional profile for a given water level (see Figure 6.46). Hence, it is assumed
that differences in flow velocities across the cross-sectional profile can be neglected. This
assumption generally does not yield for rivers. Therefore, in modelling rivers Y-Z profiles (or
Asymmetrical Trapeziums) are preferred, where conveyance is computed using the vertically
segmented conveyance approach (see section 6.1.20.2).

The vertically segmented conveyance approach is used for Y-Z profiles and Asymmetrical
Trapezium cross-sections only. Analytical formulae for computing lumped conveyance are
used for the Egg-shaped cross-section and the Round cross-section. For the remaining crosssection types, the lumped conveyance approach is used.

Figure 6.46: Concept of the lumped conveyance approach

First an asymmetrical cross-sectional profile as depicted in Figure 6.46 is transferred into a
symmetrical cross-sectional profile. Thereafter the lumped conveyance is computed as:

p
K(h) = A(h)C(h) R(h)

K(h)
A(h)
C(h)
P (h)
R(h)

Lumped conveyance at water level h
Cross-sectional area at water level h
Chézy friction value at water level h
Wetted Perimeter at water level h
Hydraulic radius at water level h (R(h) = A(h)/P (h))

If the water level in an open tabulated rises above the highest level in a cross-sectional profile,
the lumped conveyance is computed taking the flow width at this water level equal to the flow
width, defined at the highest cross-sectional level.

SOBEK, User Manual

Note: Please note that in case of a River profile, the lumped conveyance of its main section,
floodplain 1 and floodplain 2 are computed separately, and thereafter added to obtain the total
lumped conveyance of a river profile at a particular water level.
Vertically segmented conveyance approach
The vertically segmented conveyance approach is suited for modelling flow in rivers, since
in this approach it is assumed that flow velocities vary across the cross-sectional profile for a
given water level. In line with this assumption, the cross-section is divided in vertical segments
(see Figure 6.47).

Figure 6.47: Example of constructed vertical segments in a Y-Z profile
13 (yi , zi ) points red dots
9 vertical segments

Note: Conveyance table constructed from Zmin to Zmax .

A Y-Z profile is defined by a number (n) of (yi , zi ) points. For the total number (nseg ) of
vertical segments yields: nseg = n − a − 1, where a = number of succeeding (yi , zi )
points for which yi = yi+1 . So, please note that vertical walls in a Y-Z profile do not induce
a vertical segment. Moreover, the length of vertical walls is not considered in computing
the conveyance of a Y-Z profile. Omitting vertical walls in computing the conveyance of a Y-Z
profile, means that for a canal having a rectangular profile with a small ratio of width and water
depth only, substantial difference in discharge capacity can occur if such canal is modelled as
a rectangular cross-section (i.e. lumped conveyance approach) or as a rectangle shaped Y-Z
profile (i.e. vertically segmented conveyance approach). The surface level of a Y-Z profile is
equal to its highest (yi , zi ) point. In analogy, the same yields for an Asymmetrical Trapezium
cross-section.
The conveyance (Ki ) of each vertical segment is computed separately (for formulae, see

Conceptual description

conveyance per vertical segment further below). The conveyance of each inclined vertical
segment is determined by solving an integral from yi to yi+1 . The advantage of using an
integral is that irrespective of the number of user-defined intermediate points, that lie on a
straight line between (y0 , z0 ) to (y1 , z1 ), the same conveyance for the cross-sectional part
from y0 to y1 is computed. The total conveyance (Ktot ) at a particular
water level is the
P
summation of the conveyance of all the vertical segments (Ktot =
Ki ).
Conveyance tables, applied in the vertically segmented conveyance approach

A conveyance table gives the conveyance, flow width and flow area of a cross-section as function of water level. Conveyance tables are used for Y-Z profiles and Asymmetrical Trapeziums
only. These conveyance tables are made by a pre-processor before the onstart of a hydrodynamic calculation. In constructing the conveyance table of each user-defined cross-section,
it is ensured that the difference in conveyance between two succeeding water levels is less
than 1 %. Conveyance tables are used for reducing computational efforts, hence increasing
SOBEK’s computational performance.

Conveyance tables are made from the bed-level up to the highest (yi , zi ) point, irrespective of
the actual location of the highest (yi , zi ) point within the cross-sectional profile. This implies
that no distinction is made between the left and the right embankment height.
Conveyance tables for computational points located in between two user-defined cross-sections
are obtained by linear interpolating the conveyance tables, constructed at these two userdefined cross-sections (see also cross-section).
Extrapolation of conveyance tables

Say the water level (h) rises above the highest level (nmax ) of a conveyance table. In this
case the conveyance (Kh ) at water level (h) is computed as

Kh = a(h − zmin )b ,

where: zmin is the lowest level in the cross-sectional profile; and a, b are constants derived
from the conveyances at levels nmax and nmax − 1.
Lumped hydraulic output for Y-Z profiles and Asymmetical Trapezium
As a courtesy at subsection branch output, lumped hydraulic output (Q, Clumped , Aflow , Wflow
and R) are provided for Y-Z profiles and Asymmetrical Trapeziums. The discharge (Q) is
the discharge through the profile, having a flow area (Aflow ) and flow width (Wflow ). The
hydraulic radius (R) is computed on basis of Aflow and Wflow assuming a symmetrical profile
as function of water level. The latter assumption is made, since different Y-Z profiles may
have different shapes, that might have to be interpolated. The lumped Chézy value (Clumped )
is computed as

K
√ ,
Aflow R

where K is the conveyance.
Conveyance per vertical segment
A vertical segment is defined by two (y0 , z0 ) and (y1 , z1 ) points for which yields that y0 is not
equal to y1 (see Figure 6.48).

SOBEK, User Manual

Figure 6.48: Definition sketch of a vertical segment, considered in computing conveyance
for a Y-Z profile and an Asymmetrical Trapezium cross-section

Hereunder, the conveyance formulae for a vertical segment are given in case of:

Chézy roughness,
Manning roughness,
Strickler (kn ) roughness,
Strickler (ks ) roughness,
White-Colebrook (kn ) roughness, and
Bos&Bijkerk (γ ) roughness.

Chézy roughness conveyance for a vertical segment (see Figure 6.48):

d = max(d0 , d1 )
if d ≤ 0 then
k=0
else

if d < |z1 − z0 | then
if |β| ≤ 0.01 then

d 5/2
2C
k1 = |β|(1+β
2 )1/4
2
elseif |β| > 0.01 then
2C
5/2
k2 = 5|β|(1+β
2 )1/4 d
elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then
3/2
1
k3 = (1+βC2 )1/4 d0 +d
(y1 − y0 )
2
elseif |β| > 0.01 then
5/2
5/2
2C
k4 = 5|β|(1+β
− d1
2 )1/4 d0
endif
endif

Conceptual description

endif
Manning roughness conveyance for a vertical segment (see Figure 6.48):

d = max(d0 , d1 )
if d ≤ 0 then
k=0
else
if d < |z1 − z0 | then
if |β| ≤ 0.01 then

d 8/3
2
k1 = n|β|(1+β
2 )1/4
2
elseif |β| > 0.01 then
3
8/3
k2 = 8n|β|(1+β
2 )1/4 d
elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then
5/3
1
(y1 − y0 )
k3 = n(1+β1 2 )1/4 d0 +d
2
elseif |β| > 0.01 then
8/3
8/3
3
k4 = 8n|β|(1+β
− d1
2 )1/4 d0

endif
endif
endif

Strickler (kn ) roughness conveyance for a vertical segment (see Figure 6.48):

d = max(d0 , d1 )
if d ≤ 0 then
k=0

else
if d < |z1 − z0 | then
if |β| ≤ 0.01 then

−1/6
50kn
d 8/3
k1 = |β|(1+β
2 )1/4
2
elseif |β| > 0.01 then
−1/6
75kn
8/3
k2 = 8|β|(1+β
2 )1/4 d
elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then

−1/6
25kn
d0 +d1 5/3
k3 = (1+β
(y1 − y0 )
2 )1/4
2
elseif |β| > 0.01 then
−1/6
8/3
8/3
75kn
k4 = 8|β|(1+β
− d1
2 )1/4 d0

endif
endif
endif
Strickler (ks ) roughness conveyance for a vertical segment (see Figure 6.48):

d = max(d0 , d1 )
if d ≤ 0 then
k=0

SOBEK, User Manual

else
if d < |z1 − z0 | then
if |β| ≤ 0.01 then

2ks
d 8/3
k1 = |β|(1+β
2 )1/4
2
elseif |β| > 0.01 then
3ks
8/3
k2 = 8|β|(1+β
2 )1/4 d
elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then
5/3
1
k3 = (1+βk2s )1/4 d0 +d
(y1 − y0 )
2
elseif |β| > 0.01 then
8/3
8/3
3ks
k4 = 8|β|(1+β
− d1
2 )1/4 d0

endif
endif
endif

White-Colebrook (kn ) roughness conveyance for a vertical segment (see Figure 6.48):

d = max(d0 , d1 )
c1 = (1 + β 2 )1/4 ln(10)
c2 = k12n
if d ≤ 0 then
k=0
else

if d < |z1 − z0 | then
if |β| ≤ 0.01 then
if k6d ≤ 1.0005 then
n

36
0.00022
|β|(1+β 2 )1/4

36
10
log
|β|(1+β 2 )1/4

endif
elseif |β| > 0.01 then
if cd ≤ 1.495 then
2

36
d5/2 0.00213
5|β|c1

36
d5/2
5|β|c1

elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then
if

≤ 1.0005 then
18
0.00022(y1
(1+β 2 )1/4

18
10
log
(1+β 2 )1/4

endif
elseif |β| > 0.01 then
if dc 0 ≤ 1.495 and
2

d1
≤ 1.495 then
c2
5/2
5/2
d0 0.00213 − d1 0.00213

Conceptual description

≤ 1.495 and
36
5|β|c1

n o
5/2
5/2
d0 0.00213 − d1
ln dc21 − 25

d1
> 1.495 and
1.495 then
c2n≤ o
5/2
5/2
d0
36
k4 = 5|β|c1 d0
ln c2 − 52 − d1 0.00213

n o
5/2
ln dc21 − 25
ln dc20 − 52 − d1

endif
endif
endif
endif
endif

d = max(d0 , d1 )
if d ≤ 0 then
k=0

else
if d < |z1 − z0 | then
if |β| ≤ 0.01 then

Bos&Bijkerk (γ ) roughness conveyance for a vertical segment (see Figure 6.48):

2γ
d 3
k1 = |β|(1+β
2 )1/4
2
elseif |β| > 0.01 then
γ
3
k2 = 3|β|(1+β
2 )1/4 d
elseif d ≥ |z1 − z0 | then
if |β| ≤ 0.01 then
2
1
(y1 − y0 )
k3 = (1+βγ2 )1/4 d0 +d
2
elseif |β| > 0.01 then
γ
3
3
k4 = 3|β|(1+β
2 )1/4 |d0 − d1 |

endif
endif
endif
6.1.21

The computation of the water levels and discharges in the SOBEK-flow-network is performed
with the Delft-scheme. This scheme solves the De Saint-Venant equations (continuity and
momentum equation) by means of a staggered grid. In this staggered grid the water levels
are defined at the connection nodes and ζ -calculation points, while the discharges are defined
at the intermediate branches or branch segments.
In general, numerical approximations must satisfy the following requirements:

Robust, i.e. effective or capable of dealing with a wide range of practical problems, without
producing numerical instabilities,

Efficient, i.e. efficient use of computational resources such as processor time,
Accurate, i.e. sufficient accuracy given the modelling purpose.
For the Delft-scheme robustness has been the most important design aspect. By the range
of practical problems to be dealt with the following problems are included:

Drying and flooding
Deltares

SOBEK, User Manual

Super-critical flow including hydraulic jump.
The used procedure guarantees a solution. In certain flow conditions the time step is reduced
temporarily by a time step estimation procedure to avoid numerical instability.
The Delft-scheme uses a so-called minimum degree algorithm with an iterative simulation
technique. This is highly efficient in case of large networks and long time series.
The Delft-scheme is designed to produce a closed water balance, which makes it very suitable
for water quality computations.
6.1.22

Drying/flooding

When a water level upstream of a branch segment is lower than 5 mm above the bed level of
the ζ -calculation point at this upstream side, the branch segment is assumed to be dry; the
discharge through this branch segment is said to be zero. When a branch segment is dry and
upstream or downstream of the segment the water level rises higher than 10 mm above the
bed level of the ζ -calculation point at that side, the branch segment starts flooding again.
The same deadband is used for the check on drying and flooding of structures. In case of a
weir and orifice, the upstream water level is compared to the crest level. In case of culverts,
siphons and inverted siphons, the water level is compared to the maximum of the bed level
and the bottom of the structure at the upstream side.
6.1.23

Freeboard is the difference between surface level and water level at some location in the
system. It is defined from surface level to water level, so the freeboard is positive when the
water level is lower than the surface level. When the freeboard is negative, there is a flood at
that location.
Surface level

Figure 6.49: Free board

Conceptual description

Ground layer
Except for a Y-Z profile, cross sections can have a fixed horizontal ground layer (or sediment
layer). The ground layer level (top level of the ground layer) equals the bottom level (or invert
level) plus the ground layer thickness. The part of the cross-section located beneath the
ground layer level is omitted in the hydraulic computations. Hence, a ground layer reduces
both the wetted area and the wetted perimeter for a given water level. In Figure 6.50 a circular
cross section is shown with a ground layer with thickness Dgr

Figure 6.50: Ground layer in circular cross section

For a ground layer a friction value can be specified that differs from the bed friction value. The
ground layer friction value is applied for the cross-sectional width at the ground layer level only.
For the remaining wetted perimeter of the cross-section, the bed friction value is applied. The
same friction formulation (i.e. Chézy, Manning etc.) is to be applied for both the ground layer
and the remaining wetted perimeter (i.e. the bed) of the cross-sectional profile. The combined
friction that is used is computed according to:

ks
ksb
ksgr
Ob
Ogr
6.1.25

Ob ks2b + Ogr ks2gr
Ob + Ogr

Combined Strickler friction value
Strickler bed friction value
Strickler friction value of the ground layer
Wetted perimeter of the bed
Wetted perimeter of the ground layer

Measurement station
In channel flow a measurement station is placed on a branch. From a measurement station
the actual (calculated) value of a water level or a discharge can be retrieved. This value can
then be used in an algorithm of a controller.
The water level that a measurement station retrieves is the water level at the nearest calculation point. The retrieved discharge is the discharge at the branch segment where the
measurement station is located.

SOBEK, User Manual

In sewer flow the measurement station can be placed on a connection node or on a branch
Water levels are taken at the nodes, discharges at the branches.
6.1.26

Network
The schematic basis of each model is the network of branches. These branches are connected to each other at connection nodes.
One can say that the network of branches and nodes is the modelled representation of the
real geographic data of the modelled area.

ζ -calculation points

Connection nodes

Figure 6.51: Network

In the Delft-scheme used by the D-Flow 1D module, the network is split up into a staggered
grid. The water levels are defined at the connection nodes and the ζ -calculation points of this
grid, while the discharges are defined at the branch segments.
6.1.26.1

Branch
A branch in a SOBEK-Flow-model is one of the basic elements in the schematisation. A
branch connects two nodes, and has the following attributes:

Begin node
End node
Branch length
554 of 900

Conceptual description

A geographical orientation (used only in case wind friction effect is included in your model).

The direction of the branch (positive x-direction) is from begin node to end node.

Figure 6.52: Branch length in model network

When using channel flow, ζ -calculation points can be specified on a branch. If this is done, the
branch is split up into branch segments. The numerical simulation will be carried out based
on these ζ -calculation points and branch segments in a staggered grid. The discharges are
calculated at the branch or branch segments Water levels are calculated at the connection
nodes and ζ -calculation points.
In case of sewer flow, each branch has a maximum of two ζ -calculation points at the beginning
and end of that branch. The branch can be interpreted as one branch segment
6.1.26.2

Branch length
In sewer systems the length of a branch is the length from the begin connection node to the
end connection node. This length is referred to as the co-ordinate length. In open channel
systems, a branch can be made longer than this minimum co-ordinate length, with the use of
vector points on the branch. This length is referred to as vector length. With this vector length
the actual length of a meandering river or channel can be modelled. If the vector length is
defined on a branch, this length is used in the computation of the water flow equations. If this
length is not defined, the co-ordinate length is used.
Note: The vector length is always equal to or greater than the co-ordinate length

SOBEK, User Manual

A SOBEK-Flow-network consists of branches that are connected in connection nodes. These
branches can be divided by ζ -calculation points into segments; the so-called branch segments. The discharges that result from the water flow equations are defined in these branch
segments

Figure 6.53: Branch segment

In sewer networks no ζ -calculation points can be used. So each branch consists of one
branch segment.
6.1.26.4

Connection node

A connection node in a SOBEK-Flow-model is a location where branches can be joined to
other branches. Water levels are defined at the connection nodes and the ζ -calculation points.

Connection nodes

Conceptual description

Figure 6.54: Connection nodes

Note: A node located at the bounds of the model can be a connection node (with storage) or
a boundary node (no storage).
6.1.27

The Delft-scheme is developed with robustness as its most important design aspect. This
scheme can deal with phenomena such as drying/flooding, supercritical flow and flow transitions (hydraulic jumps) and guarantees a solution for every time step, though the actual computational time step can be reduced internally under certain flow conditions (large discharges
in combination with little storage).
The computational time step reduction is done by a time step estimation procedure before a
new time step or at the end of a time step when negative depths are computed. In the latter
case the step is repeated with a time step reduced by a factor 2 until a correct solution is
achieved.

SOBEK, User Manual

Simulation output parameters at branch segments
For more background information on time step reductions, see section Time step reductions
during the simulation. The simulation output parameters available at each branch segment
(see option "Simulation Info at the Branch Segments" in the file or in Results
in Charts and Results in Maps) are:

Time step estimation: This refers to the number of times that the time step is reduced,

Time step reductions during the simulation

The user can define a time step in the Settings Task block. During the computation this userdefined time step may be reduced for stability reasons (e.g. to prevent the simulation from
crashing). D-Flow 1D performs the following checks:

At the start (t = tk ) of each computational time-step, the allowable Courant time-step is

determined. This is done as follows:

For each 1D branch segment (i) its 1D Courant time step is computed as:

since the allowable Courant time step of this branch segment is smaller than the userdefined time step.
No iteration up and No iteration down: Parameters "No iteration up" and "No iteration
down", respectively refer to the number of times that convergence in the Newton iteration
process is not satisfied at the water level point with the lowest x-coordinate ("No iteration
up") and the water level point with highest x-coordinate ("No iteration down") of the branch
segment.
Negative depth up and Negative depth down: Parameters "Negative depth up" and
"Negative depth down", respectively refer to the number of times that a time step reduction is needed for avoiding negative depths at the upstream water level point (lowest
x-coordinate) and the downstream water level point (highest x-coordinate) of the branch
segment.
Total: The number of times that the allowable Courant time step is smaller than the userdefined time step and the number of times that the time step is reduced for either satisfying
the convergence condition or for avoiding negative depths.

the user-defined value for "maximum flow (1D) and velocity (2D) Courant
number" in Settings
Vol i,tot
the total volume of water at the upwind (or upstream) water level point
Qi,tk
the discharge at t = tk
Then the 1D branch segment having the smallest 1D Courant time step (e.g. the allowable 1D Courant time step) is determined. The applicable 1D time step at t = tk
is the minimum of the user-defined time step and the allowable 1D Courant time step.
The branch segment with the smallest 1D Courant time step is logged in case its 1D
Courant time step is smaller than the user-defined time step.
The 2D Courant time step for all 2D links in U-direction and for all 2D links in V-direction
are respectively computed as:

2D Courant, U-direction

2D Courant, V-direction

Conceptual description

∆xm
∆yn
Um,tk
Vn,tk

the user-defined value for "maximum flow (1D) and velocity (2D) Courant
number" in Settings
the grid spacing in x-direction
the grid spacing in y -direction
the depth-averaged flow velocity in x-direction at t = tk
the depth-averaged flow velocity in y -direction at t = tk

The allowable 2D Courant time step is the minimum of the 2D Courant time steps
of all 2D U-links and 2D V-links. The applicable 2D time step is the minimum of the
user-defined time step and the allowable 2D Courant time step.
In case of a combined 1D-2D hydraulic computation, the applied time step (∆t) is the
minimum of the applicable 1D time step and the applicable 2D time step.

In each computational time step (from t = tk to tk+1 = tk + ∆t), it is checked that for

each water level point yields that the lateral inflow volume is not larger than its volume of
water at t = tk . If this condition is not satisfied, the user defined time step is reduced
to such extend that this condition is met. The reduced time step, however, is not made
smaller than the user-defined "minimum time step" in Settings.
Due to various circumstances (discontinuities in model schematization, unrealistic boundary conditions, etc.), the above determined actual time step (∆t) may still be too large for
finding a valid solution at tk+1 = tk + ∆t. Two conditions are to be fulfilled in finding a
valid solution:
The first condition is that the Newton iteration process converges in terms of water
levels and volumes (both computed at water level points). In other words differences
in water levels and volumes between the last and previous Newton solution are to be
within the user-defined values for "epsilon for water depth" and "epsilon for volume".
In Settings, the user can define the "maximum number of Newton iterations". If the
convergence condition is not satisfied within the maximum number of Newton iterations, the time step is reduced by a factor 2. If this does not satisfy the convergence
condition, the time step is again reduced by a factor 2. The simulation is terminated if a
time step smaller than the user-defined "minimum time step" (see Settings) is needed
for satisfying the convergence condition. All water level points, that after the maximum
number of Newton iterations are conducted, still having a water level convergence
error are logged during a computational time step.
The second condition is that no negative depths (e.g. water level is below bed level)
may occur. Negative depths at a particular water level point may occur if the outflow
during a time step is larger than the volume stored at t = tk . If negative depths occur,
the time step is reduced up to a time step for which yields that the outflow during the
reduced time step is smaller than the volume stored at t = tk and hence no negative
depth occurs. The simulation is terminated if a reduced time step smaller than the
user-defined "minimum time step" (see Settings) is needed to avoid negative depths.
All water level points for which the time step needs to be reduced in order to avoid
negative depths are logged during a computational time step.

Note: If a model run requires a lot of computational effort (e.g. an unexpected long simulation
time is needed), often a large number of time step reductions during simulation is performed.
These time step reductions are needed to find a valid solution and/or to prevent the model
from crashing. Defining a smaller calculation time step in Settings may result in shorter simulation times. The reason for this, the smaller user-defined time step allows more moderated
intermediate solutions to be found. More moderate solutions reduce the number of circumstances in which the model encounters large discontinuities, which require a considerable

SOBEK, User Manual

amount of time step reductions before finding a valid solution. The final actual time step can
be much smaller than the user-defined time step. In other words: A smaller user-defined time
step can result in significant less total number of time step reductions leading to a decrease of
total computational time. This is because the total required simulation time is directly related
to the total number of computational time steps.
6.1.30

Slope
In the D-Flow 1D module slope can refer to the slope of the water level or the bed slope. If the
word "slope" is used without further indication, then it pertains to the slope of the water level
in the model. The symbol used is i:

Water level [m]
Distance [m]

For bed slope, the symbol used is ib :

with zb as the bed level.
6.1.31

Stationary computation

A stationary computation is performed in the D-Flow 1D module by running a non-stationary
simulation until a steady state is branched. During this simulation, all time depending parameters, such as lateral and boundary conditions, are set to their initial value and kept constant.
In some cases a steady state cannot be branched, for example, when a pump is switching on
and off. In that case the computation stops after 1 000 simulation steps (not time steps, see
Time step estimation) and the maximum difference of water level compared to the last time
step in the network is given. If this value is low enough (<1 mm for example) the solution can
be considered as steady.
The results of a stationary computation can be used as an initial condition for a non-stationary
simulation.
6.1.32

Summer dike
A flood plain might be separated from a river by means of a small dike, having a crest level
lower than the crest level of the main dike (see Figure 6.55). In the Netherlands large floods
usually occur in winter. The main dike and the small dike are, therefore, respectively referred
to as the “winter dike” and the “summer dike”.
The presence of a summer dike implies that the cross-sectional profile as measured in situ
(see shadowed line in Figure 6.55) does not increase monotonously with rising water levels.
When the water level becomes slightly higher than the crest level of the summer dike, first
the area behind the summer dike is to be filled, before water levels can become any higher.
This implies a local attenuation of the flood wave at water levels just above the crest level of

Conceptual description

Figure 6.55: Summer dike option, available in a river profile

the summer dike. This hydraulic phenomenon can be modelled using the summer dike option
available at a river profile.
In defining a summer dike in a river profile a distinction is to be made between:

The cross-sectional profile

The cross-sectional profile comprises of a “flow area” and a “storage area”, which in Figure 6.55 are respectively located above the blue lines and the black lines. The summation
of flow area and storage area is called the “total area”. Both flow area and total area are
defined by its width as function of elevation. At each elevation in the cross-sectional profile
yields that storage width equals total width minus flow width. Hence, no storage is defined
if total width equals flow width. The flow area of the cross-sectional profile can be divided
in three separate flow sections, respectively called the (i) main section, (ii) floodplain 1
and (iii) floodplain 2 . Each such flow section can have a different roughness value and a
different roughness formulation.
The area behind the summer-dike
In analogy with the cross-sectional profile, the “total area behind a summer dike” is divided
in a “flow area” and a “storage area”. The “Flood Plain Base Level” coincides with the
lowest part of the area behind the summer dike (see Figure 6.55).
Remark:
Both the cross-sectional profile and the area behind the summer dike should be mutually consistent with the cross-sectional profile as measured in situ (see shadowed line
in Figure 6.55). Hence, both the flow area and the storage area behind the summer
dike should not be included in the cross-sectional profile.
The so-called “transition height” is used for avoiding numerical oscillations. More precisely,
the transition height ensures that the flow area and storage area behind the summer dike
are gradually taken into computation. Transition height for summer dikes is a model-wide
parameter, that is defined in the Settings Taskblock (Edit button next to 1DFLOW (River);
Advanced settings Tab).
Lets consider the following summer dike properties:

SOBEK, User Manual

Figure 6.56: Flow area behind the summer dike as function of local water levels.

flood plain base level (zbase ) of 2 m,
summer dike crest level (zsd ) of 4 m,
transition height (T ) of 0.5 m,
storage area behind the summer dike of 200 m2 ,
flow area behind the summer dike (ExtraFlowArea) of 50 m2 , and
total area behind the summer dike (ExtraTotalArea) of 250 m2 .

In explaining how a summer dike is taken into computation, we make a distinction between:

The actual value of the (extra) flow area behind the summer dike,
The flow velocity applied to the (extra) flow area behind the summer dike, and
The actual value of the (extra) total area behind the summer dike.
The actual (extra) flow area is a unique function of the local water level (h) in the crosssectional profile (see Figure 6.56). More precisely:

If ζ < zsd ; Flow area behind the summer dike is zero.
If zsd ≤ ζ ≤ zsd + T ; Flow area behind the summer dike varies as a quadratic function
of water level (ζ ) between zero and ExtraFlowArea (= 50 m2 ).
If ζ > zsd + T ; Flow area behind the summer dike is equal to ExtraFlowArea.
The flow velocity applied to the (extra) flow area behind the summer dike is the flow velocity in
one of the three available flow sections. Hence, either the flow velocity in the main section, in
floodplain 1 or in floodplain 2. The actual flow velocity applied to the (extra) flow area behind
the summer dike is determined as follows:
1 Default the flow velocity in floodplain 2 is used.
2 However, if the wetted area of floodplain 2 becomes less than 0.4 m2 , the flow velocity in
floodplain 1 is used,

Conceptual description

3 Furthermore, if the wetted area of floodplain 1 becomes less than 0.4 m2 , the flow velocity
of the main section is used.
Remarks:
Please contact Deltares if you like to use a different threshold value (i.e. not 0.4 m2 )
for discerning which flow velocity is to be applied to the (extra) flow area behind the
summer dike.
The flow velocity applied to the (extra) flow area behind the summer dike is computed
as follows

i ∈ {main section, floodplain 1, floodplain 2}

Ui
Ci
Ri
Ai
Asd
Pi
S

average flow velocity
Chézy coefficient of the flow section
(Ai + Asd )/Pi : hydraulic radius of the flow section
wetted area of the flow section
extra flow area behind the summer dike
wetted perimeter of the flow section
water level slope
The discharge including the (extra) flow area behind the summer dike is computed as
follows

Qi = Ui (Ai + Asd )

Figure 6.57 depicts the actual (extra) total area behind the summer dike as function of the
local water level (ζ ) in the cross-sectional profile. The (extra) total area behind the summer
dike is added to the total area of the cross-sectional profile. There is a hysteresis in the extra
total area for water levels varying from flood plain base level (zbase = 2.0 m) to crest level
of summer dike plus transition height (zsd + T = 4.5 m). We call line ABC the rising limp
and line CA the falling limp of the hysteresis. The so-called “hysteresis flag” determines which
limp of the hysteris is to be followed. In case the hysteresis flag=1 the rising limp of the
hysteresis is followed, else the falling limp is followed. At the onstart of a computation yields
that the hysteresis flag=1. The actual applied extra total area behind the summer dike is
computed as follows:
1 If ζ < zbase ; Hysteresis flag is set to 1. Total area behind the summer dike is zero.
2 If zbase ≤ ζ ≤ zsd + T and hysteresis flag=1;

For zbase ≤ ζ < zsd ; Total area behind the summer dike is zero.
For zsd ≤ ζ ≤ zsd + T ; Total area behind the summer dike varies as a quadratic
function of water level (ζ ) between zero and ExtraTotalArea (= 250 m2 )
3 If zbase ≤ ζ ≤ zsd + T and hysteresis flag=0; Total area behind the summer dike
varies as a quadratic function of water level (ζ ) between zero and ExtraTotalArea.
4 If ζ > zsd + T ; Hysteresis flag is set to 0. Total area behind the summer dike is equal to
ExtraTotalArea.

SOBEK, User Manual

Figure 6.57: Total area behind the summer dike as function of local water levels.

Super-critical flow

The D-Flow 1D module can deal with super-critical flow. The flow in a branch or branch
segment is super-critical if the Froude number [−] is higher than 1:

Velocity [m/s]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Wetted area [m2 ]
Flow width [m]

Remarks:
When the Froude number is less than 1, the flow is sub-critical.
Transitions from super-critical to sub-critical flow causes an hydraulic jump.
6.1.34

The surface level is the level of the soil surface i.e. the embankment level of the cross section.
When the water level is higher than this level there is a flood. Normally water is stored above
this level on a certain storage area. When the water level drops, this storage is emptying back
into the branch or node.

Conceptual description

Transport equation
The transport of salt, temperature and sediment in estuaries, tidal rivers and alluvial rivers
can be considered as transport of conservative substance in water. These transports are
described by an advection-diffusion equation, which is called the transport equation.
Next to the additional transport equation, density differences have to be accounted for in the
momentum equation of the water flow module. The water flow module is therefore coupled
with the salt intrusion module and temperature by the density and the flow field. The concentrations are denoted by C .
The transport equation is described by an advection-diffusion equation including source term
and read:

∂C
Q C −AF D
∂x

D
Ss
Q
AT
AF
6.2.1
6.2.1.1

concentration of salt or chloride, averaged over the total cross-sectional area
[kg/m3 ]
dispersion coefficient [m2 /s]
source term [kg/(ms)]
discharge (water) [m3 /s]
total cross-sectional area [m2 ]
flow area [m2 ]

∂
∂AT C
+
∂t
∂x

Temperature: heat flux model
General

In D-Flow 1D the heat exchange at the free surface is modelled by taking into account the
separate effects of solar (short wave) and atmospheric (long wave) radiation, and heat loss
due to back radiation, evaporation and convection. In literature there is a great variety of
empirical formulations to calculate these heat fluxes across the sea surface. Most formulations
differ in the dependency of the exchange on the meteorological parameters such as wind
speed, cloudiness and humidity. Some formulations were calibrated for coastal seas others
for lakes.

Figure 6.58: Overview of the heat exchange mechanisms at the surface

SOBEK, User Manual

Legend for Figure 6.58:
radiation (flux) for clear sky condition in [J/m2 s]
heat loss due to convection (sensible) in [J/m2 s]
reflected solar radiation in [J/m2 s]
solar radiation (short wave radiation) in [J/m2 s]
net incident solar radiation (short wave), = Qs − Qsr
atmospheric radiation (long wave radiation) in [J/m2 s]
net incident atmospheric radiation (long wave)
reflected atmospheric radiation in [J/m2 s]
back radiation (long wave radiation) in [J/m2 s]
heat loss due to evaporation (latent) in [J/m2 s]

Qsc
Qco
Qsr
Qs
Qsn
Qa
Qan
Qar
Qbr
Qev

In D-Flow 1D the heat exchange at the free surface is modelled by taking into account the
separate effects of solar (short wave) and atmospheric (long wave) radiation, and heat loss
due to background radiation, evaporation and convection. Two heat flux models have been
implemented:

1 Excess temperature model
The heat exchange flux at the air-water interface is computed. Only the background temperature is required.
2 Composite temperature model
The fraction of the sky covered by clouds is prescribed (in %). The effective back radiation
and the heat losses due to evaporation and convection are computed by the model. Additionally, when air and water densities and/or temperatures are such that free convection
occurs, free convection of latent and sensible heat is computed by the model. This model
formulation typically applies for large water bodies.
For the physical background of the heat exchange at the air-water interface and the definitions,
we refer to Octavio et al. (1977) for the excess model and Lane (1989) for the composite
model.
6.2.1.2

The change in temperature Ts (in ◦ C) is given by:

Qtot
∂Ts
=
∂t
ρw cp ∆zs
with:

Qtot
ρw
cp
∆zs

total heat flux through the air-water surface (in J/(m2 s))
specific density of water (in kg/m3 )
specific heat capacity of sea water (= 3930 J/(kg K) )
water depth

In D-Flow 1D, the heat exchange at the bed is assumed to be zero. This may lead to overprediction of the water temperature in shallow areas.
Remarks:
The temperature T is by default expressed in ◦ C. However, in some formulas the absolute temperature T̄ in K is used. They are related by:

T̄ = T + 273.15.

In Equation (6.166) the total incoming heat flux is assumed to be absorbed in the water
column. This may result in an unrealistically high surface temperature when the top

Conceptual description

layer is thin. This can be prevented by absorbing the incoming radiation as a function
of depth. Currently, this is only implemented in heat flux models 4 and 5.
When using the composite heat flux model, the free convection of latent and sensible
heat is also determined.
6.2.1.3

Excess temperature model
The excess temperature model computes the heat fluxes through the water surface in such a
way that the temperature of the surface layer relaxates to the natural background temperature
specified by you. The heat transfer coefficient mainly depends on the water temperature and
the wind speed.

In the excess temperature model the solar radiation does not play an explicit role, but is part
of the background temperature.

Qtot = −λ (Ts − Ta ) ,
with:

Heat exchange coefficient, is defined by:

λ = 4.48 + 0.049Ts + f (U10 ) 1.12 + 0.018Ts + 0.00158Ts2

f (U10 ) = (3.5 + 2.0U10 )

air temperature
water surface temperature
wind function:

5.0 × 106
Sarea

wind speed
exposed water surface in m2

Composite temperature model

In the Composite temperature model, the heat fluxes through the water surface by incoming
radiation, back radiation, evaporation and convection are computed separately. Evaporation
and convection depend on the air temperature, the water temperature near the free surface,
relative humidity, and wind speed.
The total heat flux through the free surface reads:

Qtot = Qsn + Qan − Qbr − Qev − Qco ,

Qsn
Qan
Qbr
Qev
Qco

net incident solar radiation (short wave)
net incident atmospheric radiation (long wave)
back radiation (long wave)
evaporative heat flux (latent heat)
convective heat flux (sensible heat).

Qtot = Qsn − Qeb − Qev − Qco ,

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The subscript n refers to a net contribution.
Solar radiation
The short-wave radiation emitted by the sun that reaches the earth surface under a clear sky
condition is computed by means of an emperical formula

The solar radiation is computed by D-Flow 1D and is dependent on the geographical position
at the earth and the local time.

Figure 6.59: Co-ordinate system position Sun
δ : declination; θ: latitude; ωt: angular speed

Not all of the radiation is absorbed at the water surface. A part is transmitted to deeper water.
Short waves can penetrate over a distance of 3 to 30 meters, depending on the clarity of the
water, while the relatively longer waves are absorbed at the surface. Therefore, it is convenient
to separate the incoming solar insolation into two portions:
1 βQsn , the longer wave portion, which is absorbed at the surface and
2 (1 − β) Qsn , the remainder part, which is absorbed in deeper water.
The absorption of heat in the water column is an exponential function of the distance H from
the water surface:

(1 − β) Qsn =

γe−γh
(1 − β)Qsn ,
1 − e−γH

β
γ
h
H
568 of 900

part of Qsn absorbed at the water surface which is a function of the wavelength.
The default value of β in Delft3D-FLOW is 0.06.
extinction coefficient (measured) in m−1 , also related to the so-called Secchidepth γ = H 1.7
Secchi
distance to the water surface in meters.
total water depth.

Conceptual description

Remark:
The exponential decay function, Equation (6.174) has only been implemented in 3Dcomputations. Since D-Flow 1D is a depth averaged model, the distinction between
long and short wave radiation is not relevant.

The incoming energy flux at the water surface depends on the angle (declination) between
the incoming radiation and the Earth’s surface. This declination depends on the geographical
position on the Earth and the local time. The Earth axis is not perpendicular to the line
connecting the Sun with Earth. This tilting (angle δ ) varies with the time of the year and it
leads to a seasonal variation of the radiation flux. At June 21, the declination is maximal,
23.5 degrees. Of course, by the rotation of the Earth the solar radiation also varies during the
day. Near twelve o’clock local time, the sun elevation above the horizon is maximal. For an
overview of the angles used to determine the solar elevation angle γ , see Figure 6.59.
The temporal and latitude-dependent solar elevation angle γ is estimated by:

δ
ω0
ω1
φ
t

− cos (δ) cos

sin (γ) = sin (δ) sin

cos(ω0 t − 2.95)

frequency of the annual variation (= 2π/(365.24 × 24))
frequency of the diurnal variation (= 2π/24)
latitude
number of hours since 1st of january

The incoming short-wave solar radiation through a clear sky at ground level Qsc is about 0.76
of the flux incident at the top of the atmosphere (Gill, 1982):

0.76S sin(γ),
Qsc =
0.0,

sin(γ) ≥ 0,
sin(γ) < 0.

The solar constant S = 1 368 J/(m2 s) or W/m2 . This is the average energy flux at the mean
radius of the Earth.
A part of the radiation that reaches the water surface is reflected. The fraction reflected or
scattered (surface albedo) is dependent on latitude and season. Cloud cover will reduce the
magnitude of the radiation flux that reaches the sea surface. The cloudiness is expressed by
a cloud cover fraction Fc , the fraction of the sky covered by clouds. The correction factor for
cloud cover is an empirical formula. The absorption of solar radiation is calculated (Gill, 1982)
as the product of the net downward flux of short wave-radiation in cloudless conditions and
factors correcting for reflection and cloud cover:

Qsn = Qs − Qsr = (1 − α) Qsc f (Fc ) ,

Qs
Qsr
Qsc
sin (γ)
f (Fc )

solar radiation (short wave radiation) in [J/(m2 s)]
reflected solar radiation in [J/(m2 s)]
see Equation (6.176)
see Equation (6.175)

= 1.0 − 0.4Fc − 0.38Fc2

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α
Fc
S
6.2.1.6

albedo (reflection) coefficient (= 0.06)
fraction of sky covered by clouds (user-defined input)
solar constant (=1368 J m−2 s−1 )

Effective back radiation
The total net long wave radiation flux is called the effective back radiation:

Qeb = Qbr − Qan .

The atmospheric radiation depends on the vapour pressure ea , the air temperature Ta and
the cloud cover Fc . The back radiation depends on the surface temperature Ts .

emissivity factor (0.985 )
Stefan-Boltzmann’s constant = 5.67 × 10−8 in [J/(m2 sK 4 ]
the (absolute) water surface temperature in [K ].
actural vapour pressure:

√
Qeb = εσ T̄s4 (0.39 − 0.05 ea ) 1.0 − 0.6Fc2 ,

0.7859+0.03477Ta
1.0+0.00412Ta

fraction of sky covered by clouds (user-defined input)

Evaporative heat flux

Evaporation is an exchange process that takes place at the interface between water and air
and depends on the conditions both in the water near the surface and the air above it. The
evaporation depends on meteorological factors (wind-driven convection) and vapour pressures.
The evaporative heat flux Qev is defined by:

with Lv the latent heat of vaporisation in J/kg water:

Lv = 2.5 × 106 − 2.3 × 103 Ts .

The evaporation rate E is defined as the mass of water evaporated per unit area per unit time
[kg/(m2 s)]. It is computed by using a form of Dalton’s law of mass transfer:

E = f (U10 ) (es − ea ) ,

where the actual vapour pressure ea and the saturated vapour pressure es , is defined as:

0.7859+0.03477Ts
1.0+0.00412Ts

0.7859+0.03477Ta
1.0+0.00412Ta

Here rhum is the relative humidity in [-].
Remarks:

Conceptual description

The relative humidity rhum is specified as a function of time.
The vapour pressures are calculated using air and water surface temperature in ◦ C.
When the computed E is negative, it is replaced by zero, assuming that it is caused by
modelling misfit and not by the actual physical process of water condensation out ot the
air into the water.
The evaporation rate is computed from the difference in relative humidity, rather than from
the difference in vapour pressure. The contribution to the evaporative heat flux is split in a
contribution by forced convection and a contribution by free convection. These are discussed
separately.
Forced convection of latent heat

The latent heat flux due to forced convection reads:

Qev,forced = LV ρa f (U10 ) {qs (Ts ) − qa (Ta )} ,

with qs and qa the specific humidity of respectively saturated air and remote air (10 m above
water level):

0.62es
,
Patm − 0.38es
0.62ea
qa (Ta ) =
.
Patm − 0.38ea
qs (Ts ) =

(6.187)
(6.188)

The saturated and remote vapour pressures es and ea are given by Eqs. (6.184) and (6.185).
The latent heat Lv is given by equation (6.182)
The wind function in Equation (6.186) is defined as:

f (U10 ) = ce U10 ,

Free convection of latent heat

Loss of heat due to evaporation occurs not only by forced convection, wind driven, but also
by free convection. Free convection is driven by buoyant forces due to density differences
(by temperature and/or water vapour content) creating unstable conditions in the atmospheric
boundary layer (ABL). Evaporation due to free convection is important in circumstances where
inverse temperature/density gradients are present and wind speeds are almost negligible so
that the amount of forced convection is small. Neglecting free convection in this situation will
lead to underestimating the heat loss. (Ryan et al., 1974) developed a correction to the wind
function, accounting for free convection. The derivation of evaporation by just free convection
is based on the analogy of heat and mass transfer.
The latent heat flux due to free convection reads:

Qev,free = ks LV ρa (qs − qa ) ,

with the average air density:

ρa0 + ρa10
,
2

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and with the heat transfer coefficient defined as:
if ρa10 − ρa0 ≤ 0

o1/3
(ρa10 − ρa0 )

if ρa10 − ρa0 > 0

where the coefficient of free convection cf r.conv was calibrated to be 0.14, see (Ryan et al.,
1974). The viscosity of air νair is assumed to have the constant value 16.0 × 10−6 m2 /s. The
molecular diffusivity of air α m2 /s is defined as

νair
,
(6.193)
σ
with σ = 0.7 (for air) the Prandtl number. In Equation (6.190), the saturated air density is
α=

100Patm −100es
Rdry

the remote air density (10 m above the water level):

100Patm −100ea
Rdry

where Rdry is the gas constant for dry air: 287.05 J/(kg K) and Rvap is the gas constant
for water vapour: 461.495 J/(kg K). The specific humidity of respectively saturated air and
remote air (10 m above the water level), qs and qa are given by Eqs. (6.187) and (6.198). The
saturated and remote vapour pressure es and ea are defined in Eqs. (6.184) and (6.185).

Qev evaporative heat flux summarized

The total heat flux due to evaporation then results from adding the forced convection of latent
heat in Equation (6.186) and the free convection of latent heat in Equation (6.190):

Qev = Qev,forced + Qev,free
Qev,free = ks LV ρa {qs (Ts ) − qa (Ta )}
Qev,forced = LV ρa f (U10 ) {qs (Ts ) − qa (Ta )}
with:

o1/3
(ρa10 − ρa0 )

The specific humidity of saturated air

0.62es
Patm − 0.38es

The specific humidity of remote air

if ρa10 − ρa0 > 0

Lv the latent heat of vaporisation

qs (Ts ) =
qa (Ta )

if ρa10 − ρa0 ≤ 0

LV = 2.5 × 106 − 2.3 × 103 Ts
qs (Ts )

heat transfer coefficient:

0.62ea
Patm − 0.38ea

Conceptual description

wind function: ce U10
average air density:

The saturated air density is given by:

100Patm −100es
Rdry

100Patm −100ea
Rdry

saturated pressure:

0.7859+0.03477Ts
1.0+0.00412Ts

remote vapour pressure:

Rdry
Rvap
Patm
U10
ce
rhum
Ta
Ts
cf r.conv
g
α
νair
σ
6.2.1.8

remote air density (10 m above the water level):

0.7859+0.03477Ta
1.0+0.00412Ta

gas constant for dry air: 287.05 J/(kg K) is the
gas constant for water vapour: 461.495 J/(kg K)
Atmospheric pressure
Wind velocity at 10 m
Dalton number (=0.0015)
relative humidity
air temperature
water surface temperature
coefficient of free convection (= 0.14)
gravity
molecular diffusivity (= νair /σ )
viscosity of air (=16.0 × 10−6 m2 /s)
Prandtl number (= 0.7)

Convective heat flux

The convective heat flux is split into two parts, just as the evaporative heat flux. The convective heat flux is divided into a contribution by forced convection and a contribution by free
convection.

Qco = Qco,forced + Qco,free

Forced convection of sensible heat
The sensible heat flux due to forced convection is computed by:

Qco,forced = ρa cp g (U10 ) (Ts − Ta ) ,

ρa
g (U10 )
Deltares

air density as specified in input
wind speed function is defined following Gill (1982): cH U10

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Stanton number (= 0.0013)
air temperature
water surface temperature
specific heat capacity of air; = 1004.0 J/(kg K)

Free convection of sensible heat
The sensible heat flux due to free convection is computed by:

Qco,free = ks ρa cpa (Ts − Ta )

heat transfer coefficient:
if ρa10 − ρa0 ≤ 0

100Patm −100es
Rdry

remote air density (10 m above the water level):

if ρa10 − ρa0 > 0

The saturated air density is given by:

o1/3
(ρa10 − ρa0 )

average air density:

100Patm −100ea
Rdry

Stanton number (= 0.0013)
air temperature
water surface temperature
specific heat capacity of air; = 1004.0 J/(kg K)

Input parameters for composite model

The input parameters for the composite model are:

Fc
Ta
rhum
ce
cH
cp

percentage of sky covered by clouds (time dependent, Meteo data)
air temperature in ◦ C (time dependent, Meteo data)
percentage of relative humidity (time dependent, Meteo data)
Dalton number (default value: 0.0013)
Stanton number (default value: 0.0013)
specific heat capacity of water (default value: 3930 J/(kg K) for sea water)

Conceptual description

Salinity dispersion
When one of the boundaries of a river or estuary is in contact with the sea, salt water may enter
the system. Salt intrusion into a river or estuary is determined by the fresh water discharge
on the river side and mixing of the water column by the tides. Mixing occurs due to tidal shear
between streamlines of different velocities, tidal trapping of water in tidal flats or side channels,
residual currents within the cross section (tidal pumping) and turbulent mixing at small scales.
The dominant physical process is the gravitational circulation: it transports salt and thus more
dense water near the bed in landward direction and fresh water near the surface in seaward
direction. Mixing of the water column by the tide reduces the gravitational circulation.

For the one-dimensional D-Flow 1D the three-dimensional mixing processes are parametrized
into a dispersion term. This dispersion term represents the processes that cannot be described in a cross section averaged model. The advection term in D-Flow 1D only represents the transport of salt with the cross sectional averaged flow. In D-Flow 1D a dispersion coefficient is used in the advection-diffusion equation SOBEK3_TRM (2013, §1.7). The
advection-diffusion equation is coupled via a state equation, relating salinity and density, to
the momentum equation.
For estuaries several formulations for the dispersion coefficient are available. Thatcher and
Harleman (1972) defined a dispersion formula based on field observations in three estuaries
in the USA and on a tidal flume experiment. Within their formula they made distinction between shear dispersion which is also present in the fresh water region of an estuary (first part)
and tidal dispersion (second part):

D = 77 u n R5/6 + kL2e

u
n
R
k
Le
u0
s0,max
Nr
s
x

flow velocity [m s−1 ],
1
Manning coefficient [s m− 3 ],
hydraulic radius [m],
parameter for tidal dispersion to be defined by the user [-],
the estuary length [m],
absolute maximum flood flow velocity [m s−1 ],
the maximal salt concentration in the estuary mouth [kg m−3 ],
estuarine Richardson number [-],
salt concentration [kg m−3 ],
Coordinate along branch [m].

The estuarine Richardson number (Nr ) expresses the balance between the stratifying factors
(fresh water input) and the mixing factors due to the tide. Therewith it is a measure for the
degree of stratification. It is used in all formulations. For low numbers of Nr the estuary is
well mixed, while for high numbers it is highly stratified. According Fischer et al. (1979) the
transition for Nr occurs between 0.08 and 0.8. The estuarine Richardson number is defined
as:

∆ρ ghQf T
ρw u20 Pe

∆ρ
ρw
Qf
Deltares

density of sea water minus density of inflowing fresh water [kg/m3 ]
density of inflowing fresh water [kg/m3 ]
fresh water discharge [m3 /s]

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tidal period [s]
tidal prism: the water entering the estuary from the sea side during flood [m3 ]
acceleration due to gravity [m s−2 ],
Total water depth [m]

Various newer dispersion formulations exist. Kuijper and Van Rijn (2011) modified a formulation for the tidal dispersion term described by Savenije (2012). Based on Ippen and Harleman
(1961) they added a friction parameter to account for vertical mixing related to the ratio of
dissipated energy by means of bed friction and gained potential energy of the fresh river water due to an increase in density. Furthermore, they added depth explicitly in the formulation.
They distinguished between convergent (trumpet shaped) and prismatic estuaries (having
straight banks). The formulation for prismatic channels is defined at high water slack (HWS):

C
sHW S
DHW S = 6αc u0 d0 Nr1/2 √ eφx HW S
g
s0
and for convergent estuaries:

1
δu 3(a − b)
+
+
2
2ab
2a

calibration factor with default 1, and 0.7 ≤ αc ≤ 1.3 [-],
salt concentration in the mouth [kg m−3 ],
damping term for the damping of tidal amplitude [m−1 ],
Location increasing into the estuary [m],
damping coefficient [m−1 ],
cross-sectional convergence length [m],
width convergence length [m].
average water depth in a branch [m], ,
tidal excursion length [m],
Chézy coefficeint [m0.5 s−1 ],

αc
s0
φ
x
δu
a
b
h0
E0
C
6.2.3

C
sHW S
h0
E0 Nr1/2 √ eφx HW S
a
g
s0

DHW S = 60αc u0

Sediment transport capacity

The D-Flow 1D module computes the sediment transport capacity according to the following
two formulations.
Frijlink

p
Tv = D50 gµR|Se |5 exp



µ=


−0.27D90
µR|Se |
3/2

12R
D90 + √ 3ν

Conceptual description

Sediment transport capacity per m bed width [m2 /s]
Bottom roughness factor (ripple factor)
Grain diameter at which 50 % of the grains is smaller [m]
Grain diameter at which 90 % of the grains is smaller [m]
Hydraulic radius [m]
Energy slope [−]
Chézy coefficient [m1/2 /s]
Kinematic viscosity [m2 /s]. Normally 1.002 × 10−6
Water level [m]
Velocity [m/s]
Acceleration due to gravity [m/s2 ] (≈ 9.81)
Length of branch segment [m]

Tv
µ
D50
D90
R
Se
C
ν
h
u
g
x

2.1 p
Tgr
1.5
Tv = 0.053 0.3 (s − 1)gD50
Dgr

u2∗ − u2∗c
if u2∗ > u2∗c
u2∗c
Tgr = 0 if u2∗ ≤ u2∗c
√
u g
u∗ =
C

12R
10
C = 18 log
3D90

Van Rijn
(6.223)
(6.224)
(6.225)
(6.226)
(6.227)

Chézy coefficient related to bed material
Average flow velocity [m/s]
Critical shear stress velocity according to Shields [m/s]

The grain size under water is defined dimensionless by Dg r :

(s − 1)
s
rs
rw
ν

Relative density
s = s/w
Density of sediment [kg/m3 ]. Normally 2650 kg/m3
Density of water [kg/m3 ]. Normally 1000 kg/m3
Kinematic viscosity [m2 /s]

The critical shear stress velocity according to Shields u∗c can be found with

p
θcr (s − 1)gD50

−1
0.24Dgr
if Dgr ≤ 4



−0.64

if 4 < Dgr ≤ 10
0.14Dgr
−0.1
θcr = 0.04Dgr
if 10 < Dgr ≤ 20

−0.29


0.013Dgr
if 20 < Dgr ≤ 150


0.055
if Dgr > 150

Note: The sediment transport capacity computed with these formulas is always positive.
To give an indication of the direction of the sediment transport in the network, the result is
multiplied by the sign of the velocity.

SOBEK, User Manual

The mentioned formulas are defined in sediment transport capacity per meter bed width. To
arrive at a more comprehensible definition the results are multiplied with a certain characteristic width. For closed cross sections, the maximum width of the profile is taken. For open
cross sections the wetted perimeter at a certain level (normally 0.30 m) above the bed level is
taken.
Note: The parameters that are used in the formulations, like grain diameters, are constant
over the whole network
6.3
6.3.1

Hydrodynamics Overland 2DFLOW
Continuity equation (2D)

1 the continuity equation,
2 the momentum equation for the x-direction and
3 the momentum equation for the y -direction.

The continuity equation reads:

The flow in two dimensions is described by three equations:

∂ζ ∂hu ∂hv
+
+
=0
∂t
∂x
∂y
where:

velocity in x-direction [m/s]
velocity in y -direction [m/s]
water level above plane of reference [m]
total water depth [m]
depth below plane of reference [m]

The continuity equation ensures the conservation of fluid.
6.3.2

Momentum equations (2D)

For two dimensional flow, two momentum equations are calculated, together with the continuity equation 2D. The momentum equations read:

∂u
∂u
∂ζ
u|~u|
∂u
+u
+v
+g
+ g 2 + au|u| = 0
∂t
∂x
∂y
∂x
C h
∂v
∂v
∂v
∂ζ
v|~u|
+u
+v
+g
+ g 2 + av|v| = 0
∂t
∂x
∂y
∂y
C h

(6.232)
(6.233)

u
v
|~u|
ζ
C
h
d
a

velocity in x-direction [m/s]
velocity in y -direction [m/s
√ ]
velocity magnitude (= u2 + v 2 ) [m/s]
water level above plane
√ of reference [m]
Chézy coefficient [ m/s]
total water depth (= d + ζ ) [m]
depth below plane of reference [m]
wall friction coefficient [1/m]

Conceptual description

They consist of acceleration terms, the horizontal pressure gradient terms, convective terms,
bottom friction terms and wall friction terms. These equations are non-linear and they are
a subset of the well-known shallow water equations, that describe water motion for which
vertical accelerations are small compared to horizontal accelerations (this applies to tidal flow,
river flow, flood flow).
6.3.3

Branch growth formulae available at a "Flow 1D Dam Break Branch"
Two bbranch growth formulae are available at a "Flow 1D Dam Break Branch":

The Verheij-vdKnaap(2002) formula (see section 6.3.3.1), and
The vdKnaap(2000) formula section 6.3.3.2).

Verheij-vdKnaap(2002) bbranch growth formula
First the Verheij-vdKnaap(2002) bbranch growth formula is discussed. Thereafter, default
values (as well as a range of values) for the parameters used in the Verheij-vdKnaap(2002)
formula are given.
The Verheij-vdKnaap(2002) formula:

Two phase can be discerned:

Phase 1: during which the bbranch, for a constant initial width(B0 ), is lowered from its
initial dike level or crest level (zcrest level ) to its final bed level or crest level (Zmin ).
Phase 2: during which the bbranch only grows in width as long as the flow velocity through
the bbranch is larger than the critical flow velocity for eroding sediment/soil particles (uc ).
Phase 1:

For Tstart ≤ t ≤ Tstart + tPhase 1

z(t) = zcrest level −

t − TStart
tPhase 1

(zcrest level − zmin )

For t > Tstart + tPhase 1 (hence B(t) ≥ B0 ):

B(ti+1 ) = B(ti ) + ∆t

f1 f2 (g(hup −max(hdown ,zmin )))3/2
1
f g
ln(10)
u2c
1+ u2 (ti −t0 )

factor1: constant factor (input parameter) [−] (default value =1.3)
factor 2: constant factor (input parameter) [−] (default value = 0.04)

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B(t)
B0
∂B
∂t

width of the dike-bbranch at point-in-time t [m]
Initial width of the dike-bbranch [m]
Rate of bbranch width growth in time-step ∆t from ti to ti+1 [m/h]

g
acceleration due to gravity [m/s2 ]
hup
upstream water level at point-in-time t [m]
hdown
downstream water level at point-in-time t [m]
t
actual computational point-in-time [h]
Tstart + tPhase 1 = the point-in-time when the maximum bbranch-depth (zmin ) is branched,
tPhase 1
duration of phase 1, the time period over which the bbranch for a constant initial
width (B0 ) is lowered from its initial dike level or crest level (zcrest level ) to its final
bed level or crest level (zmin ) [h].
Note: T0 in hours relative to a reference time!
Tstart
computational point in time at which the development of the initial bbranch starts
[h]
u
average flow velocity in the bbranch [m/s]
uc
constant critical flow velocity for eroding sediment/soil particles (input parameter). If u > uc bbranch material is picked up by the flow [m/s]
z(t)
elevation of the dike-bbranch at point-in-time t [m]
zcrest level elevation of the crest level of the dike at t = tstart (input parameter) [m]
zmin
Elevation of the dike-bbranch at t = t0 (input parameter) [m]
Defaults in the Verheij-vdKnaap(2002) formula

To submit proper values a list of default values as well as the range of values given in the table
below can be used.
Parameter

Characterising soil strength:
The parameter uc , applied in the Verheij-vdKnaap(2002) formula may be derived from the
table given below.
Table 6.6

Bodemtype (Dutch)

Conceptual description

clay, good (firm)
clay,
moderate (little
structure)
clay moderate (considerable structured)
clay, bad (weak)

(compact; tongedraineerd = 80 - 100
kPa)
klei met 60% zand,
(stevig; tongedraineerd = 40 - 80 kPa)
goede klei met weinig structuur

goede klei, sterk

slechte klei
(slap; tongedraineerd = 20 - 40 kPa)
zand met 17% silt
zand met 10% silt
zand met 0 % silt

0.225
0.20
0.16

sand with 17% silt
sand with 10% silt
sand with 0% silt7

gras, goed
gras, matig
gras, slecht
klei, zeer goed

grass, good
grass, moderate
grass, bad
clay, very good (compacted)

In addition, it is possible to calculate uc from τc by applying the following formula:

√
uc = 0.5 τc

uc = uc,sand (1 + 0.01αPclay + β(0.65 − v)

using the defaults, α = 15, β = 1, Uc,sand = 0.2 m/s
Further on yields:

v = n/(1 − n)

where n = the soils pore fraction (default n = 0.4), and Pclay = percentage of clay.
Literature:

Formula Verheij-vdKnaap (2002):Verheij (2002)
6.3.3.2

vdKnaap(2000) bbranch growth formula

This formula consists of equations: one for sand dikes, and one for clay dikes.
The following information is used in calculating the bbranch area (or time-Area) table:

maximum allowed bbranch width Bmax ; 200 m for sand and 75 m for clay
maximum number of steps for the bbranch area (or time-Area) curve when the dam break
grows in width (nmax = 20)
minimum step size for generated a bbranch area (or time-Area) table (smin = 5 s)
minimum increase in bbranch area per time step for a generated bbranch area (or timeArea) table (dAmin =0.01 m2 )
percentage areal increase for 1st step on bbranch area (or t-A) curve to smooth linear part
with logarithmic curve (p = 10 %)

SOBEK, User Manual

Info supplied by the user through the user interface:

initial bbranch width (Bini )
maximum bbranch depth (Dmax )
start of dam break (t0 )
time to branch maximum bbranch depth (dt1 )
type of dam material (i.e. sand or clay)
either maximum bbranch width (Bmax ) or time to branch max. bbranch width (dtmax )

The dam material (i.e. sand or clay) determines the equations that will be used to compute
the time-dependent development of the branch, viz:

for sand: B(t) = 67 10 log(t/522) and t(B) = 522 × 10B/67
for clay: B(t) = 20 10 log(t/288) and t(B) = 288 × 10B/20
The info supplied by the user is checked on the following conditions:

Bini > 0
Dmax > 0
Bini + B(smin nmax ) ≤ Bmax
dt1 + smin nmax ≤ dtmax < t(Bmax )

If all conditions are met, two initial time steps (the linear part) are calculated:
1st time step: A0 = 0 m2
2nd time step: t1 = t0 + dt1 and A1 = Dmax Bini

Then, based on the end condition, the last time step is calculated according to the applicable
equation. The starting point for the equation (t = 0) is supposed to coincide with t1 .
NB: The total number of time steps is nmax time steps + 2 initial time steps (i.e. 22).
22nd time step: t21 = t0 + dtmax or t21 = t1 + t(Bmax ) and A21 = Dmax B(t21 − t1 )
Now all intermediate time steps (3rd through 21st) can be calculated. Because of the equations being logarithmic functions, these time steps are not linearly divided over the remaining
interval, but as shown in the figure below, thus producing more values for B in the region
where the curve is steep.

Figure 6.60: Dam break Bbranch vdKnaap(200), timestep subdivision

When x0 = t21 − t1 , x1 = t20 − t1 and d is a divider such that d = x0 /(t21 − t20 ) then:

1 1
xn = x0 (1 − )
and xn ≥ smin
d nmax
582 of 900

Conceptual description

(1 − smin /x0 ) nmax − 1

Based on this divider d the time steps t20 through t2 can be calculated:

ti = ti+1 + (t1 − ti+1 )/d
Ai = Dmax B(ti − t1 )

(6.244)
(6.245)

Since the logarithmic functions will evaluate negative values when closing in to t = 0, there
will often be some values (from t2 upto tk ) calculated for the bbranch width smaller than Bini .
Of course the bbranch width can not decrease, so these values are removed from the table,
except for the last one (tk with Ak such that Ak+1 > A1 ), which is used to smoothen the
linear part with the logarithmic curve.

A percentage p is introduced to determine the bbranch width value for this point according to
the following rule:

Ak = A1 + p(Ak+1 − A1 )

Figure 6.61: Bbranch width computation according vdKnaap(2000)

Formulas vdKnaap (2000): Van der Knaap (2000),
6.3.4

1D-2D connection
The 1D network is linked with the 2D grid in the following ways:

The connection between the 1D connection Node and 2D grid cell;
The connection between the 1D ζ -calculation Points and 2D grid cell.
The following rules should be kept in mind, only one connection per grid cell is allowed. In
other words, you cannot have both a connection node and calculation point in one grid cell,
nor more that one connection node or ζ -calculation point per grid cell. It is simpler to assume that 1D and 2D networks are two independent map layers, with the 2D network map
layer overlapping a 1D network. The computational code determines the connection points

SOBEK, User Manual

between 1D and 2D based on the map coordinates for the centre of 2D grid cell and the 1D
connection node / ζ -calculation node. If they fall within certain criteria, then the connection
is made between them, else not. The criteria, if expressed in mathematical terms, are as
follows:
if (|X1 − X2| ≤ ∆x/2) and (|Y 1 − Y 2| ≤ ∆y/2), where:

X1
X2
Y1
Y2
∆x
∆y

x map coordinate for 1D point
x map coordinate for 2D grid cell
y map coordinate for 1D point
y map coordinate for 2D grid cell
width of grid cell in x-direction
width of grid cell in y -direction (∆x and ∆y are equal)

then the 1D point is assumed to lie completely within the 2D grid cell.
The connection between the 2D cells and the 1D network is done in the following way (see
figure below):

The center of 1D node is internally moved to match with the center of 2D grid cell, without

changing the length of the connecting 1D branches.

The 2D Grid Cell is counted as part of 1D Node.
The flow in 1D channel below the 2D grid level is treated as 1D flow, while the flow above
the 2D Grid level is treated as 2D flow with the area of 2D grid cell.

Figure 6.62: Connections between 1D and 2D

Conceptual description

Modelling 1D2D
Principle is that the top width of the remaining (clarification below) 1D channel should be
smaller than the 2D grid cell size. The way of 1D-2D linking depends on the option you
choose in the Advanced Settings tab:

Assume No Embankments: In this case the elevation of the underlying 2D grid cell
remains the same. The 1D cross-sectional profile above the elevation of the underlying
2D grid cell is omitted (hence excluded from computation).

In case the water level is below 2D grid elevation, the flow is fully 1D only (note that
the width of the 1D channel might be (and preferably: should be) smaller than the 2D
grid cell size).
In case water level is above the 2D grid cell elevation; there is a 1D flow as well as
2D flow. In the 1D cross-sectional profile below the 2D grid cell elevation, 1D flow is
computed in accordance with the underlying 1D profile and 1D hydraulic roughness.
Above the 2D grid cell elevation, there is only 2D flow and this is of course over the full
2D grid cell size, both in x- and y - direction.

Assume Highest Level of Embankments: In this case SOBEK raises the elevation of

the underlying 2D grid cell to the highest embankment level. No part of the 1D crosssectional profile is omitted. Thereafter the computation is identical as described under
option 1 (Assume no embankments), with the notation that not the original 2D grid cell
elevation is used but the raised grid cell elevation.
Assume Lowest Level of Embankments: Same as option 2 above, but with notation that
the part of the 1D cross-sectional profile above the lowest embankment level (i.e. minimum
of left and right 1D embankments) is omitted and that the elevation of the underlying 2D
gridcell is raised to the elevation of the lowest embankment level.
In general you can best model your river fully 2D when your 1D profile width > 2D grid cell
size.
6.3.5

2D-2D connection

The 2D grid cell connection to another 2D grid cell when one grid is partially or fully overlapping another grid, is done in such a way that the 2D Grid cell of the nested grid is connected
to the 2D grid cell of underlaying grid by a branch. This branch carries the flow to and from
the two connecting grid cells. This branch is given the property of the smallest grid cell and
with a very low friction coefficient so that the hindrance of flow is negligible.
The computational core defines the connection between two 2D grid cells based on the map
coordinates for the center of each grid cells. If they fall within certain criteria, then the connection is made between them else not. The criteria, expressed in mathematical terms, are:

(|X1 − X2| ≤ ∆x) and (|Y 1 − Y 2| < Y H . . . 1)
(|Y 1 − Y 2| ≤ ∆y) and (|X1 − X2| < XH . . . 2)

(6.247)
(6.248)

X1
X2
Y1
Y2
∆x
∆x
XH
Deltares

x map coordinate for 2D grid cell in first grid
x map coordinate for 2D grid cell in second grid
y map coordinate for 2D grid cell in first grid
y map coordinate for 2D grid cell in second grid
(∆x1 /2 + ∆x2 /2)
(∆y1 /2 + ∆y2 /2)
maximum of ∆x1 /2 or ∆x2 /2
585 of 900

SOBEK, User Manual

YH
∆x1
∆y1
∆x2
∆y2

maximum of ∆y1 /2 or ∆y2 /2
width of grid cell in x-direction in first grid
width of grid cell in y -direction in first grid
width of grid cell in x-direction in second grid
width of grid cell in y -direction in second grid

The connection is made, if any of the above two criteria matches. It is possible that there are
more connections made to the same 2D grid cell from different 2D grid cells in another grid.

Figure 6.63: Connections made between different grids

Note: please bear in mind that the outside cells of any grid are removed from the calculation.
So, in the example of Figure 6.63, the connections are made between the large (parent) grid
cell and the second column of grid cells of the child grid!
6.4
6.4.1

Triggers and Controllers
Controller

The SOBEK-Flow-module offers the option to operate hydraulic structures.
The adjustable part of a hydraulic structure (e.g. crest level, crest width, Gate Lower Edge
Level [m AD]) can be adjusted by a controller. In the River Flow and Real Time Control
modules, more than one controller can operate on the same hydraulic structure, however,
a specific control parameter (crest level, etc.) can be steered by only one controller at a
time. Also, one controller can steer the same control parameter of more than one hydraulic
structure, e.g., it is possible to steer the gate lower edge level of a series of structures by only
one controller.
In case no trigger is assigned to a controller, this controller will be active during the entire
computation.
Six controller types have been implemented:
1
2
3
4
5

Interval controller
Hydraulic controller
PID controller
Time controller
Relative time controller

Conceptual description

6 Relative from value (time) controller
The parameters that can be controlled are:
Crest level of a weir
Crest level and crest width of River weir
Crest level of Advanced weir
Crest level, crest width and gate lower edge level of General structure
Crest level of Database structure
Opening height of a orifice
Capacity of a pump (Rural Flow module only)
Valve opening of a culvert
Valve opening of a siphon
Valve opening of an inverted siphon

For more details on controllers available for the Advanced weir, Database structure, General
structure and River weir, see also Appendix B (River Flow controller options).

A control frequency should be given. This frequency defines when the controller function
should be updated. This may be every time step (control frequency 1), but also after a number
of time steps (control frequency n).
Procedure for the River Flow module (usage of triggers):
The controller function is activated once for each time step in the computational process (the
controller is not updated during the iteration process of solving the flow equations). Just before
the start of the iteration process the controller is updated in the following way.
For each controller:

if (a trigger is defined for this structure) then
if ’trigger==ON’ then
activate controller function

do not activate controller function

activate controller function

As you see, a controller can be activated by a trigger, but it can also be activated by a combination of triggers. The computation of the actual control parameter (the carrying out of
controller function) for a structure is as follows:
if controller should be evaluated (depending on the user defined control frequency) then

if ’time controller’ then evaluate time controller
if ’hydraulic controller’ then evaluate hydraulic controller
if ’Interval controller’ then evaluate interval controller
if ’pid controller’ then evaluate pid controller
if ’relative time controller’ then evaluate relative time controller
if ’relative from value controller’ then evaluate relative from value controller

SOBEK, User Manual

A control frequency should also be given. This defines when the controller function should be
updated. This may be every time step (control frequency 1), but also after a higher number of
time steps.
The control frequency of an hydraulic controller can also be specified zero. This means that
the control parameter will be updated only the first time after the end of an inactive period. A
trigger should be used to activate the hydraulic controller.

Combinations of controllers

If a time controller, a relative time controller or a relative from value controller is used the
parameter ’dvalue/dt’ must be given a value. This parameter defines the maximum speed of
increase or decrease of the control parameter. It provides some physical damping, to prevent
that instabilities arise due to sudden changes in the structure opening. With for instance a
value of ’dvalue=0.1’, the speed of opening or closing of a gate is 0.1 m/s (e.g., 1 m change
of gate lower edge level in a computational time step of 10s).

The crest level, crest width or gate lower edge level of a hydraulic structure can be operated
by more than one controller. SOBEK allows up to four controllers for one structure. A specific
crest level, crest width or gate lower edge level of a hydraulic structure can be operated by
only one controller at a time. In case two or more controllers are given a value for a particular
structure parameter (e.g. crest level), then SOBEK stops the computation. By using triggers
the user should avoid the situation that two or more controllers are simultaneous active for
one and the same structure parameter.
Hydraulic controller

The hydraulic controller is a relatively simple controller type which can be used to operate
a structure as a (tabulated) function of a specified hydraulic parameter. In other words: the
crest level, opening height, pump capacity or valve opening is a function of one of the following
parameters:

Water level at a specified measurement station
Discharge at a specified measurement station
And, only for the River Flow module:

head difference over a hydraulic structure(perhaps another structure than the controlled
one!);

flow velocity at a specified measurement station;
flow direction at a specified measurement station;
pressure difference over a structure or compound structure member (perhaps another
structure than the controlled one!).

The computation procedure is straightforward. First, the value of the hydraulic argument at
the previous time step is determined. Next, the control parameter is computed by interpolation
in the controller table. In case of the discharge a user specified time lag with respect to the
current time can be taken into account.

Conceptual description

Figure 6.64: Example of hydraulic controller

If the control frequency of an hydraulic controller is specified zero, the control parameter will
be updated only at the start of an active period. A trigger should be used to activate the
hydraulic controller

In case the head difference ∆h over a structure is used as controller, the following formula
will be used:

∆h = h1 − h2

In case the pressure difference ∆P over a structure is used as controller, the following formula
will be used:

1
∆P = g(ρ1 (h1 − zs )2 − ρ2 (h2 − zs )2 )
2

This is in fact the difference between the pressure triangles with respect to the crest level zs
on both sides.
where

h1
h2
zs
ρ1
ρ2
6.4.1.3

water level at structure facing beginning of the branch;
water level at structure facing end of the branch;
crest level of structure;
water density at structure facing beginning of the branch;
water density at structure facing end of the branch.

Interval controller

The interval controller can be used to operate a structure in such a way that a specified
hydraulic parameter is maintained. The controlled parameter can be the water level at a
specified measurement station in the model, the discharge at a specified measurement station
in the model, or the sum of up to five discharges at specified measurement stations in the
model .
The user defines the following input for the interval controller:

Control parameter (crest level, crest width, gate lower edge level)
Control frequency (see controller).
A selection of the controlled parameter (water level or discharge at the measurement
station).

SOBEK, User Manual

Setpoints for the controlled parameter (constant or tabulated function of time).
The so called ”when below deadband” and ”when above deadband” control values.
These “< Deadband” and “> Deadband” values are the extreme values or upper and
lower boundaries allowed for the control parameter (e.g. crest level) (see also River Flow
Controller options). The desired direction is also determined from these values. (upward
or downward of the control parameter (e.g. crest level).
A selection of the deadband type:

fixed deadband: enter a value
deadband as a percentage of the discharge: you must enter percentages and maximum and minimum deadband values

selection of the controller interval type (or maximum allowable change in value of control
parameter):

fixed interval: you must enter fixed interval value of the controlled parameter
check velocity: enter the controller velocity or speed in m/s (positive values only)

The value of the control parameter νs is computed as follows:


1
νs,old + d∆νs if e < − 2 D
νs = νs,old
if − 12 D ≤ e ≤ 21 D

νs,old − d∆νs if e > 12 D

Deadband (in [m] in case of water level, and in [m3 /s] in case of discharge)
Deviation of the controlled variable, e = setpoint - actual measured (computed)
value
Control direction (1 or -1). We define control values a and b:

Define a as the value of the lower boundary of the control parameter. (User
interface: ”when below deadband”)

Define b as the value of the upper boundary of the control parameter. (User
interface: ”when above deadband”)

The control direction is positive if a > b and negative if b > a.
Maximum change of control structure parameter, νs = v × dt

v = maximum change of control structure parameter per second
dt = timestep in seconds

So, the rough algorithm is as follows:
if ’interval controller’ present, then

determine value at the previous time step of controlled parameter
compute deviation of the value of the controlled parameter at the previous time step from
the setpoint
compute the value of the control parameter (according to the algorithm described)
check if the control parameter is within its extreme values (if not: set the extreme value).
The extreme values are the allowed value for the control parameter (e.g. crest level) and
are equal to “< Deadband (or when below deadband)” and “> Deadband (or when above
deadband)” values.

Conceptual description

Figure 6.65: Example of interval controller

The interval controller is not a very advanced type of controller. It is, for instance, sensitive
to instabilities, particularly if the controller velocity, control frequency or deadband are not
selected properly. Also the control history (before the last time step) is not taken into account
to determine the control parameter.
A more advanced controller (the PID controller) is available as well. The PID controller takes
the control history into account, thus enabling a more appropriate behaviour of the control
parameter.
6.4.1.4

The PID-controller can be used to operate a structure in such way, that a specified hydraulic
parameter (e.g. water level or discharge) is maintained. The PID-controller consist of a Proportional, Integrating and Differentiating part. The controlled parameter can be the water
level or the discharge at a specified measurement station in the model. The user defines the
following input for the PID controller:

control parameter (crest height, width, gate lower edge level)
control frequency (see controller)
a selection of the controlled parameter (water level or discharge at the measurement station). For river flow, also the sum of discharges adding up to five measuring stations.

setpoints for the controlled parameter (constant or tabulated function of time)
initial value of the controlled parameter; note that the initial control value should preferably
be the same as for the structure definition

maximum and minimum value of the control parameter (e.g. control parameter can be

between fixed limits)
maximum change of control structure parameter per second (vmax in m/s)
Proportional gain factor Kp (determines the reaction time of the controller)
Integral gain factor Ki (reduces the standard deviation induced by Kp )
Differential gain factor Kd (provides damping in the controller)
A control (Update) frequency which may be used to filter out high frequency oscillations
in the input signal, but which must be sufficiently small to reproduce the relevant waves in
the controlled variable.

The new value of the control parameter w(t) is computed as follows:

SOBEK, User Manual

1 First compute the correction value
0

u(t) = Kp e(t) + Ki

e(t) + Kd (e(t) − e(t − 1))

2 Perform this correction value to the control parameter w(t)

w(t) = w(t − 1) + u(t)

Kp , Ki , Kd Coefficient of the PID-controller.
kj
j = 1, 2, 3. Conversion factor between the controll parameter (e.g. discharges
[m3 /s]) and the controlled parameter (e.g. water levels [m])
e(t)
deviation of the controlled parameter y(t), e(t) = ysp (t) − y(t)
u(t)
correction factor on the control parameter, e.g. e(t) ≡ 0 ⇒ u(t) = 0 ⇒ w(t)
Remark:
Equation (6.254) is slightly different from a the PID-controller as reported in Åström and
Hägglund (1995) and as report in RTC-Tools TRM (2012).
The algorithm to compute the control parameter is as follows:

determine value of controlled parameter at previous time level
compute deviation of this value from the setpoint
compute change of deviation from the setpoint (e = e(t) − e(t − 1))
compute summation of deviation from the setpoint
compute the value of the control parameter w(t)
check if the computed change of the control parameter ∆w = w(t) − w(t − 1) is within
the user-defined limitations

The gain factors Kp , Ki , Kd must be calibrated for optimal performance of the PID controller.
See section B.6
6.4.1.5

Relative time controller

The relative time controller can be used to specify the controlled parameter as a function
of time, where the time (in seconds) is given relative to the moment that the controller is
activated for the first time by a trigger. When the controller is activated for the first time, the
relative controller table is made absolute (= computational time + relative time), thereafter
the controller starts at the top of the table and continues downward until it is turned off by
the trigger. The controller table will remain absolute during the user-defined so called Start
period. In case the controller is activated after this start period has passed, the controller
table will be made absolute again. Start period = 0, means that the controller table is made
absolute each and every time that the controller is triggered. In case the user defined value
for d(value)/dt is too small to allow for the in the controller Table defined changes in control
parameter, SOBEK will divert from these defined controller parameter values in such way as
to best fit the overall controller table. d(value)/dt = 0, means that there is no restriction in
change in controller parameter over one time step. When it branches the end of the table, the
value of the controlled parameter is kept constant at the last value.

Conceptual description

Relative from value (time) controller
The relative time controller can be used to specify the controlled parameter (e.g. crest level)
as a function of time, where the time (in seconds) is given relative. The difference with the
relative time controller is the fact that when activated for the first time (or after start period has
passed, see here after), the controller does not start at the top of the controller table but at
the row that coincides with the actual value of the structure controlled parameter (e.g. crest
level) and continues from there on downwards in the controller table. The advantage of the
relative from value (time) controller is that if used cleverly discontinuities in structure controlled
parameter can be avoided.

The first time that the relative-from-value (time) controller is activated, the controller table
will be made absolute (= computational time + relative time), the controller table will remain
absolute during the so called start period. Hence in case the controller is de-activated and
activated again within the start period, the controller table remains absolute. In case the
controller is activated after the start period has passed, the controller table will be made
absolute for the then yielding computational time again. Start period = 0, means that the
controller table is made absolute each and every time that the controller is triggered. In
case the user defined value for d(value)/dt is too small to allow for the in the controller
table defined changes in controlled parameter (e.g. crest level), SOBEK will divert from these
defined controller parameter values in such way as to best fit the overall controller table. A
value of d(value)/dt = 0, means that there is no restriction in change in controlled parameter
over one computational time step. When it branches the end of the Table, the value of the
controlled parameter is kept constant at the last value.
Time controller

The time controller is the most simple and straight forward controller. The control parameter (e.g. crest level, opening height, pump capacity, valve opening) is given explicitly as a
(tabulated) function of time.

Figure 6.66: Example of time controller

SOBEK, User Manual

Triggers
A hydraulic structure can be adjusted by a controller. Each controller in SOBEK can be activated or de-activated by a trigger, which can have the value ON or OFF. Also a combination
of triggers can activate a controller, while more than one controller can be activated by one
trigger or trigger combination. In case no trigger is assigned to a controller, this controller will
be active during the entire computation.
Three different trigger types are available:
1 time trigger;
2 hydraulic trigger;
3 Time & Hydraulic trigger (combined trigger).

Moreover, it is possible to perform a logical “and” or logical “or” function on the combination of
time trigger and hydraulic trigger.

Whether a trigger is ON or OFF is determined as follows:

if AND/OR period defined then
determine AND/OR period (AND/OR)
evaluate time trigger (ON/OFF)
evaluate hydraulic trigger (ON/OFF)
trigger = OFF
if (AND and (time trigger = ON and hydraulic trigger = ON)) then
trigger = ON
if (OR and (time trigger = ON or hydraulic trigger = ON)) then
trigger = ON
else if time trigger then
evaluate time trigger (ON/OFF)
else if hydraulic trigger then
evaluate hydraulic trigger (ON/OFF)
6.4.2.1

Combinations of triggers

Up to four triggers can be combined to activate or de-activate a controller. When the user
specifies more than one trigger, he must specify how the triggers work together by specifying
the relationship between the triggers with logical and-or statements. Evaluation of AND-OR
statements are according to the usual logical rules. This means that AND statements are
evaluated before OR statements.
This results in the following:

the combination of triggers ’trig1 and trig2’, ’trig12’, is evaluated as follows:
if (trig1 == ON and trig2 == ON ) then
trig12 = ON
else

trig12 = OF F
endif

the combination of triggers ’trig1 or trig2’, ’trig12’, is evaluated as follows:
if (trig1 == ON or trig2 == ON ) then
trig12 = ON
else

Conceptual description

the combination of triggers ’trig1 and trig2 and trig3’, ’trig123’, is evaluated as follows:
if (trig1 == ON and trig2 == ON and trig3 == ON ) then
trig123 = ON
else

trig123 = OF F
endif

the combination of triggers ’trig1 and trig2 or trig3’, ’trig123’, is evaluated as follows:
if ((trig1 == ON and trig2 == ON ) or trig3 == ON ) then
trig123 = ON
else

trig123 = OF F
endif

the combination of triggers ’trig1 or trig2 and trig3’, ’trig123’, is evaluated as follows:
if ((trig1 == ON or trig2 == ON ) and trig3 == ON ) then
trig123 = ON

To determine if a time trigger is ON or OFF, a user-defined time table, is used. In the time
table periods are defined during which the trigger is either ON or OFF.
6.4.2.3

Hydraulic trigger

To determine if a hydraulic trigger is ON or OFF, first the hydraulic parameter will be calculated
or the gate lower edge level will be retrieved. After this
SOBEK checks if the computed value exceeds a user defined threshold value.
Eight hydraulic trigger types are possible:
1
2
3
4
5
6
7
8

water level at a specified location
discharge at a specified location
gate lower edge level at a hydraulic structure
crest level at a hydraulic structure
crest width at a hydraulic structure
the water level in retention area
head difference at a hydraulic structure
force difference per unit width at a hydraulic structure

The head difference at a structure used by a trigger is defined as:

∆h = h1 − h2

The force difference (∆F ) per unit width over a structure is defined as:

1
∆F = g(ρ1 (h1 − zs )2 − ρ2 (h2 − zs )2 )
2

SOBEK, User Manual

g
h1
h2
zs
ρ1
ρ2

acceleration due to gravity;
water level at structure, facing beginning of branch;
water level at structure, facing end of branch;
crest level of structure;
water density at structure, facing beginning of branch;
water density at structure, facing end of branch

If gate lower edge level, crest level or crest width is chosen two options are available:
1 the value is checked against the threshold
2 the direction of variation (increase or decrease of the value) can be checked
The following procedure is used:

determine hydraulic trigger type
determine location
determine threshold value and whether it should be triggered on a "higher" value or a

trigger = OFF
if ’hydraulic trigger type = water level’ then
if ’trigger on higher value’
if ’h(location) > value’
trigger = ON
if ’trigger on lower value’
if ’h(location) < value’
trigger = ON
elseif ’trigger type = head difference’ then
head difference = hlef t − hright of structure
if ’trigger on higher value’
if ’head difference > value’
trigger = ON
if ’trigger on lower value’
if head difference < value
trigger = ON

Time & Hydraulic triggers

The Time & Hydraulic trigger is actually a combination of a Hydraulic trigger with a Time
trigger. This can be applied in “AND” or in “OR” mode.

AND mode means: Time & Hydraulic trigger value is ON if both the Hydraulic trigger and
the Time trigger are ON.

OR mode means: Time & Hydraulic trigger value is ON if either the Time trigger or the
Hydraulic trigger is ON, but also if both Time and Hydraulic triggers are ON.
6.5
6.5.1

Hydrology (Rainfall Runoff modules)
SOBEK-Rural RR (Rainfall Runoff) concept

Conceptual description

Alpha reaction factor
The reactionfactor α is an important parameter in the De Zeeuw-Hellinga equation which is
used in SOBEK to calculate the different components of the groundwater/subsurface flow:

qt = qt−1 e−α∆t + (I + S)(1 − e−α∆t )
qt
qt−1
∆t
α
I
S

specific discharge at time t [m/d]
specific discharge at time t − 1 [m/d]
time step [d]
reaction factor [1/d]
infiltration [m/d]
seepage (percolation) [m/d]

In SOBEK, the De Zeeuw-Hellinga equation is used to calculate the following components of
flow:

groundwater drainage (towards drainpipes or channels);
surface run-off;
infiltration from open water.

For each process, the user must define specific reaction factors.

Reaction factor groundwater drainage
In SOBEK, the ground can be divided into different ground layers, each with it’s own a. The
total specific discharge is calculated by applying the De Zeeuw-Hellinga equation to all layers,
and summing the result (see Figure 6.67)

Figure 6.67: Drainage levels

Usually, the division between the ground layers is placed at the level of the drains, which are
then simulated by giving the above drain level (αd,1 to αd,3 in the figure) a much higher value
than the a below drain level (αd,4 in Figure 6.67).
To obtain indications for the values of the reaction factor one can:

use the values in the Table below (Vademecum, 1988):
α Discharge type
100–200 Surface runoff from steep slopes
1–10
Surface runoff from soils with impervious subsoil
0.3–0.7
Drainage discharge from well-drained agricultural soil
0.03–0.07 Discharge from grassland without drainage system
Measure the decrease of discharge in time. This only can be done after a period of
(heavy)rain, and no additional precipitation, and no (or very little) evaporation.

SOBEK, User Manual

Derive the α value from
q = αµ∆h

specific discharge [m/d]
groundwater level above drainage depth or open water level [m]
reaction coefficient [1/d]
storage coefficient [−]
drainage resistance [d]

Reaction factor surface run-off

When the groundwater level branches the surface level or the precipitation excess exceeds the
infiltration capacity, water is stored on land. When the storage on land is filled in a SOBEK-RR
unpaved node the surface runoff process starts.
Therefore, the user must define a reaction factor αs . The above table gives indications for the
values of this reaction factor.

Figure 6.68: Surface run-off

Reaction factor infiltration from open water

In dry periods the groundwater level can decrease. When the groundwater level is lower than
the open water level, infiltration from the open water occurs. In SOBEK-RR, this process is
described by the modified De Zeeuw-Hellinga equation. Again, the user must define a specific
reaction factor, αi
6.5.1.2

Capillary rise
Capillary rise describes the unsaturated flow in the subsoil from the groundwater to the root
zone. Capillary rise occurs in case of a water deficit in the root zone. Water deficit is defined
as a water content less than equilibrium moisture storage. If the water content in the root
zone exceeds equilibrium the excess water percolates to the groundwater. The excess water
is the potential root zone volume minus the equilibrium moisture content. To assess whether

Conceptual description

capillary rise or percolation will occur over a time step, the potential root zone volume is
determined from the net precipitation and the evapotranspiration, based on the soil moisture
storage in the root zone at the previous time step:

V 0 (t) = V (t − ∆t) + (Pn − E)∆t

V 0 (t)
potential root zone volume at time t [m]
V (t − ∆t) root zone volume after the previous time step [m]
Pn
net precipitation [m/d]
E
evapotranspiration [m/d]
∆t
time step [d]

In case of a water deficit in CAPSIM the capillary rise flux is calculated in 2 steps. First
the potential capillary rise flux is calculated. The potential capillary rise flux depends on the
groundwater level, the soil physical unit and the root zone thickness:

qpot = f (s, dg , dr )

Potential capillary rise [mm/d]
Soil physical unit [-]
Depth groundwater level [m]
Root zone thickness [m]

The potential capillary rise flux is calculated with the 1-D, steady state simulation model CAPSEV (Wesseling, 1991), assuming pF = 3 in the root zone. The potential capillary rise fluxes
are tabulated.
Secondly SOBEK-CAPSIM uses the potential capillary rise flux, the actual moisture storage
in the root zone and the equilibrium moisture storage to calculate the actual capillary rise flux,
according to:

(
−vact
qpot vveqeq−v
pF 3
=
qpot

vact > vpF 3
vact < vpF 3

Actual capillary rise flux [mm/d]
Equilibrium soil moisture content [m]
Actual soil moisture content [m]

Equilibrium soil moisture content veq
The moisture storage of the root zone at equilibrium condition is calculated with the function:

Veq = f (s, dg , dr )

the moisture storage of the root zone at equilibrium condition [m]
soil physical unit [-]
thickness of root zone [m]
depth of the groundwater level [m]

SOBEK, User Manual

Soil moisture content at pF = 3, vpF 3
The moisture storage of the root zone at pF = 3 is calculated assuming steady conditions
and a groundwater level of 10 m minus soil surface.
6.5.1.3

Crop factors agricultural crops
The fixed input file with crop names and crop factors as a function of time. 1 year of data is
enough, since it is assumed that the crop factors are constant over the years; the variation is
taken into account in the reference evaporation data and not in the crop factors.
The header of the file contains the number of crops and crop names.

*Number of crops
16
*Names
’1 grass ’
’2 corn ’
’3 potatoes ’
’4 sugarbeet ’
’5 grain ’
’6 miscellaneous ’
’7 non-arable land ’
’8 greenhouse area ’
’9 orchard ’
’10 bulbous plants ’
’11 foliage forest ’
’12 pine forest ’
’13 nature ’
’14 fallow ’
’15 vegetables ’
’16 flowers ’
*Year/Month/Day/Cropfact 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0000 1 1 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 2 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 3 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 4 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 5 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 6 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 7 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 8 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 9 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 10 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 11 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 12 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
0000 1 13 0.95 1.00 1.00 1.00 1.00 0.95 1.00 0.00 1.00 0.00 0.90 1.20 0.95 1.00 1.00 0.00
etc.

Crop factors open water
The fixed input file with open water evaporation factors is a function of time. 1 year of data is
enough; it is assumed that the evaporation factors are the same for all years.
*Surface water
1
*Names
’0.0 Surface water ’
*Year/Month/Day/Cropfact 1
0000 1 1 0.50
0000 1 2 0.50
0000 1 3 0.50
0000 1 4 0.50

Conceptual description

0000
0000
0000
0000
0000
0000
0000
0000
0000
etc.

5 0.50
6 0.50
7 0.50
8 0.50
9 0.50
10 0.50
11 0.50
12 0.50
13 0.50

De Zeeuw-Hellinga drainage formula

To simulate the flow of groundwater towards the drainage system (i.e. drain pipes and/or
channels) the modified equation of De Zeeuw-Hellinga is used in the Rainfall-Runoff module.
The theory behind this equation is treated here.
The head loss of groundwater flowing to a drain can be subdivided in head loss caused by:

vertical flow;
horizontal flow;
radial flow nearby the drain/channel;
entrance in the drain/channel.

1
1
1
1
1
1
1
1
1

In the equation of De Zeeuw-Hellinga it is assumed that the head loss is mainly caused by
radial flow and entrance loss. The head loss by horizontal flow and vertical flow is neglected.
This equation is based on a reservoir containing a volume of ground. The reservoir discharges
through a capillary tube. The discharge depends on the difference in pressure head. Thus:

discharge [m3 /d]
proportional coefficient [m2 /d]
difference in pressure head [m]

q
Q
A
c2
h
α
µ

Q
= c2 h = αµh
A

specific discharge [m/d]
discharge [m3 /d]
area [m2 ]
proportional coefficient [1/d]
groundwater level above drainage depth [m]
reaction coefficient [1/d]
storage coefficient

The water balance for time dt is:

(I + S − q)∆t = µ∆h
I
S
t

infiltration [m/d]
seepage (percolation) [m/d]
time [d]

SOBEK, User Manual

µ
∆h
I + S − αµh

and eliminating the integration constant (t = 0, q = q0 ) they lead to the equation of De
Zeeuw-Hellinga:

qt = q0 e−αt + (I + S)(1 − e−αt )
qt
q0

specific discharge at time t [m/d]
specific discharge at time 0 [m/d]

qt = qt−1 e−α∆t + (I + S)(1 − e−α∆t )

With this equation the groundwater flow to a drain can be calculated for a constant I + S .
When I + S is not constant, the I + S series can be seen as a series of constant I + S ,
positive and negative. For each constant I + S in the series the qt can be calculated, with
t depending on the start of the component. Because the De Zeeuw-Hellinga equation is
linear, superposition may be applied. It is easier though to calculate the qt for several short
successive periods wherein I + S is constant. This results in the following modified equation:
(6.270)

specific discharge at time t − 1 [m/d]
time step [d]

For each time step infiltration and seepage must be constant.

The total volume of water flowing to the drain can be calculated by integrating the equation of
De Zeeuw-Hellinga and multiplying it with the area:

Volume of groundwater flow to drain at time t [m3 ]

∆t
1 −αt
1 αt
= A − q0 e + (I + S)(t + e )
α
α
0

1 α∆t
1 −α∆t
1
1
= A − q0 e
+ (I + S)(∆t + e
) + q0 − (I + S)
α
α
α
α

q0 − (I + S)
=A
(1 − e−α∆t ) + (I + S)∆t
α

(6.273)
(6.274)
(6.275)

Substituting gives:

Aαµ∆h − A(I + S)
(1 − e−α∆t ) + A(I + S)∆t
α

Conceptual description

The average discharge Qt,average [m3 /d] is computed by

Thus the average discharge in a time step to the drain as is used by the Rainfall-Runoff
module is:

Aαµ∆h − A(I + S)
(1 − e−α∆t ) + A(I + S)
α∆t

This is the so-called modified equation of De Zeeuw-Hellinga. Two important differences from
the ‘normal’ equation of De Zeeuw-Hellinga:

the storage coefficient µ is explicit, and
the pressure head ∆h is in the Rainfall-Runoff module calculated per time step as the
difference between the groundwater level and the open water level.

DrainageDeltaH option

DrainageDeltaH=-1 ! -1=parallell systems (default), 0=stacked system;

Given the definition of the drainage levels, and the Hellinga-de Zeeuw alfa reaction factors α,
or the Ernst drainage resistances γ , there are two options for computing the relevant heads
on which the α factors or drainage resistances are applied to.

Figure 6.69: Parallell drainage systems (default: DrainageDeltaH=-1)

SOBEK, User Manual

Figure 6.70: Stacked drainage systems (DrainageDeltaH=0)

See also: as described in SOBEK input file formats.
6.5.1.7

Dry Weather Flow (DWF)

The DWF or dry weather flow can be taken into account at the RR-paved node. Also the
DWF is part of the formulation in the RR-NWRW node, Nationale Werkgroep Riolering en
Waterkwaliteit (NLingenieurs, 1978).
The dry weather flow represents return flow from domestic use, like showers, washing, flushing the toilets, etc.
The dry weather flow can be specified in one of the following ways:

as a constant flow [m3 /s] during the whole day
as a variable flow [m3 /s] for 24 hours; 1 value for each hour.
as a constant flow [m3 /s] per day per person, multiplied with the number of persons
as a variable flow [m3 /s] per hour per person, multiplied with the number of persons

For paved area, the dry weather flow is discharged into the DWF sewer in case of a separated
or improved separated system. In case of a mixed system it is discharged into the mixed
sewer system, where it is mixed with sewer inflow due to rainfall.
For a NWRW node the dry weather flow is added to the computed sewer inflow with the
NWRW rainfall-runoff model.
6.5.1.8

Equal filling controller
Given initial, target and maximum allowable upstream and downstream levels, the controller
tries to operate the weir such that the upstream and downstream open water nodes will experience the same filling percentage.

Conceptual description

The filling percentage is defined in terms of water levels as:

(actual level − target level)/(maximum allowable level − target level) × 100 %.
(6.280)
This means that the controller will try to achieve similar exceedance patterns of the target
levels, taking into account the maximum allowable levels. In calculating the flow which results
in equal filling percentages, a linear relation between water level and volume is assumed.
For open waters with a constant area this is a valid assumption. However, if the open water area increases with increasing level, the procedure will not result in exactly equal filling
percentages.

The calculated flow to branch equal filling percentages is limited by a maximum allowed flow
Qmax . This maximum flow Qmax is determined by:

Qmax = QMaxAtTargetLevel + FillingUpstream × (QMaxAtMaxLevel − QMaxAtTargetLevel).
(6.281)

The maximum flows QMaxAtTargetLevel and QMaxAtMaxLevel are user defined input data
for the equal filling controller.
Furthermore, the flow Qmax is limited (taking into account other calculated flows from previous
iterations) such that the upstream water level does not fall below target level.
6.5.1.9

Ernst drainage formula

One of the options of modelling the drainage from unpaved area towards open water is the
Ernst formulation (Ernst, 1978). Other options available are the De Zeeuw-Hellinga formulation and the Krayenhoff van de Leur formulation.
The following figure illustrates the principles of the Ernst method.

Figure 6.71: Principles of Ernst method

The equation reads:

drainage [m/d]
difference between groundwater level and drainage basis [m]
drainage resistance [d]
factor (0.65 - 0.85 (Ernst, 1978)), depending on the shape of the groundwatertable [−]

SOBEK, User Manual

The f factor can not be entered via the User Interface of SOBEK. Instead, the user has to
take this factor into account in the drainage resistance.
Evaporation (when using capsim)
The actual evapotranspiration ETact is calculated as:

where:
relative evapotranspiration factor [−]
actual soil moisture storage in the root zone [m]
equilibrium soil moisture storage in the root zone [m]
potential evapotranspiration [m]

Figure 6.72: Reduction coefficient for root water uptake, αE , as a function of soil water
pressure head h (Feddes et al., 1978).

Water uptake by roots is zero at soil water pressure h4 which is assumed to be the wilting
point, see Figure 6.72. Soil water pressure h3 is called the reduction point. In between the
wilting point and the reduction point the potential evapotranspiration rate is linearly reduced.
The location of the reduction point depends on the potential evapotranspiration. If the potential
evapotranspiration is less than or equal to 1 mm/d then the curve Elow is used. If the potential
evapotranspiration is equal to or greater than 5 mm/d then the curve Ehigh is used. In between
SOBEK-CAPSIM linearly interpolates between the reduction curves Elow and Ehigh .
Between soil water pressures h2 and h3 the evapotranspiration is at maximum (’potential’).
As a result of oxygen deficiency in the root zone, water uptake is hampered for some crops
between soil water pressures h2 and h1 . SOBEK-CAPSIM does not take this reduction into
account (αE = 1 between soil water pressures h2 and h1 ).

Conceptual description

SOBEK-CAPSIM doesn’t compute the soil waterpressure head directly, but uses the relative
root zone storage V /Veq . The relative root zone storages for h4 , h3l , h3h , h2 and h1 are
calculated by CAPSEV and tabulated in SOBEK-CAPSIM. Then Figure 6.72 can be better
explained by:

αE = 0 when 0 ≤ V /Veq < V /Veq (h4 )
0 ≤ αE ≤ 1 when V /Veq (h4 ) ≤ V /Veq < V /Veq (h3l or h3h )
αE = 1 when V /Veq ≥ V /Veq (h3l or h3h )

(6.286)
(6.287)

Evapo(transpi)ration
Open water

For open water, related to Makkink evapotranspiration, the following ’crop’ factors are used.
These values are based on Hooghart and Lablans (1988).
Value

jan-01
jan-02
jan-03
feb-01
feb-02
feb-03
mar-01
mar-02
mar-03
apr-01
apr-02
apr-03

0.50
0.50
0.70
0.80
1.00
1.00
1.20
1.30
1.30
1.30
1.30
1.30

may-01
may-02
may-03
jun-01
jun-02
jun-03
jul-01
jul-02
jul-03
aug-01
aug-02
aug-03

1.30
1.30
1.30
1.31
1.31
1.31
1.29
1.27
1.24
1.21
1.19
1.18

sep-01
sep-02
sep-03
oct-01
oct-02
oct-03
nov-01
nov-02
nov-03
dec-01
dec-02
dec-03

1.17
1.17
1.17
1.00
0.90
0.80
0.80
0.70
0.60
0.50
0.50
0.50

Decades are parts of a month, defined as: first 10 days, second 10 days and rest of the month.

Related input file:
crop factor open water
Unpaved areas

decade
jan-01
jan-02

greenhouse area

non-arable land

The potential evapotranspiration in unpaved areas depends on the vegetation. The standard
way to determine the potential evapotranspiration is to multiply the reference evaporation (p.e.
Makkink) by a so called crop factor. The crop factor can differ per vegetation, in time and per
location on earth. The default crop factors are orientated towards the Dutch situation for a
limited number of crops, listed in the table below.

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
1.04
1.04
1.04
1.43
1.43
1.43
1.57
1.57
1.57
1.68
1.65
1.61
1.33
1.31
1.18
1.17
1.17
1.17
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.71
0.63
0.50
0.40
0.33
0.23
0.78
0.91
0.91
0.91
1.04
1.04
1.04
1.05
1.05
0.92
0.77
0.64
0.50
0.17
0.17
0.25
0.26
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.23
0.23
0.15
0.15
0.15
0.15
0.15
0.15
0.16
0.16
0.16
0.17
0.17
0.25
0.26
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.95
0.95
0.95
0.95
0.95
0.95
0.95
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.90
0.90
0.90
0.90
0.90
0.95
0.95
0.95
0.95
0.95
0.95
0.95
0.95

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.65
0.78
0.91
1.04
1.04
1.04
1.18
1.18
1.18
1.03
0.89
0.74
0.61
0.17
0.25
0.26
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.23
0.23
0.52
0.52
0.52
0.79
1.05
1.18
1.16
1.14
1.12
1.09
1.07
1.06
1.05
1.05
1.05
0.40
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.23
0.23
0.15
0.65
0.91
1.05
1.05
1.18
1.16
1.14
1.12
1.09
0.83
0.83
0.70
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.90
0.90
0.90
0.90
1.00
1.00
1.00
1.05
1.05
1.05
1.15
1.15
1.15
1.20
1.20
1.20
1.25
1.25
1.25
1.10
1.10
1.10
1.05
1.05
1.05
1.00
1.00
1.00
0.95
0.95
0.95
0.90
0.90
0.90

1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20
1.20

0.95
0.95
0.95
0.95
0.95
0.95
0.95
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.90
0.90
0.90
0.90
0.90
0.95
0.95
0.95
0.95
0.95
0.95
0.95
0.95

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.23
0.23
0.15
0.15
0.15
0.15
0.15
0.15
0.16
0.16
0.16
0.17
0.17
0.25
0.26
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.52
0.65
0.78
0.91
1.04
1.18
1.18
1.18
1.03
0.76
0.16
0.17
0.17
0.25
0.26
0.26
0.26
0.30
0.44
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.71
0.63
0.50
0.40
0.33
0.23
0.23
0.23
0.23
0.23
0.52
0.52
0.52
0.79
1.05
1.18
1.29
1.27
1.24
1.21
1.19
1.18
1.17
1.17
1.17
0.40
0.45
0.50
0.50
0.71
0.83
1.00
1.00
1.00

0.95
0.95
0.95
0.95
0.95
0.95
0.95
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.90
0.90
0.90
0.90
0.90
0.95
0.95
0.95
0.95
0.95
0.95
0.95
0.95

jan-03
feb-01
feb-02
feb-03
mar-01
mar-02
mar-03
apr-01
apr-02
apr-03
may-01
may-02
may-03
jun-01
jun-02
jun-03
jul-01
jul-02
jul-03
aug-01
aug-02
aug-03
sep-01
sep-02
sep-03
oct-01
oct-02
oct-03
nov-01
nov-02
nov-03
dec-01
dec-02
dec-03

greenhouse area

non-arable land

SOBEK, User Manual

Related input file:
crop factor agricultural crops

Remarks:
The crop factor file is specified for a limited number of crops and suitable for the Dutch
situation or for simular conditions only. In other situations (or other crops) please define
your own crop factors. This can be done by changing the input file <../../fixed/cropfact>.
We recommend saving the default crop factor file first. We also recommend to save the
changed crop factor file at a different location as well, because when installing a new
release of SOBEK the crop factor file will be replaced by a new default crop factor file.
The values in the table above are based on the Makkink evapotranspiration. The
used information comes from the Dutch Cultuurtechnisch Vademecum (3rd edition),
Hooghart, Spieksma et. al, Lysimeter results and PAWN (DEMGEN) documentation.
The growing season of the specified crops is marked yellow. Outside the growing season the values are the same as the values for fallow (bare soil).
Non-arable land is assumed to be the same as fallow.
Miscellaneous is assumed to be the same as grass.
Nature depends entirely on the kind of nature. Therefore it is assumed to be the same
as grass.
For greenhouse crops (greenhouse and greenhouse-flowers), the values are set to zero.

Conceptual description

For proper use, please use the greenhouse node. Other flowers are assumed to be
bulbous plants.
For vegetables peas and beans are assumed.
For both open water as well as unpaved areas a fatal error (the programm stops) will
occur when a crop factor is used with a value lower than 0 or higher than 2.5.
When a crop factor with value 0 is used, a warning will be given in the log file ().
The programm continues.
The actual evapotranspiration can be determined by using the potential evapotranspiration
(default) or by taking into account the reduction for root water uptake as a function of soil
water pressure head (using Capsim).
Fixed level difference controller

The algorithm is given as follows:

With the fixed level difference controller one can keep the difference between the upstream
target level and downstream target level. By increasing downstream water level, SOBEK-RR
will increase the crest level. In this way, more storage capacity is created in the upstream
area.

Upstream target level T Lup
Downstream target level T Ldown
Model input, i.e. parameters computed by SOBEK-RR:
Upstream level Lup
Downstream level Ldown
Crest level = Ldown + (T Lup − T Ldown )

Model input, i.e. parameters computed by SOBEK-RR:

Upstream level Lup
Downstream level Ldown
Crest level = Ldown + (T Lup − T Ldown )

This formulation makes sure the upstream open water will only discharge to the downstream
open water if the level difference exceeds the specified fixed level. The controller does not
guarantee that the level difference is always equal to the specified fixed level. In fact, the level
difference can be lower (if the upstream water level is below the crest level), or higher. In case
the level difference is higher, the crest level is put at the desired fixed level difference, so the
water levels will move towards the desired fixed level difference.

SOBEK, User Manual

Fixed upstream level controller
This controller tries to maintain the upstream target level as long as the flow over the structure
does not exceed the maximum flow. If the flow equals to the maximum flow, the level may
increase up to the maximum level; at that time the maximum flow may also be exceeded. If
the downstream level exceeds the specified maximum downstream level, a more strict flow
limitation will be used.

The algorithm is given as follows:

The calculated flow by the controller is limited in two ways. Firstly, it is verified that this flow
can be physically realised by lowering the weir to the specified lowest value zmin (either
bottom level, or a higher user defined level). Secondly, there may be a maximum crest level
zmax which limits the operation of the weir. If not specified, the controller operates such
that negative weir flows are not allowed (this is equivalent with specifying zmax very high).
If a zmax is specified, negative flows may occur (if the downstream level is higher than the
upstream level); and also either the downstream level is above the zmax level or the upstream
level is below the target level.

Maximum flow MF
Maximum level above which the maximum flow may be exceeded ML
Maximum downstream level MD
Minimum crest level related to the reference level zmin . If it is not specified, the lowest
crest level is taken equal to the bottom level of the boundary or the RR-open water; this
keyword provides a way to specify a higher lowest level.
Maximum crest level related to the reference level zmax . If it is not specified, +9999.99 is
used, thus preventing negative flow; this is backward compatible. This keyword provides
a way to specify a lower maximum crest level.

Hydrologic Cycle

Water circulates through the hydrosphere through a maze of paths, in a cycle without a beginning or an end. Water evaporates from the oceans, is transported to other parts of the
atmosphere, and precipitates on the land or the oceans. From there, it will eventually branch
the seas via different processes known as infiltration, percolation, and groundwater flow. This
cycle of processes is known as the hydrologic cycle.
Basically, SOBEK Rainfall Runoff focuses on the following transport processes:

precipitation
evapo(transpi)ration
surface runoff
infiltration
(Drainage) outflow
Seepage
Percolation

In SOBEK RR, the user can choose from many different ways to model the flows of water
over and under the ground surface, depending on the area type. The following area types are
available:

paved area
unpaved area

Conceptual description

greenhouse area
open water
industrial area
Please refer to the corresponding sections for more information about the way the water transport and storage processes are modelled.
6.5.1.15

Improved separated sewer
The sewer type of a paved area node can be one of the following types:

mixed sewer
separated sewer
improved separated sewer

A separated sewer system has separate sewer systems for rainfall and dry weather flow. The
improved separated system is designed to reduce the sewer overflows of a separated system.
Although overflows from the rainfall sewer system do not contain waste loads originating from
DWF, they do contain waste loads from street surfaces, and thus can have negative impacts
on water quality of the receiving water (the so-called ‘first flush’)
The improved separated sewer system has a connection between the rainfall sewer and the
DWF sewer. This connection is used to store overflows from the rainfall sewer in the DWF
sewer, if storage in the DWF sewer is available and no overflow of the DWF sewer is caused.
If storage in the DWF sewer is not enough to store the overflow of the rainfall sewer system,
the rainfall sewer will still spill into open water (but less than in case of a normal separated
system).
6.5.1.16

Infiltration is the process by which water infiltrates from the surface of the ground into the root
zone (subsoil), and is thus a part of the so-called Hydrologic Cycle. The infiltration capacity is
influenced by many factors, like the condition of the soil surface and its vegetative cover, the
soil properties and the current moisture content of the soil.
In SOBEK-RR, the infiltration capacity of the unpaved areas is considered to have a constant
value in time, and can be entered in either mm/hour or mm/day.
6.5.1.17

Infiltration from open water

In dry periods the groundwater level can decrease. When the groundwater level is lower than
the open water level, infiltration from the open water occurs. The infiltration rate depends on
1 the difference between open water level and groundwater level and 2 the resistance of the
channel
In SOBEK-RR, this process is described by the modified De Zeeuw-Hellinga equation.
Therefore, the user must define a specific reaction factor, α. The difference between the open
water level and groundwater level is computed by SOBEK-RR.

SOBEK, User Manual

Figure 6.73: Infiltration from open water

Krayenhoff van de Leur drainage formula

One of the options of modelling the runoff for unpaved area is the Krayenhoff van de Leur
formulation. Another available option is the de Hellinga-de Zeeuw formulation.

The following figure illustrates the principles of the Krayenhoff van de Leur method.

Figure 6.74: Drainage according to Krayenhoff van de Leur

The reservoir coefficient j is either specified directly, or calculated as:

The (cumulative) drainage flow q is computed as:

2t
1
(1 − e−n j )
2
n
n=1,3,5,...

Conceptual description

and the (cumulative) highest groundwater level between the ditches as computed as:

n→∞
32 X 1 −n2 jt
1− 3
e
π n=1,3,5,... n3

reservoir coefficient [d]
storage coefficient (specific yield) [−]
distance between drainage ditches [m]
soil transmissibility (transmissivity) [m2 /d]

kD can be derived from:

soil permeability [m/d]
thickness of permeable layer [m]
precipitation [m]
(cumulative) drainage flow [m/d]
difference between highest groundwater level and ditch level [m]
time [d]

Given the area A [m2 ], precipitation and drainage flow can be converted to [m3 /s]
6.5.1.19

Minimum filling percentage for greenhouse storage basin

When the water level in the greenhouse storage basins becomes equal/lower than this minimum filling percentage, the withdrawal of water out of the basins will be stopped.
Default: 10 %
6.5.1.20

Minimum level difference controller

With the minimum level difference controller one can keep a minimum difference between the
upstream water level and the downstream water level. This controller is closely related to the
fixed level controller. There are two differences:

the fixed level controller determines the level difference from the specified target levels
which can be variable within the year, whereas the minimum level difference controller
uses one constant minimum level difference;
the fixed level controller allows a crest level below the values specified in the crest level
table, whereas the minimum level difference controller does not allow this.
The algorithm of the minimum level difference controller is given as follows:
User input:

Minimum level difference Min_dif
initial crest level
Model input, i.e. parameters computed by SOBEK-RR:

Downstream level Ldown
The minimum level difference controller adjusts the crest level of the weir in the following way:

SOBEK, User Manual

Crest level = Max (Crest level according to input table, (Ldown + Min_dif))
6.5.1.21

Mixed sewer
The sewer type of a paved area node can be one of the following types:

mixed sewer
separated sewer
improved separated sewer
A mixed sewer system means that there is only one system for the discharge of both rainfall
water and dry weather flow (return flow from domestic water use, e.g. showers, toilets, etc.)

Open water node

In SOBEK-RR the local surface water is represented by open water nodes. An open water
node can also be considered a storage basin in which the variation of water level follows from
the volume balance equation. In this equation an increase of the storage with higher water
levels (effect from banks) can be taken into account. An open water node is always connected
with a structure to another open water node or to a boundary node representing the boundary
of the water system.

Spilling from the sewer system after heavy rainfall thus contains a mix of rainfall water and
domestic return flow. Spilling from a mixed sewer system therefore in general has a negative
effect on the water quality of the receiving open water.

Storage at open water nodes increases through precipitation, seepage from deep groundwater, flows from adjacent paved area, unpaved area and greenhouse area, and inflow through
structures from other open water nodes or form boundaries. Open water storage decreases
through evaporation, percolation to deep groundwater, flows to unpaved area (if the open
water level is higher than the groundwater level), and flows through structures to other open
water nodes or boundaries.
In order to obtain an accurate computation of the open water level, the level changes and
flow-through-structures, which depend on water levels, are computed iteratively.

Conceptual description

Figure 6.75: Representation of the rainfall-runoff process of an open-water area

Amount of rainfall on open water node

The amount of rainfall on a open water node depends on the surface area of open water,
which can increase with an increasing water level. SOBEK does take this effect into account.
But the increase of open water surface means that in SOBEK the total area also increases. In
reality, the surface area of the unpaved area decreases. SOBEK does not take this effect into
account.
6.5.1.23

Paved area node
General

The paved area node is used to simulate the rainfall-runoff process on paved or impervious
areas.
A paved area is characterized by:

area [ha]
maximum storage on street [mm]
maximum storage in sewer [mm]
sewer pump capacity [m3 /s]
sewer type (mixed, separated, or improved separated system)
DWF (dry weather flow)

Important processes are surface runoff or sewer overflow, occurring when the storage on land
or storage in the sewer exceeds its maximum and rapid runoff occurs.

SOBEK, User Manual

Paved node surface runoff
When the amount of water on the RR-paved surface exceeds the maximum storage, surface
runoff will occur. The surface runoff can be implemented using either

no delay,
using a runoff delay coefficient, or
using a QH-relation.

The first option, no delay, means all surface runoff branches the outflow point in the same
timestep. Surface runoff can be blocked however if the open water level at the connecting
node exceeds the surface level of the paved node. But when using the ‘no delay’ option the
surface storage will immediately runoff as soon as the water level drops below the paved
surface level. This may lead to very spiky discharges from the paved node to the RR-open
water or RR-Boundary node.
The second option, using a runoff delay coefficient, is similar to the RR-Urban runoff model.
(See also the description of delay of runoff in the RR-Urban documentation, section 6.5.4.
This is formulating the surface runoff using the rational method (q = ch). The runoff delay
coefficient c is specified as a number between zero and one (1/min). A coefficient of one
means all runoff occurs in 1 minute, while a coefficient of 0.1 means only 10 % of the excess
volume will branch the open water in 1 minute.

The impact of the runoff delay coefficient on the runoff pattern is shown in the following graph.
The graph shows the rainfall time-series used, and the runoff using runoff delay coefficients
of 0.1, 0.2 and 0.5. It is assumed that there is no infiltration or sewer, and that the maximum
storage on the street is zero.
Note: The example Figure 6.76 is actually taken from a simulation of the RR-Urban inflow
model, but the behaviour for the RR-Paved node is the same.

Figure 6.76: Impact of delay coefficient on runoff pattern

Conceptual description

The third option, using a QH-relation, allows limiting of the Q based on the water level h.
Based on the interpolation table defined by the user a maximum Q is determined with which
the overflowing discharge is limited.
The used h is the water level of the open water node or RR-CF-connection node downstream
of the paved node, where the overflowing discharge of the RR-paved node is discharged to.
See the following two examples:

1 Figure 6.77 shows the result of water overflowing from two paved nodes to open water
nodes without delay of discharge from the paved nodes.
2 Figure 6.78 shows the discharges after using a QH-relation.

Figure 6.77: Discharge from Paved to Open Water without delay

SOBEK, User Manual

Figure 6.78: Discharge from Paved to Open Water using QH-relation

If the moisture storage in the root zone exceeds the equilibrium content, percolation occurs
from root zone to groundwater:

qp =
qp
V
Veq
∆t

Veq − (V (t − ∆t) + ∆V )
∆t

Percolation [m/d]
Soil moisture storage in the root zone [m]
Equilibrium moisture storage in the root zone [m]
Time step [d]

If percolation occurs, it is assumed that the percolating water branches the groundwater table
within the current time step of the groundwater.
The equilibrium moisture storage in the root zone is defined as the amount of moisture corresponding with a steady-state simulation with no-flow conditions to or from the root zone.

Conceptual description

0
0.01
0.02
0.03
0.04
0.05

0
0.1
0.2
0.3
0.4
0.5

A QH-relation can be used to represent any type of structure. When the user defines the
QH-relation as follows:

then SOBEK-RR computes the discharge Q as a function of the water level h:

Figure 6.79: QH-relation

The root zone for which the water balance is considered has a thickness which is a function
of the land use type and the soil physical unit:

root zone thickness
land use type (1,. . . ,16)
soil physical unit (1,. . . ,21)

The thickness of the root zone is assumed to be constant, regardless of season and year. The
moisture storage of the root zone at equilibrium condition is calculated with the function:

Veq = f (s, dr , dg)

the moisture storage of the root zone at equilibrium condition [m]
soil physical unit [−]
thickness of root zone [m]
depth of the groundwater level [m]

SOBEK, User Manual

Initial storage in the root zone
The initial storage in the root zone can be defined by one of the three following options:

the equilibrium root zone storage for the given crop-soil combination and specified initial
groundwater level;
the root zone storage at pF= 2;
the root zone storage at pF= 3.
Root zone thickness defining more than one crop
When the user defines more than one crop per unpaved node SOBEK calculated the overall root zone by weighted averaging. So, the area of the individual crops is also taken into
account.

For calculating the evaporation SOBEK uses the crop with the largest sub-areal.

The SOBEK Rainfall-Runoff module offers the option to operate hydraulic structures such as
weirs and orifices to a certain extent.
The available controllers are:

Time controller
Target level controller
Fixed Level difference controller
Minimum level difference controller
Equal filling controller

See their sections in the Technical Reference Manual for more information on each type of
controller.
6.5.1.29

RR routing link

The standard RR-links are links indicating connections between e.g. an unpaved node and an
open water node. The link flow in that case represents the flow from the unpaved area to the
open water. There is no difference between link inflow and link outflow.
Within SOBEK, the hydrodynamic flow aspects involving time delay between link inflow and
outflows are typically handled using the SOBEK-Channel Flow module. However, in some
cases a simple approach may be necessary. For instance, if only flow measurements at
an upstream location and a downstream location (without additional inflows in between) are
known, but no cross-section information is available. In such situations a simple routing approach can be used. An example of such a simple approach is the well-known Muskingum
method. This method is available in SOBEK-RR by using the so-called RR-Routing link.

Conceptual description

Standard Muskingum method
The standard Muskingum method is using a layered routing approach. The inflow hydrograph
is divided into a number of layers, where each layer has its own routing coefficient.
According to the standard Muskingum method (McCarthy, 1938) the outflow Q at time step
i + 1 is computed using outflow Q at time step i and inflows I at time step i and i + 1:

Qi+1 = c1 Ii + c2 Ii+1 + c3 Qi

∆T + 2Kx
2K(1 − x) + ∆T
∆T − 2Kx
c2 =
2K(1 − x) + ∆T
2K(1 − x) − ∆T
c3 =
2K(1 − x) + ∆T
c1 =

(6.296)
(6.297)

The parameter K is a proportionality factor with the dimension of time, it is dependent on the
time step you select. K is the travel time of a flood wave through the branch. The parameter
x is a dimensionless weighting factor with 0 ≤ x ≤ 0.5. In natural streams values of x
ranging from 0 to 0.3 are often found. Great accuracy in determining x may not be necessary
as the final result is relatively insensitive to the value of x.
It is easily verified that c1 + c2 + c3 = 1 and further that ∆T and K should have the same
time units. The use of the method requires choices on ∆T , K and x. The routing interval
∆T is the calculation time step size in SOBEK-RR. The chosen time step size should be
less than K , as otherwise peaks will be missed at the downstream side. It is advised the
SOBEK-RR computation time step size ∆T to be taken as 1/2 to 1/4 of K . If, however, a
∆T is selected which is much smaller than K , then c2 becomes negative. This will lead to a
dip in outflows, or even to negative outflows when the inflow starts rising. To avoid negative
coefficients the routing interval should be within the range: 2Kx ≤ ∆T ≤ K . For values of
x close to 0.5 this requirement leaves little freedom in the selection of ∆T . If one is mostly
interested in the higher part of the flood wave the above condition can be relaxed somewhat
by accepting slightly negative values for c2 .
The Muskingum routing method allows the routing to be split in multiple layers. This can be
of great value when the river contains a minor bed and a floodplain. In the floodplain the
Muskingum parameters will be completely different from the parameters of the minor bed.
An example of this computation is given below. Suppose that you use 2-layers for routing the
flood wave:
layer 1: x = 0.4
layer 2: x = 0.1

Qmax = 100 m3 s−1

SOBEK-RR will then route all discharges up to Q = 100 m3 s−1 with the parameters of the
first layer, all discharges above Q = 100 m3 s−1 will be routed with the parameters of the
second layer
(and using Qlayer2 = Qi − 100[m3 /s]).

SOBEK, User Manual

RR connection node
Similar to a Flow Connection node, now also a RR-connection node is available. The RRConnection node does not require any input data. The basic function of the RR-Connection
node is that of a confluence: adding up all flows from incoming links and supplying that to the
downstream link.
Network validation rules for RR-routing link and RR-connection nodes
The following rules apply to the use of the RR-routing link and RR-connection nodes:

a Sacramento node to an RR-connection node;
an RR-connection node to an RR-connection node;
an RR-connection node to a RR-boundary node;

The RR-routing link can be used to connect:

At RR-connection nodes, multiple upstream links are possible, but only 1 downstream
(routing) link is allowed.

Examples of network layout and ModelEdit user interface:

Figure 6.80: Example input data

Conceptual description

Figure 6.81: Possible usage in a network

The orifice is one of the structures available in the SOBEK-RR-module. The geometrical
shape is given in Figure 6.82.

Figure 6.82: Orifice

Flow across the orifice can be of the following types: drowned weir flow, free weir flow,
drowned orifice flow, free orifice flow or no flow (water levels below crest level or orifice closed)
depending on the dimensions of the structure and the flow conditions.
The following discharge equations are applied during the computations:
Free orifice flow:

q
2g(h1 − (z + µdg ))

SOBEK, User Manual

Drowned orifice flow:

p
2g(h1 − h2 )

Free weir flow:

2
g(h1 − zs )3/2
3

Drowned weir flow:

p
Q = cB(h1 − z) 2g(h1 − h2 )

Discharge across orifice [m3 /s]
Contraction coefficient [−]
Discharge coefficient [−]
Crest width [m]
Openings height [m] (openings level - crest level)
Gravity acceleration [m/s2 ]
Upstream water level [m]
Downstream water level [m]
Crest level [m]

Q
µ
c
B
dg
g
h1
h2
zs

The different formulas are applied when the following conditions occur:
Free orifice flow:

3
h1 − z ≥ dg and h2 ≤ zs + dg
2

Drowned orifice flow:

3
h1 − z ≥ dg and h2 > zs + dg
2

Free weir flow:

3
h1 − z < dg and h1 − zs > 3/2(h2 − zs )
2

Drowned weir flow:

3
3
h1 − z < dg and h1 − zs ≤ (h2 − zs )
2
2

Conceptual description

Three types of flow conditions can occur in the case of weir flow. These are free (modular)
flow, drowned (submerged) flow and no flow (water levels below crest level). If high tail water
conditions do affect the flow, the weir is said to be drowned.

Figure 6.83: Weir

The discharge through the weir is computed with the following formulas:

Free weir flow:

2
g(h1 − zs )3/2
3

Drowned weir flow:

p
Q = cB(h1 − zs ) 2g(h1 − h2 )

Q
c
B
g
h1
h2
zs

Discharge across weir [m3 /s]
Discharge coefficient [−]
Crest width [m]
Acceleration due to gravity [m/s2 ]
Upstream water level [m]
Downstream water level [m]
Crest level [m]

The different formulas are applied when the following conditions occur:
Free weir flow:

2
h2 − zs < (h1 − zs )
3

Drowned weir flow:

2
h2 − zs ≥ (h1 − zs )
3

Two-stage weir:
The flow over a 2-stage weir is determined as the sum of the two weirs:

A rectangular weir with crest level Crestlevel1 and width Width1; and

SOBEK, User Manual

A rectangular weir with crest level Crestlevel2 and width Width2.

The Rainfall Runoff module separately determines the flow conditions for both levels (free or
drowned flow, or no flow). The normal Weir formulae are used.

Figure 6.84: Two-stage weir

The crest level of the lower stage of the weir can optionally be adjusted according to the
upstream open water target level (depending on the switch specified in the Settings module).
The crest level of the second stage is not adjusted.

Figure 6.85: Two-stage weir, crest bottom width at crestlevel 1

Output for 2-stage weirs: Both the total flow over the weir and the seperate flows of the two
levels are shown.
V-notch broad-crested weir
Free weir flow:

2
g tan(α)H 2.5
5

where dc is typically between 0.85 and 1.05.

Conceptual description

Drowned weir flow
The drowned flow reduction factor is given as a function of the ratio of the upstream and
downstream waterlevels above the crest level (Bos, 1989, Par. 4.3.3).
Reduction
factor

1
0.995
0.99
0.985
0.978
0.97
0.96
0.95
0.945
0.925
0.9
0.885
0.85
0.8

0
0.1
0.2
0.3
0.4
0.5
0.6
0.67
0.7
0.8
0.87
0.9
0.96
1.0

Figure 6.86: V-notch broad-crested weir

Separated sewer

The sewer type of a paved area node can be one of the following types:

mixed sewer
separated sewer
improved separated sewer
A separated sewer has separate sewer systems for rainfall and dry weather flow. This system
is designed to reduce water quality impacts of sewer overflows on the receiving open water.
In a mixed sewer system spilling contains DWF water (domestic return flows). In a separated
sewer system however, sewer overflows usually only originate from the rainfall sewer system

SOBEK, User Manual

and not from the DWF sewer system. Therefore, the sewer overflows do not contain the waste
loads from the domestic return flows.
6.5.1.33

Silo capacity/Pump capacity
Apart from storage in rainfall basins in some greenhouse areas there is also storage of water
in silo’s. These silo’s, usual capacity approximately 200 m3 ha−1 , function as a temporary
storage before pumping the water into the soil (subsoil storage). The pump capacity for subsoil
storage usually is about 15 m3 h−1 .
Soil surface level

Surface level = constant

There are two options to define the soil surface level:

The user can define any constant surface level he wants, usually the (almost) lowest surface
level in the unpaved area.

Storage on land
groundwater level rise: when the groundwater table branches the lowest surface level,
surface runoff occurs only when the storage on land is filled.
high precipitation rate: when the net precipitation rate exceeds the infiltration rate, water
will be stored on land. Surface runoff occurs only when the storage on land is filled.

Surface level = not constant

When this option was chosen, the user can specify the soil surface level in a more detailed
way.
SOBEK does take into account up to a maximum of 100 sub-areas (default). The user can
define these areas in a table, see Figure 6.87.

Conceptual description

Figure 6.87: Change table

The user should make sure that 0 and 100 % are present in this table. In between the user
can define as many rows as he wants. Above the 100 % level it is assumed that the area does
not increase.
Note: By showing the graph of the S-curve you can check whether you entered the s-curve
data correctly.

SOBEK, User Manual

When the open water level exceeds the lowest surface level, inundation occurs. See Figure 6.88. SOBEK does take into account the extra volume to store water. SOBEK does not
take into account the precipitation and evaporation on the area of this extra storage volume.
In fact, the precipitation and evaporation on this area was already taken into account with the
surface of the unpaved area.

Figure 6.88: Inundation

Vertical infiltration of water in this extra storage area is not considered as well.
Finally, when the open water level exceeds the lowest surface level it is assumed that the
potential storage on land is equal to zero.
Initial groundwater level

When the surface level is not constant, it is assumed that the initial groundwater level is
defined w.r.t. the lowest surface level. For example, in Figure 6.87 the initial groundwater level
is defined w.r.t. the level of 0.055 m NAP.
Reaction factor α

In SOBEK it is possible to schematise the drainage process by defining four different layers.
For each layer a different reaction factor α is defined. When the surface level is not constant,
the reaction factor layers are defined relative to the surface level according to the table, see
Figure 6.89.

Conceptual description

Figure 6.89: Example of definition of reaction factor layers when the surface level is not
constant (in this case the number of sub-areas defined in the table is equal
to 6)

Actually, the above figure is a bit more complex, because default a 100 sub-areas are considered. The surface level of each sub-area is determined by interpolation of the surface level
table defined by the user.
Storage on land

Surface level is not constant:

groundwater level rise: when the groundwater table branches the lowest surface level,
immediately surface runoff occurs. Storage on land is not considered.

high precipitation rate: when the net precipitation rate exceeds the infiltration rate, water
will be stored on land. Surface runoff occurs only when the storage on land is filled.
Storage coefficient i

Surface level = not constant AND NOT using CAPSIM for unsaturated zone
The storage coefficient used to calculate the groundwater level fluctuation, is determined as
the average of the initial storage coefficients for each sub-area. The initial storage coefficient
is determined by the soil type and the distance between the soil surface and initial groundwater
level.
When the initial groundwater level exceeds part of the surface level (storage on land) then the
storage coefficients of this part of the surface are excluded from the averaging procedure.
Surface level = not constant AND using CAPSIM for unsaturated zone
CAPSIM needs , among others, the root zone depth and initial groundwater level. If the
surface level is not constant, the root zone depth and initial groundwater level passed to
CAPSIM are defined relative to the surface level (Figure 6.90). The root zone depth is equal
for each sub-area, because the root zone depth only depends on the soil type and the crop.
For each sub-area, separate actual evaporation, percolation and capillary rise, and volume of
water in the unsaturated zone are computed.

SOBEK, User Manual

The groundwater level is determined using the total percolation/capillary rise flow for all subareas. The storage coefficient used to calculate the groundwater level fluctuation, is determined as the average of the actual storage coefficients for each sub-area. When the groundwater level exceeds part of the surface level (storage on land) then the storage coefficients of
this part of the surface are excluded from the averaging procedure.

Figure 6.90: Rootzone sub areas

Storage coefficient

The storage coefficient m represents the percentage of soil-volume which is available for
storage of water. Once the storage coefficient is known, the total storage capacity can be
calculated:

storage capacity [mm]
storage coefficient [m/m]
depth to groundwater table [mm]

With the storage coefficient, the change of the groundwater level can be calculated.
Option ’Unsaturated zone = none’
Calculating groundwater level

For calculating the groundwater level the average storage coefficient is used during the simulation period (Table 6.10). This average storage coefficient depends on the drainage basis,
i.e. the distance between the surface level and the initial groundwater level. These coefficients
are provided by the Winand Staring Centre -DLO.
The soil types are:
1
2
3
4
5
6
7
8
9

loamy, humous fine sand,
peat,
heavy clay,
humous clay and peat,
light loamy sand, medium coarse sand,
loamy silt,
humous clay and peat with silty top layer,
clay and light clay,
loamless, medium coarse and coarse sand,

Conceptual description

10 silt,
11 very light clay,
12 sand with a silty top layer.
Table 6.10: Average storage coefficients depending on soil type and dranaige basis.

0.0074
0.0183
0.0302
0.0419
0.0532
0.0664
0.0805
0.0938
0.1061
0.1173
0.1372
0.1614

0.0077
0.0153
0.0226
0.0305
0.0387
0.0467
0.0545
0.0621
0.0702
0.0784
0.0939
0.1158

0.0094
0.0166
0.0226
0.0278
0.0323
0.0363
0.0399
0.0431
0.0461
0.0489
0.0538
0.0600

0.0063
0.0134
0.0206
0.0279
0.0350
0.0420
0.0486
0.0551
0.0613
0.0673
0.0786
0.0941

0.0046
0.0124
0.0220
0.0323
0.0427
0.0528
0.0625
0.0715
0.0801
0.0880
0.1024
0.1208

0.0049
0.0103
0.0158
0.0211
0.0262
0.0310
0.0364
0.0416
0.0466
0.0514
0.0605
0.0729

0.0049
0.0118
0.0181
0.0237
0.0289
0.0339
0.0386
0.0430
0.0472
0.0512
0.0586
0.0685

0.0048
0.0092
0.0132
0.0171
0.0206
0.0240
0.0271
0.0300
0.0328
0.0355
0.0404
0.0470

0.0027
0.0098
0.0162
0.0228
0.0294
0.0359
0.0422
0.0484
0.0542
0.0598
0.0704
0.0845

0.0029
0.0066
0.0105
0.0145
0.0186
0.0226
0.0265
0.0303
0.0341
0.0377
0.0446
0.0541

0.0025
0.0052
0.0079
0.0107
0.0134
0.0160
0.0185
0.0210
0.0235
0.0258
0.0303
0.0366

0.0013
0.0032
0.0052
0.0074
0.0096
0.0120
0.0143
0.0167
0.0191
0.0214
0.0261
0.0329

0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.2
1.5

Drainage
basis [m]

Calculating drainage flux

For calculating the drainage flux according to De Zeeuw- Hellinga a constant storage coefficient is used. This storage coefficient, which is the same as for calculation the changes in
groundwater level, is the storage coefficient corresponding with the initial groundwater level.
Option ’Unsaturated zone = CAPSIM’
Groundwater level

For calculating the groundwater level a storage coefficient is used depending on the actual
groundwater level during the simulation period.
Drainage flux

The storage coefficient is calculated by averaging all coefficients within in the domain of the
groundwater level and the open water level. Since the groundwater level and the open water
level may change during the simulation period, the average storage coefficient may change.
The coefficients for calculating the groundwater level and the drainage flux are tabulated in in
SOBEK. These storage coefficients depend on the soil type, the root zone thickness end the
groundwater level. Below the storage coefficients are depicted for a root zone thickness of 20
cm. SOBEK also takes into account storage coefficient for root zone thicknesses of 10 cm, 50
cm, 100 cm and 200 cm.
All coefficients are provided by Alterra.

SOBEK, User Manual

Conceptual description

SOBEK, User Manual

Conceptual description

SOBEK, User Manual

Conceptual description

Surface runoff
Surface runoff in paved areas

In paved areas surface runoff occurs when the ‘storage on street’ reservoir is completely filled.

Surface runoff in unpaved areas

In unpaved nodes surface runoff to open water can occur in two cases:
1 when the ‘storage on land’ reservoir is filled by the precipitation (minus evaporation and
infiltration into the soil).
2 when the groundwater level has branched the soil surface level. In this case, the storage
on land has not been taken into account, so surface runoff will immediately take place
when the groundwater level has branched the surface level.
In both cases the runoff process is simulated by means of the de Zeeuw-Hellinga equation.
Therefore, the user must define a specific surface runoff reaction factor.
Notice that when the soil surface is defined as a constant level, the total area defined in the
unpaved node is part of the surface runoff process. Often this causes very large discharges
to the open water.
When the soil surface is defined as a variable level, only the inundated part of the soil surface
is part of the surface runoff process.
6.5.1.37

Target level controller

With the target level controller one can control the upstream target level. The algorithm is
given as follows:
User input:

Maximum flow Qmax
Maximum allowed upstream level MAXLup
Maximum allowed downstream level MAXLdown
Upstream target level TLup
Downstream target level TLdown
Parameters computed by SOBEK-RR:
Upstream level Lup
Downstream level Ldown
Weir flow Q

SOBEK, User Manual

A weir with a target level controller tries to maintain the upstream water level at the user
specified target level TLup. Upstream here means upstream with respect to the defined link
direction. When the upstream water level gets above the target level TLup, the crest of the
weir will be lowered in order to let the excess water flow away to the downstream node. The
weir crest can be lowered until the maximum defined discharge Qmax is branched (or the
crest branches is specified minimum level, which is by default the bed level).
The discharge is kept at or below the maximum defined discharge Qmax until the upstream
water level branches the specified maximum allowed upstream level MAXLup. In that case,
the specified maximum discharge Qmax may be exceeded, but only if the downstream water
level is below the specified maximum allowed downstream water level MAXLdown.

In extreme conditions, the downstream level is allowed to exceed the specified maximum
allowed downstream water level MAXLdown, but the upstream water level will not be allowed
to rise above the maximum upstream water level MAXLup.
Note: that the controller only operates in case of upstream excess water; it is not active in
case the upstream water level is below the target level.

The computation is done using the symbols as defined above, and additionally:
TimestepSize
UpLvlEst
DoLvlInit
VolNow
VolTarget
VolMax

computation time step size in seconds
estimated upstream level, without flow over the weir
downstream level at beginning of the computation timestep
upstream volume in m3 at level UpLvlEst
upstream volume in m3 at upstream target level TLup
upstream volume in m3 at maximum allowed level MAXLup

A pseudo code of the computation is: (lines starting with ! are comments)
! Set upstream target end volume
if (DoLvlInit > MAXLdown) then
! downstream water level above maximum allowed downstream level;
! upstream level may rise until maximum allowed upstream level

EndV olume = V olM ax
else

! normal situation: target end volume corresponding with upstream target level

EndV olume = V olT arget
endif

! Set provisional flow over the weir to get to the target EndVolume
if (VolNow > EndVolume) then

QOut = min(Qmax, (V olN ow − EndV olume)/T imestepSize)
else

QOut = 0
endif
! Set provisional upstream End volume

EndV olume = V olN ow − Qout ∗ T imestepSize
! Check provisional end volume with maximum allowed upstream level (volume):
! The upstream level may never exceed the maximum allowed upstream water level

if EndV olume > V olM ax then

QOut = max(Qout, (V olN ow − V olM ax)/T imestepSize)
endif
! Final computed weir flow

Qout = min(Qout, flow with lowest possible crest level )
640 of 900

Conceptual description

Time step output
By default the time step of the results is equal to the time step of the computation. Especially
when a small time step is chosen, this results in a very large amount of output values. Then
the user can choose an other option in the Settings task in order to reduce the number of
output values.

Output reduction options in Settings:

Figure 6.91: Output reductions in Settings

In this case each 12th computed value is shown in the results graphs. The user can define
any interval he wants.

Current: each nth computed value is written to the output file;
Average: the average value of n computed values is written to the output file;
Maximum: the maximum value of n computed values is written to the output file.
Note: the user should realise that the chosen options are of great importance to the shape
of the output graph, see this example:

Figure 6.92: Time step computation

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Figure 6.93: Time step output = 12 ∗ time step computation

When SOBEK is used to compute series of precipitation events, then the maximum realised
level is written to the output file, based on all computed values. The options current, average
and maximum are not relevant anymore.
6.5.1.39

Unpaved area node
General

The unpaved area node is used to simulate the rainfall-runoff process on unpaved areas.
An unpaved area is characterized by:

total unpaved area (sum of crop areas)
groundwater area
area per crop
soil surface level
soil type
storage coefficient
root zone
saturated zone
evaporation
capillary rise/percolation from root zone to groundwater
storage on land
infiltration capacity
drainage resistance value / reaction factor (dependent on the chosen method)
seepage/percolation (constant, variable in time or calculated from a defined groundwater
head in the lower confined aquifer and the resistance value of the confining layer)
surface runoff
The unpaved area is modeled using boxes representing storage on land, storage in the unsaturated zone, and the saturated zone. The unsaturated zone is optional. The surface area is
divided into area for different crops. The sum of the crop area is the total unpaved area. This

Conceptual description

area is used for the surface storage and unsaturated zone computations. The saturated zone
computations use the groundwater area. This area is by default equal to the total unpaved
area, but can be defined separately by the user.
6.5.1.40

Unpaved surface flow link
The unpaved surface flow link is a branch type in RR which can be used to split the runoff from
a RR-unpaved node into two components: groundwater outflow (drainage) and surface runoff.
If an unpaved node has both a normal RR-link and an unpaved surface flow link connecting
it to the 1DFlow schematisation, the RR link will carry the groundwater drainage, and the
unpaved surface flow link will carry the surface runoff to the 1DFlow schematisation. In case
no unpaved surface flow link is used, the RR link will transport the total flow (groundwater
drainage plus surface runoff) to the 1DFlow schematisation.

This allows the user to specify different outflow locations for groundwater drainage and surface
runoff, and also allows to specify different waste loads or background concentrations for the
groundwater drainage and surface runoff in water quality computations.

The groundwater drainage computations use the open water level taken from the node downstream of the RR-link (remember that the driving force of the groundwater drainage is the
head difference between this open water level and the groundwater level) , while the surface
runoff computation uses the open water level taken from the node downstream of the RRunpaved surface flow link. The surface runoff is stopped when the open water level exceeds
the RR-unpaved surface level.
Sacramento Rainfall-Runoff model

Sacramento, the Segment module: implemented in SOBEK

The segment module simulates the rainfall-runoff process in part of the catchment, where the
attention is on the land-phase of the rainfall-runoff process. It is assumed that the open water
system in the segments contributes little to the shaping of the hydrograph. The conceptualisation of the processes as described in the segment module is presented in Figure 6.94.

SOBEK, User Manual

Figure 6.94: Conceptualisation of the rainfall-runoff process in a segment.

The segment module is divided into the following components, (see also Figure 6.95):

Impervious area with transfers to direct runoff
Pervious area
Upper zone

◦ Tension storage with transfers to evaporation, free water storage
◦ Free water storage with transfers to evaporation, percolation,
◦ surface runoff and interflow
Lower zone

◦ Tension storage with transfers to evaporation. free water storage
◦ Free water storage with transfers to base flow
From the impervious areas, precipitation immediately discharges to the channel. However,
impervious areas, which drain to a pervious part before branching the channel, are not considered impervious. Both zones have a tension and a free water storage element. Tension
water is considered as the water closely bound to soil particles. Generally first the tension
water requirements are fulfilled before water enters the free water storage.

Conceptual description

Figure 6.95: Schematisation of the rainfall-runoff process in a segment

In the following sub-sections the various components will be described in detail
6.5.2.2

Upper zone storage

The upper zone tension storage represents that precipitation volume required under dry conditions:

to meet all interception requirements, and
to provide sufficient moisture to the upper soil so that percolation can begin.
If the maximum storage capacity of the upper-zone tension storage is exceeded, water becomes available for the upper zone free water storage, a temporary storage from which water
percolates to the lower zone system and from which water discharges to the channel via the
interflow component. The preferred flow direction from the upper zone is the vertical direction,
i.e. percolation to the lower zone system.
Interflow occurs only when the precipitation rate exceeds the percolation rate. The upper zone
is treated as a linear storage element which is emptied exponentially: discharge = storage
∗ storage depletion coefficient. The upper zone free water storage depletion coefficient is
denoted by U ZK and the upper zone free water content by UZFWC then the interflow takes
place at a rate:

Qinterflow = U ZF W C ∗ U ZK

When the precipitation intensity exceeds the percolation intensity and the maximum interflow
drainage capacity, then the upper zone free water capacity (U ZF W M ) is completely filled
and the excess precipitation causes surface runoff.

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Lower zone storage
The lower zone consists of the

tension water storage, i.e. the depth of water held by the lower zone soil after wetting and
drainage (storage up to field capacity) and

two free water storages: the primary and supplemental storage elements representing
the storages leading to a slow and a fast groundwater flow component, respectively. The
introduction of two free lower zone storages is made for greater flexibility in reproducing
observed recession curves caused by groundwater flow.
Percolation from upper to lower zones

The percolation rate from the upper zone to the lower zone depends on the one hand on the
lower zone demand, i.e. requirements determined by the lower zone water content relative to
its capacity and on the other hand on the upper zone free water content relative to its capacity.
The lower zone percolation demand is denoted by P ERCact.dem . The upper zone free water content relative to its capacity is U ZF W C/U ZF W M . Hence, the actual percolation
intensity then reads:

P ERC = P ERCact.dem × U ZF W C/U ZF W M

The lower zone percolation demand has a lower and an upper limit:

the minimum lower zone percolation demand, and
the maximum lower zone percolation demand.

The minimum lower zone percolation demand occurs when all three lower zone storages are
completely filled. Then by continuity the percolation rate equals the groundwater flow rate
from full primary and supplemental reservoirs. Denoting the minimum demand by PBASE
then it follows:

P ERCmin.dem = P BASE = LZF P M × LZP K + LZF SM × LZSK
where:

LZF P M
LZF SM
LZP K
LZSK

lower zone primary free water storage capacity
lower zone supplemental free water storage capacity
drainage factor of primary storage
drainage factor of supplemental storage

The maximum lower zone percolation demand takes place if the lower zone is completely
dried out i.e. if its content = 0. Then the maximum percolation rate is expressed as a function
of PBASE:

P ERCmax.dem = P BASE(1 + ZP ERC)

with: ZP ERC 1 usually.
The actual lower zone percolation demand depends on the lower zone content relative to its
capacity. Computationally it means that ZPERC has to be multiplied by a function G of the
relative lower zone water content such that this function:

equals 1 in case of a completely dry lower zone
equals 0 in case of a completely saturated lower zone
646 of 900

Conceptual description

represents an approximate exponential decay of the percolation rate in case of a continuous recharge.
In the Sacramento model this function has the following form:

(lower zone capacities − lower zone content)
P
(lower zone capacities)

and the actual percolation demand is given by (see Figure 6.96):
(6.317)

P ERCact.dem = P BASE(1 + ZP ERC ∗ G)

Figure 6.96: Actual percolation demand representation

Distribution of percolated water from upper zone

The percolated water drains to three reservoirs, one tension and two free water reservoirs.
Based on the preceding comments one would expect that the lower zone tension storage
is filled first before percolation to the lower zone free water storages takes place. However,
variations in soil conditions and in precipitation amounts over the catchment cause deviations
from the average conditions. This implies that percolation to the free water reservoirs and
hence groundwater flow takes place before the tension water reservoir is completely filled.
The model allows for this to let a fraction of the infiltrated water percolate to the two free water
storages. When the tension water reservoir is full, all percolated water drains to the primary
and supplemental free water storage in a ratio corresponding to their relative deficiencies.
6.5.2.6

Groundwater flow
Base flow to the river from groundwater depends on the contents of the two lower zone free
water storages and two drainage constants expressed in fractions of the content per day. If
the actual contents of the primary and supplemental free water zones are denoted by LZFPC
and LZFSC respectively then the total base flow QBASE becomes, in accordance with the
linear reservoir theory:

QBASE = LZF P C × LZP K + LZF SC × LZSK

SOBEK, User Manual

The drainage factors LZP K and LZSK can be determined from the recession part of the
hydrograph by plotting that part of the hydrograph on semi-logarithmic paper (Fig. 6).

In the lowest part of the recession curve only the slow base flow component is acting while in
the higher stages both base flow components contribute.

Figure 6.97: Principle of computation of lower zone recession coefficient

The drainage factor LZP K follows from:

LZP K = 1 − K
where:

K
∆t
QPt0+∆t
QPt0

recession coefficient of primary base flow for the time unit used
number of time units, generally days
a discharge when recession is occurring at the primary base flow rate
the discharge t time units later

If QPmax represents the maximum value of the primary base flow, then the maximum water
content of the lower zone becomes:

and similarly the supplemental lower zone free water capacity is determined; at least this
procedure provides first estimates of the lower zone free water capacities (Figure 6.97).
The total base flow contributes completely or in part to the channel flow. A complete contribution occurs if subsurface discharge (i.e. discharge from the segment, which is not measured
at the outlet) is absent. Otherwise a fraction of the total base flow represents the subsurface
flow.

Conceptual description

Actual evapotranspiration
Evaporation at a potential rate occurs from that fraction of the basin covered by streams,
lakes and riparian vegetation. Evapotranspiration from the remaining part of the catchment is
determined by the relative water contents of the tension water zones. If ED is the potential
evapotranspiration, then the actual evapotranspiration from the upper zone reads:

U ZT W C
U ZT W M

i.e. the actual rate is a linear function of the relative upper zone water content. Where E1 <
ED water is subtracted from the lower zone as a function of the lower zone tension water
content relative to the tension water capacity:

LZT W C
U ZT W M + LZT W M

E2 = (ED − E1 )

If the evapotranspiration should occur at such a rate that the ratio of content to capacity of the
free water reservoirs exceeds the relative tension reservoir content then water is transferred
from free water to tension water such that the relative loadings balance. This correction is
made for the upper and lower zone separately. However, a fraction RSERV of the lower
zone free water storage is unavailable for transpiration purposes.
Impervious and temporary impervious areas

Besides runoff from the pervious area, the channel may be filled by rainwater from the impervious area. With respect to the size of the impervious area it is noted that in the Sacramento
model a distinction is made between permanent and temporary impervious areas where
temporary impervious areas are created when all tension water requirements are met, i.e. an
increasing fraction of the catchment assumes impervious characteristics.
6.5.2.9

Routing of surface runoff

Before the runoff from the impervious areas, the overland- and interflow branch the channel,
they may be transformed according to a unit hydrograph leading to an adapted time distribution of these flow rates.
Use can be made here of the Clark method, which is a combined time-area and storage routing method. The model requires the construction of a time-area diagram. For this isochrones
are constructed representing points of equal travel time to the segment outlet, see Figure 5.
The areas between successive isochrones is determined and subsequently properly scaled
by the time of concentration Tc . The latter is defined as the time required to have the effect of
rainfall fallen in the most remote part felt at the segment outlet. The time-area diagram can be
thought of as the outflow from the segment if only translation and no deformation takes place
of an instantaneous unit supply of rain over the entire segment. Subsequently, the time area
diagram flow is routed through a linear reservoir, which characterises the effect of storage in
the open drainage system of the segment. This reservoir is represented by the second parameter: the recession coefficient k . It is noted that the output from the reservoir represents
the instantaneous unit hydrograph (IUH). This has to be transformed into say a 1-hour unit
hydrograph, dependent on the chosen routing interval

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Figure 6.98: Principles of the Clark method for simulating surface runoff and interflow.

The two parameters Tc and k can be obtained from observed rainfall and discharge hydrographs. The time of concentration is equal to the time interval between cessation of rainfall
and the time the hydrograph has receded to its inflection point. Alternatively it is determined
from physical features of the segment as length and slope. A large number of empirical formulas are available which relate the time of concentration to topographical features of the
basin. It is noted, though, that these formulas have generally only local validity. The best is
to estimate the celerity from the flow velocities in the drainage system taking account of the
following characteristics of celerity:

If the rivulet remains inbank the celerity is about 1.5 to 1.7 times the cross-sectional flow
velocity
If the flow becomes overbank the above celerity has to be multiplied with the ratio of
the drain width and the total width of the flow at the water surface (i.e. inclusive of the
floodplain)
To the time required to travel through the drainage system one has to add the overland flow
time.
The recession coefficient k is determined from the slope of recession part of the surface runoff
hydrograph, similar to the procedure for groundwater.
6.5.2.10

Sacramento - Estimation of segment parameters

Conceptual description

Overview of parameters
The following groups of parameters can be distinguished for a particular segment:

Segment
[-] Segment area [km2 ]

Direct runoff
PCTIM

Permanently impervious fraction of segment contiguous with stream channels
ADIMP
Additional impervious fraction when all tension water requirements are met
SARVA
Fraction of segment covered by streams, lakes and riparian vegetation
Upper soil moisture zone

Proportional increase in percolation from saturated to dry conditions in lower
zone
Exponent in percolation equation, determining the rate at which percolation
demand changes from dry to wet conditions

Capacity of upper tension water zone [mm]
Capacity of upper free water zone [mm]
Upper zone lateral drainage rate (fraction of contents per day)

UZTWM
UZFWM
UZK
Percolation

Lower zone
LZTWM
LZFPM
LZFSM
LZPK
LZSK

SIDE
SSOUT
Surface runoff

Capacity of lower zone tension water storage [mm]
Capacity of lower zone primary free water storage [mm]
Capacity of lower zone supplemental free water storage [mm]
Drainage rate of lower zone primary free water storage (fraction of contents
per day)
Drainage rate of lower zone supplemental free water storage (fraction of
contents per day)
Fraction of percolated water, which drains directly to lower zone free water
storages
Fraction of lower zone free water storages which is unavailable for transpiration purposes
Ratio of unobserved to observed base flow
Fixed rate of discharge lost from the total channel flow [mm/∆t]
[-] Unit hydrograph ordinates

Internal routing interval
PM
PT1
PT2

Time interval increment parameter
Lower rainfall threshold
Upper rainfall threshold

Basically two procedures are available to get first estimates for the majority of the segment
parameters:

from observed rainfall and runoff records: this method is usually applied and works well
provided that the model concepts are applicable and that reliable records are available for
some time covering the majority of the range of flows
from soil characteristics: this method is particularly suitable if no runoff records are available, i.e. for ungauged catchments.
With respect to gauged catchments the following grouping of parameters according to the

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method of estimation can be made:

Parameters computed and estimated from basin map solely:

Segment parameter estimation for gauged catchments.

The estimation of the segment parameters is presented according to their order of appearance
in the previous sub-section. The sequence in which the estimation is done in practice is
different from this order, for which reference is made to the end of the sub-section.

segment area and SARVA
Parameters estimated from observed rainfall and runoff records:
readily: LZFPM, LZPK, LZFSM, LZSK, PCTIM
approximately: UZTWM, UZFWM, UZK, LZTWM, SSOUT and PFREE
Parameters estimated from topographic maps and rainfall and runoff records:
unit hydrograph ordinates obtained from Clark method
Parameters to be obtained through trial runs:
ZPERC, REXP, SIDE, ADIMP, RSERV
Internal routing parameters, as per requirement:
PM, PT1, PT2
In the next sub-sections guidelines are given for the determination and estimation of the
segment parameters for gauged catchments.

To allow a good comparison between the observed and simulated runoff from the basin, the
segment area (km2 ) should refer to the total segment area draining upstream of the gauging
station. Any difference between total segment area up to the main stream and the area
upstream of the gauging station can be accommodated for in the channel routing part.
Direct runoff
PCTIM

Permanently impervious fraction of the basin contiguous with stream channels. It can be
determined from small storms after a significant period of dry weather. Then the volume of
direct runoff (= observed runoff - base flow) divided by the volume of rain gives the percentage
impervious fraction of the basin. PCTIM should not be close to 1!
An example is given below.

Conceptual description

Figure 6.99: Calculation of PCTIM

Fraction of the basin, which becomes impervious as all tension water requirements are met.
It can be estimated from small storms after a very wet period. As before, the volume of
direct runoff divided by the volume of rain gives the total percentage of impervious area. The
estimate for ADIM P follows from:

ADIM P = Total Percentage Impervious − P CT IM

Fraction of the basin covered by streams, lakes, and riparian vegetation, under normal circumstances. The SARVA area is considered to be the same as or less than PCTIM (see below).
Detailed maps may be referred to in order to estimate the extent of paved areas, which drain
directly to the streams so that differences between PCTIM and SARVA can be approximated.
Generally, SARVA appears to range between 40 % and 100 % of the PCTIM value.
Upper soil moisture zone

UZTWM - the upper tension storage capacity

The depth of water, which must be filled over non-impervious areas before any water becomes
available for free water storage. Since upper zone tension water must be filled before any
stream flow in excess of the impervious response can occur, its capacity can be approximated
from hydrograph analysis. Following a dry period when evapotranspiration has depleted the
upper soil moisture, the capacity of upper zone tension water can be estimated. That volume
of rainfall, which is retained before runoff from the pervious fraction is visible, is identified as
UZTWM. To that rainfall volume the losses to evaporation during the considered period should
be added. All periods of rain following a dry period should be checked for estimation of this
parameter. Generally the capacity of the upper zone tension will vary between 25 and 175
mm, depending on the soil type.
Following the logic of the Curve Number method, where the initial abstraction before rainfall
becomes effective is estimated as 20 % of the potential maximum retention, the UZTWM

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U ZT W M = 50.8

100
− 1 [mm]
CN

CN-values range from 30 to about 90 for rural areas and are a function of:

soil type (soil texture and infiltration rate); hydrological soil groups A–D are distinguished
land use, type of land cover, treatment and hydrologic or drainage condition

UZFWM - the upper free water storage capacity

It is also a function of antecedent moisture condition, for which the condition “dry” should be
taken in view of the meaning of U ZT W M . Based on this assumption U ZT W M would
vary between 120 and 6 mm, values which are in the range of those given above, particularly
if one realises that the 20 % of the potential maximum as initial abstraction is an average
value. Reference is made to standard textbooks on hydrology for CN-values

Upper zone free water represents that depth of water, which must be filled over the nonimpervious portion of the basin in excess of U ZT W M in order to maintain a wetting front
at maximum potential. This volume provides the head function in the percolation equation
and also establishes that volume of water, which is subject to interflow drainage. Generally its
magnitude ranges from 10–100 mm. It is not generally feasible to derive the magnitude of the
upper zone free water from direct observations, and successive computer runs are required
in order to establish a valid depth.
However, if a rough estimate of U ZK is available (see below), then a rough value of U ZF W M
can be obtained from the hydrograph at the time of the highest interflow, by reducing the flow
value with primary and supplemental base flow.
UZK - the upper zone lateral drainage rate

The upper zone lateral drainage rate is expressed as the ratio of the daily withdrawal to the
available contents. Its range is roughly 0.18 to 1.0, with 0.40 generally serving as an effective
initial estimate. Though basically, this factor is not capable of direct observation and must be
determined by successive computer runs, Peck (1978) suggests the following approximate
procedure. U ZK is roughly related to the amount of time that interflow occurs following a
period with major direct and surface runoff. A long period of interflow results in a small value
for U ZK . Assuming that interflow is observed during N consecutive days and that interflow
becomes insignificant when it is reduced to less than 10 % of its maximum value it follows:

(1 − U ZK)N = 0.10

U ZK = 1 − 0.11/N

Values for U ZK as a function of N can be read from Figure 6.100.

Conceptual description

Figure 6.100: UZK as function of number of days with significant interflow

Percolation
ZPERC

The proportional increase in percolation from saturated to dry condition is expressed by the
term ZPERC. The value of ZPERC is best determined through computer trials. The initial
estimate can be derived by sequentially running one or two months containing significant hydrograph response following a dry period. The value of ZPERC should be initially established
so that a reasonable determination of the initial run-off conditions is possible.
Amstrong (1978) provides a procedure to derive ZPERC from the lower zone tension and free
water reservoir capacities and drainage rates, using Equation (6.314) and Equation (6.315).
The maximum percolation takes place when the upper zones are full and the lower zones are
empty. Assuming that the maximum daily percolation will be the maximum contents of the
lower zones, from equation Equation (6.315) it follows for ZPERC:

LZT W M + LZF P M + LZF SM − P BASE
P BASE

If data would be available on maximum percolation rates ZPERC can be estimated using
equation Equation (6.315). Values for ZPERC ranging from 5 to 80 have been used.
REXP

The exponent in the percolation equation which determines the rate at which percolation
demand changes from the dry condition, (ZP ERC + 1)P BASE , to the wet condition,
PBASE. Figure 6.98 illustrates how different values of the exponent affect the infiltration rate.
It is recommended that an initial estimate of this exponent is made from the same record
which is used in determining an initial estimate of ZPERC. The interaction between PBASE,
ZPERC and REXP may require a shift of all three terms whenever it becomes clear that a
single term should be changed. Visualising the percolation curve generated by these three
terms helps to ascertain the necessary changes. The observed range of REXP is usually
between 1.0 and 3.0. Generally a value of about 1.8 is an effective starting condition. Values
for REXP for different soils are given by Amstrong (1978) and are presented in Table 6.11.

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Table 6.11: Percolation exponent REXP for different soil types

Soil classification

Sand
Sandy loam
Loam
Silty loam
Clay, silt

1.0
1.5
2.0
3.0
4.0

LZTWM - lower zone tension water capacity [mm]

This volume is one of the most difficult values to determine effectively. In as much as carryover
moisture in this storage may exist for a period of many years, its total capacity may not be
readily discernible from available records. If a drought condition during the period of record in
the basin or in the area being studied has been sufficient to seriously affect the transpiration
process of deep rooted plants, then the period of record is usually sufficient to determine
the maximum storage value of lower zone tension water. Often, however, field data is not
adequate for this purpose. As a result, unless great care is taken, the depth of lower zone
tension water storage may inadvertently be set near the maximum deficit experienced during
the period of record rather than the actual capacity of the zone. It has been noted that the
plant growth of an area is a relatively effective indicator of the capacity of the lower zone
tension water zone. In heavily forested regions of deep-rooted conifers, this zone may be
approximately 600 mm in magnitude. In areas of deep-rooted perennial grasses this depth
is more likely to be close to 150 mm. Where vegetation is composed primarily of relatively
shallow-rooted trees and grasses, this depth may be as little as 75 mm. It should be realised
that this zone represents that volume of water, which will be tapped by existing plants during
dry periods.
An approximate procedure to estimate LZTWM from a water balance analysis is presented
by Peck (1978). For this a period is selected with direct and/or surface runoff following an
extended dry spell. The selected period is bounded by the times t1 and t2 . At both times t1
and t2 only base flow occurs. The start t1 is selected immediately prior to the occurrence of
direct/surface runoff and t2 immediately following a period of interflow. The times t1 and t2
can best be selected from a semi-log plot of the runoff, see Figure 6.101.

Conceptual description

Figure 6.101: Selection of period for LZTWM estimation

Assuming that UZTW is full and UZFWC is empty at times t1 and t2 the water balance for the
period t1 − t2 then reads:

P − R − E − DLZF P C − DLZF SC = DLZT W C

precipitation from t1 to t2 [mm]
total runoff from t1 to t2 [mm]
segment evaporation [mm]; this amount would small for most wet period and
may be neglected
DLZF P C change in storage in LZ primary free water reservoir from t1 to t2 [mm]
DLZF SC change in storage in LZ supplemental free water reservoir from t1 to t2 [mm]
DLZT W C change in the lower zone tension water [mm]
DLZTWC is a lower limit of LZTWM since:

1 The lower zone tension water reservoir may not have been fully empty at t1
2 The lower zone tension water reservoir may not have been completely filled at t2
Hence some 10 to 20 % (or more) may be added to the value obtained through Equation (6.328). If such ideal cases as assumed above cannot be found, water balances for
periods of 3 to 4 months may be considered.
In Equation (6.328) LZFPC and DLZFSC are computed as follows:

DLZF P C = LZF P C(t2 ) − LZF P C(t1 ) where LZF P C(t) = QP (t)/LZP K
(6.329)

DLZF SC = LZF SC(t2 ) − LZF SC(t1 ) where LZF SC(t) = QS(t)/LZSK
(6.330)

The primary baseflows QP at times t1 and t2 are estimated by extrapolation from other
periods. Let the discharges at t1 and t2 be denoted by Q1 and Q2, then the supplemental
baseflows follow from:

QS(t1 ) = Q1 − QP (t1 ) and QS(t2 ) = Q2 − QP (t2 )

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LZFPM - lower zone primary free water storage

LZFSM - lower zone supplemental free water storage

The maximum capacity of the primary lower zone free water, which is subject to drainage at
the rate expressed by LZP K . The value of the lower zone primary free water maximum can
be approximated from hydrograph analysis. For this the primary base flow, obtained from a
semi-log plot of the lower end of the recession curve, is extended backward to the occurrence
of a peak flow. Assuming that the primary free water reservoir is completely filled then, so
that it outflow is at maximum (QP max), its value is determined from Equation (6.321). The
effectiveness of this computation in determining the maximum capacity is dependent upon
the degree to which the observed hydrograph provides a representation of the maximum
primary base flow. If only a portion of the groundwater discharge is observable in the stream
channel, the estimated capacity based upon surface flows must be increased to include the
non-channel components by applying the term SIDE (See below).

The maximum capacity of the lower zone supplemental free water reservoir, which is subject
to drainage at the rate expressed by LZSK. A lower limit of the lower zone free water supplemental maximum can be approximated from hydrograph analysis. Figure 6.97 illustrates the
computation of the lower zone free water supplemental maximum. Note that first the primary
base flow has to be identified and corrected for, see also Equation (6.331). The effectiveness
of this computation in determining the maximum capacity is dependent upon the degree to
which the observed hydrograph provides a representation of the maximum base flow capability of the basin. If only a portion of the groundwater discharge is observable in the stream
channel, the estimated capacity based upon surface flows must be increased to include the
non-channel components by applying the term SIDE (See below).
LZPK - lateral drainage of the lower zone primary free water reservoir.

Lateral drainage rate of the lower zone primary free water reservoir expressed as a fraction
of the contents per day. The coefficient is determined from the primary base flow recession
curve. Selecting flow values from this curve at some time interval Dt apart provides with the
help of Equation (6.319) and Equation (6.320) the required estimate, see also Figure 6.97.
LZSK - lateral drainage of the lower zone supplemental free water reservoir
Lateral drainage rate of the lower zone supplemental free water reservoir, expressed as a
fraction of the contents per day. Its computation is outlined in Figure 6.97. The procedure is
similar to that of LZPK, with the exception that the flow values have to be corrected for the
primary base flow.
PFREE

The fraction of the percolated water, which is transmitted directly to the lower zone free water
aquifers. Its magnitude cannot generally be determined from hydrograph analysis. An initial
value of 0.20 is suggested. Values will range between 0 and 0.50. The analysis of early
season base flow allows an effective determination of PFREE. The relative importance of
PFREE can be determined from storms following long dry spells that produce runoff (UZTW
completely filled). If the hydrograph returns to approximately the same base flow as before
then little filling of the lower zone free water reservoirs did take place and hence the PFREEvalue can be rated small, 0 to 0.2. If, on the contrary, the base flow has increased significantly
a PFREE-value as high as 0.5 may be applicable.
RSERV

Conceptual description

Fraction of the lower zone free water, which is unavailable for transpiration purposes. Generally this value is between zero and 0.40 with 0.30 being the most common value. This factor
has very low sensitivity.
SIDE

Represents that portion of base flow, which is not observed in the stream channel. When
the soil is saturated, if percolation takes place at a rate, which is greater than the observable
base flow, the need for additional soil moisture drainage becomes manifest. SIDE is the ratio
of the unobserved to the observed portion of base flow. When the saturated soils do not
drain to the surface channel, SIDE allows the correct definition of PBASE, in order that the
saturated percolation rate may be achieved. In an area where all drainage from base flow
aquifers branches surface channels, SIDE will be zero. Zero or near zero values occur in a
large proportion of basins. However, in areas subject to extreme subsurface drainage losses,
SIDE may be as high as 5.0. It is conceivable that in some areas the value of SIDE may be
even higher.

The sub-surface outflow along the stream channel, which must be provided by the stream
before water is available for surface discharge. This volume expressed in mm/time interval
is generally near zero. It is recommended that the value of zero be utilised, and SSOUT is
applied only if the 10 log Q vs. time plot requires a constant addition in order to achieve a valid
recession characteristic. If constant volumes of flow are added to observed stream flow, the
slope of the discharge plot will be altered. That value, which is required to linearize the primary
recession, is the appropriate value of SSOUT. It should be realised that where SSOUT is
required, an effective determination of lower zone free water storages and discharge rates will
require inclusion of the SSOUT value (mm/∆t)
Surface runoff

Unit hydrograph ordinates for the routing of flow from the impervious and pervious surfaces as
well as interflow towards the segment outlet can be obtained through standard unit hydrograph
procedures. It requires the selection of rainfall events (corrected for losses) with their resulting
flood hydrographs (corrected for base flow). Note that for each event the net rainfall amount
should match with the surface runoff and interflow amount. Various procedures are available
to arrive at a unit hydrograph. If the rainfall intensity during the storm varies, multiple linear
regression and discrete convolution techniques may be applied. The regression technique is
readily available in spreadsheet software. The resulting unit hydrographs generally will show
some irregularities and hence requires some smoothing afterwards. Unit hydrographs from
various storms may appropriately be averaged to arrive at a representative unit hydrograph
for the segment.
Another option is to use the Clark method. The principle of the Clark method was dealt with
in Sub-section 2.2.8. First requirement is the derivation of a time-area diagram. If a Digital
Elevation Model (DEM) is available from a catchment with appropriate software automatic
calculation of the time-area diagram is possible. In the absence from a DEM the time-area
diagram is derived from a basin map. By estimating travel times to the basin outlet (from
river and terrain slopes, assumed roughness and flow depth) isochrones can be determined.
The areas between successive isochrones is determined leading to a first estimate of the
time-area diagram. The total time base of the time-area diagram should be the concentration
time Tc , but due to inaccurate assessment of celerities in the basin it may differ from that.
Therefore, the time base of the time-area diagram is scaled by a more appropriate estimate of
Tc . An estimate for Tc may be obtained as the time lapse between the cessation of rainfall and

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the occurrence of recession on the falling limb of the hydrograph of surface runoff. The time
base of the time-area diagram is scaled by this time lapse. Alternatively, the concentration
time is estimated from an empirical formula applicable to the region. E.g. for a number of
small catchments in the Indus basin the following equation applies:

concentration time [h]
length of river [km]
slope of main river

The units of the time-area diagram (km2 ) are converted into m3 /s by multiplication with
0.278/∆t, with ∆t in hours. Subsequently, the time-area diagram is routed through a linear
reservoir, with reservoir coefficient k , estimated from the slope of the recession curve of the
surface water hydrograph. The routing is carried out by the following equation:

Oi+1 = c1 Iav + c2 Oi
1
Iav = (Ii+1 + Ii )
2
∆t
c1 =
k + ∆t/2
k − ∆t/2
c2 =
k + ∆t/2
c1 + c2 = 1

(6.333)
(6.334)
(6.335)
(6.336)
(6.337)

average inflow during ∆t (input is in form of histogram)
outflow from the linear reservoir

The outflow from the reservoir is the Instantaneous Unit Hydrograph (IUH) for the basin, which
has to be transformed by averaging or S-curve technique into the Unit Hydrograph resulting
from a rainfall of duration equal to the routing interval.
Internal routing interval
PM
Time interval increment parameter
P t1
Lower rainfall threshold
P t2
Upper rainfall threshold

In case the time step used in the model is larger than 1 hour, the model simulates the redistribution of water between the various reservoirs with a time step, which is smaller than the time
interval of the basic data. Particularly for the infiltration process this effect could be important.
Also the rainfall will be lumped to that smaller interval. The number of increments in the time
interval is derived from:

N∆t = 1 + P M ∗ (U ZF W C ∗ F + Peff )

F =1
F = 1/2Peff /P t2
F = 1 − 1/2P t2 /Peff

for Peff < P t1

for P t1 ≤ Peff ≤ P t2

for Peff > P t2

Conceptual description

The most important parameter is seen to be PM. Taking a very small value for P M (say
P M = 0.01), then N∆t remains approximately1. If e.g. P M = 0.1 then N∆t becomes
substantially larger than 1. To limit the increase of N∆t a low value for P t1 is to be chosen in
combination with a large value of P t2 , which will reduce the value of F .
Sequence of parameter estimation
From the presentation above it will be clear that certain parameters should be estimated before
other can be assessed. The following sequence is recommended of which the first three steps
are mandatory:

Segment area
Lower zone primary free water parameters LZPK and LZFPM
Lower zone supplemental free water parameters LZSK and LZFSM
Impervious fraction PCTIM
Upper zone parameters UZTWM, UZK and UZFWM
Lower zone tension capacity LZTWM
Percolation parameters ZPERC and REXP
Remaining parameters

1
2
3
4
5
6
7
8

Linear reservoirs

An essential feature of the Sacramento model is that the free water reservoirs are considered
as linear reservoirs, i.e. there is a linear relation between the reservoir storage S and the
outflow Q:

If the recharge is indicated by I , the continuity equation for the linear reservoir reads:

Eliminating S from above equations results in a linear first order differential equation in Q:

dQ 1
1
+ Q− I =0
dt
k
k

With I constant and at t = t0 , Qt = Qt0 the solution to Equation (6.344) reads:

t − t0
t − t0
+ Qt0 exp −
Qt = I 1 − exp −
k
k

When there is no recharge to the reservoir (I = 0) Equation (6.345) reduces to:

t − t0
Qt = Qt0 exp −
k

This equation can be compared with Equation (6.319), using the same notation:

Qt = Qt0 K (t−t0 )

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1
K = exp −
k

Expressing time in days, then the amount of water released from the reservoir in 1 day
amounts according to equation Equation (6.342):

S0 − S1 = kQ0 − kQ1 = kQ0

1
1 − exp −
k

S0 = LZF P C and 1 − K = LZP K

This is seen to match with e.g. the equations for the lower zone primary free water reservoir,
where:
(6.350)

Equation (6.348) provides a means to express the lower zone free water parameters in terms
of dimensions and physical properties of aquifers. Consider the phreatic aquifer shown in
Figure 6.102, which has the following dimensions and properties:
The width of the aquifer perpendicular to the channel is L
The water table at the divides is h0 above the drainage base
The specific aquifer yield is m
The aquifer transmissivity is T .

Figure 6.102: Schematic cross-section through basin aquifer

The amount of water stored above the drainage base per unit length of channel available for
drainage is:

S = mc1 Lh0 with

Conceptual description

The discharge to the channel per unit length of channel according to Darcy with the Dupuit
assumption

dh
2T c2 h0
=
with c2 > 1
dx
(L/2)

Combining the above two equations by eliminating h0 and bringing it in the form of the linear
storage discharge relation Equation (6.342) :

c2
µL2
Q with c =
>1
4cT
c1

Hence for the reservoir coefficient k in Equation (6.342) it follows:

The reservoir coefficient k is seen to be proportional to the square of the aquifer width and
inversely proportional to T , which is logical as k is a measure for the reside-time of the
percolated water in the groundwater zone. The value of c varies between 2 and 2.5 dependent
on the shape of the water table. For the parameters K and LZPK for the lower zone primary
free water storage it then follows:

4cT
K = exp − 2
µL

4cT
and LZP K = 1 − exp −
µL2

A similar story applies for the lower zone free supplemental reservoir, which can be viewed as
representing the drainage from the shallower based denser network of the smaller channels,
see Figure 6.103. Since its main difference is with the aquifer width L, which is much smaller
than for the deeper based primary channel network, its reservoir coefficient will be smaller
than of the primary free water storage and consequently LZSK LZP K .

Figure 6.103: Cases of multiple exponential decay of recession curve

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Note that similar differences in a basin between fast and slow draining aquifers if different soils
are present leading to different transmissivities.
6.5.3

Description of the D-NAM rainfall-runoff model
The "D-NAM" rainfall-runoff model is developed at Deltares. It concerns an improvement
and expansion of the NAM rainfall-runoff model, developed at the Institute of Hydrodynamics
and Hydraulic Engineering of the Technical University of Denmark (see Nielsen and Hansen
(1973)). NAM is the abbreviaton of the Danish "Nedbør-Afstrømmings-Model" (in Dutch
"Neerslag-Afvoer Model"), meaning rainfall-runoff model.

The D-NAM rainfall-runoff model is a deterministic, lumped and conceptual model, that treats
each catchment as a single unit. Model parameters and variables, therefore, represent average values for the entire catchment area.
A comparison of the D-NAM model and the NAM model is made in section 6.5.3.18.
6.5.3.1

External forces acting on a D-NAM model

External forces (or boundary conditions) acting on a D-NAM model comprise of:

1 Rainfall (P ), defined in the "Meteo" Task block.
2 Potential evapotranspiration (EP ), defined in the "Meteo" Task block.
3 Groundwater pump discharge (GW P ump), defined on the "GWPump" tab of the D-NAM
Node in the "Schematisation" Task block.
4 External water level (h). Either defined at a RR boundary Node (rainfall-runoff modelling
only) or computed by a 1D flow model (combined rainfall-runoff and 1D flow modelling).
6.5.3.2

D-NAM storages and their water-storage capacity

The D-NAM model comprises of three different reservoirs:

1 The surface storage, that is situated on the surface of the catchment area and has an
unlimited water-storage capacity.
2 The lower zone storage, having a limited water-storage capacity only and representing the
field capacity of the root zone layer (sf c [-]). In other words the part of the soil moisture
content that can be retained against gravity.
3 The groundwater storage, having a limited water-storage capacity only and representing
the soil moisture content that can not be retained against gravity.
The lower zone storage and the groundwater storage jointly represent the water-storagecapacity of the modelled soil layer thickness (see Figure 6.104). The soil beneath the surface
level (SL [m AD]) is divided into a root zone layer with bed level RZBL [m AD] and specific
yield sy,rz [-] and a subsoil layer with bed level GW SBL [m AD] and specific yield sy,ss [-].
For water-storage-capacities yield (see Figure 6.104):

The maximum water depth in the lower zone storage (Lmax [mm]) amounts to sf c (SL −
RZBL).
The maximum water depth in the root zone part of the groundwater storage
(GW SDrz,max [mm]) amounts to (sy,rz − sf c )(SL − RZBL).
The maximum water depth in the subsoil part of the groundwater storage (GW SDss,max
[mm]) amounts to sy,ss (RZBL − GW SBL).
The maximum water depth in the groundwater storage (GW SDmax [mm]) amounts to
GW SDrz,max + GW SDrz,max .

Conceptual description

Figure 6.104: Maximum water depths in lower zone storage and groundwater storage.
The solid part of the soil (coloured yellow) can not contain any groundwater.

D-NAM external and internal fluxes

The D-NAM model discerns nine external fluxes (see Figure 6.105):
1
2
3
4
5

Rainfall into the surface storage (P ).
Evaporation from the surface storage (E1).
Interflow out of the surface storage (IF ).
Overland flow out of the surface storage (OF ).
Transpiration from the root zone layer (E2); being the summation of the transpiration
from the lower zone storage (E2LZS ) and the transpiration from the root zone part of the
groundwater storage (E2GW S,rz ).
Groundwater Pump. Either the abstraction of water contained in the groundwater storage
(GWABS,Act ) or the supply of external water (GWSU P,Act ); being the summation of the
supply of external water into the lower zone storage (DLGW P ump ) and the supply of
external water into the groundwater storage (GWGW P ump ).
Fast base flow component out of the groundwater storage (F astBF ).
Slow base flow component out of the groundwater storage (SlowBF ).
Inflow of external (ground)water (GW Inf low ); being the summation of the inflow of
external (ground)water into the lower zone storage (DLExt ) and the inflow of external
(ground)water into the groundwater storage (GWExt ).

The D-NAM model discerns four internal fluxes (see Figure 6.105):
1
2
3
4

Infiltrated water (IN F ) or water in the surface storage that infiltrates into the soil.
Infiltration into the lower zone storage (DL).
Percolation into the groundwater storage (G).
Capillary rise of water (CR), contained in the subsoil part of the groundwater storage.

SOBEK, User Manual

Figure 6.105: Schematic representation of fluxes in the D-NAM rainfall runoff model.

Computing water depths in the surface flow storage

Water depths in the surface storage (U [mm]) are computed accounting for fluxes in the
following sequence (see Figure 6.106):
1
2
3
4
5

Rainfall P [mm] is added.
Evaporation E1 [mm] (see section 6.5.3.6) is subtracted.
Interflow IF [mm] (see section 6.5.3.7) is subtracted.
Infiltrated water IN F [mm] (see section 6.5.3.8) is subtracted.
Overland flow OF [mm] (see section 6.5.3.9) is subtracted.

Figure 6.106: Water depths, thresholds and fluxes related to the surface storage

Computing water depths in the lower zone storage and overland flow storage
Water depths in the lower zone storage (L [mm]) and the groundwater storage (GW SD
[mm]) are computed accounting for fluxes (see Figure 6.107) in the following sequence:
1 Infiltration DL [mm] (see section 6.5.3.10) is added to the lower zone storage.
2 Percolation G [mm] (see section 6.5.3.10) is added to the groundwater storage.

Conceptual description

3 Transpiration E2LZS [mm] (see section 6.5.3.11) is subtracted from the lower zone storage.
4 Transpiration E2GW Srz [mm] (see section 6.5.3.11) is subtracted from the groundwater
storage.
5 Capillary rise CR [mm] (see section 6.5.3.12) is subtracted from the groundwater storage
and added to the lower zone storage.
6 Fast base flow F astBF [mm] (see section 6.5.3.13) is subtracted from the groundwater
storage.
7 Slow base flow SlowBF [mm] (see section 6.5.3.13) is subtracted from the groundwater
storage.
8 External (ground)water DLExt [mm] (see section 6.5.3.14) is added to the lower zone
storage.
9 External (ground)water GWExt [mm] (see section 6.5.3.14) is added to the groundwater
storage.
10 Abstraction by the groundwater pump GWABS,Act [mm] (see section 6.5.3.15) is subtracted from the groundwater storage.
11 Supply by the groundwater pump DLGW P ump [mm] (see section 6.5.3.16) is added to
the lower zone storage.
12 Supply by the groundwater pump GWGW P ump [mm] (see section 6.5.3.16) is added to
the groundwater storage.

Figure 6.107: Fluxes related to the lower zone storage and groundwater storage. The
solid part of the soil (coloured yellow) can not contain any groundwater.

Evaporation from the surface storage

For the evaporation (E1 [mm]) from the surface storage yields:

E1 = min(EP, U )
where:

User-defined potential evapotranspiration (see section 6.5.3.1) [mm].
Water depth in the surface storage [mm].

SOBEK, User Manual

Interflow out of the surface storage
For interflow (IF [mm]) out of the surface storage yields:

Lα = (L − LT IF )/(Lmax − LT IF ), where Lα = 0 if L ≤ LT IF
CKIF∆t = 1/(1 − (1 − 1/CKIF )∆t/86400 )
IF = (Lα /CKIF∆t ) max(0, U − UT IF )
Note: No interflow occurs if U ≤ UT IF or L ≤ LT IF
where:

LT IF
U
UT IF
∆t

User-defined reservoir coefficient applied in routing interflow [day].
Reservoir coefficient used in each time-step ∆t [s] for routing interflow [∆t].
Water depth in lower zone storage [mm].
Maximum water depth in lower zone storage (see section 6.5.3.2 and Figure 6.104) [mm].
User-defined lower-zone-storage threshold for interflow (Figure 6.106) [mm].
Water depth in the surface storage [mm].
User-defined surface-storage threshold for interflow (Figure 6.106) [mm].
User-defined time-step [s].

CKIF
CKIF∆t
L
Lmax

Infiltrated water into the soil

For infiltrated water (IN F [mm]) from the surface storage into the soil yields:

IN Fcap,∆t = IN F Cap (∆t/3600)
DLmax = Lmax − L.

Gmax = min(GW SDmax − GW SD , Gpot,max (∆t/86400) )
IN F = min(U , IN Fcap,∆t , DLmax + Gmax )

Note: Infiltrated water (IN F ) equals zero if IN F Cap = 0
where:

GW SD
GW SDmax
IN F Cap
IN F Cap∆t
L
Lmax

Available water-storage-depth in the lower zone storage [mm].
Water depth that can potentially be stored in the groundwater storage
[mm].
User-defined maximum rate of percolation into the groundwater storage [mm/day].
Water depth in the groundwater storage [mm].
Maximum water depth in the groundwater storage (see section 6.5.3.2
and Figure 6.104) [mm].
User-defined maximum infiltration rate for water contained in the surface storage [mm/hr].
Amount of water contained in the surface storage that infiltrates into
the soil in time-step ∆t [mm/hr].
Water depth in lower zone storage [mm].
Maximum water depth in lower zone storage (see section 6.5.3.2 and
Figure 6.104) [mm].

Conceptual description

Water depth in the surface storage [mm].
User-defined time-step [s].

Overland flow out of the surface storage
Overland flow (OF [mm]) is determined using an approximate analytical formula that:
1 Describes overland flow with the Manning roughness formula for open channel flow.
2 Assumes that the catchment area is a rectangular container with drainage length CL [m]
and width B [m], having a slope S [-] towards its overland outflow point.
3 Assumes that overland flow occurs in such way, that at each point-in-time yields that water
depths in the surface storage are constant in space.

This approximate analytical formula is given below:

OF D = max(0 , U − UT OF )

−3/2
√
OF = OF D − 1000 (OF D/1000)−2/3 + (2 ∆t S)/(3 n CL)

Note: No overland flow occurs if U ≤ UT OF .
where:

OF D
U
UT OF
n
∆t
6.5.3.10

Overland flow depth (see Figure 6.106), defined as the water depth in the surface storage above UT OF [mm].
Water depth in the surface storage [mm].
Surface-storage threshold for overland flow [mm].
Manning value for the surface roughness of the catchment area [s/m1/3 ].
User-defined time-step [s].

Infiltration into the lower zone storage and percolation into the groundwater storage
Infiltrated water (IN F [mm], see section 6.5.3.8) is distributed as infiltration in the lower zone
storage (DL) [mm] and percolation in the groundwater storage (G) [mm] (see Figure 6.108).
This distribution is done as follows:

SOBEK, User Manual

Figure 6.108: Distributing infiltrated water (IN F ) over the lower zone storage and the
groundwater storage. The solid part of the soil (coloured yellow) can not
contain any groundwater.

1 DLBeneathLT P [mm] is the part of the infiltrated water (IN F ) that is stored in the lower
zone storage beneath the lower-zone-storage threshold for percolation (LT P [mm], see
Figure 6.108).

DLBeneathLT P = max(0 , min(LT P − L , IN F )).
where:

Water depth in the lower zone storage [mm].
Lower-zone-storage threshold for percolation [mm].

The value for LT P determines the degree in which infiltrated water (IN F ) is distributed
over the lower zone storage and the groundwater storage as proposed by Nielsen and
Hansen (1973). More precisely:

If LT P = Lmax the distribution proposed by Nielsen and Hansen (1973) is overruled.
Since, first the lower zone storage is completely filled up before infiltrated water can
percolate into the groundwater storage.
If 0 ≤ LT P < Lmax the distribution proposed by Nielsen and Hansen (1973) becomes applicable as soon as the lower zone storage is filled up to LT P , meaning
that part of the infiltrated water (IN F ) can percolate into the groundwater storage (or
G > 0) before the lower zone storage is at field capacity (or L < Lmax ).
2 DLN H,AboveLT P [mm] (see Figure 6.108) is the part of the infiltrated water (IN F ) that, in
line with the Nielsen and Hansen (1973) distribution, infiltrates into the lower zone storage
above LT P .

DLN H,AboveLT P = min(ADAboveLT P , (1 − (L/Lmax ))(IN F − DLBeneathLT P ))
where:

Available water-storage-depth in the lower zone storage above
LT P [mm].

Conceptual description

Maximum water depth in the lower zone storage (see section 6.5.3.2
and Figure 6.104) [mm].

3 GN H [mm] (see Figure 6.108) is the part of the infiltrated water (IN F ) that, in line with
the Nielsen and Hansen (1973) distribution, percolates into the groundwater storage.

GN H = IN F − DLBeneathLT P − DLN H,AboveLT P
4 The actual percolation (G [mm]) follows from limiting GN H to the user-defined maximum
percolation rate Gpot,max [mm/day].

G = max(GN H , Gpot,max (∆t/86400))

where:
User-defined maximum rate of percolation into the groundwater storage
[mm/day].
User-defined time-step [s].

5 For the actual infiltration into the lower zone storage (DL [mm], see Figure 6.108) yields.

DL = IN F − G

Transpiration from the root zone layer

Transpiration from the root zone layer (E2 [mm], see Figure 6.107) respectively comprises of
transpiration from the root zone part of the groundwater storage (E2GW S,rz [mm]) and transpiration from the lower zone storage (E2LZS [mm]). E2GW S,rz and E2LZS are computed
as follows:

GW SDrz = max(0, GW SD − GW SDss,max )

E2 = min(L + GW SDrz , (EP − E1)(L + GW SDrz )/(Lmax + GW SDrz ))
E2GW S,rz = min(E2 , GW SDrz ).
E2LZS = E2 − E2GW S,rz
where:

E1
EP
GW SD
GW SDrz
GW SDss,max
L
Lmax

Evaporation from the surface storage (see section 6.5.3.6) [mm].
User-defined potential evapotranspiration (see section 6.5.3.1) [mm].
Water depth in the groundwater storage [mm].
Water depth in the root zone part of the groundwater storage [mm].
Maximum water depth in the root zone part of the groundwater storage (see section 6.5.3.2 and Figure 6.104) [mm].
Water depth in the lower zone storage [mm].
Maximum water depth in the lower zone storage (see section 6.5.3.2
and Figure 6.104) [mm].

SOBEK, User Manual

Capillary rise
For capillary rise (CR [mm], see Figure 6.107) yields:

CR = min(Lmax − L , GW SD , (∆t/86400) CRpot,max )
where:

CRpot,max User-defined maximum capillary rise [mm/day].
GW SD Water depth in the groundwater storage [mm].
L
Water depth in the lower zone storage [mm].
Lmax
Maximum water depth in the lower zone storage (see section 6.5.3.2 and Figure 6.104) [mm].
User-defined time-step [s].

Note: The surface level (SL [m AD]) and the bed level of the groundwater storage (GW SBL
[m AD]) determine the thickness of the soil layer, that is considered in a D-NAM model. So the
bed level of the groundwater storage is to be considered as watertight. Therefore, CRpot,max
is set equal to zero if GW SD = 0, this irrespective of the user-defined value for CRpot,max .
Fast and slow base flow component

Base flow occurs only if the external water level (h [m AD]) is below the groundwater level
(GW L [m AD]). Base flow equals zero if h ≥ GW L (see Figure 6.109). Water contained in
the lower zone storage can not flow out as base flow, since this water can be retained against
gravity.

Figure 6.109: Computing the Fast base flow component and the Slow base flow component. The solid part of the soil (coloured yellow) can not contain any
groundwater.

The fast base flow component (F astBF ) and the slow base flow component (SlowBF ) are

Conceptual description

computed as follows (see Figure 6.109):

GW SDss = min(GW SD , GW SDss,max )
GW SDrz = max(0 , GW SD − GW SDss,max )
GW L = GW SBL + (GW SDss /1000 sy,ss ) + ((GW SDrz + L)/1000 sy,rz )
ZF astBF = max(h, TF astBF )
ZSlowBF = max(h, TSlowBF )

dHSlowBF = max(0, GW L − ZSlowBF )

dHF astBF = max(0, GW L − ZF astBF )

GW SDZF astBF = f (ZF astBF , SL , RZBL , GW SBL , sy,rz , sf c , sy,ss )

GW SDZSlowBF = f (ZSlowBF , SL , RZBL , GW SBL , sy,rz , sf c , sy,ss )
Vpot,F astBF = max(0, GW SD − GW SDZF astBF )

Vpot,SlowBF = max(0, GW SD − GW SDZSlowBF )

CKF astBF∆t = 1/(1 − (1 − 1/CKF astBF )∆t/86400 )

CKSlowBF∆t = 1/(1 − (1 − 1/CKSlowBF )∆t/86400 )

F astBFpot = min(Vpot,F astBF , 1000(dHF astBF /CKF astBF∆t ) )
SlowBFpot = min(Vpot,SlowBF , 1000(dHSlowBF /CKSlowBF∆t ) )
GWOutflow pot = FastBFpot + SlowBFpot

F astBF = F astBFpot if GWOutflow pot ≤ Vpot,FastBF

F astBFpot
if GWOutflow pot > Vpot,FastBF
F astBF = Vpot,F astBF GWOutflow
pot

SlowBF = SlowBFpot if F astBF + SlowBFpot ≤ Vpot,SlowBF
SlowBF = Vpot,SlowBF − F astBF if F astBF + SlowBFpot > Vpot,SlowBF
where:

CKF astBF
CKF astBF∆t
CKSlowBF
CKSlowBF∆t
dHF astBF
dHSlowBF

User-defined reservoir coefficient applied in routing the fast base
component (CKF astBF > 1) [day].
Reservoir coefficient used in each time-step ∆t [s] for routing the
fast base component [∆t].
User-defined reservoir coefficient applied in routing the slow base
component (CKSlowBF > 1) [day].
Reservoir coefficient used in each time-step ∆t [s] for routing the
slow base component [∆t] .
Hydraulic head (or driving force) of the fast base flow component [m].
Hydraulic head (or driving force) of the slow base flow component

SOBEK, User Manual

GW SDZF astBF
GW SDZSlowBF

h
L
RZBL
sf c
SL
sy,rz

Vpot,SlowBF
ZF astBF
ZSlowBF
∆t
6.5.3.14

F astBFpot
SlowBFpot
GW L
GWOutflow pot
GW SBL
GW SD
GW SDrz
GW SDss
GW SDss,max

[m].
Potential fast base flow component [mm].
Potential slow base flow component [mm].
Groundwater level [m AD].
Potential groundwater outflow (=F astBFpot + SlowBFpot ) [mm].
Bed level of the groundwater storage [m AD].
Water depth in the groundwater storage [mm].
Water depth in the root zone part of the groundwater storage [mm].
Water depth in the subsoil part of the groundwater storage [mm].
Maximum water depth in the subsoil part of the groundwater storage
(see section 6.5.3.2 and Figure 6.104) [mm].
Water depth in the groundwater storage if GW L equals ZF astBF
[mm].
Water depth in the groundwater storage if GW L equals ZSlowBF
[mm].
External water level [m AD].
Water depth in the lower zone storage [mm].
Bed level of the root zone layer [m AD].
Field capacity of the soil in the root zone layer [-].
Surface level of the catchment area [m AD]
Specific yield of the root zone layer (ratio of the volume of water in a
fully saturated root zone layer to its total soil volume) [-].
Specific yield of the subsoil layer (ratio of the volume of water in a
fully saturated subsoil layer to its total soil volume) [-].
Threshold for the fast base flow component. Only water in the groundwater storage above TF astBF may flow out as fast base flow [m AD].
Threshold for the slow base flow component. Only water in the
groundwater storage above TSlowBF may flow out as slow base flow
[m AD].
Volume of water in the groundwater storage, that is potentially available for drainage by the fast base flow component [mm].
Volume of water in the groundwater storage, that is potentially available for drainage by the slow base flow component [mm].
Drainage level of the fast base flow component [m AD].
Drainage level of the slow base flow component [m AD].
User-defined time-step [s].

External (ground)water flowing into the lower zone storage and groundwater storage
Inflow of external (ground)water into the soil (GWInflow [mm]) occurs only if the external
water level (h [m AD]) is above the groundwater level (GW L [m AD]). GWInflow equals
zero if h ≤ GW L (see Figure 6.110). The sequence of filling the lower zone storage and the
groundwater storage by inflowing external (ground)water is as follows:

Firstly, the subsoil part of the groundwater storage is completely filled-up
Secondly, the lower zone storage is completely filled-up.
Thirdly and finally, the root zone part of the groundwater storage is filed-up.

Conceptual description

Figure 6.110: Determining the inflow of external (ground)water (GWInflow ). The solid
part of the soil (coloured yellow) can not contain groundwater.

The inflow of external (ground)water (GWInflow [mm]), the part following into the lower zone
storage (DLExt [mm]), and the part flowing into the groundwater storage (GWExt [mm]) are
computed as follows (see Figure 6.110):

GW SDss = min(GW SD , GW SDss,max )

GW SDrz = max(0 , GW SD − GW SDss,max )

GW L = GW SBL + (GW SDss /1000 sy,ss ) + ((GW SDrz + L)/1000 sy,rz )
dHGW Inf low = max(0, h − GW L)

Vpot,GW Inf low = f (h , GW L , SL , RZBL , GW SBL , sy,rz , sy,ss )
CKGWInflow ∆t = 1 /(1 − (1 − 1 /CKGWInflow )∆t/86400 )
GWInflow = min(1000 (dHGWInflow /CKGWInflow ∆t ) , Vpot,GWInflow )
DLExt = max(0 , min(Lmax − L , GW SD + GWInflow − GWSDss,max )
GWExt = GW Inf low − DLExt
where:

CKGWInflow
CKGWInflow ∆t
dHGWInflow

User-defined reservoir coefficient, applied for the inflow of external
(ground)water (CKGWInflow > 1 ) [day].
Reservoir coefficient used in each time-step ∆t [s] for computing the
inflow of external (ground)water [∆t].
Hydraulic head (or driving force) for the inflow of external (ground)water
[m].

SOBEK, User Manual

h
L
Lmax
RZBL
sf c
SL
sy,rz
sy,ss

Vpot,GW Inf low

Groundwater level [m AD].
Bed level of the groundwater storage [m AD].
Water depth in the groundwater storage [mm].
Water depth in the root zone part of the groundwater storage [mm].
Water depth in the subsoil part of the groundwater storage [mm].
Maximum water depth in the subsoil part of the groundwater storage
(see section 6.5.3.2 and Figure 6.104) [mm].
External water level [m AD].
Water depth in the lower zone storage [mm].
Maximum water depth in the lower zone storage (see section 6.5.3.2
and Figure 6.104) [mm].
Bed level of the root zone layer [m AD].
Field capacity of the soil in the root zone layer [-].
Surface level of the catchment area [m AD].
Specific yield of the root zone layer (ratio of the volume of water in a
fully saturated root zone layer to its total soil volume) [-].
Specific yield of the subsoil layer (ratio of the volume of water in a
fully saturated subsoil layer to its total soil volume) [-].
Volume of water in both the lower zone storage and the groundwater storage, that potentially can be filled-up by the inflow of external
(ground)water [mm].
User-defined time-step [s].

GW L
GW SBL
GW SD
GW SDrz
GW SDss
GW SDss,max

Abstraction by the groundwater pump

Abstraction by the groundwater pump (GWABS,Act [mm], see Figure 6.107) occurs only if
the groundwater pump discharge (GW P ump [m3 /s]) is greater than zero. Water contained
in the lower zone storage can not be abstracted by the groundwater pump. GWABS,Act is
computed as follows:

GWABS,max = GW SD

GWABS,pot = max(0 , (1000∆t /CatchmentArea) GWPump)
GWABS,Act = min(GWABS,max , GWABS,pot )
where:

Maximum water depth in the groundwater storage that can be abstracted by the groundwater pump [mm].
Potential water depth that can be abstracted according to the userdefined groundwater pump discharge [mm].
Water depth in the groundwater storage [mm].
User-defined time-step [s].

Conceptual description

Supply by the groundwater pump
Supply of water by the groundwater pump (GWSU P,Act [mm]), see Figure 6.107) occurs only
if the groundwater pump discharge (GW P ump [m3 /s]) is less than zero. The sequence
of filling the lower zone storage and the groundwater storage by the groundwater pump is as
follows:

Firstly, the subsoil part of the groundwater storage is completely filled-up
Secondly, the lower zone storage is completely filled-up.
Thirdly and finally, the root zone part of the groundwater storage is filed-up.
Supply of water by the groundwater pump (GWSU P,Act ) comprises of supply to the lower zone
storage (DLGW P ump [mm]) and supply to the groundwater storage (GWGW P ump [mm]).
DLGW P ump and GWGW P ump are computed as follows:

GWSU P,max = (GW SDmax − GW SD) + (Lmax − L)

GWSU P,pot = max(0 , −(1000∆t /CatchmentArea) GWPump)
GWSU P,Act = min(GWSU P,max , GWSU P,pot )

ADGW S,ss,GW P ump = max(0, GW SDss,max − GW SD))

DLGW P ump = min(Lmax −L, GWSU P,Act −min(ADGW S,ss,GW P ump , GWSU P,Act ))
GWGW P ump = GWSU P,Act − DLGW P ump
where:

ADGW S,ss,GW P ump Water-storage-depth available in the subsoil part of the groundwater
GW SD
GW SDmax

GW SDss,max
GWSU P,max
GWSU P,pot
L
Lmax
∆t

storage for the supply of water by the groundwater pump [mm].
Water depth in the groundwater storage [mm].
Maximum water depth in the groundwater storage (see section 6.5.3.2
and Figure 6.104) [mm].
Maximum water depth in the subsoil part of the groundwater storage
(see section 6.5.3.2 and Figure 6.104) [mm].
Maximum water-storage-depth available for the supply of water by
the groundwater pump. Sum of available water-storage-depth in the
lower zone storage and groundwater storage. [mm].
Potential water depth that can be supplied according to the userdefined groundwater pump discharge [mm].
Water depth in the lower zone storage [mm].
Maximum water depth in the lower zone storage (see section 6.5.3.2
and Figure 6.104) [mm].
User-defined time-step [s].

SOBEK, User Manual

D-NAM output time-series
Table 6.12 provides an overview of the output time-series available for each D-NAM rainfallrunoff model. The second column contains for each output time-series the symbols that are
used in equations.
Please note that the "Runoff node" is to be checked on the "Output options" tab in RR Settings in order to obtain the output time-series (see Table 6.12) available under "Runoff Node"
in "Results in Charts" Task block.
Table 6.12: Overview of D-NAM output time-series
Symbols

Rainfall
PotEvap

Rainfall as defined in the "Meteo Task" block
Evapotranspiration as defined in the "Meteo
Task" block.
Sum of evaporation from surface storage
(E1) and transpiration from the lower zone
storage (E2).
Equals overland flow (OF ) + interflow (IF )
+ fast base flow component (F astBF ) +
slow base flow component (SlowBF ) - inflow of external (ground)water into the soil
(GW Inf low).
Equals overland flow (OF ) + interflow (IF )
+ fast base flow component (F astBF ) +
slow base flow component (SlowBF ) - inflow of external (ground)water into the soil
(GW Inf low).

Name of Output Time Series

D-NAM ExternalWaterLevel
D-NAM GWPumpDefinedDischarge

External water level.
Groundwater pump discharge.

D-NAM EvapSurfaceStorage
D-NAM EvapRootZoneLayer
D-NAM EvapRootZonePartGWStorage

E1
E2
E2GW S,rz

D-NAM EvapLowerZoneStorage
D-NAM OverlandFlow
D-NAM Interflow
D-NAM FastBaseFlow

E2LZS
OF
IF
F astBF

D-NAM SlowBaseFlow

D-NAM ExternalGWInflow
D-NAM ExternalGWInflowLowerZoneStorage

GW Inf low
DLExt

D-NAM ExternalGWInflowGroundwaterStorage

D-NAM GWPumpAbsGroundwaterStorage

D-NAM GWPumpSupLowerZoneStorage

D-NAM GWPumpSupGroundwaterStorage

Evaporation from the surface storage.
Transpiration from the root zone layer.
Transpiration from the root zone part of the
groundwater storage.
Transpiration from the lower zone storage.
Overland flow (outflow from surface storage).
Interflow (outflow from surface storage).
Fast base flow component (outflow from
groundwater storage).
Slow base flow component (outflow from
groundwater storage).
Inflow of external (ground)water into the soil.
Inflow of external (ground)water into the
lower zone storage.
Inflow of external (ground)water into the
groundwater storage.
Abstraction of water from the groundwater
storage by the groundwater pump.
Supply of water into the lower zone storage
by the groundwater pump.
Supply of water into the groundwater storage
by the groundwater pump.

D-NAM Infiltration

D-NAM InfiltrationLowerZoneStorage

D-NAM Percolation

D-NAM CapillaryRise

D-NAM DepthSurfaceStorage

Water contained in the surface storage that
infiltrates into the soil.
Water contained in the surface storage that
infiltrates into the lower zone storage.
Water contained in the surface storage that
percolates into the groundwater storage.
Capillary rise of water from the subsoil part of
the groundwater storage into the lower zone
storage.

Water depth in the surface storage.

Conceptual description

Table 6.12: Overview of D-NAM output time-series
Name of Output Time Series

D-NAM DepthLowerZoneStorage
D-NAM DepthGroundwaterStorage
D-NAM VolumeSurfaceStorage

D-NAM VolumeLowerZoneStorage

D-NAM VolumeGroundwaterStorage

D-NAM GroundWaterLevel

D-NAM GroundWaterTableDepth

D-NAM AvailableSoilStorage

Water depth in the lower zone storage.
Water depth in the groundwater storage.
Volume of water contained in the surface
storage.
Volume of water contained in the lower zone
storage.
Volume of water contained in the groundwater storage.
Groundwater level (measured in metres
above datum).
Groundwater table depth (measured in metres below surface level).
Volume in the soil that is still available for the
storage of water.

D-NAM GWPumpActualDischarge

D-NAM GWPumpActual-DefinedDischarge

DR
AF
Act−Def ined

Equals fast base flow component (F astBF )
+ slow base flow component (SlowBF ) - inflow of external (ground)water into the soil
(GW Inf low).
Actual groundwater pump discharge. Positive if water is abstracted. Negative if water is
supplied.
Actual groundwater pump discharge minus
the user-defined groundwater pump discharge. If positive, the amount of discharge
that could not be supplied. If negative,
the amount of discharge that could not be
abstracted.

Comparing the D-NAM model and the NAM model

Concepts of the Nielsen and Hansen (1973) NAM model implemented into the D-NAM model
are:
1 Interflow occurs only if the water depth in the lower zone storage (L) is above the lowerzone-threshold for interflow (LT IF ). Interflow is a function of the relative moisture content
in the lower zone storage above LT IF . (see factor Lα in section 6.5.3.7).
2 Percolation may occur if the water depth in the lower zone storage is below field capacity
(see section 6.5.3.10).
3 Transpiration from the root zone layer (E2) is a function of the relative moisture content in
the root zone layer (see section 6.5.3.11).
Reasons for developing the D-NAM rainfall-runoff model are:

1 The NAM model stores water on the surface of a catchment area in three different stacked
on each other storages, being the NAM surface storage, the NAM interflow storage and
the NAM overland flow storage. As a result hereof, water contained in the latter two NAM
storages is not available for evaporation and for infiltration into the soil.
In the D-NAM model all water on the surface of a catchment area is contained in one
surface storage only and hence all water on the surface of a D-NAM model is at any pointin-time available for evaporation, interflow, infiltration into the soil and overland flow (see
Figure 6.106).
2 The NAM surface storage, receiving precipitation has a watertight bed and a maximum
water-storage-capacity. Hence, water contained in the NAM surface storage can not directly infiltrate into the soil. Only if the water depth in the NAM surface storage, after
accounting for evaporation and inflow into the interflow storage, exceeds its maximum
water-storage-capacity, the surplus of water in the NAM surface storage is divided into
infiltration into the soil and inflow into the overland flow storage. This division of surplus
water in the NAM surface storage is, however, made irrespective of the actual water depth

SOBEK, User Manual

in the NAM overland flow storage.
In the D-NAM model the surface storage has an unlimited water-storage-capacity and its
bed is not watertight, allowing water to infiltrate into the soil (IN F ). Infiltrated water is
limited by the actual water depth in the surface storage, the available water-storage-depth
in the soil, and the user defined maximum infiltration and percolation capacity (see section 6.5.3.8).
Additional functionalities in the D-NAM model with respect to the NAM model are:

1 The D-NAM model makes a distinction between the specific yield of root zone layer and
the specific yield of the subsoil layer (see section 6.5.3.2)
2 The NAM model is suited for free discharging catchment areas only. The D-NAM model
allows for the inflow of external (ground)water (see section 6.5.3.14), that is required in
modelling deltaic areas.
3 The D-NAM model determines overland flow using the Manning formula for open channel
flow (see section 6.5.3.9).
4 The D-NAM model makes a distinction between a fast and a slow base flow component
(see Figure 6.109).
5 The D-NAM model includes a groundwater pump, that can abstract water (see section 6.5.3.15
or supply water (see section 6.5.3.16).
SOBEK-Urban RR (Rainfall Runoff) concept
Delay of Runoff

The delay of runoff (in SOBEK-Urban Rainfall-Runoff) depends on the average distance to the
inflow location in sewer system, the slope and the geometry of the catchment. The formula
which describes the runoff to the sewer system is the formula of the Rational Method:

inflow into sewer [mm/min]
runoff factor [1/min]
rainfall, dynamic storage on catchment [mm]

The runoff factor, c, is a function of length, roughness and slope. Twelve different area types
are described in the ‘Dutch Guidelines for sewer systems computations, hydraulic functioning’.
The types and default values are presented in Table 6.13.
Table 6.13: Default parameters of Delay of Runoff (Rational Method)

Runoff factor,
c

Surface storage,
h

1
2
3
4
5
6
7
8
9

closed paved
closed paved
closed paved
open paved
open paved
open paved
roof
roof
roof

with a slope
flat
stretched flat
with a slope
flat
stretched flat
with a slope
flat
stretched flat

0.5
0.2
0.1
0.5
0.2
0.1
0.5
0.2
0.1

0.0
0.5
1.0
0.0
0.5
1.0
0.0
2.0
4.0

Conceptual description

Table 6.13: Default parameters of Delay of Runoff (Rational Method)

unpaved
unpaved
unpaved

with a slope
flat
stretched flat

Runoff factor,
c
0.5
0.2
0.1

Surface storage,
h
2.0
4.0
6.0

An area ‘with a slope’ is an area with a slope more than 4 %. A stretched flat area is an area
with the distance to the nearest inflow point in the sewer larger than 100 meters.

Horton equation
The description of the infiltration in the Urban version of the Rainfall Runoff module (NWRW
model; Nationale Werkgroep Riolering en Waterkwaliteit (NLingenieurs, 1978)) is based on
the formula of Horton:

Decreasing infiltration capacity:

ft = fe + (fb − fe )e−ka t

Recovering infiltration capacity:

ft = fe − (fb − fe )e−kh t

infiltration capacity at moment of time t [mm/h]
maximum infiltration capacity at t=0 [mm/h]
minimum infiltration capacity [mm/h]
time factor decreasing infiltration capacity [1/h]
time factor recovering infiltration capacity [1/h]
time [h]

The rate of decreasing and recovering infiltration capacity between the maximum value fb and
the minimum value fe depends on the time factors ka and kh. See also the table below. It is
assumed that at the beginning of each rainfall event, the infiltration capacity is at its maximum.
Infiltration capacity is decreasing as long as there is water stored on the surface. If infiltration
capacity branches the minimum value, and there is still water on the surface, it will remain at
the minimum value. Infiltration capacity will increase as soon as the surface is dry and it is
not raining. If infiltration capacity branches the maximum value and there is no water on the
surface, it will remain at the maximum value.
Table 6.14: Default parameters Horton equation

Infiltration
capacity
maximum, fb

Infiltration
capacity
minimum, fe

Time factor
decreasing,
ka

Time factor
recovering,
kh

closed paved
closed paved
closed paved
open paved

with a slope
flat
stretched flat
with a slope

0.0
0.0
0.0
2.0

0.0
0.0
0.0
0.5

0.0
0.0
0.0
3.0

0.0
0.0
0.0
0.1

SOBEK, User Manual

Table 6.14: Default parameters Horton equation

Infiltration
capacity
maximum, fb

Infiltration
capacity
minimum, fe

Time factor
decreasing,
ka

Time factor
recovering,
kh

5
6
7
8
9
10
11
12

open paved
open paved
roof
roof
roof
unpaved
unpaved
unpaved

flat
stretched flat
with a slope
flat
stretched flat
with a slope
flat
stretched flat

2.0
2.0
0.0
0.0
0.0
5.0
5.0
5.0

0.5
0.5
0.0
0.0
0.0
1.0
1.0
1.0

3.0
3.0
0.0
0.0
0.0
3.0
3.0
3.0

0.1
0.1
0.0
0.0
0.0
0.1
0.1
0.1

Choosing the appropriate Rainfall Runoff concept

SOBEK provides three different Rainfall Runoff concepts. Basically all three have the task to
transform rainfall intensities into an outflow discharge towards open water. However, they all
have different environments in which they fit best. In this chapter, you are explained which
Rainfall Runoff concept to use.

The original SOBEK-Rural Rainfall Runoff concept.

This concept has originally been developed by WL | Delft Hydraulics for use in low lying
areas, such as polders. It provides a wide range of modelling objects, such as unpaved
areas, weirs, greenhouses and waste water treatment plants.
The SOBEK-Urban Rainfall Runoff concept (NWRW; NLingenieurs (1978))
This concept is only active for modelling objects of the Sewer Flow module, thus for sewer
pipes and manholes. The rainfall runoff options that are attached to those object types are
always of this concept.
The Sacramento Concept
Throughout the world, Sacramento has become a hugely popular Rainfall Runoff concept
for use in river basins and catchment areas. SOBEK now provides modelling objects that
support this concept. Objects of this type can easily be combined with objects from the
original SOBEK-Rural Rainfall Runoff concept!
The HBV Concept
The Hydrologiska Byråns Vattenbalansavdelning (HBV) model was introduced back in
1972 by the Swedisch Meteological and Hydrological Institute (SMHI). It has started as a
simple lumped model for river basins, but currently also distributed model versions (Lindström et al., 1997) are available. These HBV model concept are also available in SOBEK.
The SCS Curve Number Concept
The SCS Curve Number Concept is a simple, widely used and efficient method for determining the amount of runoff from a rainfall event in a river basin. Although the method is
designed for a single storm event, it can be scaled to find average annual runoff values.
This concept is available in SOBEK too.

Conceptual description

The HBV, SCS and External Runoff Concepts
A runoff timeseries file, necessary for the RR-external runoff node, and the temperature timeseries file, necessary when the RR-HBV node is used, can not be created in the SOBEK interface yet. It is assumed these are created outside of SOBEK and put in the <{Sobek}\Fixed>
directory, where {Sobek} indicates the directory where SOBEK is installed, e.g. .
The format of the runoff time-series and temperature time-series file is exactly the same as the
format of the SOBEK rainfall (<*bui>) file. The files must be located in the <{Sobek}\Fixed>
directory, the same directory where the SOBEK rainfall files are located. SOBEK assumes
the extension <*.RNF> for the runoff file, and <*.TMP> for the temperature file.

So when the rainfall file is selected, the corresponding runoff file should be
called .
The runoff file can contain data series for a different number of stations (and other stations)
as the rainfall file.

The runoff station mentioned in the RR-runoff node input data screen refers to a station in the
runoff file, just like the meteo station specified at RRnodes refers to the meteo station (rainfall
station) in the rainfall file.
Note that the timestep of the runoff file can be different from the timestep in the rainfall file.
Just as for the rainfall timestep and the RR computation timestep, the runoff timestep and the
RR computation timestep should ’fit’ in the sense that the timestep in the runoff file should be
a multiple of the RR computation timestep.
The runoff timeseries are specified in [m3 /s]. The runoff timeseries is directly put on the
downstream RRlink of the RR-runoff node. This link typically connects the RRrunoff node
with an RR-connection node, an RR- boundary node or an RR-CF connection.
Definitions:
Area adjustment factor
The area adjustment factor allows you to specify an (optional) area adjustment factor on the
rainfall data, to reflect differences between point station rainfall and areal basin rainfall. The
factor is usually between 0 and 1, although for flexibility a value larger than 1 could be allowed.
Default value is 1.
Initial AMC
The SCS model derives maximum retention and initial losses based on the Curve Number.
The present implementation assumes average antecedent moisture conditions, the curve
number is referred to as CNII. The curve number CNII for a watershed can be estimated as a
function of land use, soil type, and antecedent watershed moisture, using tables published by
the SCS.
6.5.4.1

Real Time Control (RTC module)

SOBEK, User Manual

Reservoir in SOBEK
Reservoirs are important structures in practical water resources management. A reservoir is
considered as advanced control, so it is implemented in the SOBEK real time control module
(SOBEK-RTC).
The following figure illustrates some of the reservoir concepts and terminology, like:

dead storage;
bottom gate (main gate);
turbine intake; and
spillway level.

Backwater outlets are not yet shown in the figure. The backwater gates represent abstractions
or spills from the reservoir which are not located at the main dam site.

Figure 6.111: Reservoir

Reservoir concept
The SOBEK reservoir includes the following aspects:

Reservoir operation rules (flood control curve, target curve, firm storage curve, hedging
rules below firm storage);

Multiple outlets (bottom gates, turbines, spillways, including backwater outlets)
Important here are the following 2 remarks:

not all outlets are obligatory,
outlets may be located on the same link, or on different links.

Conceptual description

Q-H relations describing the relation between maximum flow and net-head for all outlets

(reflecting physical limitations);
Time series of maximum flows per outlet (reflecting imposed management);
Time series of release targets for downstream demands for all outlet links;
Time series of release targets for energy generation;
The operation of the SOBEK reservoir is based on the initial reservoir level and expected
inflow (defined by other decision parameters in SOBEK-RTC)

Application possibilities

The SOBEK-RTC reservoir module uses the initial reservoir level and an expected reservoir
inflow, together with the reservoir input data, to compute the desired release through the bottom gate, turbine and spillway gate. The initial reservoir level and the expected reservoir
inflow are to be defined using decision parameters in SOBEK-RTC. This also allows for applications in flood-early warning systems (FEWS), where the determination of expected inflow
is an important aspect.

Furthermore, the reservoir module computes decision parameters for all outlet gates, which
can be used to define other decision parameters in RTC. The user thus has the possibility to
modify or overrule the decision parameters computed by the reservoir module. The setting of
the actual structure flows in SOBEK is determined by the decision parameter used to set the
structure flow, as specified by the user in the measure input file.
An important extra possibility of the SOBEK reservoir is that the outlets may be located on
different links. In practice, it quite often occurs that the outflows of main gate (bottom gate),
turbine and spillway do not come together on the same downstream link.
In the SOBEK reservoir design, there can be multiple bottom gates, turbines, and spillways.
Each of them may be on different outlet links, but also there may be several bottom gates,
on the same link or each on a different link. Backwater gate can thus be modelled in SOBEK
using a bottom gate on a separate link, with an appropriate downstream demand time series,
and appropriate Q-H relation describing the (physical) maximum abstraction capacity as a
function of the net head (=the head above intake level).
If these abstractions are to be modelled separate from the reservoir, SOBEK has the possibility to use a lateral discharge node. However, abstractions at these nodes are not depending
on the actual water level.
Rainfall and evaporation

In SOBEK, rainfall and evaporation can be modelled by specifying a lateral discharge using
a time series of rainfall or evaporation values in mm/timestep, and specifying a constant area
on which this rainfall/evaporation series applies. When applying this for a reservoir, one can
define the area at average target level as the area to be used in this computation.

SOBEK, User Manual

Release targets
For the SOBEK reservoir, the user should specify time series of downstream release targets (demands) to be supplied from the reservoir. Since there may be different outlet links in
SOBEK, these demands need to be specified for all different outlet links. This is done using
input time series. It is anticipated that future versions allow to define the reservoir release targets by using decision parameters, summing the demands of various lateral discharges from
SOBEK-CF and/or SOBEK-RR. This gives a huge flexibility. However, the current approach
of directly specifying the release targets as input variables is very appropriate for testing and
comparing with any distribution model. In SOBEK, the user specifies a time series of desired
turbine flows as well.
Maximum flows

The maximum capacities of all outlet gates can be specified using a Q-h interpolation relation.

For the turbine gate, a distribution model determined the maximum possible flow through the
turbines based on the turbine characteristics (installed capacity, generation efficiency, head
loss relation etc.). In SOBEK, these hydropower data is not included, and a Q-h interpolation
relation for the turbines is specified directly.
SOBEK offers the extra possibility to impose other maximum flows as well. These can be
maximum flows reflecting e.g. water rights, or other limits imposed by the water authorities.
These maximum flows can be specified as time series for all outlet gates separately.
Reservoir operation

The rule curves of the SOBEK reservoir are using the same concepts as Deltares RIBASIM
distribution model, i.e. distinction is made between a flood control curve, a target curve and
a firm storage curve. Furthermore, the hedging rules on storage are implemented. These
hedging rules specify how releases are reduced when the reservoir is below firm storage.

The operation of the reservoir is as follows:

If the reservoir is above flood control level, try to come down to the flood control level
by any means. Just like in a distribution model, SOBEK uses first the turbines, then the
bottom gate, and finally the spillway. In case of multiple bottom gates, SOBEK simply uses

Conceptual description

first the first bottom gate, then the second, etc.
If the reservoir is between flood control level and target level, the reservoir is allowed to
release more water, but only through the turbines (i.e. if extra energy can be generated). In
case of multiple turbine outlets, SOBEK simply uses the order in which the turbine outlets
are specified in the input data.
If the reservoir is between target level and firm storage level, no special action is taken.
If the reservoir is below firm storage, hedging rules are applied. They specify how much
the discharge from the reservoir is reduced, depending on the actual reservoir water level.
The releases on all outlet different links are reduced with the same percentage.

SOBEK, User Manual

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manual. Tech. rep., Staring Centrum, Wageningen.

SOBEK, User Manual

A Dimension of Steel Cunnete Cross-sections
Table A.1: Steel cunette cross-section

Type 1: Three circle segments, a >= 120 degrees, a1 = 0 degrees; r3 =0
Type 2 & 3: Three circle segments only, a < 120 degrees, a1 = 0 degrees; r3 =0
Type 4: Four circle segments

W
cm
100
120
140
160
180
200
210
220
230
240
250
260
270
280
290
300
310
320

W = Width, including wave height (WH)
H = Height, including wave height (WH)
r = Radius r, including half the wave height (WH)
r1 = Radius r1, including half the wave height (WH)
r2 = Radius r2, including half the wave height (WH)
r3 = Radius r3, including half the wave height (WH)
a = Angle a
a1 = Angle a1
WH = Wave height of corrugated construction material

190
209
209
220
226
234
246
265

78
98
116
131
136
154
161
168
179
174
185
192
189
210
206
212
224
230

50
60
70
80
90
100
105
110
115
120
126
130
133
140
144
150
154
160

80
90
110
182
150
170
202
242
222
210
200
230
224
250
242
270
261
290

20
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

28
38
41
38
46
49
47
45
50
54
59
57
59
59
63
62
66
65

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:
SGME formerly:

147
141
155
160
166
171
175
173

94,5
109,5
104,5
109,5
113,5
116,5
122,5
136,5

220,5
252,5
277,5
277,5
348,5
291,5
302,5
312,5

48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5

0
0
0
0
0
0
0
0

55,5
56,5
55,5
56,5
56,5
58
59,5
62,5

0
0
0
0
0
0
0
0

5
5
5
5
5
5
5
5

SGM-1-1
SGM-1-2
SGM-1-3
SGM-1-4
SGM-1-5
SGM-1-6
SGM-1-7
SGM-1-8

EM 1
EM 2
EM 3
EM 4
EM 5
EM 6
EM 7
EM 8
EM 9
EM 10
EM 11
EM 12
EM 13
EM 14
EM 15
EM 16
EM 17
EM 18

continued on next page

SOBEK, User Manual

Table A.1 – continued from previous page
H

265
274
283
290
296
305
317
327
337
353
366
365
385
386
392
396
414
419
434
440
445
472
478
483
489
505
510
410
417
431
438
444
459
473
480
487
500
508
522
527
534
551
557
571
578

180
190
192
196
201
207
211
220
221
226
229
237
237
246
252
259
262
269
272
277
285
286
292
300
304
308
315
290
296
300
306
311
316
320
326
331
336
341
346
351
357
361
367
371
377

134,5
136,5
142,5
144,5
147,5
152,5
158,5
163,5
169,5
178,5
186,5
183,5
196,5
195,5
196,5
198,5
207,5
209,5
217,5
220,5
222,5
239,5
241,5
243,5
244,5
254,5
256,5
206,5
209,5
216,5
219,5
222,5
230,5
238,5
241,5
244,5
252,5
254,5
263,5
265,5
268,5
277,5
280,5
288,5
290,5

312,5
397,5
437,5
442,5
442,5
452,5
462,5
462,5
462,5
462,5
464,5
552,5
492,5
492,5
656,5
552,5
652,5
672,5
702,5
712,5
712,5
578,5
652,5
722,5
862,5
742,5
742,5
492,5
601,5
505,5
567,5
654,5
580,5
532,5
592,5
664,5
601,5
670,5
612,5
679,5
752,5
692,5
762,5
702,5
772,5

48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
48,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5
81,5

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

63,5
60,5
60,5
61,5
61,5
62,5
63,5
65,5
66,5
68,5
71,5
66,5
73,5
73,5
66,5
70,5
69,5
69,5
70,5
71,5
72,5
83,5
79,5
77,5
71,5
78,5
80,5
101,5
99,5
104,5
101,5
99,5
104,5
108,5
107,5
104,5
110,5
107,5
113,5
111,5
108,5
114,5
111,5
116,5
113,5

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

SGM-1-9
SGM-1-10
SGM-1-11
SGM-1-12
SGM-1-13
SGM-1-14
SGM-1-15
SGM-1-16
SGM-1-17
SGM-1-18
SGM-1-19
SGM-1-20
SGM-1-21
SGM-1-22
SGM-1-23
SGM-1-24
SGM-1-25
SGM-1-26
SGM-1-27
SGM-1-28
SGM-1-29
SGM-1-30
SGM-1-31
SGM-1-32
SGM-1-33
SGM-1-34
SGM-1-35
SGM-1-36
SGM-1-37
SGM-1-38
SGM-1-39
SGM-1-40
SGM-1-41
SGM-1-42
SGM-1-43
SGM-1-44
SGM-1-45
SGM-1-46
SGM-1-47
SGM-1-48
SGM-1-49
SGM-1-50
SGM-1-51
SGM-1-52
SGM-1-53

continued on next page

Dimension of Steel Cunnete Cross-sections

Table A.1 – continued from previous page
H

593
599
605
611
627
632

381
387
392
398
402
408

299,5
302,5
304,5
306,5
315,5
317,5

702,5
777,5
852,5
952,5
862,5
902,5

81,5
81,5
81,5
81,5
81,5
81,5

119,5
116,5
114,5
111,5
118,5
116,5

SGM-1-54
SGM-1-55
SGM-1-56
SGM-1-57
SGM-1-58
SGM-1-59

185
194
228
254
289
328
343
370
377
410
418
439
446
454
489
497
519
526
548
563
584
611
630
649
676
683
702
716
729
748
768
794
814
840
860
886
906
932

155
160
173
188
207
220
230
244
249
257
262
277
367
372
387
392
409
414
418
429
445
461
472
475
498
503
514
512
523
540
550
566
576
592
603
618
629
645

93
97
118
128
145
169
174
187
190
216
217
222
223
227
245
249
259
263
276
282
292
305
315
326
338
341
351
360
366
374
384
397
407
420
430
443
453
466

172
226
177
291
476
316
419
506
602
383
425
617
394
426
392
417
511
550
441
493
592
645
658
581
724
768
779
654
721
846
856
913
922
980
989
1047
1055
1114

63
63
63
63
63
63
63
63
63
63
63
63
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131
131

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

159
166
137
158
167
143
155
158
163
137
143
157
175
178
165
168
176
179
161
167
175
176
175
165
175
177
176
165
169
176
175
176
175
176
175
176
175
176

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:

MA 1
MA 2
MA 3
MA 4
MA 5
MA 6
MA 7
MA 8
MA 9
MA 10
MA 11
MA 12
MA 13
MA 14
MA 15
MA 16
MA 17
MA 18
MA 19
MA 20
MA 21
MA 22
MA 23
MA 24
MA 25
MA 26
MA 27
MA 28
MA 29
MA 30
MA 31
MA 32
MA 33
MA 34
MA 35
MA 36
MA 37
MA 38

continued on next page

SOBEK, User Manual

Table A.1 – continued from previous page
H

953
978
1001
1027
1047
1072
1092
1118
1138
1163
1183
1208

655
671
737
754
765
781
792
809
820
836
847
864

477
489
501
513
523
536
546
559
569
582
592
604

1121
1180
923
963
974
1015
1026
1067
1077
1118
1129
1170

131
131
166
166
166
166
166
166
166
166
166
166

0
0
0
0
0
0
0
0
0
0
0
0

175
176
177
178
177
178
177
178
178
178
178
178

0
0
0
0
0
0
0
0
0
0
0
0

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:
SGMA formerly:

MA 39
MA 40
MA 41
MA 42
MA 43
MA 44
MA 45
MA 46
MA 47
MA 48
MA 49
MA 50

219
229
240
302
340
372
381
402
419
465
529
546
567
589
604
623
639
660
668
695
723
744
765
794
816
837
859
888
909
930
952
973

169
173
178
205
224
266
270
278
287
303
328
337
345
353
362
365
374
382
387
394
424
432
440
453
461
470
478
491
499
507
515
524

115
118
127
163
179
198
201
213
219
251
289
292
304
317
319
342
343
355
356
381
390
402
415
428
441
454
467
479
492
505
518
531

155
177
173
225
297
323
363
386
496
452
516
625
644
665
818
644
771
789
870
759
838
857
876
964
982
1000
1017
1111
1127
1144
1161
1177

63
63
63
63
63
98
98
98
98
98
98
98
98
98
98
98
98
98
98
98
112
112
112
112
112
112
112
112
112
112
112
112

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

129
137
128
124
136
122
127
126
135
123
121
129
128
128
135
122
130
129
132
124
128
127
126
129
128
128
127
129
129
128
127
127

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:
SGMB formerly:

MB 1
MB 2
MB 3
MB 4
MB 5
MB 6
MB 7
MB 8
MB 9
MB 10
MB 11
MB 12
MB 13
MB 14
MB 15
MB 16
MB 17
MB 18
MB 19
MB 20
MB 21
MB 22
MB 23
MB 24
MB 25
MB 26
MB 27
MB 28
MB 29
MB 30
MB 31
MB 32

continued on next page

Dimension of Steel Cunnete Cross-sections

Table A.1 – continued from previous page
H

SGMB formerly: MB 33
SGMB formerly: MB 34
SGMB formerly: MB 35

288
330
337
345
361
376
391
427
434
449
458
480
509
524
550
573
597
627
647
655
677
707
720
745
757
769
781
812
832
849
861
871
892
905
929

273
303
310
316
328
341
354
377
384
397
402
422
480
493
511
530
548
574
585
591
611
637
641
659
673
677
692
717
728
740
754
759
779
800
819

144
165
169
172
181
188
196
213
217
224
229
240
254
262
275
287
299
314
324
327
339
353
360
372
378
384
390
406
416
424
430
435
446
452
464

317
300
331
367
370
451
566
450
485
571
522
661
492
581
491
588
630
824
645
679
796
1012
758
795
961
831
1001
1091
980
978
1167
1104
1260
1191
1229

108
108
108
108
108
108
108
108
108
108
108
108
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
188
215
215

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

243
229
231
234
231
236
241
227
229
234
229
236
238
241
230
235
234
240
229
230
235
240
228
228
235
228
234
235
230
228
235
232
235
235
235

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

WA1
WA2
WA3
WA4
WA5
WA6
WA7
WA8
WA9
WA10
WA11
WA12
WA13
WA14
WA15
WA16
WA17
WA18
WA19
WA20
WA21
WA22
WA23
WA24
WA25
WA26
WA27
WA28
WA29
WA30
WA31
WA32
WA33
WA34
WA35

continued on next page

SOBEK, User Manual

Table A.1 – continued from previous page
H

322
329
369
383
408
422
463
483
496
532
557
582
601
622
644
669
694
722
737
762
789
812
830
855

278
284
306
318
335
348
369
388
400
415
432
450
468
521
539
557
574
599
603
620
645
655
666
684

161
165
184
191
204
211
231
241
248
266
278
291
300
311
322
334
347
361
368
381
395
406
415
428

348
393
346
412
457
552
479
600
710
570
612
656
793
591
691
738
784
984
836
883
1086
977
980
1027

90
90
90
90
90
90
90
90
90
90
90
90
90
157
157
157
157
157
157
157
157
157
157
157

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

209
213
197
204
205
211
198
206
212
197
198
199
206
199
205
205
206
213
205
205
211
206
204
205

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

WB2
WB3
WB4
WB5
WB6
WB7
WB8
WB9
WB10
WB11
WB12
WB13
WB14
WB15
WB16
WB17
WB18
WB19
WB20
WB21
WB22
WB23
WB24
WB25

106,6 214,6 48,2

109,9 267,2 48,2

120,6 281,4 48,2

123,7 352,8 48,2

126,7 467,1 48,2

134,3 360,6 48,2

137,1 456,4 48,2

Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.

198
211
219
226
240

model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis

continued on next page

Dimension of Steel Cunnete Cross-sections

Table A.1 – continued from previous page
H

145,2 369,8 48,2

150,5 580,9 48,2

158,7 455,4 48,2

167,3 391,6 48,2

169,9 460,7 48,2

178,8 403,6 48,2

180,5 467,8 48,2

183,1 552,2 48,2

192,2 476,2 48,2

194,3 553,2 48,2

196,6 656,3 48,2

198,8 801,8 48,2

207,5 649,7 48,2

216,9 563,1 48,2

218,7 647,9 48,2

220,7 758,4 48,2

230,1 648,4 48,2

239,7 578,6 48,2

245,1 861,3 48,2

254,5 741,4 48,2

365
380
387
392
397
413
430
435
440
457

Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.

model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis

continued on next page

SOBEK, User Manual

Table A.1 – continued from previous page
H

256,2 847,6 48,2

205,9 491,7 81,2

216,9 505,2 81,2

219,9 567,9 81,2

222,5 654,3 81,2

230,6 580,9 81,2

244,3 664,4 81,2

252,7 601,9 81,2

263,9 614,6 81,2

266,2 680,2 81,2

268,7 759,2 81,2

277,3 689,8 81,2

279,6 763,7 81,2

288,5 699,7 81,2

290,8 770,3 81,2

299,7 710,1 81,2

304,3 857,2 81,2

306,5 953,2 81,2

480
487
501
508
522
529
535
550
557
571

Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.
Old
w.r.t.

model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis
model, measures
central axis

continued on next page

Dimension of Steel Cunnete Cross-sections

Table A.1 – continued from previous page
W

315,4 861,3 81,2

317,5 951,2 81,2

470
494
519
545
570
593
618
647
672
697
723
747
773
796

430
448
468
487
507
524
544
582
602
621
641
659
678
696

237,5
249,5
261,5
274,5
287,5
298,5
311,5
325,5
338,5
350,5
363,5
375,5
388,5
400,5

574,5
623,5
669,5
710,5
759,5
784,5
825,5
828,5
865,5
907,5
952,5
981,5
1025
1058

142,5
142,5
142,5
142,5
142,5
142,5
142,5
172,5
172,5
172,5
172,5
172,5
172,5
172,5

0
0
0
0
0
0
0
0
0
0
0
0
0
0

238
237
237
236
236
235
234
237
237
236
236
235
235
235

0
0
0
0
0
0
0
0
0
0
0
0
0
0

5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1
5,1

WU1
WU2
WU3
WU4
WU5
WU6
WU7
WU8
WU9
WU10
WU11
WU12
WU13
WU14

54
55
72
89
91
108
125
126
143
160

30
40
50
60
70
80
90
100
110
120

80
116
153
189
225
262
298
334
370
407

11
11
11
11
11
11
11
11
11
11

0
0
0
0
0
0
0
0
0
0

13,7
15,1
16,5
17,9
19,3
20,7
22,1
23,5
24,9
26,3

0
0
0
0
0
0
0
0
0
0

1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3

DM/2-1
DM/2-2
DM/2-3
DM/2-4
DM/2-5
DM/2-6
DM/2-7
DM/2-8
DM/2-9
DM/2-10

51
71
86
106
121
136

33,2
50,7
63,2
80,7
95,7
110,7

95,7
155,7
195,7
270,7
295,7
380,7

10,9
10,9
10,9
10,9
10,9
10,9

13
16
17
20
22
24

1,3
1,3
1,3
1,3
1,3
1,3

D-M.2-1
D-M.2-2
D-M.2-3
D-M.2-4
D-M.2-5
D-M.2-6

133
143
148
153
158
163
169

79
92
95
99
106
109
113

189
147
180
228
199
245
314

52
52
52
52
52
52
52

178
152
161
169
158
166
173

3,2
3,2
3,2
3,2
3,2
3,2
3,2

LA1
LA2
LA3
LA4
LA5
LA6
LA7

66
101
126
161
191
221
157
181
189
197
210
218
225

Old
w.r.t.
Old
w.r.t.

model, measures
central axis
model, measures
central axis

60
80
100
120
140
160
180
200
220
240

continued on next page

SOBEK, User Manual

Table A.1 – continued from previous page
H

239
246
260
267
281
288
295
309

173
179
183
189
193
199
204
209

120
123
131
134
142
145
148
156

262
325
278
336
294
348
421
361

52
52
52
52
52
52
52
52

0
0
0
0
0
0
0
0

163
170
160
167
157
164
170
161

0
0
0
0
0
0
0
0

3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2

164
174
183
196
205
213
227
235
249
257
271
280
294
302
316

113
118
122
126
130
135
138
143
146
151
155
159
163
167
171

92
94
97
108
109
111
122
124
136
137
149
150
163
163
177

131
170
236
194
260
385
284
397
306
415
326
430
348
446
367

42
42
42
42
42
42
42
42
42
42
42
42
42
42
42

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

107
119
130
117
128
138
126
135
123
133
121
131
120
129
118

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

LA8
LA9
LA10
LA11
LA12
LA13
LA14
LA15

LB1
LB2
LB3
LB4
LB5
LB6
LB7
LB8
LB9
LB10
LB11
LB12
LB13
LB14
LB15

70
80
100
120
140
160
180
200
220
240

3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2
3,2

55
63
72
89
91
108
125
126
143
160

35
40
50
60
70
80
90
100
110
120

98
116
153
189
225
262
298
334
370
407

11
11
11
11
11
11
11
11
11
11

0
0
0
0
0
0
0
0
0
0

180
180
180
180
180
180
180
180
180
180

0
0
0
0
0
0
0
0
0
0

1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3
1,3

M1
M2
M3
M4
M5
M6
M7
M8
M9
M10

197
266
289
344
359
382
437
460

201
231
254
323
312
329
386
409

84
124
116
146
148
169
198
187

179
314
359
314
494
538
494
538

70
70
70
122
70
70
122
122

169
190
199
210
284
334
291
306

112
119
81
74
100
120
102
79

32
28
47
51
38
28
37
48

5,5
5,5
5,5
5,5
5,5
5,5
5,5
5,5

UF1
UF2
UF3
UF4
UF5
UF6
UF7
UF8

B River Flow controller options
This is a more detailed description of the use of the so called River Flow controllers. Following
topics are discussed:

General
Controlling Procedure Applied in River Flow
Overview of Controllers Available in River Flow
Trigger Procedure Applied in River Flow
Overview of Triggers Available in River Flow

General
A distinction is to be made between a controller, a control parameter, and a controlled
parameter, viz:

A controller is referred to as the computational procedure, which facilitates the userdefined way of controlling a particular structure;

A control parameter refers to a parameter, which acts as the input to the controller in order
to control another parameter, being the controlled parameter;

A controlled parameter refers to the parameter, which the user likes to be controlled in a
specific way during a computation.

Consider the fact that a user likes to maintain the discharge, flowing out of a small barrage
constant in time by manipulating the crest level of a weir accommodated in this barrage. For
this case the user can use the interval controller. The crest level of the weir will be the
control parameter, while the outflow discharge is the controlled parameter.

Consider a weir operated by a time controller, which maintains the user-defined time-dependent
crest levels of the weir. In this case the crest level is the controlled parameter. It will be obvious that there is no control parameter in this example.
Following parameters of hydraulic structures can be used for controlling purposes, viz:

River weir: crest level can be adjusted.
Advanced weir: crest level can be adjusted.
General structure: crest level, crest width and gate lower edge level can be adjusted.
Database structure: crest level can be adjusted.

In the River Flow module compound structures can be defined, where several different type
of hydraulic structures can be defined next to each other at the same location. Each member
of the compound structure may have its own triggers and controllers.

SOBEK, User Manual

Controlling Procedure Applied in the River Flow module
The procedure, applied in SOBEK, for controlling hydraulic structures is as follows:

The user has the option to define a trigger that is assigned to a particular controller. Dur-

ing a computation a trigger can either be "ON" or "OFF". In case a trigger is "ON", the
corresponding controller will be activated, resulting in the fact that a particular hydraulic
structure will be controlled in a used-defined way. In case a trigger is "OFF", the corresponding controller will be deactivated. In case no trigger is assigned to aparticular
controller, this controller will be active during the entire computation. It is not fruitful to use
a relative time controller and a relative from value (time) controller without triggers;
A controller can be activated or de-activated by a trigger or by a combined trigger (maximum of four triggers can be combined to one combined trigger);
A maximum of four controllers can be assigned to one particular hydraulic structure. It
is to be mentioned that checks are not carried out for inconsistencies in the formulations
of the four user-defined controllers.
The controller is only activated once during a computational time step (i.e. at the beginning of a time step execution), meaning that the value of the controlled parameter is
not updated during the Newton iteration process of solving the flow equations;
The user has to define the control frequency, which refers to the time interval, after
which the controlled parameter is to be updated again, in case the controller has not yet
been de-activated. A default value for the control frequency is 1 (one), meaning that the
controlled parameter will be updated at the beginning of each and every time step for
which the controller has not yet been deactivated.

Overview of Controllers Available in the River Flow module
Six different types of controllers are available, viz:
1
2
3
4
5
6
B.1

Time controller,
Relative time controller,
Relative from value (time) controller,
Hydraulic controller,
Interval controller, and
PID controller.

Time controller

The time controller can be used for changing the settings of a hydraulic structure (controlled
parameter) during a computation.
The controlled parameter can for instance be:

the crest level of a hydraulic structure,
the crest width of a hydraulic structure, or
the gate lower edge level of a hydraulic structure

Please note that there is no control parameter in case of a time controller.
Following input is to be specified for a time controller, viz:
Regarding the controlled parameter

Define whether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.

River Flow controller options

Specify the time-dependent values of the controlled parameter.
Regarding the control parameter:
A control parameter is not applicable.
Regarding the controller and control procedure:

Update frequency: This defines how often the controller function should be updated.

Normally this will be every time-step, but can also be an interval of more time steps.
When you enter 1, the controller will be updated every time-step; for 2 it will be updated
every second time-step, and so on. Default is 1.
Control mechanism: The procedure followed by the time controller is straightforward.
Based on the computational time ∆t, SOBEK determines in the user-defined time-table
the requested value for the controlled parameter. After that SOBEK takes care that this
value is given to the controlled parameter (e.g. the crest level, the crest width or the gate
lower edge level of the hydraulic structure)
Control accuracy and applicability: Using this option the user should pay much attention in specifying a realistic time-table for the controlled parameter in order to avoid
instabilities in the computation. A realistic time-table for the controlled parameter means
a time-table which can be met from the hydrodynamic point of view.
Relative time controller

The relative time controller can be applied for changing the settings of a hydraulic structure
(controlled parameter) during a computation. The relative time controller is, therefore, a time
controller type of controller.
The difference with the time controller option comprise of the fact that in the relative time
controller option, the values for the controlled parameter have not to be specified for the entire
computation time. When activated the relative time controller starts at the top of the userdefined time-table and from there on continues downward until the controller is de-activated
by its trigger (see also control mechanism).
The controlled parameter can for instance be:

the crest level of a hydraulic structure,
the crest width of a hydraulic structure, or
the gate lower edge level of a hydraulic structure.

Please note that there is no control parameter in case of a Relative time controller.
Following input is to be specified for a relative time controller, viz:
Regarding the controlled parameter:

Define wether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.

Specify the relative time-dependent values of the controlled parameter.
Regarding the control parameter:

A control parameter is not applicable.

SOBEK, User Manual

Regarding the controller and control procedure:

Update. Frequency This defines how often the controller function should be updated.
Normally this will be every time-step, but can also be an interval of more time steps.
When you enter 1, the controller will be updated every time-step; for 2 it will be updated
every second time-step, and so on. Default is 1.

For the first time that the controller is activated, the relative time table will be made
absolute (= computation time + relative time) and the controller will start from the
top of the table and will continue downwards untill the controller is deactivated by its
trigger. The table will remain absolute during the user defined so called Start period.
In other words in case the controller is de-activated and activated again within this
Start period, the controller table remains absolute and at the point-in-time when the
controller is activated again, the value coresponding to this absolute point-in-time will
be obtained from the controller Table. In case the controller is activated after the so
called Start period has passed, the controller table will be made absolute again and
the controller will start from the top of the table and will continue downwards;
Start period=0, means that each time the controller is triggered, the controller table
will be made absolute;
When the controller branches the end of the controller time table, the value of the
controlled parameter is kept constant at the value found in the last row of the time
table;
In case the user defined value for d(value)/dt is too small to allow for the in the
controller table defined changes in controlled parameter, SOBEK will divert from these
defined controlled parameter values in such way as the best fit the overal defined
controller table. d(value)/dt=0 means that there is no restriction in change in controlled
parameter over one computational time step.

Control mechanism:

Control accuracy and applicability: Using this option the user should pay much attention in specifying a realistic time-table for the controlled parameter in order to avoid
instabilities in the computation. In addition the value of the controlled parameter at the
moment that the controller is activated should be preferably be known in order to avoid
large discontinuities and hence instabilities during the computation, which might even result in a termination of the program. A realistic time-table for the controlled parameter
means a time-table which can be met from the hydrodynamic point of view.
B.3

Relative from value (time) controller

The relative from value (time) controller can be used for changing the settings of a hydraulic structure (controlled parameter) during a computation. The relative from value (time)
controller is, therefore, a time controller type of controller. For the relative from value (time)
controller, the values for the controlled parameter have not to be specified for the entire computation time. The relative from value (time) controller is usually applied when the actual values of the controlled parameter are unknown at the moment in which the relative from value
(time) controller is activated. Therefore, when activated the relative from value (time) controller first determines the actual value of the controlled parameter. After that the relative from
(time) value controller starts in the user-defined time-table at the actual value of the controlled
parameter and continues downwards from this value onwards (see also control mechanism).
In this way possible large discontinuities in the value of the controlled parameter are avoided
and hence instabilities in SOBEK computations, leading to the possible termination of the
program.
Following input is to be specified for a relative from value controller, viz:

River Flow controller options

Regarding the controlled parameter:

Define wether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.

Specify the relative time-dependent values of the controlled parameter.
Regarding the control parameter:
A control parameter is not applicable.
Regarding the controller and control procedure:

Update frequency: This defines how often the controller function should be updated.

Normally this will be every time-step, but can also be an interval of more time steps.
When you enter “1”, the controller will be updated every time-step; for “2” it will be updated
every second time-step, and so on. Default is 1.

For the first time that the controller is activated, the relative time table will be made
absolute (= computation time + relative time). The controller will determine the actual
value of the controlled parameter. After that the controller searches for the line in the
user-defined time table, which has the same value as the actual value of the controlled
parameter. From there on the controller will continue downwards in the controller
table untill it is de-activated. The controller table will remain absolute during the user
defined so called Start period. In other words in case the controller is de-activated
and activated again within this Start period, the controller table remains absolute and
at the point-in-time when the controller is activated again, the value corresponding to
this absolute point-in-time will be obtained from the controller table, which might lead
to a discontinuity in controlled parameter value. In case the controller is activated after
the so called Start period has passed, the controller table will be made absolute again
and the controller willl start at the row coinciding with the actual value for the controlled
parameter;
Start period=0, means that each time the controller is triggered the controller table will
be made absolute;
When the controller branches the end of the controller time table, the value of the
controlled parameter is kept constant at the value found in the last row of the time
table;
In case the user defined value for d(value)/dt is too small to allow for the in the controller defined changes in controlled parameter, SOBEK will divert from these defined
controlled parameter values in such way as to best fit the overall defined controller
table. A value for d(value)/dt = 0 means that there is no restriction in the allowable
change in controlled parameter value over one computational time step.

Control mechanism: The procedure of the relative from value controller is as follows:

Control accuracy and applicability: Using this option the user should pay much attention in specifying a realistic time-table for the controlled parameter in order to avoid
instabilities in the computation. A realistic time-table for the controlled parameter means
a time-table which can be met from the hydrodynamic point of view.

SOBEK, User Manual

Hydraulic controller
The hydraulic controller can be used to operate a hydraulic structure (i.e. the controlled
parameter) based on the actual value of a specified hydraulic parameter (i.e. the control
parameter).
The controlled parameter can for instance be:

the crest level of a hydraulic structure,
the crest width of a hydraulic structure, or
the gate lower edge level of a hydraulic structure
The control parameter can be either:

the actual value of a water level at a specific location,
the actual value of the averaged flow velocity in the total flow section at a specific location,
the actual direction of the flow at a specific location,
the actual value of a discharge at a specific location (or the sum of the actual discharge at
a maximum five locations),
the actual head-difference over a hydraulic structure. The head-difference of another
structure than the controlled structure can be used.
the actual pressure-difference over a hydraulic structure or the member of a compound
structure. The pressure-difference of another structure than the controlled structure can
be used.

The following input is to be specified for a Hydraulic controller, viz:
Regarding the controlled parameter.

Define whether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.

Note that the requested values for the controlled parameter are determined from the controller Table (see below). It is, therefore, not necessary to specify the minimum and maximum value of the control parameter as well as the maximum possible adjustment of the
control parameter over a time step
Regarding the control parameter.

Definition of the type of hydraulic control parameter (i.e. whether it is a water level, a
velocity, the flow direction, a discharge, a head difference over a structure, or a pressure
difference over a structure).
Definition of the location of the hydraulic control parameter (i.e. either the specific location
(in case of a water level, a velocity, the flow direction or discharge) or the concerning
structure in case of a head difference or pressure difference).
Definition of the controller-function (or controller table) for the specified hydraulic control
parameter. The controller-function contains the relation between the actual value of the
hydraulic control parameter and the by the user requested value of the controlled parameter (e.g. the crest height, the crest width or the gate lower edge level of the controlled
hydraulic structure).
Regarding the controller and control procedure.

Update frequency: This defines how often the controller function should be updated.
Normally this will be every time-step, but can also be an interval of more time steps.

River Flow controller options

Interval controller

The interval controller can be used to operate a hydraulic structure (i.e. the control parameter) in such way that user-specified values of a hydraulic parameter (i.e. controlled
parameter) are maintained.
The controlled parameter can be either:

a water level at a specific location, or
a discharge at a specific in the model.

Note:
The location of the to be controlled parameter should be under the control range of the concerning hydraulic structure.
The control parameter can for instance be either:

the crest level of a hydraulic structure;
the crest width of a hydraulic structure, or
the gate lower edge level of a hydraulic structure.

The following input is to be specified for a Interval controller, viz:
Regarding the controlled parameter:

Definition of the controlled parameter (i.e. water level or discharge at a particular location
in the model).

Setpoints for the controlled parameter. These are in fact the user-defined values for the

controlled parameter. There are two possibilities in SOBEK, viz:
a constant water level or discharge, or
a time-dependent water level or discharge, defined by means of a table.

Definition of the dead band type. On basis of the specified dead band type, SOBEK
determines whether the value of the controller v (e.g. crest height, crest width or gate
lower edge level of the hydraulic structure) are to be adjusted. The following dead band
types are available in SOBEK, viz:

When you enter “1”, the controller will be updated every time-step; for “2” it will be updated
every second time-step, and so on. Default is 1.
Control mechanism: The procedure followed by the Hydraulic controller is straightforward. First, the actual value of the hydraulic controller for t = t is determined. Next the
value of controlled parameter (e.g. the crest height, crest width or gate lower edge level
of the hydraulic structure) is obtained by interpolation in the user-defined controller table.
Finally SOBEK adjusts the actual value at t = t + ∆t of the crest height, crest width or
gate opening of the hydraulic structure in accordance with the findings of the interpolation
in the controller table.
Control accuracy and applicability: Using this option the user should pay much attention in specifying a realistic controller-function (i.e. the relation between the value of the
control parameter and the requested value of the controlled parameter) in order to avoid
instabilities in the computation. A realistic controller-function means a function which can
be met from the hydrodynamic point of view.

a constant dead band value D , or.
a dead band D as percentage of the discharge.

SOBEK, User Manual

In this case except for the percentage, the minimum and maximum dead band values are to
be specified as well.
Regarding the control parameter:

Define wether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.

The so called “< Dead band” and “> Dead band” control values, that defines the direc-

tion in which the control parameter (e.g. gate lower edge level) should move in order to
maintain the defined set points for the controlled parameter (e.g. water level). In case actual value for controlled parameter is below set point + dead band, the control parameter
should move towards the value specified for “< Dead band”. In case the controlled parameter is above set point + dead band, the control parameter should move towards the
value specified for “> Dead band” (see also control mechanism below). Please note that
only positive value for the control interval (dVs) can be defined.
The “< Dead band” and “> Dead band” control values are also the range allowed for
the control parameter (e.g. crest level) in order to try to maintain the controlled parameter
within its defined set points.
Definition of the control interval (dvs) , which refers to the user-defined change in the value
of the control parameter over 1 (one) time step. The reason why the user has to define a
control interval (dvs) is the fact that in reality it takes time to adjust the crest height, crest
width or gate lower edge level of hydraulic structure. In practical situations there is a limit
to the change in the value of the control parameter over a time step. In SOBEK two types
of control interval can be defined, viz:

fixed control interval, meaning that if required the value of the control parameter can be
adjusted with a constant value only (for instance 0. 1 m’ in case of a gated structure).
variable control interval, meaning that if required the value of the control parameter
can be adjusted by the product of the actual computational time step ∆t times the
user-defined adaptation velocity v . For instance in case of a crest level as control
parameter and an adaptation velocity v of 0.002 m/s, means that over a time step ∆t
= 10 s, the change in value of the control parameter (if activated by its trigger) will be
10 × 0.002 = 0.02 m.

Regarding the controller and control procedure:

The update frequency: which refers to the time interval after which SOBEK updates the
value of the to-be-controlled parameter in case the controller has not yet been de-activated
by its trigger or combined trigger (see also point 3 under General aspects of controllers),

The control mechanism: SOBEK applies the following algorithm for determining whether
the value of the control parameter (v.) is to be updated, viz:
if −0.5D < e < +0.5D then Vs = Vs,old
if e < −0.5D then Vs = Vs,old + d∆vs
if e > +0.5D then Vs = Vs,old − d∆vs
in which:

dead band (in [m] in case of water level, and in [m3 /s] in case of discharge),
control direction (1 or -1).
Positive if “> Dead band” control value larger than “< Dead band” control
value.
Negative if “> Dead band” control value smaller than “< Dead band” control
value.
deviation of the controlled parameter

River Flow controller options

= setpoint - actual value of the controlled parameter
control interval (fixed value or computed by ∆Vs = |v|∆t,

adaptation velocity, please note that v is always positive
value of the control parameter in the previous time step.
Controller accuracy and applicability: The interval controller is not a very advanced
type of controller. It is for instance, sensitive to instabilities, in particular if the adaptation
velocity, control frequency or dead band are not selected properly. Also the control history
(before the last time step is not taKi ng into account to determine the control parameter.
PID controller

The controlled parameter can be either:

As for the interval controller, the PID controller, can be used to operate a hydraulic structure
(i.e. the control parameter) in such way (i.e. by adjusting its crest level, crest width or gate
lower edge level) , that user-specified values of a hydraulic parameter (i.e. controlled parameter) are maintained. The difference with the interval controller option comprises of the fact
that the PID controller option does take the control history into account.

a water level at a specific location, or
a discharge at a specific location in the model.

Note:
The location of the controlled parameter should be under the control range of the concerning
hydraulic structure.
The control parameter can for instance be either:

the crest level of a hydraulic structure,
the crest width of a hydraulic structure, or
the gate lower edge level of a hydraulic structure

The following input has to be specified for a PID controller:

Regarding controlled parameter:
Definition of the controlled parameter (i.e. water level or discharge at a particular Iocation
in the model).
Setpoints for the controlled parameter. These are in fact the user-defined values for the
controlled parameter. There are two possibilities in SOBEK:
1 a constant water level or discharge, or
2 a time-dependent water level or discharge, defined by means of a table.

SOBEK, User Manual

Regarding control parameter:
Define whether it is the crest height, crest width or gate lower edge level of a particular
hydraulic structure.
Initial value of the control parameter (e.g. initial crest width).
Maximum and minimum value of the control parameter (e.g. maximum and minimum values for the gate lower edge level).
Maximum adaptation velocity of the control parameter (vmax ). This refers to the maximum
change in the value of the control parameter over one computational time step. For instance in case of a crest level as control parameter vmax = 0.02 m/s means that over a
time step ∆t = 60 s, the crest may be lowered or raised over 0.02 × 60 = 1.2 m.
Regarding controller and control procedure:

The control frequency, which refers to the time interval after which SOBEK updates the

value of the to-be-controlled parameter in case the controller has not yet been de-activated
by its trigger or combined trigger,

Control mechanism: Values for the following parameters are to be defined by the user:

Kp , proportional gain factor.
0
Ki , integral gain factor.
0
Kd , differential gain factor.

The value of the control parameter w(t) (i.e. user-defined water level or discharge) is
computed as follows:
1 First compute the correction value
0

u(t) = Kp e(t) + Ki

e(t) + Kd (e(t) − e(t − 1))

2 Perform this correction value to the control parameter w(t)

w(t) = w(t − 1) + u(t)

Kp , Ki , Kd Coefficient of the PID-controller (Åström and Hägglund, 1995).
kj
j = 1, 2, 3. Conversion factor between the controll parameter (e.g. discharges [m3 /s]) and the controlled parameter (e.g. water levels [m])
e(t)
deviation of the controlled parameter y(t), e(t) = ysp (t) − y(t)
u(t)
correction factor on the control parameter, e.g. e(t) ≡ 0 ⇒ u(t) = 0 ⇒
w(t) is unchanged.
0
0
0
The above given equation for computing w(t) on basis of w(t − 1), Kp , Ki , Kd , e(t)
and e(t − 1), refers to the fact that, for the PID controller method, the control history is

taken into account.
The following limitations are applied for the change in the control parameter ∆w(= w(t)−
w(t − 1)) over one user-defined timestep (can be specified in Settings):
The value of the control parameter w(t) cannot become larger than the user-defined
maximum value.
The value of the control parameter w(t) cannot become smaller than the user-defined
minimum value.
The change in the control parameter cannot become larger than the user-defined maximum allowable change in the control parameter dvmax (= vmax ∆t) over one userdefined time-step.

River Flow controller options

If necessary the computed value for the controlled parameter w(t) according to the formula above is overruled by a value for the controlled parameter that meets the limitations
specified above.
Controller accuracy and applicability: Since the PID controller is taking into account
the history of the control parameter it is supposed to be more accurate than the interval
controller.
0

Selection of gain factors Kp , Ki and Kd
0

The gain factors Kp , Ki and Kd must be calibrated for optimal performance of the PID
controller. For example the calibration can be carried out as follows:
0

the chosen control parameter (see note below)
0

Take Ki , Kd equal to zero, increase the value of Kp gradually from zero until the solution
0
starts to oscillate. The sign of Kp must be chosen dependent of the type of structure and

Decrease Kp until the controller is stable again.
0
Increase the value of Kd gradually. In case of small fast reacting channels start with
0
0.5Kp , in case of slow reacting channels like big rivers start with Kp . When the controller
starts to oscillate, decrease Kd .
0
0
Tune Kp and Kd until the result is satisfactory.
0

In most cases Ki can be kept zero. The Ki factor can be used to smooth the movements
of the controller, but is often not necessary, the water movements are already smoothing by it
0
self. In case of non-constant target values the Ki factor is even disturbing a proper functioning
of the controller and should not be used at all.
A strict procedure for this calibration can not be presented, since the procedures and results
are depending on the type of model. However after having some experience with tuning
PID controllers the modeller will gain some ’Fingerspitzengefühl’ as the Germans call it. In
a model with several structures with PID controllers which have the same order of dimensions like channel section lengths, cross-section sizes, and structures, the K -factors tuned
for one controller are a best guess for the other ones. Often they can be the same for all
structures/controllers.
Note:
Gain factors may be positive or negative. The choice of the sign depends on the type of
the control structure (e.g. crest level, crest width or gate lower edge level) and the location
(upstream or downstream of structure) and type (e.g. water level or discharge) of the hydraulic
parameter that is controlled by the PID controller. For example, consider a PID controller that
at a bifurcation tries to maintain a constant discharge, ysp (t), flowing into one branch by
manipulating the crest level of a River weir located in the branch that should receive this
constant discharge. In case the discharge, y(t), flowing into the branch of which its discharge
is controlled is too large, then the deviation e is negative (i.e. e(t) = ysp (t) − y(t) < 0).
From a hydraulic point of view the crest level w(t) of the river weir is to be raised in order to
0
reduce the discharge flowing into the controlled branch. In order to achieve the Kp gain factor
should be negative.
Note:
The hydraulic parameter must be taken at a location which is directly influenced by the PID
controller. The PID controller reacts also on the effect of its own actions. So it is not possible
to properly calibrate a PID controller with a controlled (hydraulic) parameter which location is
outside the influence area of the control structure.

SOBEK, User Manual

C Deprecated functionality
C.1

Linkage node
Note: The Flow - Linkage node is considered deprecated functionality. It is currently only
available for the purpose of backward compatibility. In SOBEK versions 2.12.004 and upwards, it is possible to add interpolation of Flow - Cross Section data between branches using
the Flow - Connection node. It is recommended to use this functionality rather than the Flow
- Linkage node.
The Flow -Linkage node is deprecated, see section C.1.2 for information on how to convert
existing linkage nodes in the model to connection nodes.

Flow - Linkage node (deprecated)
Description

In this chapter, the Flow - Linkage node is described.

As described in more detail below, the Flow - Linkage node was intended to easily add and
remove small tributaries to a parent river. Thus, the use of this node was limited to situations
where inflows have discharges of at least an order of magnitude lower than the parent river.
Please note that the Flow - Linkage Node option was not designed for modelling bifurcations.

For a detailed description of this node’s possible network configurations: see the "Flow Linkage node topology" section from the Reference Manual

This type of node is a combination of a normal Flow - Connection node and a Flow - calculation
point node. It has the following features:

The linkage node it does not change if you use the option .
The location is fixed.

The linkage node can be used as start or end node (like a normal connection node) for
other branches.

It is very useful to have the main river as one long branch and to make the tributary rivers
confluencing with linkage nodes. See the picture below, with the branch IDs displayed. Branch
1 is the main river, while all other branches are confluences of other rivers (the inflows have
discharges of at least an order of magnitude lower than the parent river).

Figure C.1: River confluences with linkage nodes

The advantage of this method above using normal connection nodes for all the confluences is

SOBEK, User Manual

that the interpolation of cross-sectional data interpolation over the main river always continues.
This is shown in the picture below. Although there are only two profile nodes at the main
branch, the interpolation is done like there are no confluences. By using normal connection
nodes for the confluences the interpolation only can be forced by added profile nodes with a
definition that should be interpolated by the modeller.

Figure C.2: River confluences for linkage nodes showing interpolation over linkage node
for main channel

Topology
Note: The Flow - Linkage node is considered deprecated functionality. It is currently only
available for the purpose of backward compatibility. In SOBEK versions 2.12.004 and upwards, it is possible to add interpolation of Flow - Cross Section data between branches using
the Flow - Connection node. It is recommended to use this functionality rather than the Flow
- Linkage node.
As described in more detail below, the Flow - Linkage node was intended to easily add and
remove small tributaries to a parent river. Thus, the use of this node was limited to situations
where inflows have discharges of at least an order of magnitude lower than the parent river.
Please note that the Flow - Linkage Node option was not designed for modelling bifurcations.
The modeller can easily connect new branches to Linkage nodes. This works similar to normal
connection nodes.
There is an extra functionality to join existing branches together as one branch, where the
existing connection nodes are replaced by linkage nodes. This operation is very useful as
many river systems are imported from GIS files, where each river section is defined as a
single branch. By using the edit action, it is possible to join all these single
branches to one branch.
To make this option working correctly, it is required to have the option enabled.

Deprecated functionality

Figure C.3: Check mark Allow Edit for selected objects

Furthermore, the active node type should be the Flow - Linkage node.

Figure C.4: Select Flow - Linkage node

The next step is to select the branches you want to join. This selection should include the
connection nodes.

SOBEK, User Manual

Figure C.5: Select branch to join

Now you have to select the action .

Figure C.6: Select action

You will be asked by the editor if you are sure. If so, you press Yes and the join operation will
be performed.

Deprecated functionality

Figure C.7: Join branches by the selectd path window

The existing connection nodes will be replaced by linkage nodes. Notice that also boundary
nodes or flow connection nodes with lateral flow and storage will be replaced if they are in the
selected path. You will lose the boundary, storage and/or flow definitions in that case.

Figure C.8: Existing node is replaced by Linkage Node

How to replace linkage nodes with connection nodes

This short tutorial will show you how to replace Flow - Linkage Nodes with Flow - Connection
Nodes and how to enable interpolation of bathymetry data over a Flow - Connection Node.
This tutorial is different from the other tutorials in that it is intended for users with existing
SOBEK models containing linkage nodes. Linkage nodes are considered deprecated (abandoned) functionality and should not be used. For more information about linkage nodes, and
why they were abandoned, see: Linkage node.
If you do not have any models with linkage nodes, this tutorial can be safely skipped as it does
not provide any essential information not already covered by other tutorials.

Start SOBEK.
Click on the Open Project button.
Select a project containing a linkage node you wish to replace.
Open the case you want to edit.

SOBEK, User Manual

Figure C.9: A schematisation with a Flow - Linkage Node.

Double click the ’Schematisation’ task block.
Click on the Edit Model button.

Your schematisation with a linkage node might look something like Figure C.9.
In the example shown in the screenshot, branch IDs have been visualised. This can be very
useful when editing the model as described below. It is possible to visualise branch IDs by
following these steps:

Select ’Options’ - ’Network Data...’.
On the tab ’Link’, select the radio button Branch.
Click on OK.

In the screenshot of our example, you can see two branches in the schematisation. Branch 2
is the main branch, and branch 3 is the tributary.
First we will change the linkage node into a Connection Node. By definition a connection node
is the start or end of a branch. So before we can place the connection node, it is necessary
to split the two branches into three branches:

Select the Edit Network button.
Select the
node, Flow-Connection Node.
Select the button Split branch at node in the ’Branch’ toolbar.
Now your button bar should look like this:

Finally, left-click on the Flow - Linkage Node.

Deprecated functionality

Figure C.10: Example schematisation after the linkage node has been replaced by a connection node.

The linkage has now been replaced by a connection node. In the example, the northern part
of the main branch has now become branch 4. See Figure C.10.

Now all that is left is to define between which branches we want to interpolate bathymetry
data.
Select the connection node.
Click on your right mouse button and select ’Model data’ - ’Flow Model’.
Turn on the option ’Interpolate Cross-section Bathymetry (only) over node’.
Click on the listbox next to First Branch and select branch: ’2’.
Click on the listbox next to Second Branch and select branch: ’4’.

See Figure C.11 for a filled in example using the above data.

Finally, click on OK.

SOBEK, User Manual

Figure C.11: The filled in Data Edit screen for the example connection node.

Using this method, linkage nodes can be replaced by connection nodes. In the above example, the Cross-section Bathymetry data is interpolated between branch 2 and branch 4.
Please note that every branch in SOBEK should contain at least one Cross-Section node.
Depending on the schematisation performing the above steps might therefore require the
user to add an extra cross-section after replacing the linkage node with a connection node.
Don’t forget to save your network before leaving NETTER.

For more information about connection node interpolation, see also: Flow - Connection node.
C.2
C.2.1

Rainfall Runoff Friction

Flow - RR-Friction (deprecated)
Friction node description

The RR Friction node creates a water level difference between two nodes that calculate open
water levels. The Friction node is designed to simulate the backwater effects of a narrow
channel with certain length, friction and bank slopes.

Deprecated functionality

Friction node input screens
When starting the model data editor for an RR Friction node type, the following tab will be
available for input:

Figure C.12: Data for friction, the friction tab

The following parameters should be entered here:

Manning coefficient n: The hydraulic friction of the channel that the friction node represents

Characteristic length L: The length of the channel that the friction node represents
Bottom width B : The bed width of the channel that the friction node represents
Slope: The tangent of the channel bank sides slope. (Not the slope of the channel bed
itself!) 0 means that the banks are vertical. 1 means that the banks have a 45 degree
slope.
See also:
The Friction chapter from the RR Technical Reference Manual

SOBEK, User Manual

Figure C.13: Connecting two RR open water nodes through an RR friction node

Friction node connections

RR Open Water nodes:

RR boundary nodes:

CF RR on Flow connection nodes:

The RR Friction should always interconnect two of the following nodes:

CF RR on channel connections:

RR Friction nodes can be used to connect two RR Open water nodes (i.e. in polder systems):

But they can also be used to connect an RR Open Water node to a Channel Flow connection
(i.e. in areas discharged by gravity where the second order water courses are modelled in an
RR open water node, and the first order water courses are modelled in the SOBEK Channel
Flow module).

Deprecated functionality

Figure C.14: Connecting an RR Open Water node to a Channel via an RR Friction node.

RR Friction node (deprecated)

A friction node can be put between two open water nodes to account for a significant hydraulic
gradient. The discharge equation reads:

√
1
AR2/3 i
n

Discharge [m3 /s]
Manning coefficient [s/m1/3 ]
Wetted area [m2 ]
Hydraulic radius [m]
Average hydraulic gradient [m/m]

The wetted area is calculated by

A = DW
A
D
W
Deltares

Wetted area [m2 ]
Average depth [m]
Average width [m]

SOBEK, User Manual

1
D = (h1 − h2 ) − h0
2
h1
h2
h0

Upstream water level [m wrt reference level]
Downstream water level [m wrt reference level]
Bed level [m wrt reference level]

Figure C.15: Explanation of symbols for calculating the wetted area

When the friction node is put in between two RR-open water nodes, the bottom level h0 is
computed as the average of the bottom level of both open water nodes. When the friction
node is put in between a RR-open water node and a RR- boundary node, the bottom level h0
is set equal to the bottom level of the open water node.
The average width is calculated by

W = B + tan(α)D
B

Bottom width [m]

The hydraulic gradient is calculated by

hydraulic gradient [m/m]
Upstream water level [m wrt reference level]
Downstream water level [m wrt reference level]
Characteristic length of water course [m]

The hydraulic radius R is defined as the wetted area of the cross section divided by the wetted
perimeter.

Wetted area [m2 ]
Wetted perimeter [m]

The wetted perimeter P is calculated by

P = B + 2D
B
D
α
726 of 900

Bottom width [m]
Average depth [m]
angle of the side slope with vertical

D SOBEK input file formats
D.1
D.1.1

SOBEK Input file formats: the Model Database 4.00
Philosophy behind the Model Database
The combination of all SOBEK input files is called the Model Database.
The Model Database consists of a number of ASCII-files, which are logically separated into a
number of layers; each layer covers a number of files. Each file contains the definition of one
or more SOBEK-objects. In most cases the object has an attribute id which is the key to that
particular object.

For more information on the layers, see the chapter Subdivision into layers Database
For more information on the design conventions, see the chapter Input conventions
For exact description of certain input files, see the chapter of the module that has your

interest:
For the modules Channel Flow, River Flow and Sewer Flow: chapter 1DFLOW and Overland Flow(2D)
For the modules Rainfall-Runoff: chapter RR (Rainfall Runoff)
For the module Real Time Control: chapter RTC (Real Time control)
Structure of the Model Database: subdivision into layers
The following layers are distinguished in SOBEK:
1
2
3
4
5
6
7
8
9
10
11
12
13

Topography (TP)
Cross section (CR)
Structure (ST)
Friction (FR)
Condition (CN)
Initial conditions (IN)
Meteo (MT)
Dispersion (salt) (D)
Grid (GR)
Run time data (RT)
Transport (TR)
Substance (SB)
Measurements (ME)(cannot be edited by user)

In SOBEK, a distinction has been made between the objects as defined in the topography
layer and the necessary data for these objects. Most of the objects in the topography layer
are connected to the data objects via a so-called ’carrier id’.
There are two exceptions on this rule:

the data from the run-time layer (layer 10) and
the substances (layer 12)
Both of these data objects are not directly connected to an object from the topography layer.
The data in every other layer is either specified for a specific location or as a ’global definition’.
Each layer consists of one or more files, each containing data stored in records. These
records always start with a specific keyword in CAPITALS, and end with the same keyword in

SOBEK, User Manual

lower-case.
The following list gives an overview of the different layers and their files. It should be noted
that not all files are necessary. For example, salt-related files are not necessary when the
salt module is not used. The file containing the file names has a standard Windows-INI file
structure. This means that the keywords are fixed and the file names behind the ’=’ can be
chosen freely. Within a layer the keywords should be unique.

[SOBEK ASCII Layer definition]
Version=2.01

[Topography layer]
ntw=network.ntw
net=network.tp
cpt=network.cp
dat=nodes.dat
xyc=network.d12

[Cross Section layer]
net=network.cr
def=profile.def
dat=profile.dat

[General]
SettingsFile=settings.dat

[Structure layer]
net=network.st
def=struct.def
dat=struct.dat
con=control.def
trg=trigger.def
cmp=struct.cmp
vlv=valve.tab
dbs=struct.def
[Friction layer]
bed=friction.dat
glf=friction.dat
exr=friction.dat
wnd=friction.dat
[Grid layer]
net=network.gr

[Condition layer]
net=network.cn
flb=boundary.dat
fll=lateral.dat
sab=boundary.sal
sal=lateral.sal
fbd=boundlat.dat

[Initial Conditions layer]
igl=initial.dat
ifl=initial.dat
isa=initial.sal
[Runtime Data layer]
flt=..\work\runtime.dat
fln=..\work\runtime.dat
flm=..\work\runtime.dat
flh=..\work\runtime.dat
san=..\work\runtime.dat

SOBEK input file formats

sam=..\work\runtime.dat
sah=..\work\runtime.dat
inc=incclass.dat
net=network.me
[Meteo layer]
wnd=wind.#
bui=event.#
wlc=wnd_loc.dat

1DFLOW and Overland Flow(2D)
General principles of the model database

The SOBEK model database contains a number of ASCII-files. The database is logically
separated into a number of layers; each layer consists of a number of files. Each file contains
the definition of one or more SOBEK-objects. In most cases the object has an attribute id
which is the key to that particular object.

[Dispersion layer]
gld=globdisp.dat
lod=lokdisp.dat
fwt=freshwat.dat
mou=mouth.dat
brm=brmouth.dat

The following layers are distinguished in SOBEK:

Global definitions
Topography (TP)
Cross section (CR)
Structure (ST)
Friction (FR)
Condition (CN)
Initial conditions (IN)
Meteo (MT)
Dispersion (salt) (D)
Grid (GR)
Run time data (RT)
Transport (TR)
Substance (SB)
Measurements (ME) (cannot be edited by user)

In SOBEK, a distinction has been made between the objects as defined in the topography
layer and the necessary data for these objects. Most of the objects in the topography layer
are connected to the data objects via a so-called ’carrier id’.
There are two exceptions on this rule:

the data from the run-time layer (layer 10) and
the substances (layer 12)
Both of these data objects are not directly connected to an object from the topography layer.
The data in every other layer is either specified for a specific location or as a ’global definition’.
Each layer consists of one or more files, each containing data stored in records. These

SOBEK, User Manual

records always start with a specific keyword in CAPITALS, and end with the same keyword in
lower-case.

[SOBEK ASCII Layer definition]
Version=2.01
[Global model] Rivers only
NrOfFiles=1
glb=defglb.1
[Topography layer]
NrOfFiles=7
ntw=network.ntw
net=network.tp
cpt=network.cp
nfl=network.fl
nsa=network.sa
nsm=network.sm
dat=nodes.dat
[Cross section layer]
NrOfFiles=3
net=network.cr
def=profile.def
dat=profile.dat
[Structure layer]
NrOfFiles=9
net=network.st
def=struct.def
dat=struct.dat
con=control.def
trg=trigger.def
sal=struct.sa
cmp=struct.cmp
cms=structcmp.sa
dbs=struct dbs
[Friction layer]
NrOfFiles=4
bed=bedfric.dat
wnd=windfric.dat
exr=exresist.dat
glf=globfric.dat
[Condition layer]
NrOfFiles=10
net=network.cn
flb=boundfl.dat
fll=laterfl.dat
wqb=boundwq.dat
wql=laterwq.dat
sab=boundsa.dat
sal=latersa.dat
mob=boundmo.dat
mon=nodesmo.dat
mol=latermo.dat
[Initial Conditions layer]
NrOfFiles=5
igl=incondgl.dat
ifl=incondfl.dat
iwq=incondwq.dat
isa=incondsa.dat
imo=incondmo.dat

The following list gives an overview of the different layers and their files. It should be noted
that not all files are necessary. For example, salt-related files are not necessary when the
salt module is not used. The file containing the file names has a standard Windows-INI file
structure. This means that the keywords are fixed and the file names behind the ’=’ can be
chosen freely. Within a layer the keywords should be unique.

[Meteo layer]
NrOfFiles=4
wnd=wind.mt
sun-sunshine.mt
wat=wattemp.mt
air=airtemp.mt
[Dispersion layer]
NrOfFiles=5
gld=globdisp.dat
lod=lokdisp.dat
fwt=freshwat.dat
mou=mouth.dat
brm=brmouth.dat
[Grid layer]
NrOfFiles=3
net=grid.tp
seg=wqsegm.tp
lim=segmlm.tp
[Runtime Data layer]
NrOfFiles=18
flt=flowtim.dat
fln=flownum.dat
flm=flowmap.dat
flh=flowhis.dat
san=saltnum.dat
sam=saltmap.dat
sah=salthis.dat
sen=sednum.dat
sem=sedmap.dat
seh=sedhis.dat
mon=mornum.dat
mom=mormap.dat
moh=morhis.dat
wqt=wqtim.dat
wqn=wqnum.dat
wqm=wqmap.dat
wqh=wqhis.dat
pwq=prepwq.dat
[Transport layer]
NrOfFiles=1
dat=transprt.dat
[Substance layer]
NrOfFiles=1
sub=substanc.def

SOBEK input file formats

Global definitions file

This file is only present in case of SOBEK-River. An example of this file is as follows:
ca 0
APAC fl sd mp apac
mv 0
LRVD tp cr st cn in fr rt ds tr mt sb gr lrvd
LMTS xi 0.00 xa 150000.00 yi 0.00 ya 150000.00 lmts
rh 0
Only the first 2 record are used by the Parser
record 1:
ca

area code: 0 = river 1 = estuary

SOBEK, User Manual

record 2 (APAC):
APAC fl sd mp ..apac
This record contains the module identifiers. If an identifier is present the corresponding module will be activated. The identifiers are:
flow module
salt module
sediment module
morphology
2D-morphology
make water quality aggregation file
water quality module
Mozart coupling

fl
sl
sd
mp
m2
pq
wq
mz

validation flag (1=model has been validated) (only for UI)

record 4 (LRVD):

Contains layer information (only for UI)
record 5 (LMTS):

Contains the dimensions of the area of the model (only for UI)
record 6:
rh
D.4

refence level (only for UI)

Files in this layer

[2D grid layer]
NrOfFiles=1
net=..\work\network.d12

net-file (2D Grid layer)

This file describes the basic definition of 2D Grid [s] and the definitions of 1D Nodes (points)
or 1D branches (lines) lying within the 2D Grid. This also holds for 2D Points (Boundary
condition, Initial condition, Dam break structure) and 2D Line (combination of more than one
Boundary node)
DOMN id ’Example Sobek-FLS, Use New’ nm ’Example Sobek-FLS, Use New’
GFLS nc 61 nr 92 x0 101950 y0 463350 dx 100 dy 100 cp 0 fnm ” gfls
ISCHILDOF ci ’parent’
CHILDBLOCK ltX 124100 ltY 437400 rbX 126200 rbY 435800 ltC 11 ltR 1 rbC 32 rbR 17
childblock
PARENTBLOCK ltC 1 ltR 11 rbC 22 rbR 27 parentblock
ischildof
PT12 id ’92.31’ nm ’92.31’ ci ” lc 0 px 104994.2 py 454294.2 mc 31 mr 91 pt12

SOBEK input file formats

PT12 id ’2_1’ nm ’2_1’ ci ’2’ lc 300.9696 px 104994.9 py 454595.1 mc 31 mr 88 pt12
LI12 id ’1’ nm ’1’ ci ” lc 0 bx 105683.4 by 454213.5 ex 107991.5 ey 454213.5 bc 38 br 92 ec
61 er 92 li12
LI12 id ’l_bound’ nm ’bound’ ci ” lc 0 bx 257778.51 by 585767.76 ex 257774.22 ey 584358.75
bc 7 br 3 ec 7 er 17
TBLE cells 15
’7’ ’3’ <
..
’7’ ’17’ <
tble
li12
LM12 id ’l_meetraai’ nm ’meetraai’ ci ” lc 0 bx 257778.51 by 585767.76 ex 257774.22 ey
584358.75 bc 7 br 3 ec 7 er 17
TBLE cells 15
’7’ ’3’ <
..
’7’ ’17’ <
tble
TBLE crossings
PTCR cb ’10_7’ ci ’5’ lc 607.94 px 257776.34 py 585056.86 mc 7 mr 10 ptcr
tble
lm12
domn
where:
id
nm

2D grid id
2D grid name

GFLS...gfls = 2D grid definition
where:
nc
nr
x0
y0
dx
dy
cp 0
fnm

number of column (m) in X direction
number of rows (n) in Y direction
X coordinate
Y coordinate
distance between two grid points in X directions (m)
distance between two grid points in Y directions (n)
= 0 leftTop Corner (if grid definition file is *.dem, *.bil)
= 3 leftBottom Centre (if grid definition file is ARC-INFO *.asc)
name of grid definition file (for example *.dem, *.asc etc.)

ISCHILDOF .. ischildof = definition of child-parent relation in case of multiple domain
where:
ci

identification of Parent domain

CHILDBLOCK .. childblock = definition of rectangular within Parent domain by the child domain.
where:
ltX
ltY

left top X coordinate (center of child 2D grid cell)
left top Y coordinate (center of child 2D grid cell)

SOBEK, User Manual

rbX
rbY
ltC
ltR
rbC
rbR

right bottom X coordinate (center of child 2D grid cell)
right bottom Y coordinate (center of child 2D grid cell)
Left Column number of Parent domain cut by Child domain
Right Column number of Parent domain cut by Child domain
RightColumn number of Parent domain cut by Child domain
Right Column number of Parent domain cut by Child domain

PARENTBLOCK .. parentblock = definition of rectangular within Child domain by the Parent
domain.
where:
Left Column number of Child domain cut by Parent domain
Right Column number of Child domain cut by Parent domain
RightColumn number of Child domain cut by Parent domain
Right Column number of Child domain cut by Parent domain

ltC
ltR
rbC
rbR

PT12 .. pt12 = definition of 1D and 2D Nodes (Points) lying within 2D grid

id
nm
ci
lc
px
py
mc
mr

point object id
point object name
branch id (carrier id)
position relative to the branch origin (always 0)
X-coordinate
Y-coordinate
column position within 2D grid (m) in X direction
row position within 2D grid (n) in Y direction

LI12 .. li12 = definition of 2D Boundary Line or 1D2D Internal Boundary Line (lying within 2D
Grid)
where:
id
nm
ci
lc
bx
by
ex
ey
bc
br
ec
er

line object id
line object name
”
0
begin X-coordinate
begin Y-coordinate
end X-coordinate
end Y-coordinate
begin column position within 2D grid (m) in X direction
begin row position within 2D grid (n) in Y direction
end column position within 2D grid (m) in X direction
end row position within 2D grid (n) in Y direction

LM12 .. lm12 = definition of 2D Measurement Line (meetraai)
where:
id
nm
ci
lc

line object id
line object name
”
0

SOBEK input file formats

bx
by
ex
ey
bc
br
ec
er

begin X-coordinate
begin Y-coordinate
end X-coordinate
end Y-coordinate
begin column position within 2D grid (m) in X direction
begin row position within 2D grid (n) in Y direction
end column position within 2D grid (m) in X direction
end row position within 2D grid (n) in Y direction

TBLE cells ncells tble = table of 2D grid cells and ncells is number of cells in table
TBLE crossings .. tble = table of 1D Channel/pipe crossing the 2D Measurement Line
PTCR .. ptcr = definition of 1D channel/pipe crossing the 2D Measurement Line

id of the branch
if of the branch
location on branch from beginning point
column position within 2D grid (m) in X direction.
row position within 2D grid (n) in Y direction.
X-coordinate of 2D grid point
Y-coordinate of 2D grid point

cb
ci
lc
mc
mr
px
py

Condition layer

This layer contains data for boundary conditions and lateral discharges.
Files in this layer

[Condition layer]
NrOfFiles=10
net=network.cn
flb=boundfl.dat
fll=laterfl.dat
wqb=boundwq.dat
wql=laterwq.dat
sab=boundsa.dat
sal=latersa.dat
mob=boundmo.dat
mon=nodesmo.dat
mol=latermo.dat

flb-file (condition layer)

This file contains de boundary conditions for the FLOW modules.
For Channel Flow, Sewer Flow and River Flow:
FLBO id ’1’ st 0 ty 0 h_ wd 0 1.2 0 flbo (constant H)
or
FLBO id ’1’ st 1 ty 0 q_ wd 0 1.2 0 flbo (constant Q)
or (variable discharge)
FLBO id ’1’ st 0 ty 1 q_ dt 1 TBLE .. tble flbo (variable Q)
or
FLBO id ’1’ st 0 ty 1 h_ dt 1 TBLE .. tble flbo (variable H)
or (Fourier boundary)

SOBEK, User Manual

FLBO id ’1’ st 1 ty 1 q_ df 2 TBLE .. tble h0 0.5 w0 0.1 flbo
or (tidal boundary)
FLBO id ’1’ st 1 ty 1 q_ di 2 TBLE .. tble h0 0.5 flbo
or tables library
FLBO id ’TH5’ st 0 ty 0 h_ wt 11 ’TH5’ flbo
where:

ty
h_ wd 0
h_ wt 1
h_ wt 11
h_ wf 2
h_ wi 3
h_ wd 1
h_ wd 4
q_ dw 0
q_ dw 1
q_ dt 1
q_ df 2

id
storage on boundary node (storage only possible in case of SOBEK Urban)
0 = no storage
1 = storage
type boundary 0 = water level 1 = discharge
constant water level (only for ty 0)
variable water level as a function of time (TBLE ... tble)
use table from table library
only in SOBEK River: Fourier boundary for water level
only in SOBEK River: tidal boundary for water level
h_ wd 4
water level as a function of Q column 1 = Q column 2 = h
constant discharge
q_ dw 4
variable discharge as function of time (TBLE ... tble)
SOBEK Estuarium model: Fourier boundary.

table with amplitude, phase
q_ di 3

SOBEK Estuarium model: tidal boundary

table with amplitude, frequency, phase.
q_ dw 4

Q = Q(H) according to Q-H table
column 1 = h
column 2 = Q
only for Fourier and tidal boundary
only for Fourier optie w0

Note: h_ wd 1, h_wd 4, q_ dw 1 and q_ dw 4 are handled by the Parser in the same manner.
For Overland Flow:

1D2DInternal Boundary Line:

D2LI id ’bound’ nm ’1D2D Internal Boundary Line’ ty 4 cp ’20’ d2li
2D Boundary Node:
D2PT id ’bound’ nm ’Boundary Node’ ty 0 h_wd 0 10.0 d2pt
2D Boundary Line:
D2LI id ’bound’ nm ’Boundary Line’ ty 1 q_ dw 0 0.5 d2li
where:
id

SOBEK input file formats

h_ wd 0
h_ wd 1

boundary type
0 = water level
1 = flow/Flux
2 = velocity
4 = 1D2D Boundary Line.
10.0 constant water level; only for ty 0
water level as a function of Q *** not implemented yet
column 1 = discharge Q [m3 /s]
column 2 = water level h [m w.r.t. reference level]
note: only for ty 0
variable water level as a function of time (TBLE ... tble)
column 1= time in hours from start of simulation
column 2 = water level h [m w.r.t. reference level]
note: only for ty 0.
0.5 = constant discharge [m3 /s];
note: only for ty 1
Q=Q(H) according to Q-H table
column 1 = water level h [m w.r.t. reference level]
column 2 = discharge Q [m3 /s]
note: only for ty 1
= variable discharge as a function of time (TBLE ... tble)
column 1 = time in hours from start of simulation
column 2 = discharge Q [m3 /s]
note: only for ty 1
= velocity as a function of time (TBLE ... tble)
column 1 = time in hours from start of simulation
column 2 = velocity [m/s]
note: only for ty 2
identification of the connected 1D2D Internal Boundary Node (node only available in Channel Flow)

BTBL id ’TH5’ ty 0 h_ wt PDIN 0 0 pdin
TBLE
’2001/01/01;00:00:00’ .33
’2001/01/01;01:00:00’ .64
’2001/01/01;02:00:00’ .83
’2001/01/01;03:00:00’ .81
’2001/12/31;20:00:00’ -.3
’2001/12/31;21:00:00’ .27
’2001/12/31;22:00:00’ .8
’2001/12/31;23:00:00’ 1.1
tble btbl

BTBL id ’107’ sc 0 lt 0 PDIN 1 0 pdin
TBLE
’1990/01/01;00:00:00’ 2102.4
’1990/01/02;00:00:00’ 1716
’1990/01/03;00:00:00’ 1954.3
’1990/01/04;00:00:00’ 1734.9
’1990/09/26;00:00:00’ 112.8
’1990/09/27;00:00:00’ 130.24
’1990/09/28;00:00:00’ 216.23

SOBEK, User Manual

’1990/09/29;00:00:00’ 152.37
’1990/09/30;00:00:00’ 99.31
tble btbl
fll-file (condition layer)
This file contains the lateral discharges on nodes/branches for the FLOW module.
Lateral discharge on branch:

FLBR id ’3’ sc 0 lt 0 dc lt 0 ir 0 ms ’station 1’ ii 0.005 ar 600000 flbr
or
FLBR id ’Intensity from Meteostation’ sc 0 lt 0 dc lt 7 ir 0.003 ms ’meteostation’ ii 0.002 ar
1000 flbr
or
FLBR id ’Constant intensity’ sc 0 lt 0 dc lt 6 ir 0.003 ms ’meteostation’ ii 0.002 ar 1000 flbr
or
FLBR id ’1’ ci ’1’ sc 0 lt 0 dc lt 1 0 0TBLE .. tble flbr
or
FLBR id ’11’ sc 0 lt 0 dc lt 0 1 0flbr
or
FLBR id ’107’ sc 0 lt 0 dc lt 11 ’107’ flbr

lateral structures:

FLBR id ’1’ sc 0 lt 0 dc lt 4 0 0 sd ’S1’ wl ow 0 -1 0 flbr
or
FLBR id ’1’ sc 0 lt 0 dc lt 4 0 0 sd ’S1’ wl ow 1 TBLE .. tble flbr

dc lt
dc lt 1
dc lw 2

dc lt 3
dc lt 4
dc lt 5
dc lt 6
dc lt 7
dc lt 11
ir
ms

id
section (for 2D morphology !)
0 = left (=main section; default)
1 = right
length of discharge
0 = point discharge (m3/s)
>0 = discharge over a certain length (m2/s) (not in SOBEK-Urban/Rural)
-1 = discharge over the entire length of the branch (m3/s) (new in SOBEK
Urban/Rural)
table:dc lt 0= constant value,
’real’ table (first column=time, second column=discharge)
as a function of the waterlevel (not in SOBEK Urban/Rural)
column 1 = h
column 2 = Q
linked to another lateral discharge (’2nd station’) (not in SOBEK Urban/Rural)
indicates lateral structure on a branch
retention
rational method with constant intensity
with intensity from the rainfall station
from a table library
constant intensity (mm/s)
meteo-station

SOBEK input file formats

ii
ar
sd
ci
wl ow
wl ow 0
wl ow 1

seepage/infiltration intensity (mm/s)
runoff area [m2 ]
id of structure definition (see STRUCT.DEF; only in case dc lt 4)
id of second station (only in case of dc lt 3; not in SOBEK Urban/Rural)
table with water levels outside the lateral structure
constant as a table,
’real’ table

FLND id ’1’ bi ’1’ ’2’ aw dd
TBLE ..
tble
dd
TBLE ..
tble
flnd

where:
bi
aw dd

Sobek-lateral discharges on a node (Only for 2D-morphology):

branch id’s
alpha w0 as a function of Q
column 1 = table, discharge
column 2 = alpha w
alpha w1 as function of Q
column 1 =table, discharge
column 2 = alpha w

Only for SOBEK Urban/Rural
lateral discharge on node:

FLNO id ’1’ dc lt 0 -1.0 0 flno
or lateral structure on node:
FLNO id ’1’ lt 0 dc lt 4 0 0 sd ’S1’ wl ow 1 TBLE .. tble flno
where:
id
dc lt

id
table with lateral discharge
dc lt 0= constant as table,
dc lt 1= ’real’ table
column 1 = time
column 2 = discharge
dc lt 4= indicates the structure being a lateral structure.
dc lt 5 = retention
id of structure description (see STRUCT.DEF)
table with water levels outside the lateral structure
wl ow 0= constant as table,
wl ow 1= ’real’ table

diffuse lateral discharge on the branch
FLDI id ’15263’ ci ’15263’ sc 0 lt -1 dc lt 0 2 0 fldi

SOBEK, User Manual

Where:
id
ci
sc 0 lt -1
dc lt 0
dc lt 1
dc lt

id
id of second station
diffuse
constant value [m3 /s/m]
= table
table with lateral discharge
dc lt 0= constant as table,
dc lt 1= ’real’ table

pipes with infiltration (trenches)

TRCH id ’38’ di ’3’ dl 1.05 dh 2.55 rt 22 pt 0.22 oi 2 il 0 pm 1 rg 2222 gl tt 0 1.45 trch
or
TRCH id ’36’ di ’19’ dl 0.1 dh 2 rt 10 pt 0.4 oi 2 il 0 pm 1 rg 1111 gl tt 1 PDIN 0 0 ” pdin
TBLE ’2011/11/29;00:00:00’ 1.11 <
’2011/11/29;01:00:00’ 1.22 <
’2011/11/29;02:00:00’ 1.33 <
’2011/11/29;03:00:00’ 1.44 <
tble trch

(branch carrier)ID of Pipe with Infiltration
ID of cross-section definition for trench (Id of cross-section of pipe is stored as
normal.)
Note: There is no difference in cross section definition of channel or trench or
pipe.
Distance invert level, the distance between the invert level of the pipe and the
invert level of the trench.
Trench height, if not (properly) specified the surface level is used as top of
trench.
Resistance factor pipe-trench
Porosity trench
option for initial water level trench
0 = Value specified by keyword il (default)
1 = Same as water level pipe
2 = Same as groundwater level
Initial water level trench (for oi = 0)
Permeability of ground/soil
0 = Completely impermeable, no interaction between groundwater and trench
1 = Permeable
Resistance factor trench-ground, only relevant when ground is permeable
groundwater level
0 = Constant groundwater level, only relevant when ground is permeable
1 = Table with groundwater level varying in time
column 1
column 2

date/time stamp
groundwater level

SOBEK input file formats

mob-file (condition layer)
This file contains the boundary conditions on nodes for the sediment/ morphology modules.
MPBO id ’1’ cy 1 bl bt 1
TBLE ..
tble
mpbo
where:

lo
lo sd 0
lo sd 2

id of the boundary condition
condition type
0 = load (as a constant, f(time), of f(Q))
1 = bed level (as a constant, of f(time)
load type
load as constant
load as function of the discharge Q
column 1 = Q
column 2 = load
column 3 = load right (only when using 2D morphology option)
load as function of time
column 1 = time
column 2 = load
column 3 = load right
bed level table
bl bt 0 = constant
bl bt 1 = table
column 1 = time
column 2 = bed level
column 3 = bed level right

Note: The field se is generated internally by the user interface. se 0 = no 2D morphology,
se 1 = 2D morphology on next branch. This field is not required.
D.5.4

mol-file (condition layer)

This file contains the descriptions of the lateral discharges of sediment on branches.
MPBR id ’2’ ty 0 le 0 lt dl 0 10.0 mpbr
or

MPBR id ’2’ ty 1 le 0 di ’1’ ct co 0 50.0 mpbr
where:
id
ty

id
type condition:
1 = concentration
0 = dry load
section (only for 2D morphology option)
0 = left (default)
1 = right
length

SOBEK, User Manual

dry load table (only for ty 1)
lt dl 0 = constant
lt dl 1 = table function
column 1 = time
column 2 = load
id of accompanying lateral discharge (only for ty 1: concentration)
sediment load table (only for ty 0)
ct co 0 = constant,
ct co 1 = table
column 1 = time
column 2 =sediment load

mon-file (condition layer)

This file contains the description for morphology on nodes. For every node the distribution
of sediment over the different branches needs to be given. When the module Morphology is
used, there is a maximum of three branches for every node. This means that there are three
combinations of two branches related to the node.
MPND id ’0’ ty 0 1 0 aa 9.9999e+009 2 9.9999e+009
ba 9.9999e+009 0 9.9999e+009 rt d0 ’Distribution Ratio’
TBLE
tble
rt d1
TBLE
tble
rt d2 bi ’0’ ’1’ ’2’ se 0 0 0 as m0 as m1 ex 9.9999e+009 9.9999e+009 ds 1 ta 0 mpnd
or

MPND id ’1’ ty 0 0 0 aa 9.9999e+009 9.9999e+009 9.9999e+009
ba 9.9999e+009 9.9999e+009 9.9999e+009 rt d0 rt d1 rt d2 bi ’2’ ’3’ ’4’
se 0 0 0 as m0 as m1 ex 9.9999e+009 9.9999e+009 ds 0 ta 0 mpnd
Where:
id
ty

aa
ba
rt d0
rt d1
rt d2
bi

id
type distribution per combination of two branches (max. 3 combinations)
0 =proportional (distribution according to the ratio of the discharges)
1 =linear (according to a linear relation)
2 =ratio (distribution according to interpolation relation of ratios of Q and Sediment load)
alfa; only for type 1: linear distribution
beta; only for type 1: linear distribution
distribution ratio table first couple
distribution ratio table second couple
distribution ratio table third couple
branch id’s of connection branches
as m0=alpha sedredge values for branch-couple 1; only if the 2D-morphology
option is selected.
as m1=alpha sedredge values for branch-couple 2; only if the 2D-morphology
option is selected.
exponents of sediment-distribution according to Wang:
exponent k for discharges

SOBEK input file formats

exponent m for widths
distribution used for each branch-couple or for all branches attached to the
node:
0 = for all branches attached to the node
1 = for each branch-couple
type of distribution in case ds = 0 (all branches of node)
0 = proportional
3 = exponential function according to Wang

Note: The field se is generated internally by the user interface. se 0 = no 2D morphology, se
1 = 2D morphology on next branch. This field is not required.
net-file (condition layer)

For Channel Flow, Sewer Flow and River Flow:
Locations flow conditions:

This file contains information about the locations in the network for which conditions are defined.

FLBO id ’1’ nm ’Bound_cond1’ ci ’4’ flbo Note: Fixed order
FLND id ’2’ nm ’Flowatnode1’ ci ’1’ flnd Note: Fixed order
FLBR id ’1’ nm ’Lateralflow op tak1’ ci ’1’ lc 100. Flbr Note: Fixed order
FLDI id ’1_1’ ci ’15263’ fldi Note: Diffuse lateral discharge whole branch
The following 3 types are only defined in SOBEK Urban/Rural:
FLNO id ’1’ nm ’Lateralflow op knoop1’ ci ’4’ flno
FLNX id ’1’ nm ’External Lateralflow knoop1’ ci ’3’ flnx
FLBX id ’1’ nm ’External Lateralflow op tak1’ ci ’5’ lc 50. flbx

Note: The ’Flow at node’ (FLND) can only be used in the case when 2D-morfology branches
connect to the node.
Locations conditions water quality:

WQBO id ’1’ nm ’ Wqbound1’ ci ’4’ wqbo
WQBR id ’2’ nm ’wq_at_branch’ ci ’5’ lc 300. wqbr
Locations conditions salt:

STBO id ’0’ nm ’Saltbound1’ ci ’4’ stbo
STBR id ’1’ nm ’Salt lat disch’ ci ’3’ lc 50. Stbr
STBR id ‘1’ nm ‘Salt lat conc ci ‘-1’ Stbr
Locations conditions sediment/morphology:
MPBO id ’1’ nm ’Sed_bound’ ci ’0’ mpbo
MPND id ’3’ nm ’Sed_disch_node’ ci ’2’mpnd
MPBR id ’5’ nm ’Sed_disch’ ci ’4’ lc 50. mpbr
where:

SOBEK, User Manual

id of the condition (boundary or lateral discharge)
name of the condition
carrier id (node id in case of a boundary or node condition, branch id in case of
a branch condition)
location (only in combination with a branch-id)

For Overland Flow:
1D2D Internal Boundary Node (node is only available in Channel Flow):
FL2B id ’pnt1D2Dboundary’ ci ’pnt1D2Dboundary’ px 101991.8 py 458610.7 fl2b
2D Boundary Node:

2D Boundary Line and 1D2D Internal Boundary Line:

D2PT id ’bound’ nm ” ci ’1’ px 101991.8 py 458610.7 d2pt

where:
id
nm
ci
px
py
bx
by
ex
ey

D2LI id ’l_bound’ nm ” ci ’l_bound’ bx 105683.4 by 454213.5 ex 107991.5 ey 454213.5 d2li

boundary id
boundary name
2D grid id
X coordinate within 2D Grid
Y coordinate within 2D Grid
begin X coordinate within 2D grid for Boundary Line
begin Y coordinate within 2D grid for Boundary Line
end X coordinate within 2D grid for Boundary Line
end Y coordinate within 2D grid for Boundary Line

Initial Condition Node:

D2IN id ’1’ ci ’1’ px 101991.8 py 458610.7 d2in
where:
id
ci
px
py

Initial Condition Node id
2D grid id
X coordinate within 2D Grid
Y coordinate within 2D Grid

SOBEK input file formats

sab-file (condition layer)
This file contains the boundary conditions for the saltmodule (SA)
STBO id ’1’ ty 1 co co 1
TBLE ..
tble
tl 0 tu 0 stbo
where:

id
type of boundary
zero flux
concentration
concentrations (only for type 0)
as constant
as table
time
concentrations
Thatcher-Harleman time lag (only for SOBEK River, concentration boundary)
time lag used (only for SOBEK River model, concentration boundary)

id
ty
1
0
co co
co co 0
co co 1
column 1
column 2
tl
tu

sal-file (condition layer)

This file contains the descriptions of the lateral discharges for the saltmodule (SA).
STBR id 0 ty 0 le 100 lo lt 0 10 0 co ct 0
TBLE ..
tble
stbr
STBR id 0 ty 1 le 100 co ct 1
TBLE ..
tble
stbr
where:

id
ty
le
lo lt
lo lt 0
lo lt 1
di
co ct
co ct 0
itemco ct 1

id of the lateral discharge of salt
type condition 0 = dry substance 1 = concentration
length
load table (for ty 0)
= constant
= table as function of time
id of accompanying lateral discharge (when ty 1: concentration)
concentration table (only for ty 1)
= constant
= table as function of the time

SOBEK, User Manual

wqb-file (condition layer)
This file contains de boundary conditions for 1DWAQ-module
WQBO id ’1’ ct ct 0 as SLST .. slst wqbo
where:
id
concentration type
constant boundary concentration
boundary concentration as table function of time:
time
values for all substances as function of time
between keywords SLST and slst a list:

the active substances
type (0=constant, 1=variable)
the value

id
ct ct
ct ct 0
ct ct 1
column 1
column 2
as

Note: : If a time-dependant boundary condition is used (ct ct 1) for one substance, it is still
possible to enter constant values for other substances using the keyword as.
Only one timetable can be entered, so when more substances have a time dependant boundary concentration, they should be entered in the same table for every timestep.
Note: The order of the substances after the keyword as SLST slst is identical as the order
in the table with concentrations as a function of time in the field ct ct 1
D.5.10

wql-file (condition layer)

This file contains the 1DWAQ conditions of the lateral discharges
SOBEK River FLBR
FLBR id ’1’ hs flbr
where:
id
hs

id lateral discharge
has substances
0 no
1 yes
active substances

Between the keywords SLST slst a list of substances, the type of discharge (0=constant,
1=variable) and the value. A variable concentration is only possible when the flow itself varies.
Note: : Specification of water quality conditions; Keywords FLBR en WQBR
In SOBEK River two keywords are used to specify these conditions, FLBR and WQBR. This
depends on whether the condition is associated with lateral flow or with an input of a dry
substance. It seems logical, however, to switch to the use of only one keyword, WQBR.

SOBEK input file formats

Cross Section layer
Files in this layer
[Cross section layer]
NrOfFiles=3
net=network.cr
def=profile.def
dat=profile.dat

dat-file (cross section layer)

This file contains a reference to the cross-section definition and information about the relative
height of the cross-section.
CRSN id ’crossloc1’ di ’crossdef1’ rl -0.5 ll -0.4 rs 0.9 ls 0.9 crsn
Note: Fixed order

Items in one record; ll, rs and ls optional, separated by 1 or more blanks where:
id
di
rl
ll
fg
us
ds
rs
ls

id of cross-section location
id of cross-section definition
reference level 1 (SOBEK River/Rural: level at the cross-section; SOBEK Urban/Rural: level at the end of the pipe)
reference level 2 (SOBEK Urban/Rural: level at the beginning of the pipe)
specification of flap gate (Pipe Only: 0 = None, 1 = Only Positive Flow, 2 = Only
Negative Flow)
upstream slope (not in SOBEK Urban/Rural)
Downstream slope (not in SOBEK Urban/Rural)
Surface level right (same units as rl)
Surface level left (same units as rl)

In SOBEK-River a bed-level (code bl) was already given for the cross-section descriptions
(except for the tables, here it is given in the table itself). In addition, a local reference level rl
at the cross-section needs to be given.
In SOBEK Urban/Rural however, it is not possible to give a bed level for every cross-section
description. In this case, the bed level is given when placing the cross-section on a branch
(pipe) by means of the keywords rl and ll. These keywords give the bed levels of the bottom
of the pipe at the end and the beginning of the pipe, so that the slope is determined by the
length of the pipe and the difference in height rl-ll.
In SOBEK-River, rl stands for the reference level at the location of the cross-section, while
the slopes on the left and right side can differ. In the case of more cross-sections on one
branch, the bed level slope between the cross-sections is assumed to be constant (based on
the bed levels at the cross-sections corrected for local reference levels). For interpolation of
the cross-sections both the up- and the downstream slopes are used.
In SOBEK-Rural for open water, only rl is used and interpreted the same way as in SOBEKRiver.

SOBEK, User Manual

def-file (cross section layer)
This file contains the descriptions of the cross sections. SOBEK River distinguishes 3 sections
while SOBEK Urban/Rural only distinguishes 1 section.

tabulated
trapezium
open circle
sedredge (2D morfology)
closed circle
5.
egg shaped (width)
egg shaped 2 (radius) not implemented
closed rectangular not implemented
9.
yz table
asymmetrical trapeziodal

0
1
2
3
4
5
6
7
8
9
10
11

The following types of cross sections are considered:

Tabulated cross section

CRDS id ’Crdef1’ nm ’Tabel1’ ty 0 wm 86.23 w1 0 w2 0 sw 0 lt lw
TBLE
-2.5516.8016.80 <
-1.0030.1330.13 <
-0.6530.1330.13 <
0.0086.2386.23 <
tble
dk 0 dc 99999. db 99999. df 99999. dt 99999.
gl 0.5 gu 0
crds
where:
id
nm
ty
wm
w1
w2
sw
lt lw
dk
dc
db
df
dt
gl
gu

cross section definition id
cross section definition name
type cross section (0=table)
width main channel
width floodplain 1 (used in River profile only, else value = 0)
width floodplain 2 (used in River profile only, else value = 0)
sediment transport width (not in SOBEK Urban/Rural) Default 0. Only important for module sediment/morphology
table for table profile between keywords TBLE and tble; the table contains
height, total width en flowing width.
summer dike (1 = active, 0 = not active) (in River profile only)
dike crest level in River profile only()
floodplain base level behind dike (in River profile only)
flow area behind dike (in River profile only)
total area behind dike (in River profile only)
ground layer depth (meter relative to bed level). In case of River profile, always
0
ground layer to be used within hydraulics calculation (1) or not (0). In case of
River profile, always 0

SOBEK input file formats

In the Data Editor there are 5 other types of cross-sections available, however they are treated,
stored and processed as tabulated cross-sections. These types are:
1
2
3
4
5

Rectangular
Elliptical
Arch
Cunette
Steel Cunette

To be able to represent these cross-sections in the Data Editor properly, the records for this
cross-sections contain some extra keywords, which do not have any influence on the results
and are used by the Data Editor only.

Rectangular:
width
height

These keywords for the different types are:

Elliptical:
ew
eh
Arch:
aw
ah
aa

width
height
height

Steel Cunette:
sh
sr
sr1
sr2
sr3
sa
sa1

height
radius r
radius r1
radius r2
radius r3
angle a
angle a1

SOBEK, User Manual

Trapezium cross section
CRDS id ’Crdef2’ nm ’Trapezium’ ty 1 wm 86.0 w1 0 w2 0 sw 0 bw 10 bs 0.5 aw 100 gl 0.5 gu
0 crds
Where:
cross section definition id
cross section definition name
type cross section (1=trapezium)
bed level
width main channel
width floodplain 1 (in SOBEK Urban/Rural always 0)
width floodplain 2 (in SOBEK Urban/Rural always 0)
bottom width
bank slope (horizontal/vertical)
maximum flow width
ground layer depth (meter relative to bed level)
ground layer to be used within hydraulics calculation (1) or not (0).

Only important for module sediment/morphology (River)

id
nm
ty
bl
wm
w1
w2
bw
bs
aw
gl
gu

sediment transport width (not in SOBEK Urban/Rural)

Open circle cross section

CRDS id ’Crdef3’ nm ’Opencirkel’ ty 2 rd 5 gl 0.5 gu 0 crds
where:
id
nm
ty
bl
rd
gl
gu

cross section definition id
cross section definition name
type of cross section (2=open circle)
bed level
radius
ground layer depth (meter relative to bed level)
ground layer to be used within hydraulics calculation (1) or not (0).

Note: This profile cannot be used for sediment calculations (River). A table should be used
instead.
D.6.6

Sedredge cross section

Only for 2D morphology calculations (SOBEK-River). ’left’ means main channel, and ’right’ is
the floodplain.
CRDS id ’Crdef4’ nm ’Sedredge’ ty 3 ll 3 rl 2.5 lw 10 rw 5 crds
Where:
id
nm
ty
ll
rl
lw

cross section definition id
cross section definition name
type cross section (3=2D morphology sedredge profile)
left bed level
right bed level
left bed width

SOBEK input file formats

right bed width

Closed circle cross section: (only SOBEK Urban/Rural)
CRDS id ’Crossdef5’ nm ’Geslotencirkel’ ty 4 rd 4 gl 0.5 gu 0 crds
Where:

cross section definition id
cross section definition name
type cross section (4=closed circle)
bed level
radius
ground layer depth (meter relative to bed level)
ground layer to be used within hydraulics calculation (1) or not (0).

id
nm
ty
bl
rd
gl
gu

Egg shaped cross section: (only SOBEK Urban/Rural)

CRDS id ’Crossdef6’ nm ’Ei’ ty 6 bo 0.5 gl 0.5 gu 0 crds
Where:
id
nm
ty
bl
bo

cross section definition id
cross section definition name
type cross section (6=egg shaped)
bed level
bottom width profile;

For this profile, the height is considered to be 1.5 * the width.
gl
gu
D.6.9

ground layer depth (meter relative to bed level)
ground layer to be used within hydraulics calculation (1) or not (0).

y-z table cross section: (only SOBEK Urban/Rural)

CRDS id ’Crdef’ nm ’y-z table1’ ty 10 lu 0 st 0 lt sw 0 12.0 lt yz
TBLE
0.0 12.0 <
1.0 10.0 <
2.0 9.0 <
3.0 9.5 <
4.0 10.5 <
5.0 11.0 <
tble
gl 0
gu 0
crds
or
CRDS id ’Crdef’ nm ’y-z table1’ ty 10 lu 0 st 0 lt sw
TBLE
12.0 0 <
20.0 1 <
tble

SOBEK, User Manual

lt yz
TBLE
0.0 12.0 <
1.0 10.0 <
2.0 9.0 <
3.0 9.5 <
4.0 10.5 <
5.0 11.0 <
tble
gl 0
gu 0
crds

lt sw 0
lt sw
lt yz

cross section (profile) definition identification
cross section (profile) definition name
type of cross section (10 = yz table)
calculation of conveyance
0 = Open vertically segmented (default)
1 = Open lumped
2 = Closed lumped
storage type
0 = reservoir
1 = loss of water above the highest point in the cross-sectional profile (deprecated since SOBEK 2.12.002a)
storage width on surface in m
storage width on surface level as tabulated function of level above surface level
in m (starting from zero).
table for y-z values.

Y horizontal distance increasing from the left to right,
Z vertical distance increasing from bottom to top in m.

In other words, use a coordinate system to define the Y-Z profile.
ground layer depth (meter relative to bed level). Unused for y-z profiles and set
to 0.
ground layer to be used within hydraulics calculation (1) or not (0). Unused for
y-z profiles and set to 0.

Asymmetrical trapeziodal cross section: (only SOBEK Urban/Rural)
CRDS id ’Crdef’ nm ’Asymmetrical Trapezium1’ ty 11 st 0 lt sw 0 12.0 lt yz
TBLE
0 .0 12.0 <
1.0 10.0 <
2.0 9.0 <
3.0 9.5 <
4.0 10.5 <
5.0 11.0 <
tble
gl 0
gu 0
crds

SOBEK input file formats

CRDS id ’Crdef’ nm ’Asymmetrical Trapezium1’ ty 11 st 0 lt sw
TBLE
12.0 0 <
20.0 1 <
tble
lt yz
TBLE
0 .0 12.0 <
1.0 10.0 <
2.0 9.0 <
3.0 9.5 <
4.0 10.5 <
5.0 11.0 <
tble
gl 0
gu 0
crds
Where:
id
nm
ty
st

lt sw 0
lt sw
lt yz

cross section (profile) definition identification
cross section (profile) definition name
type of cross section (11 = asymmetrical trapezium)
storage type
0 = reservoir
1 = loss of water above the highest point in the cross-sectional profile (deprecated since SOBEK 2.12.002a)
storage width on surface in m
storage width on surface level as tabulated function of level above surface level
in m (starting from zero).
table for y-z values.
Y horizontal distance increasing from the left to right ,
Z vertical distance increasing from bottom to top in m.

In other words, use a coordinate system to define the Y-Z profile.
ground layer depth (meter relative to bed level)
ground layer to be used within hydraulics calculation (1) or not (0).

net-file (cross section layer)

This file contains the definitions of the cross-section locations.

If the file version is 1.1 or higher (CR_1.1 in the first line), also records indicating the nodes
with storage are written to the file.
The cross-sections are defined using the CRSN record.
CRSN id ’c1’ nm ’crossdef1’ ci 10 lc 250.6 crsn Note: Fixed order
Where:
id
nm

id of cross-section location
name of cross-section definition

SOBEK, User Manual

carrier id (branch id)
distance from the beginning of the branch

The storage nodes is defined using STON record.
STON id ’2’ ci ’1’ lc 0 st ’Normal’ ston
Where:
id
ci
lc
st

node id
dummy
dummy
dummy

Only the node id is used, but all record keywords must be present and have a (dummy) value.
If no STON record is written for the node, then the storage as defined in the file nodes.dat
should be skipped.

In the old definition of the file (version 1.0) all storage data on nodes is always used, although
the actual node type in the User Interface does not suggest this functionality.
Dispersion layer

This layer contains the information for modelling the dispersion, which is used by the saltmodule.
Files in this layer

[Dispersion layer]
NrOfFiles=5
gld=globdisp.dat
lod=lokdisp.dat
fwt=freshwat.dat
mou=mouth.dat
brm=brmouth.dat

brm-file (dispersion layer)

This file contains the branch-mouth relations in SOBEK River, necessary for the Thatcher/Harleman formula and the empirical formula.
BRMT id ’2’ nm ’noname’ ci ’10’ mi DLST ’3’ ’4’ ’6’ dlst brmt
Where:
id
nm
ci
mi

branch-mouth id
name of the branch-mouth relation
carrier id (branch id)
necessary estuary-mouth id’s between the keywords DLST dlst (node id’s)

SOBEK input file formats

gld-file (dispersion layer)
This file contains some global definitions concerning the dispersion: the type of dispersion
formulation, and some other global parameters.
GLDS op 0 ty 0 f1 1 glds
or
GLDS op 1 ty 0 f1 1 f2 2 glds

GLDS op 1 ty 1 ds tt
TBLE ..
tble glds
or
GLDS op 2 ty 0 f1 1 f3 3 f4 4 glds
or

GLDS op 3 ty 0 f1 1 f3 3 f4 4 glds
or

GLDS op 2 ty 2 ds tt DSPN id ’2’ nm ’modelwide’ ci ’-1’ ty 0 f1 1 f3 3 f4 4 dspn glds
Where:
op

f1
f2
f3
f4
dt tt

option type formulation
0 = option 1 (dispersion coefficient as a function of location or time)
1 = option 2 (dispersion coefficient as a linear function of the concentrationgradient: f 1(x, t) + f 2(x, t)dc/dx)
2 = Thatcher-Harleman formula
3 = empirical formula, based on Thatcher-Harleman
type:
0 = constant
1 = f(time)
2 = f(place) (only for ’model wide’ definition)
f1(x,t) in [m2 /s]
f2(x,t) in [m6 /(kg s)]
f3(x,t) [-]
f4(x,t) [-]
dispersion table as function of the time
column 1 = time

the other columns are a selection of f1, f2, f3, f4, dependant of the type of dispersion chosen.
DSPN=keyword for the description of the model wide dispersion formulation (carrier id ’-1’).
Only relevant when dispersion is given as function of the location (type 2). The description of
the DSPN record is given in the lod-file. In this case, constants will always be used for the
model wide description.

SOBEK, User Manual

Note: Functions f1 through f4 als defined as f (x, t); this means that they can either depend
of the place (f (x)) OR the time (f (t)), but NOT both.
Note: When defining global dispersion, f1 through f4 can be either a constant or a function
of time. The lod-file contains descriptions of Dispersion as a function of place.
D.7.3

fwt-file (dispersion layer)
This file contains de fresh water discharge data necessary for using an empirical formulation
(ty 3 in the gld-file) in SOBEK River.
FWTR id ’0’ nm ’freshwat1’ ci ’1’ lc 50 sg 0 fwtr

id of the sweet water discharge/ extraction
name
carrier id (branch id)
location
sign
0 = positive (discharge)
1 = negative (extraction)

id
nm
vci
lc
sg

lod-file (dispersion layer)

This file contains the location-dependant dispersion information. These are linked to a branchid. This file is only necessary dispersion is entered as a function of place, in the gld-file.
DSPN id ’1’ nm ’Dispersietak1’ ci ’1’ ty 0 f1 11 f3 12 f4 13 dspn
or

DSPN id ’2’ nm ’Dispersietak2’ ci ’3’ ty 2 dl lt
TBLE ..
tble
dspn
Where:
id
nm
ci
ty

id dispersion
name
carrier id (=branch id)
type of dispersion function:
0 = constant
1 = f(time)
2 = f(place)
see gld-file
dispersion table as function of the location on the branch
column 1 = location
the other columns any one of f1, f2, f3, f4 depending on the chosen dispersion
formulation in the gld-file.

SOBEK input file formats

mou-file (dispersion layer)
This file contains the so-called mouth parameters; they are only necessary for the Thatcher/Harleman formulation and the empirical formulation in case of an estuary model.
For the Thatcher-Harleman dispersion formulation:
MDSP id ’1’ nm ’noname’ ci ’4’ dm 1 cm 2 um 3 rm 1035 qm 5 mdsp
The empirical formula needs a couple of additional parameters:
MDSP id ’1’ nm ’noname’ ci ’4’ dm 1 cm 2 um 3 rm 1035 qm 5 p0 0 p1 1 u0 2 u1 3 mdsp

id mouth id
name
carrier id of the node
reference water depth [m]
reference salt concentration [kg/m3 ]
characteristic flood velocity [m/s]
rho seawater (default 1035 kg/m3 )
initial fresh water discharge [m3 /s]
p0 [m3 ]
p1 [m2 ]
u0 [m/s]
u1 [1/s]

id
nm
ci
dm
cm
um
rm
qm
p0
p1
u0
u1

Files in this layer

[Friction layer]
NrOfFiles=4
bed=bedfric.dat
wnd=windfric.dat
exr=exresist.dat
glf=globfric.dat

Friction information is connected to branches, and not to cross-sections. This means that no
information is necessary about the place of the friction on the branch, as it is for the crosssections. The friction itself can depend on for example the location on the branch (!), the
discharge, or the water level. Friction can be specified for main- and subsections.
D.8.1

bed-file (friction layer)
This file contains the bed friction data per branch.
For Channel Flow, Sewer Flow and River Flow:
BDFR id ’1’ ci ’1’ mf 7 mt cp 0 20 0 mr cp 0 20 0 s1 6 s2 6 sf 7 st cp 0 20 0 sr cp 0 20 0 bdfr
Fixed number of items in one record, separated by 1 or more blanks
Where:

SOBEK, User Manual

s2
sf
st
st cp
sr

mt
mt fq
mt fh
mt cp

id of bed friction definition
name of the bed friction definition (not in SOBEK Urban/Rural)
carrier id = id of the branch
main friction type (main = main channel)
0 = Chézy
1 = Manning
2 = Strickler Kn
3 = Strickler Ks
4 = White-Colebrook
5=6=7 = De Bos and Bijkerk
friction in positive flow direction
friction=f(Q)
C=f(h)
friction as a constant or as a function of the location on the branch
For fq, fh, and cp: a constant (entered as a table) or a real table:
0 = constant
1 = variable
The options fq and fh may have more dimensional tables:
column 1 =Q or h value,
column n = friction value on different locations along the branch for every Q or
h
Thus, the options fq and fh are a function of the location on the branch and Q
(of h).
The option cp (friction as function of the location) has a two-dimensional table:
column 1 = location along the branch
column 2 = friction-coefficient
friction in negative direction:
mr fq =friction=f(Q)
mr fh =friction=f(h)
mr cp =friction as a constant or as a function of the location on the branch)
Option fq, fh, and cp may contain a constant given in a table or a table.
0 = constant
1 = variable
friction for floodplain 1 (not in SOBEK Urban/Rural)
can be either ’equal to main section’, or Chézy/. . . /Nikuradse. (0=Chézy,. . . ,6=Equal
to main section)
Note: Engelund cannot be used for the floodplains.
friction for floodplain 2 (not in SOBEK Urban/Rural)
ground layer friction type (0 – 7 ) (for further details see description for mf)
friction in positive direction
(for all friction types, for further details see description for mt)
ground layer friction in negative direction
sr cp for all friction types (for further details see description for mt)
c1 cp,fq,fh=floodplain 1 friction coefficients (friction can be defined as a function
of Q, of h, of the location or as a constant.
r1 cp,fq,fh=floodplain 1 reversed flow friction coefficients as a function of Q, of
h, of the location or as a constant.
c2 cp,fq,fh=floodplain 2
r2 cp,fq,fh=floodplain 2 reversed flow
d9 f9=D90

Same friction for both directions (for SOBEK-River only)

SOBEK input file formats

This feature is optional. It is defined by the flags em, er, e1, e2, e3, e4. If these flags are
present (in this order) they should follow the carrier id (ci ‘ ‘) immediately. These flags are only
used by the user interface. For the parser bed friction is fully defined by the keys mf etc.

BDFR id ’33’ nm ’(null)’ ci ’31’ em 0 er 0 e1 0 e2 0 e3 0 e4 0 mf 0 mt fh 3 50 9.9999e+009
’Chézy Coefficient Waterlevel’ PDIN 0 0 ” pdin CLTT ’H’ ’603.5’ cltt CLID ’(null)’ ’(null)’ clid
TBLE
-0.5 52.79 <
0 49.69 <
0.5 48.98 <
1 53.66 <
1.5 56.96 <
2 65.4 <
2.5 63.92 <
3 62.03 <
3.5 59.89 <
4 59.02 <
4.5 59.97 <
5 59.68 <
tble
mr fh 3 50 9.9999e+009 ’Chézy Coefficient Waterlevel’ PDIN 0 0 ” pdin CLTT ’H’ ’603.5’ cltt
CLID ’(null)’ ’(null)’ clid
TBLE
0 53.13 <
0.5 49.9 <
1 49.3 <
tble s1 0 c1 cp 0 35 9.9999e+009 r1 cp 0 35 9.9999e+009 s2 6 c2 cp 0 9.9999e+009
9.9999e+009 r2 cp 0 9.9999e+009 9.9999e+009 d9 f9 0 9.9999e+009 9.9999e+009
bdfr
Where:
em

flag for main section
1 = bed friction for negative flow equals the definition for positive flow
0 = different friction definitions for both directions
flag for main section
1 = bed friction for positive flow equals the definition for negative flow
0 = different friction definitions for both directions
flag for floodplain 1
1 = bed friction for negative flow equals the definition for positive flow
0 = different friction definitions for both directions
flag for floodplain 1
1 = bed friction for positive flow equals the definition for negative flow
0 = different friction definitions for both directions
flag for floodplain 2
Same meaning as e1
flag for floodplain 2
Same meaning as e2

Cross section related Friction
CRFR id ’fricid’ nm ’Friction1’ cs ’Crdef’
lt ys
TBLE

SOBEK, User Manual

0.0 3.0 <
3.0 5.0 <
tble
ft ys
TBLE
7 20 <
7 20 <
tble
fr ys
TBLE
7 20 <
7 20 <
tble
crfr
Where:

cs ’Crdef’ = cross section definition id (only for yz profile and asymmetrical trapezium) to which
this friction definition applies
lt ys= table for y values which defines the sections (in this case 2) within the profile for definition
of friction, flow, etc.
Number of rows defines the number of defined sections and value per row defines the start
of a section and end of a section (horizontal distance increasing from the left to right ). For
example, the first defined section starts at Y= 0.0 (including) till Y =3.0 (not including), and
so on. Note: the defined sections should be based on the same coordinate system used in
defining yz table.
ft ys= table for friction values in positive direction for (in this case 2) sections (division) of cross
section with friction type (0-7), constant friction value, the number of rows should be the same
as number of sections defined in the ’lt ys’.
fr ys =table for friction values in negative direction for (in this case 2) sections (division) of
cross section with friction type (0-7), constant friction value the number of rows should be the
same as number of sections defined in the ’lt ys’.
Structure Friction (for SOBEK Rural / Urban only)

STFR id ’1’ ci ’Culvert1’ mf 7 mt cp 0 20 0 mr cp 0 20 0 s1 6 s2 6 sf 7 st cp 0 20 0 sr cp 0 20
0 stfr
Fixed number of items in one record, separated by 1 or more blanks
Where:
ci
mf

id of structure definition
main friction type (main = main channel)
0 = Chézy
1 = Manning
2 = Strickler Kn
3 = Strickler Ks
4 = Nikuradse
5 = Engelund

SOBEK input file formats

6=7 = De Bos and Bijkerk
friction in positive flow direction
mt fq =friction=f(Q)
mt fh =C=f(h)
mt cp =friction as a constant or as a function of the location on the branch
For fq, fh, and cp: a constant (entered as a table) or a real table:
0 = constant
1 = variable
The options fq and fh may have more dimensional tables:
column 1 =Q or h value,
column n = friction value on different locations along the branch for every Q or
h
Thus, the options fq and fh are a function of the location on the branch and Q
(of h).
The option cp (friction as function of the location) has a two-dimensional table:
column 1 = location along the branch
column 2 = friction-coefficient
friction in negative direction:
mr fq =friction=f(Q)
mr fh =friction=f(h)
mr cp =friction as a constant or as a function of the location on the branch)
Option fq, fh, and cp may contain a constant given in a table or a table.
0 = constant
1 = variable
friction for floodplain 1 (not in SOBEK Urban/Rural)
can be either ’equal to main section’, or Chézy/../Nikuradse. (0=Chézy,..,6=Equal
to main section)
Note: Engelund cannot be used for the floodplains.
friction for floodplain 2 (not in SOBEK Urban/Rural)
ground layer friction type (0 - 7 ) (for further details see description for mf)
friction in positive direction
st cp = (for all friction types, for further details see description for mt)
ground layer friction in negative direction
sr cp for all friction types (for further details see description for mt)
c1 cp,fq,fh=floodplain 1 friction coefficients (friction can be defined as a function
of Q, of h, of the location or as a constant.
r1 cp,fq,fh=floodplain 1 reversed flow friction coefficients as a function of Q, of
h, of the location or as a constant.
c2 cp,fq,fh=floodplain 2
r2 cp,fq,fh=floodplain 2 reversed flow
D90

For Overland Flow:
D2FR id ’1’ nm ’Frictie1’ ci ’1’ mf 0 mt cp 0 45 0 mw cp 0 45 0 d2fr
where:
id
nm
ci
mf

bed friction definition id
bed friction definition name (not available yet)
carrier id = branch id
main friction type (main = main channel)
0 = Chézy

SOBEK, User Manual

exr-file (friction layer)
This file contains the definition of ’extra resistance’.

TBLE
..
..
tble xrst

Where:
id
nm
ty

XRST id ’5’ nm ’XRS05’ ty 0 rt rs

1 = Manning
4 = White Colebrook
bed friction
mt cp 0 60 0 = all other cases
(Chézy / Manning etc. as constant or dependent on the location)
0 = constant
mw cp 2 ’c:\sobek\fls_files\bedfrict.asc’ ’ ’
2 = file
mw = wall friction
mw cp 0 60 0 = all other cases
(Chézy / Manning etc. as constant or dependent on the location)
0 = constant
mw cp 2 ’c:\sobek\fls_files\walfrict.asc’ ’ ’
2 = file

= id of the extra resistance definition
= name of the resistance definition
= type of extra resistance
0 = extra resistance based on ξ(∆H = ξ × Q × |Q|)
= table with extra resistance
column 1 = water level
column 2 = extra resistance

glf-file (friction layer)

This file contains two groups of global data:

data necessary for the Engelund bed friction formula
global bed friction parameters
As these parameters are defined globally, they are not linked to any specific location.
GLFR dd 1.65 s1 0.474 s2 0.55 p1 -6 p2 2.75 p3 5.5 p4 4.125 p5 -0.2 p6 2.447
a1 0.0005 a2 6e-005 ra 1.205
BDFR id ’0’ ci ’0’ mf 4 mt cp 0 0.003 0 mr cp 0 0.003 0 s1 6 s2 6 bdfr glfr
Where:

SOBEK input file formats

dd
s1
s2
p1
p2
p3
p4
p5
p6
a1
a2
ra

delta D (global Engelund parameter)
sigma1 (global Engelund parameter)
sigma2 (global Engelund parameter)
as11 (global Engelund parameter)
as12 (global Engelund parameter)
as21 (global Engelund parameter)
as22 (global Engelund parameter)
as31 (global Engelund parameter)
as32 (global Engelund parameter)
alpha1 (for wind friction)
alpha2 (for wind friction)
rho air (for wind friction)

wnd-file (friction layer)

BDFR .... bdfr contains the global/default bed friction data.

This file contains information for calculation of the wind friction. Other information like the wind
speed and direction is stored in the meteo-layer.
WNDS id ’0’ nm ’null’ ci ’0’ lc 9.9E+009 sh ws 0 0 9.9E+009 wnds
or

WNDS id ’1’ nm ’null’ ci ’4’ lc 9.9E+009 sh ws 2
TBLE ...
tble
wnds
Where:

id
nm
ci
lc
sh ws

id of wind friction definition
name of the wind friction definition
carrier id (id of the branch)
location on branch (not used)
wind shielding table
0 constant
2 variable as a function of the location on the branch
column 1 = location
column 2 = wind shielding factor (1=no wind shielding).

Global wind friction is indicated by the extra keyword GLFR ... glfr, with carrier id ci ’-1’.
D.9

Grid layer
Files in this layer

[Grid layer]
NrOfFiles=3
net=grid.tp
seg=wqsegm.tp
lim=segmlm.tp

SOBEK, User Manual

net-file (grid layer)
SOBEK automatically connects an id to a grid point. This is necessary to process the results
per grid point via the HIS file format.
Grid table per branch
GRID id ’1’ ci ’1’ re 2 dc 2 gr gr
TBLE ..
tble
grid
Where:

id of the grid table
carrier id (=branch id)
type of branch identifiers
re 0 = default
re 2 = identifier based on name and distance
number of decimals
grid table, with the distance of every grid point from the beginning of the branch.
See ’Table’.

GRID id ’0’ nm ’(null)’ ci ’0’ lc 9.9999e+009 se 0 oc 0 gr gr ’GridPoints on Branch
with length: 10000.0’ PDIN 0 0 ” pdin CLTT ’Location’ ’1/R’ cltt CLID ’(null)’ ’(null)’ clid TBLE
...
tble
grid
D.9.2

seg-file (grid layer)

This file contains the definition of the segments for the 1DWAQ module.
SGMT id ’1’ nm ’Segment1’ sl DLST 3 4 2 dlst uo 0 sgmt
Where:
id
nm
sl
uo

segment id
segment name
segment limits, indicated by a list between the keywords DLST and dlst. This
list refers to id’s from the file with segment limits (lim-file)
parallel
0 = no
1 = yes

Groundwater layer
Files in this layer:

[Groundwater layer]
NrOfFiles=1
gwm=groundwater.gwm

SOBEK input file formats

gwm-file (groundwater layer)
This file contains the groundwater parameters per branch (SOBEK River only)
GWPR id ’1’ nm ’gw’ ci ’-1’ mu tm 0 45 9.9999e+009 kd tk 0 1400 9.9999e+009 gc tg 0 20
9.9999e+009 hb th 0 2.5 9.9999e+009 gwpr
With:

id of the groundwater definition
name of the groundwater definition
carrier id (= id of the branch)
storage coefficient table
0 = constant
1= table (f(x)) TBLE ...
(1st column=x, 2nd column= storage coefficient in [-])
hydraulic conductivity table
0 = constant
1= table (f(x)) TBLE ...
(1st column=x, 2nd column= hydraulic conductivity in [m2/d])
entrance resistance table
0 = constant
1= table (f(x)) TBLE ...
(1st column=x, 2nd column= entrance resistance in [d/m])
initial groundwater level table
0 = constant
1= table (f(x)) TBLE ...
(1e column=x, 2e column= initial groundwater level in [m])

gwn-file (runtime-data layer)

The runtime-data layer (gwn-file) contains the numerical parameters. These consist of the
following parameters:
GWNM dh 0.000000 lr 0 ll 0 av 0 ol 0 bl 0 gwnm
where:
dh
lr
ll
av
ol
bl
D.11

length of the period containing recent water levels in n∆t
length of the period containing less recent water levels in n∆t
length of the period containing less recent data, for which the average is calculated n∆t
length of the period containing ancient water levels n∆t
time between equilibrium water level and the first SOBEK water level n∆t

Initial Conditions layer
This layer contains the descriptions of the initial conditions. These can either be defined
globally or per branch. Furthermore, there are the options of auto-start (only for Flow module)
and restart.
Files in this layer

[Initial Conditions layer]

SOBEK, User Manual

NrOfFiles=5
igl=incondgl.dat
ifl=incondfl.dat
iwq=incondwq.dat
isa=incondsa.dat
imo=incondmo.dat

ifl-file (initial conditions layer)
This file contains the description of initial conditions of the flow module. For global flow conditions the additional keywords GLIN glin (and carrier id -1) are used.

FLIN id ’1’ nm ’Initcond1’ ci ’1’ q_ lq 0 0.01 ty 1 lv ll 1
TBLE ..
tble
flin
or

For Channel Flow, Sewer Flow and River Flow:

GLIN FLIN id ’1’ nm ’Initcond1’ ci ’-1’ q_ lq 0 0.01 ty 0 lv ll 0 0.05 flin glin
where:
id
nm
ci
q_ lq

id
name
carrier id (branch id)
initial discharge
q_ lq 0 = as a constant,
q_ lq 2 = as a function of the location on the branch
column 1 = location
column 2 = discharge
type water level/depth
1 = water level
0 = water depth
value for depth or water level
lv ll 0 = constant
lv ll 2 = table as function of the location op de branch
column 1 = location,
column 2 = water depth or water level

For Overland Flow:

D2IN id ’11’ ci ’-1’ lc 0 ty 1 lv ll 0 9.88 d2in
where:
id
ci
lc
ty

initial condition point id
branch id
0
type water level
1=water level (always 1)
lv ll 0 9.88 = constant water level [m w.r.t. reference level]

SOBEK input file formats

igl-file (initial conditions layer)
This file contains global definitions that have been entered in the UI in the settings screen.
GLIN fi 1 fr ’null’ glin
Where:
fi

flow init
0 = user defined
1 = auto start
restart filename

imo-file (initial conditions layer)

MPIN id ’1’ ci ’8’ ty 2 dt gs
TBLE ..
tble
mpin
and

This file contains the initial conditions for the sediment/ morphology module (SA). Global WQ
initial conditions start with GLIN, have a carrier id of -1, and end with glin.

GLIN MPIN id ’1’ ci ’-1’ ty 0 c3 35 cm 40 c5 50 c9 90 mpin glin
Where:
id
nm
ci
ty

c3
cm
c5
c9
r3
rm
r5
r9
dt gs

id
name
carrier id (branch id)
type
0 = constant
2 = as function of the location
D35 constant
Dmedium constant
D50 constant
D90 constant
right D35 constant (only 2D morphology)
right Dmedium constant (only 2D morphology)
right D50 constant (only 2D morphology)
right D90 constant (only 2D morphology)
table met grain sizes:
column 1 = location along the branch
column 2 = D35 value
column 3 = Dmedium value
column 4 = D50 value
column 5 = D90 value
For 2D morphology:
column 1 = location
column 2 = D35 left
column 3 = D35 right
column 4 = Dmedium left
column 5 = Dmedium right

SOBEK, User Manual

column 6 = D50 left
column 7 = D50 right
column 8 = D90 left
column 9 = D90 right
Note: relation initial condition and bed-friction formulation
There is a relation between the type of initial condition and the type of bed friction on the
branch; for example, the Engelund friction needs only the D50 and D90 constants, Nikuradse
Dm and D90, Strickler Kn D50, Chézy f(Q) D35 and D50, and Chézy f(location) D50 and D90.
D.11.4

isa-file (initial conditions layer)

STIN id ’1’ nm ’Init1’ ci ’5’ ty 0 co co 0 90 stin

This file contains the initial conditions for the salt module (SA). Global WQ initial conditions
start with GLIN, have a carrier id of -1, and end with glin.

GLIN STIN id ’0’ nm ’Initglobal’ ci ’-1’ ty 1 co co 0 50 stin glin
Where:
id
nm
ci
ty

id of the initial condition
name of the initial condition
carrier id
type concentration:
0 = salt
1 = chloride
table with initial salt conditions
co co 0 = constant
co co 2 = table as a function of the location on branch
column 1 = location
column 2 = load

iwq-file (initial conditions layer)

This file contains the initial conditions for the WQ module (WQ). Global WQ initial conditions
start with GLIN, have a carrier id of -1, and end with glin.
WQINid ’1’ nm ’Initcond1’ ci ’1’
ac 1 as SLST ’Surtemp’ 0 11 ’dTR1’ 0 123 slst is SLST slst
wqin
or
GLIN WQINid ’0’ nm ’Initglob’ ci ’-1’
ac 1 as SLST ’Surtemp’ 0 11 ’dTR1’ 0 123 slst is SLST slst
wqin glin
Where:
id
nm

id of the initial condition
name of the initial condition

SOBEK input file formats

carrier id (branch id)
active
between the keywords SLSR and slst:

active substances
name of substance,
type initial condition (0=constant, 1/2= f(. . . ),
initial concentration

between SLST and slst: list with inactive substances

Measured Data layer

[Measurements]
NrOfFiles=1
net=..\work\network.me

Files in this layer:

In SOBEK Urban/Rural, it is possible to define measurement stations that can be used as
target value locations for controllers.
net-file (measured data layer)
For Overland Flow:
History Node:

MEPT id ’11’ nm ” px 102791.8 py 459887.6 mept
Measurement Line (meetraai):

MELM id ’l_meetraai’ nm ’meetraai’ ci ” lc 0 bx 257778.51 by 585767.76 ex 257774.22 ey
584358.75 bc 7 br 3 ec 7 er 17 melm
where:
id
nm
ci
lc
px
py
bx
by
ex
ey
bc
br
ec
er
D.13

id of the history node or measurement line
name of the history node or measurement line
” (always blank)
0 (always 0)
X-coordinate within 2D grid
Y-coordinate within 2D grid
Begin X-coordinate within 2D grid for Measurement Line
Begin Y-coordinate within 2D grid for Measurement Line
End X-coordinate within 2D grid for Measurement Line
End Y-coordinate within 2D grid for Measurement Line
begin column position within 2D grid (m) in X direction
begin row position within 2D grid (n) in Y direction
end column position within 2D grid (m) in X direction
end row position within 2D grid (n) in Y direction

Meteo layer
Files in this layer

SOBEK, User Manual

[Meteo layer]
NrOfFiles=4
wnd=wind.mt
sun-sunshine.mt
wat=wattemp.mt
air=airtemp.mt

This layer contains de descriptions of the meteo data which can be specified either globally
or per branch. This layer can be compared to the friction layer in the sense that there is no
separate file that contains references to locations, because the data is specified directly per
branch. In all files the keywords GLMT and glmt (with carrier id -1) can be used to specify a
’model wide’ meteo description.
air-file (meteo layer)

This file contains data about the air temperature. It can be used optionally by the 1DWAQ
module. GLMT lmt and a carrier id of -1 indicate a global definition.

GLMT MTEO id ’1’ nm ’globalairtemp’ ci ’-1’ au 0 mteo glmt

MTEO id ’2’ nm ’airtemp1’ci ’1’ au 1 at ta 0 10 mteo
Where:
id
ci
au

id of the air temperature definition
carrier id (= id of the branch)
air temperature used
0 = no
1 = yes
air temperature table
0 = constant
1 = table
column 1 = time
column 2 = air temperature

sun-file (meteo layer)

This file contains information about the sunshine per branch; this information can be used
optionally in the water quality module. GLMT, glmt and a carrier id of -1 indicate a global
definition.
GLMT MTEO id ’1’ nm ’globalsun’ ci ’-1’ su 1 sh ts 1
TBLE ..
tble
mteo glmt
and
MTEO id ’2’ nm ’suntak4’ci ’4’ su 0 mteo
Where;
id

id of the sunshine definition

SOBEK input file formats

name of the sunshine definition
carrier id (= id of the branch)
sunshine used
0 = no
1 = yes
sunshine table
0 = constant
1 = table
column 1 = time
column 2 = sunshine in W/m2

wat-file (meteo layer)

This file contains information about the water temperature, that can be used optionally in the
salt module and water quality module. GLMT glmt and a carrier id of -1 indicate a global
definition.

GLMT MTEO id ’1’ nm ’globalwattemp’ ci ’-1’ tu 1 tp tw 1
TBLE ..
tble
mteo glmt

MTEO id ’3’ nm ’wattemp3’ci ’3’ tu 0 mteo
Where:
id
ci
tu

id of the water temperature definition
carrier id (= id of the branch)
water temperature used
0 = no
1 = yes
water temperature table
0 = constant
1 = table
column 1 = time
column 2 = water temperature

wnd-file (meteo layer)

This file contains de wind descriptions per branch; this information can be used optionally in
the flow module. GLMT, glmt and a carrier id of -1 indicate a global definition.
GLMT MTEO id ’1’ nm ’globalwind’ ci ’-1’ wu 1 wv tv 0 3 wd td 0 270 mteo glmt
and
MTEO id ’2’ nm ’windtak1’ci ’1’ wu 0 mteo
Where:
id
nm
ci

id of the wind definition
name of the wind definition
carrier id (= id of the branch)

SOBEK, User Manual

wind used
0 = no
1 = yes
wind velocity table
0 = constant
1 = table (f(time)) TBLE ...
column 1 = time
column 2 = wind velocity in m/s
wind direction table
0 = constant
1 = table (f(time)) TBLE ...
column 1 = time
column 2 = wind direction in degrees, North=0, East = 90, West=270

Run Time Data layer

This layer contains a number of different data elements for different modules. Files in this
layer

[Runtime Data layer]
NrOfFiles=18
flt=flowtim.dat
fln=flownum.dat
flm=flowmap.dat
flh=flowhis.dat
san=saltnum.dat
sam=saltmap.dat
sah=salthis.dat
sen=sednum.dat
sem=sedmap.dat
seh=sedhis.dat
mon=mornum.dat
mom=mormap.dat
moh=morhis.dat
wqt=wqtim.dat
wqn=wqnum.dat
wqm=wqmap.dat
wqh=wqhis.dat
pwq=prepwq.dat

In this case there are 5*4-3+1=18 files (4 files per module, FL, SA, SE, MO, WQ, but no file
with timeparameters for SA, SE and Mo, and an extra file for the link with WQ).
D.14.1

flh-file (SOBEK River) (run time data layer)

This file contains control parameters for the Flow History output.

FLHS it ITMS h\_ qt itms bi DLST ’1’ ’2’ dlst lc RLST 40 100 rlst
sl DLST ’0’ ’2’ dlst dl DLST ’0’ ’3’ dlst ts 1 flhs

List with History output items, between keywords ITMS and itms. The same
items as for the MAP output can be selected. Extra available items are (only for
structures):
gate height
crest height

SOBEK input file formats

cw
qs
bi
lc
sl
dl
ts
D.14.2

crest width
flow at structure
list with branch-id’s, between keywords DLST dlst
list with location on branch, between keywords RLST rlst
list with structure id’s, between keywords DLST dlst
list with lateral discharge id’s, between keywords DLST dlst
output-interval in number of time steps

flm-file (run time data layer)
This file contains information for the map output of the flow module. Map output is generated
for all locations.

List of map output items, between keywords ITMS itms.

In SOBEK River the following items can be chosen:
h
at
af
am
a1
a2
qt
qm
q1
q2
ct
cm
c1
c2
ff
fm
f1
f2
st
et
ts

FLMP it ITMS h\_ qt itms st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 10 flmp

water level
area total
area flow section
flow area main section
flow area floodplain1
flow area floodplain2
total discharge
discharge main section
discharge floodplain 1
discharge floodplain 2
total Chézy
Chézy main section
Chézy floodplain 1
Chézy floodplain 2
flow width section
flow width main section
flow width floodplain 1
flow width floodplain 2
start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of time steps)

fln-file (run time data layer)
This file contains numerical parameters for the flow module.
FLNMg_ 9.81 th 0.55 ps 0.5 rh 1000 ur 0.5 mi 50 sw 0.01 sd 0.1 cm 1 er 0 us 1
in 0.001 pc 1000 xn 50 sm 0.01 dt 1 flnm
Where:
g
th
ps

gravity acceleration (9.81 m/s2)
theta (default 0.55)
psi (default 0.5)

SOBEK, User Manual

rh
ur
mi
sw
sd
sr
cm

er
us
in
pc
xn
sm
dt
xr

rho (density of water; default 1000)
under relaxation (default 0.5)
max. number iterations (default 50)
stop criteria water level (default 0.01)
stop criteria discharge (default 0.1)
relative discharge stop criteria
calculation mode
0 = steady
1 = unsteady (default = unsteady)
continue after convergance
1 = no
0 = yes
extra resistance (default 0)
under relaxation structure (default 1)
increment numerical differences structures (default 0.001)
pseudo-Courant number (default 1000)
max. number of iteration nodal administration matrix (default 50)
stop criteria, used in solving the nodal administration matrix
transition height for summer dikes (default 1)
type extra resistance
0 = eta
1 = ksi

flt-file (run time data layer)

This file contains the time related parameters for flow module.
For River model:

FLTM bt ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ct ’00:10:00’ cd 0 fltm
For an estuary model:

FLTM bt ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ tp ’12:00:00’ tt 75 tf 1 nt 1 if 0 fltm
Where:
bt
et
ct
cd
tp
tt
tf
nt
if
ri

begin time
end time
computation time step (hh:mm:ss); only for river model
computation time step days; only for river model
tidal period: length of tidal period (hh:mm:ss, default 12 hour)
time tidal: number of time steps per tidal period (default 75)
tidal flow: number of tidal periods per flow period (default 1)
number of flow periods per morphology time (default 1)
number of initial flow periods (default 0)
restart interval (number of time steps) (0 = write information at the end of simulation)

SOBEK input file formats

lim-file (grid layer)
This file contains the segment boundaries for the WQ module.
SGLM id ’2’ nm ’Segmentlimit3’ ci 5 lc 180. st 2 sg 1 10 sglm
id
nm
ci
lc
st
sg

id of segment boundary
name of segment boundary
carrier id (branch id)
location
state 1 = ** 2 = **
list of id’s of the upper en lower segments

moh-file (run time data layer)

This file contains data for morphology History output:

MPHS it ITMS sd itms bi DLST ’1’ ’2’ dlst lc RLST 40 100 rlst mphs

List of map output items, between keywords ITMS itms.

Choice between:
lv
dz
ab
cr
da
sd
lc

bed level
increase of bed level
mean bed level of main channel
adapted cross sections
increase of cross-sectional area [m2]
integrated sediment transportbi=list with branch-id’s, between keywords DLST
dlst.
list with location on branch, between keywords RLST rlst. (gl=between DLST
en dlst: a list with grid points id’s; not yet implemented)

mom-file (run time data layer)

This file contains data for morphology map output.

MPMP it ITMS lv cr itms st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 1 mpmp
Where:
it

List of map output items, between keywords ITMS itms.

Choice between:
lv
dz
ab
cr
da
sd
st
et
ts

bed level
increase of bed level
mean bed level of main channel
adapted cross sections
increase of cross-sectional area [m2]
integrated sediment transport
start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of calculation time steps)

SOBEK, User Manual

pwq-file (run time data layer)
This file contains a parameter for the link between the flow module and the WQ module.
PRNM at 5 prnm
Where:
at

aggregation time step: indicates the number of time steps of the flow module
that equal one time step of the WQ module.

mon-file (run time data layer)

MPNM sf 1.01 me 0 mi 10 mpnm
Where:

stability factor
method of adapting cross sections
0 = equal over transport width
1 = proportional to local water depth
max. number of iterations

This file contains the numerical parameters for the morphology module.

sah-file (run time data layer)

This file contains data for the History output of the salt modules.

STHS it ITMS st sh itms bi DLST ’1’ ’2’ dlst lc RLST 40 100 rlst ts 1 sths
Where:
it
gl
bi
lc
ts
D.14.11

list with History output items, between keywords ITMS and itms.
between DLST and dlst: a list with grid point id’s
list with branch-id’s, between keywords DLST dlst
list with location on the branch, between keywords RLST rlst
report time step (in number of time steps)

sam-file (run time data layer)

This file contains the control data for the map output of the salt module.

STMP it ITMS st sh itms st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 1 stmp
Where:
it

list with selected output items, between keywords ITMS itms.

Available items are:
sa
dp
dn
st
et
ts

salt concentration
dispersion coefficient
density
start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of time steps)

SOBEK input file formats

san-file (run time data layer)
This file contains numerical parameters for the salt module.
STNM el 1000 fr 10 stnm
Where:
el
fr

estuary length
upper boundary Forester filter

seh-file (run time data layer)
This file contains data for the sediment history output.

SDHS it ITMS sd itms bi DLST ’1’ ’2’ dlst lc RLST 40 100 rlst ts 1 sdhs
Where:

bi
lc
ts
D.14.14

list with History output items, between keywords ITMS and itms. See SDMP
records.
list with branch-id’s, between keywords DLST dlst
list with location on branch, between keywords RLST rlst
report time step (in number of time steps)

sem-file (run time data layer)

This file contains data for the sediment map output.

SDMP it ITMS sd itms st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 10 sdmp
Where:
it

List of map output items, between keywords ITMS itms.

Choice between:
sd
lt
rt
ex
st
et
ts

sediment transport
sediment transport left channel (only for 2D morphology)
sediment transport right channel (only for 2D morphology)
sediment exchange van left naar right (only for 2D morphology)
start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of time steps)

SOBEK, User Manual

sen-file (run time data layer)
This file contains the numerical parameters for the sediment transport module.
SDNM kv 1e-006 rd 1.65 pk 0.4 al 0.2 rn 1 sdnm
Where:
kv
rd
pk
al

wqh-file (run time data layer)

kinematic viscosity
relative density
packing factor
alluvial layer factor
rn=reduction parameter for actual transport width

This file contains description of the 1DWAQ module history output.

Where:
st
et
ts
se
sb

WQHS st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 1 se DLST dlst sb TLST tlst wqhs

start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of time steps)
list of selected segments, between keywords DLST dlst
list of selected substances and process output items, between keywords TLST
tlst.

wqm-file (run time data layer)

This file contains the control parameters for the map output of the 1DWAQ module.
WQMP st ’1994/01/01;00:00:00’ et ’1994/02/01;12:00:00’ ts 1 sb TLST tlst wqmp
Where:
st
et
ts
sb
D.14.18

start time (yyyy/mm/dd;hh:mm:ss)
end time (yyyy/mm/dd;hh:mm:ss)
report time step (number of time steps)
list of selected substances, between keywords TLST tlst

wqn-file (run time data layer)

This file contains numerical parameters for the 1DWAQ module.
WQNM mn 1 sn 0 wqnm
Where:
mn

main integration option
.. = backward in space and time
.. = modified 2nd order Runge Kutta
.. = 2nd order Lax Wendroff
.. = alternating direction implicit
.. = Modified Flux Corrected Transport

SOBEK input file formats

.. = fully implicit integration in time
sub integration option

option 1:
.. = flows and dispersion as specified
.. = dispersion only if flow is not zero
.. = flows and dispersion as specified; no dispersion over open boundaries
.. = dispersion only if flow is not zero; no dispersion over open boundaries

wqt-file (run time data layer)

option 2:
.. = use flow concentration transport over open boundaries
.. = use higher order approximation

This file contains time parameters for the 1DWAQ module
WQTM ct ’01:00:00’ cd 0 wqtm

computation time step (hh:mm:ss)
computation time step days

Structure layer

Files in this layer

[Structure layer]
NrOfFiles=9
net=network.st
def=struct.def
dat=struct.dat
con=control.def
trg=trigger.def
sal=struct.sa
cmp=struct.cmp
cms=structcmp.sa
valve.tab
dbs=struct.dbs

cmp-file (structure layer)
(only SOBEK River)

This file contains de data of the compound structures.
STCM id ’1’ st DLST ’1’ ’2’ dlst stcm
Where:
id
st

id of the compound structure
list of structure id’s of all structures in the compound, between keywords DLST
dlst.

SOBEK, User Manual

cms-file (structure layer)
(only SOBEK River)
This file contains the information of the compound structures for salt calculations, and is not
necessary for calculations without the salt module or when no compound structures are being
used.
The file is identical to the ’sal’ file except for two differences:

the id is now the identifier of the compound structure (instead of a normal structure id)
there is no ’cm’

con-file (structure layer)

This file contains the definition of the controllers for the structures.
There are 6 types of controllers:

STCM id ’1’ sy 1 el 1 er 2 l1 3 l2 4 r1 5 r2 6 sl 1 sr 2 stcm

0 time controller
1 hydraulic controller
2 interval controller
3 PID controller
4 relative time controller (not in SOBEK Urban/Rural)
5 relative from value controller; not in SOBEK Urban/Rural)
0. time controller:
River Controller:

CNTL id ‘24’ nm ‘RivCntrl’ ct 0 ca 2 ac 1 cf 1 ta 1 1 0 0 gi
’2”3”-1”-1’ ao 1 1 1 1 mc 0.0046 ti tv PDIN 0 0 pdin
TBLE
’1999/01/02;04:20:00’ 0
’1999/01/02;04:28:00’ 0.57
’1999/01/02;13:14:00’ 0.57
’1999/01/02;13:17:00’ 0
’1999/01/02;17:01:00’ 0
tble cntl
Urban/Rural Controller:

CNTL id ‘60’ nm ‘UrbRur’ ct 0 ac 1 ca 2 cf 1 mc 0 bl 1 ti tv
TBLE
’2004/11/26;00:00:00’ 2.2
’2004/11/26;01:00:00’ 2.33
’2004/11/26;02:00:00’ 2.12
’2004/11/26;03:00:00’ 2.2
’1999/01/02;17:01:00’ 0
tble cntl
2D Breaking – Dam controller:

SOBEK input file formats

CNTL id ’##9’ nm ’2DdambrkContr’ ct 0 ca 5 ac 1 cf 1 ta 0 0 0 0 gi ’-1’ ’-1’ ’-1’ ’-1’ ao 1 1 1 1
mc 1110 ti tv PDIN 0 1 ’365;00:00:00’ pdin
TBLE
’2000/01/01;00:00:00’ 5 <
’2000/01/01;01:00:00’ 4 <
’2000/01/01;03:30:00’ 3 <
’2000/01/01;06:00:00’ 1 <
tble cntl
Where:

id of the controller definition
name of the controller definition
controller type
0 = time controller
controlled parameter
0 = crest level
1 = crest width; (not in Urban/Rural Controller)
2 = gate height
3 = pump capacity (SOBEK Urban/Rural; not implemented)
4=
5 =bottom level of 2D grid cell
controlled active yes/no
1 = active
0 = inactive
update frequency (number of timesteps)
trigger active (not in Urban/Rural Controller, 4 in River Controller)
0 = not active
1 = active
id of trigger description, -1 in case of non-active triggers (no triggers available
for Urban/Rural Controller, maximum of 4 triggers for a River Controller)
and(=1)/or(=0) relations when using more triggers (not in Urban/Rural Controller, maximum of 4 triggers for a River Controller)
Example: [tr1 AND tr2] OR [tr3 AND tr4];
The combined trigger comprising of the four individual triggers tr1, tr2, tr3 and
tr4 is evaluated as follows:
1) the combined trigger is “true” in case trigger tr1 is “true” and trigger tr2 is
“true”;
2) the combined trigger is “true” in case trigger tr3 is “true” and trigger tr4 is
“true”;
3) the combined trigger is “false” for all situations except for the ones described
under point 1) and 2) above.
dValue/dt, denotes max. change velocity in controlled structure parameter (always 0 for Urban/Rural Controller)
interpolation method table (only for Urban/Rural Controller)
0 = no interpolation, a block function
1 = linear interpolation
time table

PDIN . . . . pdin = Characteristics of Time controller table
1st : 0/1 = Lineair function/Block function
2st : 0/1 = No periodicity/Use periodicity of

SOBEK, User Manual

3st : periodicity in ddd;hh;mm;ss (only in case 2st =1)
TBLE . . . tble = Time controller table
Note :
For structure type 13 (SOBEK Urban/Rural 1D Dambreak Node, and for Formula 2 i.e:
td 2 = Verheij-vdKnaap (2002), the time table only has two rows
for example:

1. hydraulic controller:

River Controller:

TBLE
’2000/01/06;10:00:00’ 0 < (‘Start Time’ Opening area in sq.m)
’2000/01/06;11:00:00’ 44.9 < (‘Time to branch lowest Level’ Opening area in sq m)
tble

CNTL id ’P_1’ nm ’P_Amerongen’ ct 1 ca 0 ac 1 cf 1 ta 1 0 0 0 gi ’5’ ’-1’ ’-1’ ’-1’
ao 1 1 1 1 cp 1 mp 0 ml ’l_88’ ’61’ ’-1’ ’-1’ ’-1’ hc ht PDIN 0 0 pdin
TBLE
-999 5.71<
25 5.71 <
261 4.61<
504 3.48<
641 -1<
6000 -1<
tble cntl
Urban/Rural Controller:

CNTL id ‘60’ nm ’ExampleCntrl’ ct 1 ca 2 cf 1 ml ’l_88’ cp 1 bl 1 hc ht 1
TBLE
1 3.2<
2 4.2 <
2.5 4.45<
3 4.5<
tble cntl
Where:
id
nm
ta
gi
ao
ct
ac

id of the controller definition
name of the controller definition
trigger active (not in Urban/Rural Controller, 4 in River Controller)
id of trigger description (not in Urban/Rural Controller, 4 in River Controller)
and/or relations when using more triggers (not in Urban/Rural Controller, 4 in
River Controller)
controller type
1 = hydraulic controller
controller is active
1 = active

SOBEK input file formats

0 =not active
controlled parameter
0 = crest level
1 = crest width; (not in Urban/Rural Controller)
2 = gate height
3 = pump capacity (SOBEK Urban/Rural; not implemented)
control frequency (number of timesteps)
id of measurement node (5 locations in River Controller, at present 1 in
Urban/Rural Controller)
time lag between controlling parameter and controlled parameter
id of branch used for measuring (control branch)
(5 locations in River Controller, not in Urban/Rural Controller)
location (relative to beginning of branch) used for measuring (control location)
(5 locations in River Controller, not in Urban/Rural Controller)
type of measured parameter
0 = water level (on branch cb location cl)
1 = discharge (on branch cb location cl)
The following types of control parameters are available in River but not in Urban/Rural Controller:
2 = head difference (at a structure)
3 = velocity (on branch cb location cl)
4 = flow direction
5 = pressure difference
Interpolation method table (only SOBEK Urban/Rural)
0 = none (block function)
1 = linear
control table with relation between measured and controller parameter
column 1 = measured parameter or summons of measured parameters
column 2 = settings of the controlled parameter
branch location used (not in Urban/Rural Controller)
0 = no
1 = yes
whether the 5 possible branch locations are being used by the hydraulic controller; the table contains de value of the controlled parameter for the total of the
selected parameter. Note: this is sensitive to the branch direction.
structure id (only for controlling head difference or pressure difference; not in
Urban/Rural Controller)
positive stream (only for controlling flow direction: control parameter 4=stream
direction; not in Urban/Rural Controller)
negative stream (only when using control parameter 4=stream direction; not in
Urban/Rural Controller)

2. Interval controller:
River Controller:
CNTL id ’18066’ nm ‘Arjan’ ct 2 ca 1 ac 1 cf 1 ta 1 0 1 0 gi ’5’ ’-1’ ’4’ ’-1’ ao 1 1 1 1
cp 1 ml ‘89’ ui 1.5 ua 2.5 cn 1 cv 0.05 dt 1 pe 20 di 200 da 205 sp tc 1 PDIN 0 0 pdin
TBLE
‘1999/11/30;00:00:00’ 1.5
‘1999/11/30;01:00:00’ 1
‘1999/11/30;02:00:00’ 1.25
tble cntl

SOBEK, User Manual

Rural Controller:
CNTL id ’60’ nm ‘IntervCntrl’ ct 2 ac 1 ca 2 cf 1 ml ‘89’ cp 0 ui 3.2 ua 2.7 cn 1 du 0 cv 0.025
dt 0 d_0.05 bl 1 sp tc 0 1.23 0 cntl
Where:
id
nm
ta
gi
ao

id of the controller definition
name of the controller definition
trigger active (not in Urban/Rural Controller, 4 in River Controller)
id van trigger description (not in Urban/Rural Controller, 4 in River Controller)
and/or relations when using more triggers (not in Urban/Rural Controller, 4 in
River Controller)
controller type
2 = interval controller
controller is active
1 = active
0 =not active
controlled parameter
0 =crest level
1 =crest width; not in Urban/Rural Controller
2 =gate height
3 =pump capacity (Urban/Rural Controller)
control frequency (number of time steps)
id of branch used for measuring (control branch) (not in Urban/Rural Controller)
location (relative to beginning of branch) used for measuring (control location) )
(not in Urban/Rural Controller)
id of measurement node
type of measured parameter
0 = water level (on branch cb location cl)
1 = discharge (on branch cb location cl)
Us minimum
Us maximum
control interval type
0 = fixed interval
1 = variable
d(U) (fixed interval)
control velocity (variable interval)
dead band type
0 = fixed
1 = as percentage of the discharge (Not in Urban/Rural Controller)
dead band step size (fixed)
dead band percentage D (not in Urban/Rural Controller)
minimum dead band value (not in Urban/Rural Controller)
maximum dead band value (not in Urban/Rural Controller)
interpolation method table (only in Urban/Rural Controller)
0 = none (block function)
1 = linear
constant set point
table with set point varying in time:
column 1 = date/time stamp,
column 2 = set points of the controlled parameter

sp tc 0
sp tc 1

SOBEK input file formats

3. PID controller:
River Controller
CNTL id ’18067’ nm ’PIDCntrl’ ct 3 ca 0 ac 1 cf 1 ta 1 1 1 0 gi ’2’ ’7’ ’4’ ’-1’ ao 1 1 1 1 cp 0 ml
’116’ u0 1.5 ui 1 ua 2.5 va 0.5 pf 1.5 if 0.05 df 0.5 sp tc 0 1.5 0 cntl
Urban/Rural Controller

TBLE
’1999/11/30;00:00:00’ 1.25
’1999/11/30;01:00:00’ 1.25
’1999/11/30;02:00:00’ 1.75
tble cntl

id
nm
ta
gi
ao
ct
ac

CNTL id ’60’ nm ’PIDCntrl’ ct 3 ac 1 ca 2 cf 1 ml ’116’ cp 0 ui 0.7 ua 1.7 u0 1.25 pf 0.56 if 0.04
df 0.25 va 0.01 bl 1 sp tc 1

ui
ua
u0
pf
if
df

id of the controller definition
name of the controller definition
trigger active (not in Urban/Rural Controller, 4 in River Controller)
id van trigger description (not in Urban/Rural Controller, 4 in River Controller)
and/or relations when using more triggers (not in Urban/Rural Controller, 4 in
River Controller)
controller type
3 = PID controller
controller is active
1 = active
0 = not active
controlled parameter
0 = crest level
1 = crest width; (not in Urban/Rural Controller)
2 = gate height
3 = pump capacity (Urban/Rural Controller)
control frequency (number of time steps)
id of branch used for measuring (control branch) (not in Urban/Rural Controller)
Only one location can be used here, as opposed to the hydraulic controller,
where 5 locations can be entered.
control location (relative to the beginning of the branch) (not in Urban/Rural
Controller)
id of measurement node
type of measured parameter
0 = water level (on branch cb location cl)
1 = discharge (on branch cb location cl)
Us minimum
Us maximum
Us initial (not used, initial value is taken from structure definition)
K factor proportional
K factor Integral
K factor differential

SOBEK, User Manual

sp tc 0
sp tc 1

maximum speed of change (i.e. m/s for the crest of a movable weir)
interpolation method table (only Urban/Rural Controller)
0 = none (block function)
1 = linear
constant set point
table with set point varying in time:
column 1 = date/time stamp
column 2 = set points of the controlled parameter

4. ’relative time’ controller’/ 5. ’relative from value’ controller (only River Controller) is
the definition:
Relative Time Controller

CNTL id ‘P_0’ nm ‘P_Driel’ ct 4 ca 0 ac 1 cf 1 ta 0 1 0 0 gi ‘-1”3”-1”-1’ ao 1 1 1 1 mc 5 mp 0 ti
vv PDIN 0 0 pdin
TBLE
0 1.5
240 2
600 1.5
tble cntl
Relative from Value Controller

CNTL id ‘P_0’ nm ‘P_Driel’ ct 5 ca 0 ac 1 cf 1 ta 0 1 0 0 gi -1 3 -1 -1 ao 1 1 1 1 mc 5 mp 0 ti
vv PDIN 0 0 pdin
TBLE
0 1.5
240 2
600 1.5
tble cntl
Where:
id
nm
ta
gi
ao
ct

id of the controller definition
name of the controller definition
trigger active
id of the trigger description
and/or relations when using more triggers
Controller type
4 = relative time controller
5 = relative from value controller
controller active yes/ no
1 = active
0 =not active
controlled parameter
0 = crest level
1 = crest width
2 = gate height
control frequency (number of time steps)
max. change of dValue / dT
minimum period between two active periods of the time controller
table with set point varying in time:
column 1 = relative time

SOBEK input file formats

column 2 = set point of the controlled parameter
Note: Relative time stamps
In a River Controller, the relative time is indicated by the number of time steps. So when the
size of the time steps changes, the reaction speed of the controller will change as well.

dat-file (structure layer)

This file contains information about every structure in the network. This information consists
of a number of parameters of the structure and a reference to the description used for the
structure in the "def" file.

Note: Relative controllers
The ’relative time controller’ and the ’relative from value’ controller are derived from the time
controller. The time controller uses the absolute time while the relative time controller uses
the time from the moment the controller is active. This type of controller is used by BOSNieuwe Waterweg to control the sluices with a fixed procedure, but variable starting time.The
’relative from value controller’ uses the actual value of the controlled parameter from the
moment the controller is active. Thus, the relative time is not set to zero, but set to the value
found in the given table.

For Channel Flow, Sewer Flow and River Flow:
Urban/Rural structure:

STRU id ’59’ nm “ dd ’59’ ca 1 cj ’59’ stru
or

Single River Structure:

STRU id ’123’ nm “ dd ’17130’ df 1.5 ca 0 1 1 0 cj ’-1’ ’18070’ ‘P_1’ ‘-1’ cm 0 stru
or

River Structure which is member of Compound Structure:

STRU id ’105##1’ nm ‘Member01’ dd ’17129’ ca 1 0 0 0 cj ’18042’ ’-1’ ‘-1’ ‘-1’ cm 1 mo ‘105’
stru
Where:
id
nm
dd
ca

id of the structure
name of the structure
id of the structure definition (refers to the def-file)
indicates whether a controller is used (controller is active)
1 = active
0 = inactive
controller id’s
compound structure (Only in River Structure)
0 = the structure is not part of a compound structure
1 = the structure is part of a compound structure
member of compound structure (in case cm= 1) (Only in River Structure)
structure inertia damping factor

SOBEK, User Manual

if not present a default (setting) value will be used
Note: Controllers
In SOBEK Urban/Rural only one controller can be used for every structure; in SOBEK River
the maximum is 4; when less controllers are being used, the list of ’active controllers’ is filled
with 1 or more ’0’, and the list of controller id’s with 1 or more ’-1’.
For Overland Flow:
D2ST id ’49’ nm ’Houtrib2’ dd ’##4’ ou 0 ca 0 0 0 0 cj ’-1’ ’-1’ ’-1’ ’-1’ d2st
D2ST id ’56’ nm ’Houtrib1’ dd ’##3’ ou 1 ca 1 0 0 0 cj ’##5’ ’-1’ ’-1’ ’-1’ d2st

id of the structure
name of the structure
id of the “Decrease in Height Table” (refers to the struct.def file)
denotes if a “Decrease in Height Table” or a “Controller” is active
0 = Decrease in Height Table is active
1 = Controller is active
indicates if controllers are active, applicable only in case ou=1, max. four controllers
1 = active
0 = inactive
controller id’s
-1 = no controller is active
##5 = controller id (refers to the control.def file)

dbs-file (structure layer in SOBEK RE)

This file is only used in SOBEK-RE, see also the description of the definition of the Database
Structure in the structure Def-File.
This file contains the data bases of data base structures
STDS id ‘6’ db qt 5 TBLE .
0 1 2 3 4 5 6 7 8 9 < gate, h2/dh values.
1 0 -11 -12 -14 -15 U U U U < h1, Q-values
3 9 7 0 -11 -13 -16 U U U < h1, Q-values
5 15 12 11 5 0 -12 -15 -16 U < h1, Q-values
7 U U U 10 9 8 0 -7 -9 < h1, Q-values
9 U U U U 11 9 3 1 0 < h1, Q-values
tble
db fi 5 TBLE
59<
15<
16<
18<
49<
59<
tble
stds
id

identification of structure

SOBEK input file formats

table containing the data base.
table that defines the part of the data base that has been filled in by the user.

Description of data base table (db qt).

The data base table contains a number of matrices (in this release 1 matrix). Every matrix

def-file (structure layer)

This file contains general definitions of structures. The following types of structures are distinguished:
0
1
2
3
4
5
6
7
8
9
10
11
12
13
112

River weir (River module only)
River advanced weir (River module only)
General structure (River module only)
River pump (River module only)
Database structure(River module only)
Weir
Orifice
Pump
Culvert, Siphon and Inverse siphon
Universal weir
Bridge
Bbranch growth 1D Dam break node
Bbranch growth 2D Dam break node

corresponds to one gate value. The matrices in the table are in the order of increasing
gate heights. Instead of gate height also a crest level or crest width can be used.
The first row contains a gate height and then H2- or dH-values.
The next rows contain discharges, but the first column contains a H1-value.
Not all discharges need to be defined by the user. The remaining discharges are determined by an extrapolation process in the UI. In this example the extrapolated values are
identified by U.
The H1, H2 and dH-values must increase along rows and columns.

SOBEK River weir:

STDS id ’17130’ nm ’Weir’ ty 0 cl 1.5 cw 3 cs 0 po 1 ps 0.82 pt pr PDIN 0 0 “ pdin
TBLE
0.82 1.00
0.86 0.95
0.90 0.90
0.94 0.80
0.96 0.70
0.97 0.60
1.00 0.00
tble no 1 ns 0.82 nt nr PDIN 0 0 “pdin
TBLE
0.82 1.00
0.86 0.95
0.90 0.90
0.94 0.80
0.96 0.70

SOBEK, User Manual

0.97 0.60
1.00 0.00
tble stds
Where:

id of the structure definition
name of the structure definition
type structure (0=SOBEK weir)
crest level
crest shape
0 = broad
1 = triangular
2 = round
3 = sharp
crest width
correction coefficient for positive flow direction
submergence limit for positive direction
reduction table for positive flow direction
first column = (h2 - z) / (h1 - z)
second column = reduction factor for positive flow direction
correction coefficient for negative flow direction
first column = (h2 - z) / (h1 - z)
second column = reduction factor for negative flow direction
submergence limit for negative flow direction
reduction table for negative flow direction

SOBEK River advanced weir:

STDSid ’17131’ nm ’advanced Weir’ ty 1 cl 1.5 sw 5 ni 7
ph 10 nh 10 pw 3nw 3pp 0.01np 0.01 pa 0.1na 0.1
stds
Where:
id
nm
ty
cl
sw
ni
ph
nh
pw
nw
pp
np
pa
na

id of the structure definition
name of the structure definition
type structure (1] SOBEK advanced weir)
crest level
sill width
number of piers
upstream face height for positive flow direction
upstream face height for negative flow direction
(height of the weir relative to the bed level at the upstream side)
weir design head for positive flow direction
design head for negative flow direction
pier contraction coefficient for positive flow direction
pier contraction for negative flow direction
abutment contraction coefficient for positive flow direction
abutment contraction coefficient for negative flow direction

Note: ph, pw, pp and pa are coefficients for positive flow;
nh, nw, np and na are coefficients for negative flow.

SOBEK input file formats

SOBEK River general structure:
STDS id ’17129’ nm ’General’ ty 2
w1 75 wl 46.8 ws 46.8 wr 46.8 w2 75
z1 -6.5 zl -6.5 zs -6.5 zr -6.5 z2 -6.5 gh 20
pg 0.71 pd 0.64 pi 1 pr 0.8 pc 1
ng 0.71 nd 0.64 nf 1 nr 0.8 nc 1 er 1
stds
Where:

id of the structure definition
name of the structure definition
type of structure (2] SOBEK general structure)
w1: width upstream side of structure
wSdl: width structure upstream side
wS: width structure centre
wSdr: width structure downstream side
w2: width downstream side of structure
zb1: bed level upstream side of structure
zbSl: bed level upstream side structure
zbS: bed level at centre of structure
zbSr: bed level downstream side structure
zb2: bed level downstream side of structure
gate lower edge level
free gate flow in positive flow direction
drowned gate flow in positive flow direction
free weir flow in positive flow direction
drowned weir flow in positive flow direction
contraction coefficient for positive flow direction
free gate flow in negative flow direction
drowned gate flow in negative flow direction
free weir flow in negative flow direction
drowned weir flow in negative flow direction
contraction coefficient for negative flow direction
extra resistance
if not present a default (setting) value will be used

id
nm
ty
w1
wl
ws
wr
w2
z1
zl
zs
zr
z2
gh
pg
pd
pi
pr
pc
ng
nd
nf
nr
nc
er

SOBEK River pump:

STDSid ’17127’ nm ’Pomp Example’ ty 3 dn -1 rt cr 1 PDIN 0 0 pdin
TBLE
01
1 .8
2 .6
3 .2
tble ct lt 1 PDIN 0 0 “ pdin
TBLE
12 1.7 1.5 0 0
tble stds
Where:
id
nm

id of the structure definition
name of the structure definition

SOBEK, User Manual

type of structure (3] SOBEK River Pump)
control direction 1 = suction side control, pumps in positive branch direction.
-1 = suction side control, pumps in negative branch direction.
2 = delivery side control, pumps in positive branch direction.
-2 = delivery side control, pumps in negative branch direction.
reduction table for the pump capacity, as a function of the water level difference.
first column = level difference,
second column = reduction factor
constant
table
(one row) table with pump capacity and start and stop levels.
The first item is the pump capacity, the second and the third item are the start
and stop levels at the suction side of the pump and the
fourth and the fifth item are the start and stop levels at the delivery side of the
pump.

rt cr 0
rt cr 1
ct lt

SOBEK-River Database structure:

The Database Structure consists of a set of one STDS-record and a MATR-record:
STDS id ’##3’ nm ’DB-Struc Example’ ty 4 cl 2.34 di 0 dm 1 d2 0stds
MATR id ‘##3’ db qt 5
TBLE
0 0 .5 1 2 3
0 0 -150.77 -212.77 -300.77 -335.77
.5 150.77 0 -150.77 -259.77 -335.77
1 212.77 150.77 -212.77 0 -300.77
2 300.77 259.77 212.77 0 -212.77
3 335.77 335.77 300.77 212.77 0
tble
db fi 5
TBLE
55
14
15
15
15
25
tble matr
Where in the STDS record:
id
nm
ty
cl
di

id of the structure definition
name of the structure definition
type of structure (4] databse structure)
crest level or reference level for values h1, h2 in database
interpolation type
0 = linear
1 = spline
third dimension of data base i.e. number of gate values. In this release 1.
value at second axis
0 : h2
1 : dh = h1 - h2
and where in the MATR record:

SOBEK input file formats

identification of structure
table containing the data base
table that defines the part of the data base that has been filled in by the user.

Description of data base table (db qt).

The data base table contains a number of matrices (in this release 1 matrix). Every matrix

corresponds to one gate value. The matrices in the table are in the order of increasing
gate heights. Instead of gate height also a crest level or crest width can be used.
The first row contains a gate height and then H2- or dH-values.
The next rows contain discharges, but the first column contains a H1-value.
Not all discharges need to be defined by the user. The remaining discharges are determined by an extrapolation process in the UI. In this example the extrapolated values are
identified by U.
The H1, H2 and dH-values must increase along rows and columns.

Note:
In SOBEK-RE the data in the MATR-record is written as an STDS-record with the same format
in a separate file, thd dbs-file.
SOBEK Urban/Rural weir:

STDS id ’S003’ nm ’stuw3’ ty 6 cl -1.5 cw 2.5 ce 1 sc 1 rt 0 stds
Where:
id
nm
ty
cl
cw
ce
sc
rt

id of the structure definition
name of the structure definition
type of structure (6] SOBEK Urban/Rural weir)
crest level
crest width (-1 : look at profile)
discharge coefficient (depends on crest shape)
lateral contraction coefficient
possible flow direction (relative to the branchdirection):
0 : flow in both directions
1 : flow from begin node to end node (positive)
2 : flow from end node to begin node (negative)
3 : no flow

SOBEK Urban/Rural orifice:

STDS id ’S003’ nm ’test onderlaat’ ty 7 cl -2.0 cw 1.0 gh 0.5 mu 0.63 sc 1 rt 0 mp 1 0.96 mn
0 0 stds
Where:
id
nm
ty
cl
cw
gh
mu
sc
rt

id of the structure definition
name of the structure definition
type of structure (7 ] SOBEK Urban/Rural orifice)
crest level
crest width
gate height
contraction coefficient
lateral contraction coefficient
possible flow direction (relative to the branch direction):

SOBEK, User Manual

0 : flow in both directions
1 : flow from begin node to end node (positive)
2 : flow from end node to begin node (negative)
3 : no flow
maximum flow in positive direction
mp , where switch
0 : do not use
1 : use max. flow
maximum flow in negative direction
mp , where switch
0 : do not use
1 : use max. flow

Where:
id
nm
ty
dn

STDS id ’4’ nm ’Pomp 4’ ty 9 dn 2 rt cr 1
TBLE
2 0.5 <
5 0.7 <
8 0.9 <
tble ct lt 1
TBLE10 0.05 -0.20 0.05 1.50 <
10 0.10 -0.10 0.10 1.25 <
5 0.20 -0.05 0.20 1.00 <
tble stds

SOBEK Urban/Rural pump:

id of the pomp definition
name of the pomp definition
type of structure (9 = pump)
flow direction/ control
1 = upward control
2 = downward control
3 = downward + upward control
-1, -2, -3 : same as positive, but flow direction opposite to branch direction. Or,
in the case of a lateral structure, for an extraction of water.
rt cr 1
reduction function of the water level difference, in a table
column 1 = water level difference (suction side - pressure side)
column 2 = reduction factor for capacity
rt cr 0 1 0 constant reduction factor (in this case, the reduction factor is 1).
ct lt 1
Table with 5 columns.
column 1 = extra capacity;
column 2 and 3 =start- en stop level for suction side
column 4 and 5 =start- en stop level for pressure side
SOBEK Urban/Rural Culvert, Siphon and Inverted Siphon:
STDS id ’culvert1’ nm ’culvert’ ty 10 tc 1 ll -2.0 rl -1.0 si ’Crdef’ li 0.63 lo 0.63 lb 0 ov -2.2 tv 1
‘Table1’ rt 0 dl 10.0 hs 7.6 he 8.8 stds
Where:
ty

type of structure
10 = culvert or siphon or inverted siphon

SOBEK input file formats

rl
ll
si
li
lo
lb
ov
tv

type of culvert
1 = culvert
2 = siphon
3 = inverted siphon
bed level (right)
bed level (left)
id of cross section definition (profile.def), only closed profiles
inlet loss coefficient
outlet loss coefficient
bend loss coefficient
initial opening level of valve
table of loss coefficient
0 no table, no valve
1 valve present, reference to table in file valve.tab. See detailed decription of
this file below.
possible flow direction (relative to the branch direction):
0 : flow in both directions
1 : flow from begin node to end node (positive)
2 : flow from end node to begin node (negative)
3 : no flow
length of culvert, siphon or inverted siphon
start level of operation of siphon
end level of operation of siphon

SOBEK Urban/Rural Universal weir:

STDS id ’weir1’ nm ’UniversalWeir’ ty 11 cl 1.5 si ’trapezium1’ ce 1.0 sv 0.667 rt 0 stds
where:
ty
cl
si
ce
sv
rt

type of structure
11 = Universal Weir
crest level
id of cross section definition (profile.def), only YZ Table Profile and Asymmetrical Trapezium Profile
coefficient in discharge formulation
water level based modular limit for rectangular sections, default 0.667 not to be
edited
possible flow direction (relative to the branch direction):
0 : flow in both directions
1 : flow from begin node to end node (positive)
2 : flow from end node to begin node (negative)
3 : no flow

SOBEK Urban/Rural Bridge:
STDS id ’bridge1’ nm ’bridge’ ty 12 tb 2 si ’trapezium1’ pw 0.5 vf 1.15 li 0.63 lo 0.63 dl 10.0 rl
-1.0 stds
where:
ty
tb

type of structure
12 = bridge
type of bridge
2 = pillar bridge

SOBEK, User Manual

3 = abutment bridge
4 = fixed bed bridge
5 = soil bed bridge
id of cross section definition (profile.def), only open profiles (if tb = 3,4, or 5)
total width of pillars in direction of flow (if tb] 2)
shape factor (if tb] 2)
inlet loss coefficient
outlet loss coefficient
length of bridge in flow direction.
bottom level

si
pw
vf
li
lo
dl
rl

SOBEK Urban/Rural 1D Dam break node:

STDS id ’dambreak’ nm ’Sobekdambreak’ ty 13 cl 1.5 cs 1 cw 10 ml -0.5
stds
where:

id of the structure definition
name of the structure definition
structure type (13] SOBEK dambreak)
crest level ] Initial top level w.r.t. reference level [m]
crest shape
0 = broad crest (default)
crest width - initial width/gap [m]
minimum level w.r.t. reference level [m]
type of dambreak-formula
1 = vdKnaap (2000) [default for backward compatibility]
2 = Verheij-vdKnaap(2002)
3 = ... not defined yet
flag for using once hydraulic trigger i.s.o. start date/time
0 = use start date/time [default for backward compatibility]
1 = use once hydraulic trigger
alpha constant for Verheij-vdKnaap(2002) (note: it is f1] F + one)
beta constant for Verheij-vdKnaap(2002)
critical flow velocity sediment/soil [m/sec] for Verheij-vdKnaap(2002)
coefficient of discharge (not used)
possible flow direction (relative to the branch direction):
0 : flow in both directions (default and only possible value)

The following parameters are only used to generate the controller table
eq 0
eq 1
ts
dt
ec

sand for vdKnaap (2000) formula (if type of dambreak formula = vdKnaap; thus
td = 1)
clay for vdKnaap (2000) i.e td = 1 (if type of dambreak formula = vdKnaap; thus
td = 1)
time start in ’yyyy/mm/dd;hh:mm:ss’
elasped time after the time start to branch lowest level ml in ’dd:hh:mm:ss’
maximum bbranch width in m - for vdKnaap (2000)
0 200 = constant width of 200 m

Initial top level w.r.t. reference level [m] - maximum initial opening depth [m] = minimum level
w.r.t. reference level [m]
SOBEK Urban/Rural 2D Dam break node:

SOBEK input file formats

D2SD id ’dam’ nm ’breakstruct’ ty 112 t0 0.0 t1 4.0 dh lt 1
TBLE .... tble
d2sd
where:

net-file (structure layer)

id
id of the structure definition
nm
name of the structure definition
ty
structure type (112 ] 2D Dam break node)
t0
start time in hours from start of simulation
t1
end time (not if if table) in hours
dh lt 1
decrease in height with time - table with time in hours and height decrease in m
dh lt 0 10.0 constant value - linear decrease in height m start at start time
wg 0 0
width growth at rate of 5% of grid size *** not yet implemented
wq 1 0.6 width growth at rate specified in m/sec *** not yet implemented
wd 0 0
no increase in width growth with time (assumed total grid size at beginning of
break) *** not yet implemented
wd 10.5 = increase in width with time in m till grid size *** not yet implemented

This file contains information about the placement of structures in the network. For every
place in the network that contains a structure, there is a definition:
For Channel Flow, Sewer Flow and River Flow:
STRU id ’S003’ nm ’Sluis3’ ci ’5’ lc 5007.6 stru
or

STCM id ’1’ nm ’compound23’ ci ’3’ lc 100 stcm
where:
id
nm
ci
lc

id of the structure
name of the structure
id of the branch (carrier id)
position relative to the beginning of the branch

In SOBEK Rural, the keyword STRU is used. For compound structures in SOBEK River, the
keyword STCM is used.
For Overland Flow:

D2ST id ’7’ nm ’ ’ ci ’-1’ lc 0 px 106075.3 py 458695.3 d2st
where:
id
nm
ci
lc
px
py

id of the structure
name of the structure
id of the branch (carrier id)
position relative to the beginning of the branch (always 0)
X coordinate within 2D grid
Y coordinate within 2D grid

SOBEK, User Manual

sal-file (structure layer)
(only SOBEK River)
This file contains the data for salt calculations using single (non-compound) structures, and
is not necessary for calculations without the salt module. The information for the compound
structures is contained in another file, structcmp.sa.
STRU id sy 1 el 1 er 2 l1 3 l2 4 r1 5 r2 6 sl 1 sr 2 cm 0 stru
Where:

el
er
l1
l2
r1
r2
sl
sr
cm

structure id
type of salt modelling (salt type)
0 = equal salt concentrations on both sides of the structure
1 = different, complex formulation
2 = different, simple formulation
effective length Left (if sy=1)
effective length Right (if sy=1)
gamma1Left (if sy=1)
gamma2Left (if sy=1)
gamma1Right (if sy=1)
gamma2Right (if sy=1)
gammaSLeft (if sy=2)
gammaSRight (if sy=2)
compound structure:
0=structure is not part of a compound structure
1=structure is part of a compound structure

trg-file (structure layer)
Only in SOBEK River.

This file contains the definition of the triggers.
A trigger can be defined as:
Time Trigger:

TRGR id ’##12’ nm ’TimTrig’ ty 0 t1 0 tp 0 tt tr PDIN 1 0 pdin
TBLE
’1986/07/04;00:00:00’ 0 0 0 0 <
’1986/07/04;01:00:00’ 1 0 0 0 <
’1986/07/04;02:00:00’ 0 0 0 0 <
’1986/07/04;03:00:00’ 1 0 0 0 <
’1986/07/04;04:00:00’ 0 0 0 0 <
tble trgr
or
Hydraulic Trigger:

TRGR id ’##14’ nm ’HydTrig2’ ty 1 t1 0 tp 4 ts ’12’ ch 0 tt tr PDIN 1 0 pdin
TBLE
’1988/08/11;01:00:00’ 0 0 1 4.5 <

SOBEK input file formats

’1988/08/11;02:00:00’ 0 0 0 5 <
’1988/08/11;03:00:00’ 0 0 0 4.5 <
tble trgr
or
Combined Trigger:

id of the trigger
name of the trigger
trigger type
0 = time
1 = hydraulic
2 = combined (both time and hydraulic)
once trigger
0 = normal trigger (default)
1 = once trigger (only possible for hydraulic trigger)
trigger parameter (for hydraulic /combined triggers only)
0 = water level at branch location
1 = head difference over structure
2 = discharge at branch location
3 = gate lower edge level of structure
4 = crest level of structure
5 = crest width of structure
6 = waterlevel in retention area
7 = pressure difference over structure

TRGR id ’##15’ nm ’CombiTrig’ ty 2 t1 0 tp 0 ml ’61’ tt tr PDIN 1 0 pdin
TBLE
’1991/04/06;00:00:00’ 1 1 0 2 <
’1991/04/06;01:00:00’ 1 0 1 5 <
’1991/04/06;02:00:00’ 0 1 0 3.3 <
’1991/04/06;03:00:00’ 1 0 1 4.5 <
’1991/04/06;04:00:00’ 0 1 0 3.55 <
tble trgr

Note:
These number differ from the ones used in the Nefis file, which uses 1,2,3,4,5,6,7,8.
A trigger refers to exactly 1 location (branch-location or structure)
ml
ts
ch

measurement station id
structure id (for hydraulic/combined triggers only)
check on (only relevant if trigger parameter=3,4,5)
0 = value (default)
1 = direction
trigger table containing 5 columns:
column 1 = time (all types of triggers, including the hydraulic trigger; in this case,
the setpoint can de defined in time)
column 2 = on/off (for time trigger and combined trigger),
column 3 = and/or (for combined trigger),
column 4 = operation (hydraulic trigger: < or >)
column 5 = trigger parameter (for hydraulic and combined trigger)

SOBEK, User Manual

Valve.tab (structure layer)

Where:
nm
lt lc
D.16

VLVE id ’Table1’ nm ’Valve for culvert’ lt lc
TBLE
0 2.1 <
0.1 1.96 <
0.2 1.80 <
0.3 1.74 <
0.4 1.71 <
0.5 1.71 <
0.6 1.71 <
0.7 1.64 <
0.8 1.51 <
0.9 1.36 <
1.0 1.19 <
tble
vlve

Table for loss coefficients of valve. Each table refers to valves which is set in different position
with relation to the structure. (for example before the culvert, within the culvert, etc. etc.)

name of the table which specifies the position of valve with relation to the structure
table for opening height of valve in percentage versus loss coefficient

Substance layer

This layer is different from the other layers. Firstly, there is no field id or nm starting a record.
Secondly, all processes are stored in one record and not in one record per process.
Files in this layer

[Substance layer]
NrOfFiles=1
sub=substanc.def

sub-file (substance layer)
sub=substanc.def

This file contains information about (i) the list of substances for SOBEK WQ, (ii) active processes for SOBEK WQ, (iii) constants for SOBEK WQ and (iv) list of output variables for
SOBEK WQ.
SBST id ’cTR1’
md 1
nm ’Conservative tracer 1’
un ’mg/l’
as 1
sp 0
ct 0.1
ou 1
sbst

SOBEK input file formats

id (Character)
type of list (Integer)
1 = substance
2 = constant
3 = active process
0 = output for SOBEK WQ yes/no
name (only relevant when md=1)
unit (only relevant when md=1)
(only relevant as md=1)
1 = active substance
0 = inactive substance
constant (only relevant when md=2)
constant (only relevant when md=2)
(relevant for all values of md)
1 = write as output
0 = don’t write as output

The type table indication: (general)
0 = constant

1 = table as function of the time

2 = table as function of the location on the branch

3 = table as function of h for more locations on a branch, distances in CLTT
4 = table as function of Q for more locations on a branch, distances in CLTT
The name of the table (generated by the UI) (Optional)
The period and interpolation method:

PDIN
0 0 ” =interpolation continuous, no periodicity
1 0 ” =interpolation block, no periodicity
1 1 ’1;00:00:00’=interpolation block, periodicity on, defined as "d;hh:mm:ss", so in this example 1 day
0 1 ’365;00:00:00’=interpolation continuous, periodicity on, so in this example 1 year
pdin
The header per column between quotes
CLTT ’kop1’ ’kop2’ cltt
The labels id
CLID ’null’ ’null’ clid
The table

SOBEK, User Manual

Every record is separated with < sign. In case of an array with 1 column, 1 number per
record; in case of an arry with 2 columns, 2 numbers,.........
TBLE

<
<
tble
Example of bed-friction as function of water level at one location for flow- and reverse-flow
direction:

BDFR id ’33’ nm ’(null)’ ci ’31’ em 0 er 0 e1 0 e2 0 e3 0 e4 0 mf 0 mt fh 3 50 9.9999e+009
’Chézy Coefficient Waterlevel’ PDIN 0 0 ” pdin CLTT ’H’ ’603.5’ cltt CLID ’(null)’ ’(null)’ clid
TBLE
-0.5 52.79 <
0 49.69 <
0.5 48.98 <
1 53.66 <
1.5 56.96 <
2 65.4 <
2.5 63.92 <
3 62.03 <
3.5 59.89 <
4 59.02 <
4.5 59.97 <
5 59.68 <
tble
mr fh 3 50 9.9999e+009 ’Chézy Coefficient Waterlevel’ PDIN 0 0 ” pdin CLTT ’H’ ’603.5’ cltt
CLID ’(null)’ ’(null)’ clid
TBLE
0 53.13 <
0.5 49.9 <
1 49.3 <
tble
s1 0 c1 cp 0 35 9.9999e+009 r1 cp 0 35 9.9999e+009 s2 6 c2 cp 0 9.9999e+009 9.9999e+009
r2 cp 0 9.9999e+009 9.9999e+009 d9 f9 0 9.9999e+009 9.9999e+009 bdfr
Tables in network layer
Example:

’GridPoint Table’ PDIN 0 0 ” pdin CLTT ’Location’ ’1/R’ cltt CLID ” ” clid
TBLE
0 0 ” ’2’ ’2’ <
298.250949765087 0 ’2’ ’287_1’ ’3’ <
596.501899530173 0 ’4’ ’287_2’ ’7’ <
894.75284929526 0 ’7’ ’287_3’ ’5’ <
1193.00379906035 0 ’5’ ’287_4’ ’8’ <
1491.25474882543 0 ’8’ ’287_5’ ’6’ <
1789.50569859052 0 ’6’ ’287_6’ ’287_8’ <
2087.75664835561 0 ’287_8’ ’287_7’ ’287_9’ <
2386.00759812069 0 ’287_9’ ’287_8’ ’287_10’ <
2684.25854788578 0 ’287_10’ ’287_9’ ’287_11’ <

SOBEK input file formats

2982.50949765087 0 ’287_12’ ’1_30’ ” <
tble grid
D.17

Topography layer

[Topography layer]
NrOfFiles=6
net=network.tp
cpt=network.cp
nfl=network.fl
nsa=network.sa
nsm=network.sm
dat=nodes.dat

cpt-file (topography layer)

Files in this layer:

This file contains the data for the wind curving points for every branch. It contains information
about the direction of parts of the branch relative to the north; this information is necessary
for the calculation of the wind friction.
BRCH id ’1’ cp 1 ct bc Note: Fixed order
TBLE ....
tble
brch
Where:
id
cp
ct bc

branch id,
number of curving points
curving point table
TBLE ... tble = Table with ’curving points:
column 1 = location on the branch in meters
column 2 = angle (0 = north, 90= east)

dat-file (topography layer)

This file contains data for the modelling of different kinds of storage for nodes in sewer calculations and for the specification of interpolation of cross-section bathymetry over the node
along two branches.
Node with storage:

NODE id ’1’ ty 0 ws 1.0 ss 100.0 wl -4.05 ml -1.0 node
Where:
id
ty

node id
type water on street
1 = reservoir
2 = closed
3 = loss
storage area (manhole)
street storage area

SOBEK, User Manual

bed level storage reservoir (manhole)
street level

Where:
ct sw TBLE .. tble = table for storage in well
ct ss TBLE .. tble = table for storage at street

PDIN 1 0 ’ ’ pdin = block function
PDIN 0 0 ’ ’ pdin = linear interpolation

NODE id ’0-62’ ty 1 ct sw PDIN 1 0 ’ ’ pdin
TBLE
16.28 2 <
20.84 2 <
tble ct ss PDIN 0 0 ’ ’ pdin
TBLE
20.85100 <
21.9150 <
tble
node

Interpolation of cross-section bathymetry over the node along specified branches:
NODE id ’ND-4’ ty 0 ni 1 r1 ’rch-1’ r2 ’rch-2’ node
Where:
id
ty
ni

node id
Node type, always 0, interpolation only for Connection Node
interpolation over Node
1 = On
0 = Off (default, also if record not present)
branch id
branch id, r1 and r2 cannot be the same. In case of ni = 0, r1 and r2 are ignored.

net-file (topography layer)

This file contains the date for the topography: the definitions and positions of the nodes and
branches.
The node definition:

NODE id ’1’ nm ’Node1’ px 11404.2 py 123768.5 nodeNote: Fixed order
Where:
id
nm
px
py

node id
name of the node
position X (X coordinate)
position Y (Y coordinate)

The branch definition:
BRCH id ’1’ nm ’Tak1’ bn ’1’ en ’2’ al ’1233.4’ brchNote: Fixed order

SOBEK input file formats

Where:
id
nm
bn
en
al

branch id
branch name
id begin node
id end node
actual length

Linkage nodes are described in NDLK records. A linkage node is handled as a normal calculation at the actual branch. The linkage node can be used as a start or end connection node
for another branch. For the actual branch, this linkage node should also be decribed in the
grid layer, at the same position at the branch.
NDLK id ’125’ ci ’RIV_350’ lc 25261.4 ndlk

nfl-file (topography layer)

id of linkage node
branch id, where the linkage node is handled as calculation point
location at the branch

This file contains the information for the ’dry bed procedure’ in the flow module of SOBEK
River (NOT for SOBEK Urban/Rural). The data is necessary for each branch.
BRCH id ’1’ db 1 th 0.01 sh 10.0 brch
Where:
id
db
th
sh
D.17.5

branch id,
dry bed procedure active (1) or not (0)
threshold
slot depth (depth Preismann)

nsa-file (topography layer)

This file contains extra data for the boundary-nodes in a estuarium-model, necessary for the
salt module. Only SOBEK River, NOT for SOBEK Urban/Rural.
NODE id ’1’ mt 0 node
Where:
id
mt

node id
mouth
0 = boundary node does not have estuarium mouth
1 = boundary node does have estuarium mouth

This information is necessary for the choice of the formulation of the dispersion, when the
Thatcher-Harleman of the ’user defined’ option have been chosen. See dispersion layer for
more information.

SOBEK, User Manual

nsm-file (topography layer)
This file contains the extra information necessary for the sediment/morphology module of
SOBEK. Only SOBEK-River, NOT for SOBEK Urban/Rural.
BRCH id ’1’ sd 0 fl 1 ft fl
TBLE
....
tble
rf 0 brch
Where:
branch id
sedredge option
0 = no 2D morphology on this branch (default)
1 = 2D morphology on this branch
fixed layer (1=active, 0=not active)
fixed layer table (between keywords TBLE en tble)

The first column in the table contains the locations along the branch and the second column
contains the layer.
reduction function
0 = sinus
1 = linear

Transport formula layer

The descriptions of this layer are defined either globally or for a branch (linked to branch-id’s).
Files in this layer

[Transport layer]
NrOfFiles=1
dat=transprt.dat

dat-file (transport formula layer)

This file contains the parameters of the transport formulas used. It is only necessary when
the sediment/ morphology modules are used. A transport formula can be defined for every
branch. GLTR gltr and a carrier id of -1 indicate a global definition.
TRNS id ’1’ nm ’trans1’ ci ’3’ ty 0 mu 1 e1 0.4 e2 0.1 e3 0.5 e4 0.3 e5 0.1 e6 0.01 e7 1 trns
or
TRNS id ’3’ nm ’trans2’ ci ’1’ ty 5 mu au bu gu tc rf trns
or
GLTR TRNS id ’2’ nm ’globaltrans’ ci ’-1’ ty 1 mu 1.1 trns gltr
Where:

SOBEK input file formats

mu
au
bu
gu
tc
rf

id transport
name
carrier id (branch id, -1 for a global definition)
type of transport formula
0 = Engelund/Hansen
1 = Meyer-Peter/Muller
2 = Ackers/White
3 = van Rijn
4 = Parker/Klingemann
5 = User formula
multiplication
alpha_u (only for type 5: user formula)
beta_u (only for type 5: user formula)
gamma (only for type 5: user formula)
theta_c (only for type 5: user formula)
ripple factor (only for type 5: user formula)
0 = calculated by the model, (calculate)
1 = to be defined by user (define)
value ripple factor (only for type 5, with switch rf=1)
7 extra parameters, only when using 2D morphology

RR (Rainfall Runoff)
Introduction

This document describes the model database (MDB) of Sobek-RR available in SOBEK version 2.08 and higher.
RR datafiles
Control layer

Ini file (Delft_3B.Ini)
Topography layer

node file (3b_nod.tp)
link file (3b_link.tp)
runoff file (3b_runoff.tp)
Paved area layer

data file (paved.3b)
storage definition file (paved.sto)
dry weather flow file (paved.dwa)
table file (paved.tbl)

Unpaved area layer

data file (unpaved.3b)
storage definition file (unpaved.sto)
alfa definition file (unpaved.alf)
infiltration definition file (unpaved.inf)
seepage definition file (unpaved.sep)

SOBEK, User Manual

table file (unpaved.tbl)
Greenhouse layer

data file (greenhse.3b)
roof storage file (greenhse.rf)
silo definition file (greenhse.sil)
Open water layer

Structure layer
data file (struct3b.dat)
definition file (struct3b.def)
controller file (contr3b.def)
table file (struct3b.tbl)

data file (openwate.3b)
seepage definition file (openwate.sep)
table file (openwate.tbl)

data file (bound3b.3b)
table file (bound3b.tbl)
NWRW layer

data file (pluvius.3b)
dry weather flow file (pluvius.dwa)
general data (pluvius.alg)
table file (pluvius.tbl)

data file (wwtp.3b)
table file (wwtp.tbl)
Industry layer

data file (industry.3b)
table file (industry.tbl)
Sacramento layer

data file (sacrmnto.3b)
capacities and contents definition file (sacrmnto.cap)
unit hydrograph definition file (sacrmnto.uh)
other data file (sacrmnto.oth)

Meteo and fixed files

storage coefficients soil types <..\..\fixed\bergcoef>
crop factors agricultural crops <..\..\fixed\cropfact>

SOBEK input file formats

Capsim soil types <..\..\fixed\bergcoef.cap>
Capsim rootzone data <..\..\fixed\root_sim.inp>
Capsim unsaturated zone data <..\..\fixed\unsa_sim.inp>
greenhouse class file <..\..\fixed\kasklasse>
greenhouse initialisation file <..\..\fixed\kasinit>
greenhouse water use file <..\..\fixed\kasgebr>
crop factors open water <..\..\fixed\crop_ow>
rainfall file (1 or more events)
evaporation file
Default defition file <..\fixed\3bEdit.def>
Optional: New format greenhouse class file <..\fixed\3B\NewKasKlasData.dat>
Optional: New format greenhouse initialisation file <..\fixed\3B\NewKasInitData.dat>
Optional: New format greenhouse water use file <..\fixed\3B\NewKasGebrData.dat>
Optional: New format crop data <..\fixed\3B\NewCropData.dat>
Optional: New format open water crop factor data <..\fixed\3B\NewCropOWData.dat>
Optional: New format soil data <..\fixed\3B\NewSoilData.dat>

The files of the Topography layer are generated by the SOBEK Network Editor (Netter). The
other files are generated by other user interface programs like Settings, ModelEdit and Meteo,
or generated using a conversion tool. At the moment, there are conversion tools to convert
SUF-HYD files (Dutch standard files for sewer systems) and Diwa-Hydra files (an old Dutch
stationary open channel flow model). In the conversion of SUF-HYD files, the SOBEK-RR
input files for the NWRW layer are automatically generated.
Boundary layer

Data file: Bound3B.3B

This file contains the data for the nodes of model type 6 (boundary)
BOUN id ’1’ bl 0 -0.5 is 100. boun
With
id
bl

node identification
boundary level type
bl 0 0.5 = fixed boundary level, of 0.5 m NAP
bl 1 ’bound_1’ = variable boundary level with table identification ‘bound_1’
(data in Bound3B.Tbl file)
bl 2 ’3’ = variable boundary level, with on-line coupling SOBEK.
Data taken from id ‘3’ in the SOBEK-HIS-file.
initial salt concentration (mg/l)

Boundary table file: Bound3b.Tbl
Boundary water levels and salt concentrations as a function of time, in case of option 1. Data
is known before the simulation starts.
BN_T id ’bnd_level’ nm ’IJsselmeer’ PDIN 1 0 ’ ’ pdin
TBLE
1997/01/01;00:00:00 -1.5 200<
1997/05/01;00;00;00 -1.45 220<
1997/10/01;00:00:00 -1.50 200<
tble

SOBEK, User Manual

bn_t
With
id
nm

table identification
name of table
PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period
0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss
1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss

Control layer
Ini file: DELFT_3B.Ini

TBLE .. tble contains the table, first column is the date (year month day hour minute second),
the second column contains the boundary level in meters w.r.t. reference level (NAP), and the
third column contains the salt concentration (only used if salt computation option is switched
on).

This file is set-up with a Windows INI type of filestructure. If records are not present, defaults
will be used.
[System]
CaseName= Test
DebugFile=0
DebugTime=1 1
DebugTime2=900 905
DebugTimeCapsim=0 0
Version=2.04
SkipBinfile=-1
! In 2.07 Altijd =-1;
! In 2.05 en 2.06 optioneel inlezen van data uit ASCII ipv Bin file.
CaseSensitive=-1
! -1=yes; 0=no. Default -1. (ARS 4988)
TimeMessage=-1
! -1=yes.Default 0=no. Shows time on screen after reading input
! data and just before starting actual calculations, and immediately
! after finishing actual calculations
[OutputOptions]
OutputTimestep=1
*1=yes, 0=no;
OutputEvent=1
*1=yes,0=no
OutputOverall=1
* not used?
OutputDetail=47
*number event
OutputScreen=0
*1=yes, 0=no
OutputOpenwater=1
*1=output w.r.t. NAP, 0=w.r.t. referemce level
OutputGroundwater=1
*1=w.r.t. NAP, 0=w.r.t. surface level
OutputBoundary=2
*0=no, 1=yes, Rijnland format; 2=yes, Pluvius format
OutputAtTimestep=1
*Output every xx timestep
OutputAtTimestepOption=1 *1=Current value, 2=Average value, 3=Maximum value
Reduced Output=0
!-1=yes: only output at open water, structures.
! Also balances and link flows.
! 0=no (default)
ExtendedBalance=0
! 0=no, -1=yes. Default=0
OutputRRPaved=0
! 0=no, -1=yes. Default=-1.
OutputRRUnpaved=1
! 0=no, -1=yes. Default=-1.
OutputRRGreenhouse=0
! 0=no, -1=yes. Default=-1.
OutputRROpenWater=1
! 0=no, -1=yes. Default=-1.
OutputRRStructure=0
! 0=no, -1=yes. Default=-1.
OutputRRBoundary=0
! 0=no, -1=yes. Default=-1.
OutputRRNWRW=0
! 0=no, -1=yes. Default=-1.
OutputRRWWTP=0
! 0=no, -1=yes. Default=-1.
OutputRRIndustry=0
! 0=no, -1=yes. Default=-1.

SOBEK input file formats

OutputRRSacramento=0
! 0=no, -1=yes. Default=-1.
OutputRRBalance=1
! 0=no, -1=yes. Default=-1.
OutputRRSalt=0
! 0=no, -1=yes. Default=-1.
OutputRRLinkFlows=1
! 0=no, -1=yes. Default=-1.
[Options]
Dirlisting=1
(1=yes,0=no; within CMT always 1; indicator use @ in filenames)
WeirSettingTargetLevel=0 (Weir setting yes/no adjusted to be $<$= upstream target level; 0=no
UnsaturatedZone=0
(0=no,1=Capsim,)
InitGwlOption=-1
! This option is relevant when the initial groundwater level is
! specified with respect to surface level
! If no Scurve is used, initialisation is done w.r.t. the specified
! constant surface level.
! If an Scurve is used, it depends on the switch InitGwlOption
! 0 =when using SCurve: initialisation of groundwaterlevel w.r.t
! specified constant surface level
! Default=-1= in case of using Scurve: initialisation of
! groundwaterlevel relative to lowest point of the Scurve
InitBcOption=0
!How to initialize storage coefficients unpaved area
! 0 = using open water target level (default)
! 1 = using initial groundwater level
InitCapsimOption=1
! 0 = default old initialisatie,
! 1 = at equilibrium moisture,
! 2 = at moisture content for pF=2
! 3 = at moisture content for pF=3
CapsimPerCropArea=0
! 0 = call Capsim with crop area averaged data once per
! unpaved area
! Default= -1=call Capsim for each crop area seperately
KvdlVariatieOpenwater=0 !0 = groundwater level follows changes open water level (default)
!1 = treat changes open water level as rainfall/evaporation
KvdLInitOpenwater=0
!1=treat initial level difference open water - groundwater
!as rainfall/evaporation; see KvdLVariatieOpenwater option.
!default = 0
KvdLDimensionInDays=30 !Number of days history to be taken into account in Krayenhoff
! van de Leur calculations. If missing, backwards compatibility is
! accomplished by assuming 10 days, with a maximum of 999
! timesteps. If the record is specified, there is no maximum
! anymore. Only a warning is given if the number of timesteps
! exceeds 1000.
UnpavedScurveAreas=100 ! Number of sub areas for SCurve; default=100.
UnpavedScurveAlfaOption=0 ! 0 = absolute, 1=relative w.r.t. surface level; Default=0.
DrainageDeltaH=-1
! -1=parallell systems (default), 0=stacked system;
MinimumDepthCF=0.0
! Minimum depth in Channel Flow boundaries
! Below this level RR-unpaved infiltration from CF are stopped
ControlModule=-1
(-1=with control module, 0=without)
MaalstopModule=-1
(-1=with RTC module, 0=without)
ModFlowModule=0
(-1=with Modflow module, 0=without) \textbf{not yet operational}
WLMModule=0
!( -1=with WLM, 0=without) \textbf{not yet operational }
WQModule=0
!( -1=with WQ module, 0=without) \textbf{not yet operational}
SaltComputation=1
! -1=yes, 0=no.
SaltConcOutput=0
! -1=yes, 0=no.
SaltConcRainfall=8
(8 mg/l)
MinFillingPercentage=10 (below 10\% no extractions for greenhouse from storage basins)
RestartIn=1
(Use binary restart input file; 1=yes, 0=no)
RestartOut=0
(write binary restart file)
LowestRestartGwl=
! laagste toegestane restart grondwaterstand in m - maaiveld
SkipBoundaryLevelFromRestartFile=0 !0 or -1, default=0;
!-1 = do not use boundary levels from restart file
MaxIterations=5
! maximum aantal iteraties binnen 1 tijdstap (default=5)
DetailedGwlComputation=-1 ! --1 = yes (default)
StepGwlStorageCoefficient=0.01 !Default 0.01 m.
CheckRootzoneGwl=-1
!-1=yes, 0=no (default).Checks whether groundwater levels
! is in the rootzone and sets storage coefficient to 0.01
BinaryInput=0
! -1=yes, 0=no
BinaryOutput=0
! -1=yes, 0=no
Defaultdataset=0
!1=yes,0=no; option from rainfall rainfall file
(=1 default dataset, 0 for the 44-year series)

SOBEK, User Manual

EvaporationYear=-1
!-1 = check on year = rainfall year (default),
!xxxx=use data from year xxxx
GreenHouseYear=1951
!-1 = check on year = rainfall year (default),
!xxxx=use data from year xxxx
VolumeCheckFactorToCF=1 ! A multiplier on the computed maximum volume to be exchanged.
! Default=1. A large value effectively means that the volume check ! is not active.
VolumeCheckFactorToOW=1.0 ! A multiplier on the computed maximum volume to be exchanged.
! Default=1.0. A large value effectively means that the volume check ! is not activ
DetailedVolumeCheckMessages=-1 ! Enables extra information in Sobek\_3B log file in order to sh
CoefRz=0.1
! 4 Interpolation coefficients for interpolation in Capsim tables
CoefGwl=100.
! 2 coefficients en 2 power coefficients, voor root zone and
!groundwater level
PowerRz=2.
!Default power coefficients PowerRz=PowerGwl=2
PowerGwl=2.
! weight coefficients CoefRz=0.1 and CoefGwl=100.
CheckBalance=0
! 0 = no detailed output balance error per timestep, -1=yes
OpenWaterLevelComputations=Advanced
! Simple or Advanced. Default =Advanced
! Advanced = take into account storage on land of neighbouring
! nodes in computing open water levels
OpenWaterPrecipitation=0 ! 0 = rainfall at area at actual level, (Default)
! -1=at area at lowest surface level of connected nodes,
! if no paved/unpaved/greenhouse nodes connected, the area at
! maximum allowable level is used.
StructureOperation=
! 0 = Operate structure depending on initial level. (=default)
! 1 = Use SetFractionTime to switch on/off.
! (Sept 1999, ARS xxxx) For internal use only.
DrownedWeirDepth=
! Switch to set which depth is used in weir formula. Default=0.
! 0 = lowest depth; 1 = maximum depth; 2=average depth;
EmulateUnixOnPc=
! default=false; for testing Sobek-Parallell functionality only

For internal use only.

HeaderRunoffOutAlways=

! default=false; for testing Sobek-Parallell functionality only.

For internal use only.

! default=true, if =0 then false.
!(ARS5176=surface runoff bug fixed in April/May 2000)
FixARS8842=
! default=true, if =0 then false.
!(ARS8842=added volume check to unpaved module drainage to
! open water, January 2002)
FixARS11610=
! default=true, if =0 then false.
! (ARS11610=added volume check for drainage from unpaved area to boundary (CF node)
FixARSControllerLvlCheck=
! default=true, if =0 then false.
!(Extra check that the computed weir controller flow satisfies the
! possible flow directions)
FixARS10084=
! default=.false., if=-1 then true.
! if gw on surface, include water laye
FixARS12253=
! default=.false., if=-1 then true
! NWRW runoff delay correction (1s-1min) (in temporary version this switch was call
CumulativeGroundwaterExceedance=0 ! 0=Sum, 1=Sum of squares above threshold; default=0
MessageInundation=
! 1 = detailed inundation message per node and timestep,
! 0 = no message
MessageVolumeCheck=
! 1 = yes, 0 = no message
MessagePerTimestep=
! 1 = 1 message per inundation timestep, 0 = no message
DailyRainfallStartHour= ! Option to specify start hour of daily rainfall.
! Default=0. 8=daily rainfall starts at 8 o’clock in the morning
EstimateRemainingDuration=
! 0 = no, -1=give estimate remaining runtime on screen
GenerateAanvoerAbr=
! 1= yes, 0=no; default=0
LargeBalanceErrorPercentage=
! Percentage ($>$0).
! An error message will be given if the total balance error for the
! RR simulation exceeds this percentage. Default value = 1.0
NewFormatCropFactors=0 ! 0=no, -1=yes. Option to use new format crop factors.

SOBEK input file formats

CropDefinition=’Default’
! If NewFormatCropFactors=-1, CropDefinition= is used to specify
! the set of crop definitions used. Default set is named ‘Default’.
! In the crop definition, crop names and crop factors are specified.
OpenWaterCropDefinition=’Default’
! Cf. CropDefinition, but now for open water crop factor
NewFormatSoilData=0
! 0=no, -1=yes. Option to use new format soil data.
SoilDefinition=’Default’
! If NewFormatSoilData=-1, SoilDefinition= is used to specify
! the set of soil data used. Default set is named ‘Default’.
! In the soil definition, soil names and soil data like storage
! coefficients are defined
NewFormatKasdata = 0
! 0=no, -1=yes. Option to use new format greenhouse data.
KasDefinition=’Default’ ! If NewFormatKasdata is used, then KasDefinition= is used to
! specify the set of fixed greenhouse data used. This set contains
! greenhouse initialisation data and greenhouse water use data.
ParseTokenMethod=0
! 0=no (default), -1=yes. Alternative method of parsing input files;
! at the moment only available for NWRW nodes.
HisConvergence=0
! 0=no (default), -1=yes. Option to generate an extra His file called
! Convergence.His containing convergence info
! (compare with FlowAnal.His file of Sobek-CF-SF)
StructComp=0
! 0=no (default, backwards compatible), -1=yes.
! If Structcomp=.true., then the same internal iteration criteria are
! used for weir, orifice and friction nodes.
RunOffOutHis=0
! --1 = Runoff.Out in HIS format, 0=no.
SeparateRWA\_DWA
! --1=yes,separate DWA and RWA in Runoff.Out file, 0=no
DWAString=’DWA’
! String to add to NWRW location for DWA
RWAString=’RWA’
! String to add to NWRW location for RWA
NWRWContinuous=-1
!-1=yes, 0=no. Simulate NWRW model continuously for series of
! events, using an additional continuous bui file covering all events.
ConstantHdeZBergC=-1
!0=(default) no; --1=constant Hellinga-deZeeuw coefficient used.
WriteRestartFileWithAdimC=0
! 0=no, -1=yes (default); includes AdimC Sacramento in resta
VnotchWeirNrInterpolationpoints=14 ! number of interpolation points for Vnotch weir.
VnotchWeirh2h1Ratio=0.8 0.85 0.885 0.9 0.925 0.945 0.95 0.96 0.97 0.978 0.985 0.99 0.995 1.0
! Default values for H2H1 ratio Vnotch weir.
! Should be given for specified number of interpolation points.
VnotchWeirDrownedFlowReductionfactor= 1.0 0.96 0.9 0.87 0.8 0.7 0.67 0.6 .5 0.4 0.3 0.2 0.1
! Default values for drowned weir flow reduction factor
RestartOrderStrict=-1
!-1=true, 0=false. Default =0.
ReduceRROpenWaterInfiltrationAtNegativeVolume=-1 !0=false, -1= true, default value = false
[TimeSettings]
TimestepSize=3600
(computation timestepsize in seconds)
Timeweightfactor=0.5
! weight factor of t=t0 and t=t + delta t.
TimestepExchange=3600
! exchange timestepsize in seconds,
! should be a multiple of the computation timestepsize
! Default = equal to computation timestep
! At the moment, only for Modflow coupling a multiple is allowed.
ExchangeOption=Detail
! Detail, Average or Current;

! At the moment only option Detail is impemented!.

NightFromHrs=23
! night yours from - to
NightToHrs=7
WeekHrsasNight=1
! Weekend hours (Saturday, Sunday) to be considered as night?
! 1=yes, 0=no
EvaporationFromHrs=7
! daily evaporation from - to
EvaporationToHrs=19
PeriodFromEvent=0
! period derived from rainfall event file. -1=yes (default);0=no.
StartTime=1995/01/01;00:30:00
! Start date and time of simulation (within rainfall event)
EndTime=1995/01/01;01:55:00
! End date and time of simulation period

General layer
Storage coefficients soil types <..\..\fixed\bergcoef>
The fixed input file with soil type names and storage coefficients as a function of the soil type
and drainage basis. 12 soil types, 12 values for the drainage basis, followed by the table

SOBEK, User Manual

with 12 lines (1 line per drainage basis) with the storage coefficients for all soil types for that
particular value of the drainage basis.

*Comment lines start with an * in column 1
*Bergingscoefficient, afh. ontw.diepte en grondsoort
*aantal grondsoorten (=12)
1 ’loamy, humous fine sand (mu = 0.115 per m)’
2 ’peat (mu = 0.103 per m)’
3 ’heavy clay (mu = 0.089 per m)’
4 ’humous clay and peat (mu = 0.085 per m)’
5 ’light loamy, medium coarse sand (mu = 0.084 per m)’
6 ’loamy silt (mu = 0.072 per m)’
7 ’humous clay and peat with silty top layer (mu = 0.069 per m)’
8 ’clay and light clay (mu = 0.062 per m)’
9 ’loamless, medium coarse and coarse sand (mu = 0.060 per m)’
10 ’silt (mu = 0.058 per m)’
11 ’very light clay (mu = 0.048 per m)’
12 ’sand with a silty top layer (mu = 0.044 per m)’
*aantal ontw.diepten (=12) (tov maaiveld)
-0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 -1.0 -1.2 -1.5
2
3
4
5
6
7
8
9
10
11
12
*Grond1
0.0074 0.0077 0.0094 0.0063 0.0046 0.0049 0.0049 0.0048 0.0027 0.0029 0.0025
0.0183 0.0153 0.0166 0.0134 0.0124 0.0103 0.0118 0.0092 0.0098 0.0066 0.0052
0.0302 0.0226 0.0226 0.0206 0.0220 0.0158 0.0181 0.0132 0.0162 0.0105 0.0079
0.0419 0.0305 0.0278 0.0279 0.0323 0.0211 0.0237 0.0171 0.0228 0.0145 0.0107
0.0532 0.0387 0.0323 0.0350 0.0427 0.0262 0.0289 0.0206 0.0294 0.0186 0.0134
0.0664 0.0467 0.0363 0.0420 0.0528 0.0310 0.0339 0.0240 0.0359 0.0226 0.0160
0.0805 0.0545 0.0399 0.0486 0.0625 0.0364 0.0386 0.0271 0.0422 0.0265 0.0185
0.0938 0.0621 0.0431 0.0551 0.0715 0.0416 0.0430 0.0300 0.0484 0.0303 0.0210
0.1061 0.0702 0.0461 0.0613 0.0801 0.0466 0.0472 0.0328 0.0542 0.0341 0.0235
0.1173 0.0784 0.0489 0.0673 0.0880 0.0514 0.0512 0.0355 0.0598 0.0377 0.0258
0.1372 0.0939 0.0538 0.0786 0.1024 0.0605 0.0586 0.0404 0.0704 0.0446 0.0303
0.1614 0.1158 0.0600 0.0941 0.1208 0.0729 0.0685 0.0470 0.0845 0.0541 0.0366

Crop factors agricultural crops <..\..\fixed\cropfact>

The fixed input file with crop names and crop factors as a function of time.
1 year of data is enough, since it is assumed that the crop factors are constant over the years;
the variation is taken into account in the reference evaporation data and not in the crop factors.
The header of the file contains the number of crops and crop names.
*Aantal gewassen
16
*Namen
’grass
’corn
’potatoes
’sugarbeet
’grain
’miscellaneous
’non-arable land
’greenhouse area
’orchard
’bulbous plants
’foliage forest
’pine forest
’nature
’fallow
’vegetables
’flowers

’
’
’
’
’

’
’
’
’
’
’
’
’
’
’
’

0.0013
0.0032
0.0052
0.0074
0.0096
0.0120
0.0143
0.0167
0.0191
0.0214
0.0261
0.0329

SOBEK input file formats

1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.35
0.35
0.35

2
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

3
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

4
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

5
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

Capsim soil types <..\..\fixed\bergcoef.cap>

6
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

7
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

8
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00

9
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.35
0.35
0.35

10
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

11
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.35
0.35
0.35

*Gemiddelde
1996
1 1
1996
1 2
1996
1 3
1996
1 4
1996
1 5
1996
1 6
1996
1 7
1996
1 8
1996
1 9
1996
1 10
1996
1 11
1996
1 12
1996
1 13
etc.

File containing the names of the 21 soil types of the Staring reeks used in Capsim.

1 ’Veengrond met veraarde bovengrond’
2 ’Veengrond met veraarde bovengrond, zand’
3 ’Veengrond met kleidek’
4 ’Veengrond met kleidek op zand’
5 ’Veengrond met zanddek op zand’
6 ’Veengrond op ongerijpte klei’
7 ’Stuifzand’
8 ’Podzol (Leemarm, fijn zand)’
9 ’Podzol (zwak lemig, fijn zand)’
10 ’Podzol (zwak lemig, fijn zand op grof zand)’
11 ’Podzol (lemig keileem)’
12 ’Enkeerd (zwak lemig, fijn zand)’
13 ’Beekeerd (lemig fijn zand)’
14 ’Podzol (grof zand)’
15 ’Zavel’
16 ’Lichte klei’
17 ’Zware klei’
18 ’Klei op veen’
19 ’Klei op zand’
20 ’Klei op grof zand’
21 ’Leem’
The list of 21 Capsim soil types in English:
Soil1
Soil2
Soil3
Soil4
Soil5
Soil6
Soil7

Decomposed clayey peat over eutrophic peat: peat soil with decomposed topsoil (hVb, hVc)
Decomposed mesotrophic peat over a coarse textured, sandy subsoil: peat soil
with decomposed topsoil (aVz, hVz)
Humic very fine textured, clay topsoil over eutrophic peat: peat soil with a clay
cover (pVb, kVb)
Humic very fine textured, clay topsoil over coarse textured, sandy subsoil: peat
soil with a clay cover (kVz)
Humic, medium textured, sandy topsoil over coarse textured, sandy subsoil:
peat soil with sand cover (iWz, iWp)
Decomposed clayey peat over unripened clay: peat soil with decomposed topsoil (W0)
Eolian, coarse textured sandy soil: sandy soil (Zd20, Zd21)

12
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.40
0.40
0.40

13
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.35
0.35
0.35

14
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.

SOBEK, User Manual

Podzolic, coarse textured sandy soil: sandy soil (Hd21)
Podzolic, medium textured sandy soil: sandy soil (Hn21)
Podzolic, medium textured sandy soil over coarse textured sand:sandy soil
(Hn21g)
Podzolic, medium textured sandy soil over boulder clay: sandy soil (Hn23x)
Plaggen, coarse textured sandy soil: sandy soil (zEZ21)
Humic gleysol, coarse textured sandy soil: sandy soil (pZg23)
Podzolic, coarse textured sandy soil: sandy soil (gHd30)
Calcareous, medium textured, clay soil: alluvial soil (Mn25A)
Medium textured clay soil: alluvial soil (Mn35A, Rd90A, Rd90C)
Fine textured clay soil: alluvial soil (Rn44C, gMn83C, kMn48C, Rn47C)
Fine textured clay over mesotrophic peat: alluvial soil (RvO1C, Mv41C)
Medium textured clay over sand: alluvial soil (Mn22A)
Medium textured clay over coarse textured sand: alluvial soil(n52A)
Eolian, medium textured loam: lvss soil (BLd6)

Soil11
Soil12
Soil13
Soil14
Soil15
Soil16
Soil17
Soil18
Soil19
Soil20
Soil21

Capsim rootzone data <..\..\fixed\root_sim.inp>

Soil8
Soil9
Soil10

This file contains the rootzone data. The lay-out of the file is column-wise, with:
column 1 = soil type
column 2 = crop type
column 3 = root zone thickness (mm)
column 4 = relative root zone storage for h1
column 5 = relative root zone storage for h2
column 6 = relative root zone storage for h3l
column 7 = relative root zone storage for h3h
column 8 = relative root zone storage for h4

The soil water pressure heads h1, h2, h3l, h3h, h4 are used to define evaporation reduction
(see technical reference for more explanation).
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10

0.40
0.60
0.60
0.60
0.60
0.60
0.50
0.50
0.60
0.50
0.60
0.60
0.50
0.20
0.40
0.60
0.40
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50
0.50

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000
1.000

0.760
0.757
0.760
0.760
0.713
0.713
0.713
0.757
0.760
0.760
0.760
0.760
0.760
0.760
0.760
0.760
0.628
0.673
0.676
0.676
0.607
0.607
0.607
0.673
0.676
0.676

0.669
0.695
0.695
0.695
0.658
0.658
0.658
0.695
0.669
0.669
0.669
0.669
0.669
0.669
0.713
0.713
0.486
0.580
0.580
0.580
0.527
0.527
0.527
0.580
0.542
0.542

0.479
0.479
0.434
0.434
0.434
0.434
0.434
0.479
0.479
0.479
0.479
0.479
0.479
0.479
0.513
0.548
0.249
0.302
0.254
0.254
0.254
0.254
0.254
0.302
0.302
0.302

SOBEK input file formats

Capsim unsaturated zone data <..\..\fixed\unsa_sim.inp>
This file contains the unsaturated zone data. The lay-out of the file is column-wise, with:

column 1 = soil type
column 2 = rootzone thickness (cm)
column 3 = groundwater level (meter below surface)
column 4 = root zone soil moisture storage in equilibrium conditions (mm)
column 5 = potential capillary rise (mm/day)
column 6 = storage coefficient (m/m)
1 10 0.00 61.6 5.000 0.000
1 10 0.10 61.0 5.000 0.010
1 10 0.20 59.8 5.000 0.018
1 10 0.30 58.7 5.000 0.029
1 10 0.40 57.7 3.546 0.038
1 10 0.50 56.7 2.392 0.049
1 10 0.60 55.9 1.780 0.062
1 10 0.70 55.1 1.397 0.070
1 10 0.80 54.4 1.134 0.081
1 10 0.90 53.8 0.942 0.091
1 10 1.00 53.2 0.797 0.101
1 10 1.10 52.6 0.684 0.110
1 10 1.20 52.1 0.595 0.119
1 10 1.30 51.6 0.521 0.126
1 10 1.40 51.2 0.461 0.135
1 10 1.50 50.8 0.410 0.142
1 10 1.60 50.4 0.367 0.149
1 10 1.70 50.0 0.330 0.156
1 10 1.80 49.6 0.298 0.162
1 10 1.90 49.3 0.271 0.168
1 10 2.00 49.0 0.246 0.174
1 10 2.10 48.7 0.225 0.180
1 10 2.20 48.4 0.206 0.185
1 10 2.30 48.1 0.190 0.190
1 10 2.40 47.8 0.175 0.195
1 10 2.50 47.6 0.162 0.199
1 10 3.00 46.4 0.112 0.220
1 10 4.00 44.6 0.060 0.251
1 10 5.00 43.2 0.035 0.275
1 10 10.00 39.1 0.002 0.341
1 20 0.00 123.2 5.000 0.000
1 20 0.10 122.6 5.000 0.010
1 20 0.20 120.8 5.000 0.010
1 20 0.30 118.5 5.000 0.018
1 20 0.40 116.4 5.000 0.028
1 20 0.50 114.4 3.916 0.039
1 20 0.60 112.6 2.749 0.052
1 20 0.70 111.0 2.074 0.063 etc.
Greenhouse class file <..\..\fixed\kasklasse>

This file contains the definition of the greenhouse classes; the name, the maximum storage
(in m3/ha), the maximum depth (m), and en evaporation indicator (0=no evaporation,1=yes)

SOBEK, User Manual

*Kasklassen
*Code Name Max\_berging in m3/ha, Max.diepte, wel/geen verdamping uit bassins
1 ’$<$500 m3/ha’
0
0.
0
2 ’ 500-1000’
500
0.5
0
3 ’1000-1500’
1000
1.
0
4 ’1500-2000’
1500
1.5
1
5 ’2000-2500’
2000
2.
1
6 ’2500-3000’
2500
2.5
1
7 ’3000-4000’
3000
3.
1
8 ’4000-5000’
4000
4.
1
9 ’5000-6000’
5000
5.
1
10 ’$>$6000-m3/ha’ 6000
5.
1

Greenhouse initialisation file <..\..\fixed\kasinit>

Grootte
0
Maand
1
1
1
1
1
1
1
1
1
1
1
1
1
1

bassin
500
Dag
1
2
3
4
5
6
7
8
9
10
11
12
13
14

(m3/ha)
1000
1500
2000
2500
3000
4000
5000
6000
Ruimte voor
waterberging
(m3)
0
0
0
0
31
100
215
519
829
0
0
0
0
8
77
191
495
803
0
5
5
5
13
82
196
500
808
0
0
0
0
0
67
181
484
792
0
0
0
0
0
5
118
419
725
0
0
0
0
0
0
108
409
715
0
3
3
3
3
3
112
412
718
0
0
0
0
0
0
85
384
689
0
0
0
0
0
0
63
362
666
0
0
0
0
0
0
32
330
633
0
0
0
0
0
0
0
204
503
0
0
0
0
0
0
0
181
479
0
0
0
0
0
0
0
152
449
0
0
0
0
0
0
0
127
424

*
*
*Jaar
1951
1951
1951
1951
1951
1951
1951
1951
1951
1951
1951
1951
1951
1951

The greenhouse initialisation file defines the free space (available storage) at the start of the
simulation for each greenhouse class. It contains data from 1951 up to 1999. This data is
only used for defining the initial storage in the greenhouse storage basins.

Greenhouse water use file <..\..\fixed\kasgebr>

This file defines the actual water use (m3/ha) from the greenhouse storage basins by the
greenhouse crops for each day. Values are depending on year and date, but are assumed
independant of the size of the greenhouse storage basins (so independant of the greenhouse
class).
Voor alle kasklassen hetzelfde
*
EACT
*Jaar Maand Dag
1951
1
1
8.36
1951
1
2
7.04
1951
1
3
8.04
1951
1
4
7.04
1951
1
5
7.04
1951
1
6
7.04
1951
1
7
7.72
1951
1
8
7.04
1951
1
9
9.43
1951
1
10
7.53
1951
1
11
7.31
1951
1
12
10.94
1951
1
13
7.31
1951
1
14
7.51

Crop factors open water <..\..\fixed\crop_ow>

SOBEK input file formats

The fixed input file with open water evaporation factors as a function of time. 1 year of data is
enough; it is assumed that the evaporation factors are same for all years.

0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.50
0.50
0.50

*Oppervlaktewater
1
*Namen
’0.0 Oppervlaktewater
1
*Gemiddelde
1994
1
1
1994
1
2
1994
1
3
1994
1
4
1994
1
5
1994
1
6
1994
1
7
1994
1
8
1994
1
9
1994
1
10
1994
1
11
1994
1
12
1994
1
13
etc.

Rainfall file (1 or more events)

This file contains the rainfall data: the number of stations, the names (id’s) of the rainfall
stations, the number of rainfall events, the rainfall data timestep size (may be different from
the computation timestep size), the start date and duration of each event and the rainfall data
for each event.
*Name of this file: \SOB_LITE\FIXED\DEFAULT.BUI
17:13:50
*Date and time of construction: 17-04-1997
*Enige algemene wenken:
*Gebruik de default dataset voor overige invoer (altijd 1)
1
*Aantal stations
1
*Namen van stations
’Station1’
*Aantal gebeurtenissen (omdat het 1 bui betreft is dit altijd 1)
*en het aantal seconden per waarnemingstijdstap (10800 = 3x3600)
1 10800
*Elke commentaarregel wordt begonnen met een * (asteriks).
*Eerste record bevat startdatum en -tijd, lengte van de gebeurtenis in dd hh mm ss
*Het format is: yyyymmdd:hhmmss:ddhhmmss
*Daarna voor elk station de neerslag in mm per tijdstap.
1996 1 1 0 0 0 1 3 0 0
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2

Evaporation file
This file contains the evaporation data. It is assumed that meteo stations occur in the same
order as in the rainfall file. If the evaporation file contains less stations, missing stations will
use data from the first station in the file.

SOBEK, User Manual

*Name of this file: \SOB\_LITE\FIXED\DEFAULT.EVP
10:04:25
*Date and time of construction: 10-03-2000
*Verdampingsfile
*Meteo data: evaporation intensity in mm/day
*First record: start date, data in mm/day
*Datum (year month day), verdamping (mm/dag) voor elk weerstation
*jaar maand dag verdamping[mm]
1996
1
1
0
1996
1
2
0

Default defition file <..\fixed\3bEdit.def>
This file contains some default values for records in the Sobek-RR MDB files for all types of
3B-nodes. The file is used by ModelEdit.

Optional: New format greenhouse class file file..\fixed\3B\NewKasKlasData.dat
This file contains the greenhouse class specification in a new format, which allows extensions
by the user.

The file contains two type of records: the KASD records and KLAS records. In the KASD
records the global definitions are placed, including references to the greenhouse initialisation
and greenhouse water use definitions. The KLAS record contains the greenhouse class definition. The file can contain multiple KASD and KLAS records. Selection of the actual records
used is done per case in the file (see description of the NewFormatKasData=
and KasDefinition= records).
An example input file:

KASD id ’Default’ nm ’Default kas initialisation’ nc 10 kk ’Default kasklassen’ ki ’Default kas
initialisation data’ kg ’Default kasgebruik data’ kasd
KASD id ’Low’ nm ’Low kas initialisation’ nc 10 kk ’Default kasklassen’ ki ’Low kas initialisation
data’ kg ’Low kasgebruik data’ kasd
KASD id ’Periodic test’ nm ’Periodic test’ nc 10 kk ’Default kasklassen’ ki ’Periodic kas initialisation data’ kg ’Periodic kasgebruik data’ kasd
KASD id ’My own mix’ nm ’My own mix’ nc 10 kk ’Default kasklassen’ ki ’Low kas initialisation
data’ kg ’Periodic kasgebruik data’ kasd
with
id
nm
nc
kk
ki
kg

greenhouse definition id
greenhouse definition name
number of greenhouse classes
reference to greenhouse class definition
reference to greenhouse initialisation definition
reference to greenhouse water use definition

The KLAS record contains the greenhouse class definition.
KLAS id ’Default kasklassen’
nm ’<500 m3/ha’ ’ 500-1000’ ’1000-1500’ ’1500-2000’ ’2000-2500’ ’2500-3000’ ’3000-4000’

SOBEK input file formats

’4000-5000’ ’5000-6000’ ’>6000-m3/ha’
mxstorage 0 500 1000 1500 2000 2500 3000 4000 5000 6000
mxdepth 0. 0.5 1. 1.5 2. 2.5 3. 4. 5. 5.
evap 0 0 0 1 1 1 1 1 1 1
KLAS
with
greenhouse class definition id
names of greenhouse classes
maximum storage per greenhouse class (m3/ha)
maximum depth per greenhouse class (m)
0=no evaporation, 1=evaporation from greenhouse class storage basins (per
class)

id
nm
mxstorage
mxdepth
evap

Optional: New format greenhouse initialisation file <..\fixed\3B\NewKasInitData.dat>
This file contains the greenhouse initialisation data in a new format, which allows extensions
by the user. The file contains INIT records. The INIT record contains a time table of greenhouse initial free storage. The table is a standard SOBEK time table with options for interpolation and periodicity. The file can contain multiple INIT records; selection of the actual record
used is based on the selected greenhouse definition from the greenhouse class file.
An example input file:

INIT id ’Default kas initialisation data’ PDIN 1 0 pdin TBLE
’1951/01/01;00:00:00’ 0 0 0 0 31 100 215 519 829 1078 <
’1951/01/02;00:00:00’ 0 0 0 0 8 77 191 495 803 1052 <
’1951/01/03;00:00:00’ 0 5 5 5 13 82 196 500 808 1057 <
’1951/01/04;00:00:00’ 0 0 0 0 0 67 181 484 792 1040 <
’1951/01/05;00:00:00’ 0 0 0 0 0 5 118 419 725 971 <
’1951/01/06;00:00:00’ 0 0 0 0 0 0 108 409 715 960 <
’1951/01/07;00:00:00’ 0 3 3 3 3 3 112 412 718 964 <
’1951/01/08;00:00:00’ 0 0 0 0 0 0 85 384 689 934 <
’1951/01/09;00:00:00’ 0 0 0 0 0 0 63 362 666 910 <
’1951/01/10;00:00:00’ 0 0 0 0 0 0 32 330 633 876 <
’1951/01/11;00:00:00’ 0 0 0 0 0 0 0 204 503 743 <
’1951/01/12;00:00:00’ 0 0 0 0 0 0 0 181 479 718 <
’1951/01/13;00:00:00’ 0 0 0 0 0 0 0 152 449 687 <
’1951/01/14;00:00:00’ 0 0 0 0 0 0 0 127 424 661 <
’1951/01/15;00:00:00’ 0 0 0 0 0 0 0 86 382 617 <
’1951/01/16;00:00:00’ 0 8 8 8 8 8 8 95 390 626 <
’1951/01/17;00:00:00’ 0 0 0 0 0 0 0 0 212 442 <
’1951/01/18;00:00:00’ 0 0 0 0 0 0 0 0 98 325 <
’1951/01/19;00:00:00’ 0 0 0 0 0 0 0 0 60 286 <
’1951/01/20;00:00:00’ 0 0 0 0 0 0 0 0 34 259 <
’1951/01/21;00:00:00’ 0 0 0 0 0 0 0 0 0 219 <
’1951/01/22;00:00:00’ 0 0 0 0 0 0 0 0 0 209 <
...
...
’1995/10/10;00:00:00’ 0 125 361 799 1216 1668 2135 2994 3346 3419 <

SOBEK, User Manual

’1995/10/11;00:00:00’ 0 135 370 808 1226 1677 2145 3004 3356 3429 <
’1995/10/12;00:00:00’ 0 150 385 823 1241 1693 2161 3020 3372 3446 <
’1995/10/13;00:00:00’ 0 159 394 833 1250 1702 2170 3030 3382 3456 <
’1995/10/14;00:00:00’ 0 176 412 851 1269 1721 2189 3049 3402 3476 <
’1995/10/15;00:00:00’ 0 190 426 865 1283 1735 2204 3064 3417 3492 <
’1995/10/16;00:00:00’ 0 203 439 878 1297 1749 2218 3079 3432 3507 <
’1995/10/17;00:00:00’ 0 212 448 887 1305 1758 2227 3088 3441 3516 <
’1995/10/18;00:00:00’ 0 224 460 899 1318 1770 2239 3100 3454 3530 <
’1995/10/19;00:00:00’ 0 237 473 913 1331 1784 2253 3115 3469 3544 <
’1995/10/20;00:00:00’ 0 240 477 916 1334 1787 2257 3118 3472 3548 <
’1995/10/21;00:00:00’ 0 257 494 933 1352 1805 2274 3136 3491 3567 <
’1995/10/22;00:00:00’ 0 274 511 951 1370 1823 2293 3155 3510 3586 <
’1995/10/23;00:00:00’ 0 292 529 969 1388 1841 2311 3174 3529 3606 <
’1995/10/24;00:00:00’ 0 309 546 987 1406 1860 2330 3193 3549 3626 <
’1995/10/25;00:00:00’ 0 324 562 1002 1422 1876 2346 3209 3565 3643 <
’1995/10/26;00:00:00’ 0 324 562 1002 1421 1875 2345 3209 3565 3642 <
’1995/10/27;00:00:00’ 0 310 547 987 1406 1860 2330 3192 3548 3625 <
’1995/10/28;00:00:00’ 0 325 562 1002 1422 1876 2346 3209 3564 3642 <
’1995/10/29;00:00:00’ 0 342 579 1019 1439 1893 2363 3226 3583 3660 <
’1995/10/30;00:00:00’ 0 357 594 1035 1455 1909 2379 3243 3599 3677 <
’1995/10/31;00:00:00’ 0 371 609 1050 1470 1924 2395 3259 3616 3694 <
’1995/11/01;00:00:00’ 0 275 511 950 1368 1821 2290 3150 3504 3579 <
’1995/11/02;00:00:00’ 0 254 490 928 1346 1798 2267 3127 3480 3554 <
’1995/11/03;00:00:00’ 0 262 498 936 1354 1806 2275 3135 3488 3562 <
’1995/11/04;00:00:00’ 0 274 510 949 1367 1819 2288 3148 3502 3576 <
’1995/11/05;00:00:00’ 0 289 525 964 1382 1834 2303 3164 3517 3592 <
’1995/11/06;00:00:00’ 0 299 535 974 1392 1845 2314 3175 3528 3603 <
tble
init
INIT id ’Low kas initialisation data’ PDIN 1 0 pdin TBLE
’1951/01/01;00:00:00’ 0. 0. 0. 0. 0. 24. 74. 223. 322. 372. <
’1951/01/02;00:00:00’ 0. 0. 0. 0. 0. 0. 45. 193. 292. 341. <
’1951/01/03;00:00:00’ 0. 0. 0. 0. 0. 0. 44. 192. 291. 340. <
’1951/01/04;00:00:00’ 0. 0. 0. 0. 0. 0. 24. 172. 270. 318. <
’1951/01/05;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 101. 197. 243. <
’1951/01/06;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 86. 182. 227. <
’1951/01/07;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 84. 179. 225. <
’1951/01/08;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 50. 145. 190. <
’1951/01/09;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 21. 115. 159. <
’1951/01/10;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 77. 120. <
’1951/01/11;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
’1951/01/12;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
’1951/01/13;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
...
...
’1995/10/10;00:00:00’ 0. 72. 73. 408. 842. 1334. 1629. 2348. 2772. 2893. <
’1995/10/11;00:00:00’ 0. 76. 78. 412. 847. 1339. 1634. 2353. 2778. 2898. <
’1995/10/12;00:00:00’ 0. 83. 85. 420. 855. 1347. 1642. 2361. 2786. 2907. <
’1995/10/13;00:00:00’ 0. 88. 89. 424. 859. 1351. 1646. 2366. 2791. 2912. <
’1995/10/14;00:00:00’ 0. 96. 98. 433. 868. 1360. 1656. 2376. 2802. 2923. <
’1995/10/15;00:00:00’ 0. 102. 105. 440. 875. 1368. 1663. 2384. 2810. 2932. <
’1995/10/16;00:00:00’ 0. 109. 111. 446. 882. 1375. 1670. 2391. 2817. 2940. <
’1995/10/17;00:00:00’ 0. 111. 113. 448. 884. 1377. 1673. 2394. 2820. 2943. <
’1995/10/18;00:00:00’ 0. 116. 119. 454. 890. 1383. 1679. 2400. 2827. 2950. <

SOBEK input file formats

’1995/10/19;00:00:00’ 0. 122. 125. 461. 897. 1390. 1686. 2407. 2834. 2957. <
’1995/10/20;00:00:00’ 0. 122. 124. 460. 896. 1389. 1685. 2406. 2834. 2957. <
’1995/10/21;00:00:00’ 0. 126. 129. 464. 900. 1394. 1690. 2412. 2839. 2963. <
’1995/10/22;00:00:00’ 0. 130. 133. 469. 905. 1399. 1695. 2418. 2845. 2969. <
’1995/10/23;00:00:00’ 0. 134. 138. 474. 910. 1404. 1701. 2423. 2852. 2976. <
’1995/10/24;00:00:00’ 0. 139. 143. 479. 916. 1410. 1707. 2430. 2859. 2983. <
’1995/10/25;00:00:00’ 0. 143. 147. 483. 920. 1415. 1712. 2435. 2864. 2989. <
’1995/10/26;00:00:00’ 0. 137. 140. 477. 914. 1408. 1705. 2428. 2857. 2982. <
’1995/10/27;00:00:00’ 0. 116. 119. 456. 892. 1386. 1683. 2406. 2834. 2958. <
’1995/10/28;00:00:00’ 0. 120. 123. 459. 896. 1390. 1687. 2410. 2839. 2964. <
’1995/10/29;00:00:00’ 0. 124. 127. 464. 901. 1395. 1692. 2416. 2845. 2970. <
’1995/10/30;00:00:00’ 0. 127. 131. 468. 905. 1399. 1697. 2420. 2850. 2975. <
’1995/10/31;00:00:00’ 0. 131. 135. 472. 909. 1404. 1701. 2425. 2855. 2981. <
’1995/11/01;00:00:00’ 0. 29. 32. 367. 802. 1295. 1591. 2312. 2739. 2861. <
’1995/11/02;00:00:00’ 0. 0. 2. 337. 772. 1265. 1560. 2280. 2706. 2827. <
’1995/11/03;00:00:00’ 0. 0. 1. 336. 772. 1264. 1560. 2280. 2706. 2827. <
’1995/11/04;00:00:00’ 0. 1. 3. 338. 773. 1266. 1562. 2282. 2708. 2830. <
’1995/11/05;00:00:00’ 0. 3. 5. 340. 776. 1269. 1564. 2285. 2711. 2834. <
’1995/11/06;00:00:00’ 0. 4. 6. 341. 777. 1270. 1566. 2287. 2713. 2836. <
tble
init
INIT id ’Periodic kas initialisation data’ PDIN 1 1 ’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
’1994/02/01;00:00:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
’1994/03/01;00:00:00’ 0. 10. 10. 10. 10. 10. 10. 10. 10. 10. <
’1994/04/01;00:00:00’ 0. 20. 20. 20. 20. 20. 20. 20. 20. 20. <
’1994/05/01;00:00:00’ 0. 30. 30. 30. 30. 30. 30. 30. 30. 30. <
’1994/06/01;00:00:00’ 0. 40. 40. 40. 40. 40. 40. 40. 40. 40. <
’1994/07/01;00:00:00’ 0. 50. 50. 50. 50. 50. 50. 50. 50. 50. <
’1994/08/01;00:00:00’ 0. 50. 50. 50. 50. 50. 50. 50. 50. 50. <
’1994/09/01;00:00:00’ 0. 40. 40. 40. 40. 40. 40. 40. 40. 40. <
’1994/10/01;00:00:00’ 0. 30. 30. 30. 30. 30. 30. 30. 30. 30. <
’1994/11/01;00:00:00’ 0. 20. 20. 20. 20. 20. 20. 20. 20. 20. <
’1994/12/01;00:00:00’ 0. 10. 10. 10. 10. 10. 10. 10. 10. 10. <
’1994/12/31;23:59:00’ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. <
tble
init
Optional: New format greenhouse water use file <..\fixed\3B\NewKasGebrData.dat>
This file contains the greenhouse water use data in a new format, which allows extensions by
the user. The file can contain several GEBR records, in which typical water uses of greenhouses are specified in a standard SOBEK time table. Selection of the GEBR record to be
used is done by the selection of the greenhouse definition from the greenhouse class file. An
example input file is given below.
GEBR id ’Default kasgebruik data’ PDIN 1 0 pdin TBLE
’1951/01/01;00:00:00’ 8.36 <
’1951/01/02;00:00:00’ 7.04 <
’1951/01/03;00:00:00’ 8.04 <
’1951/01/04;00:00:00’ 7.04 <
’1951/01/05;00:00:00’ 7.04 <
’1951/01/06;00:00:00’ 7.04 <
’1951/01/07;00:00:00’ 7.72 <
’1951/01/08;00:00:00’ 7.04 <

’1951/01/09;00:00:00’ 9.43 <
’1951/01/10;00:00:00’ 7.53 <
’1951/01/11;00:00:00’ 7.31 <
’1951/01/12;00:00:00’ 10.94 <
’1951/01/13;00:00:00’ 7.31 <
’1951/01/14;00:00:00’ 7.51 <
’1951/01/15;00:00:00’ 9.81 <
’1951/01/16;00:00:00’ 10.61 <
’1951/01/17;00:00:00’ 7.31 <
’1951/01/18;00:00:00’ 9.17 <
’1951/01/19;00:00:00’ 7.31 <
’1951/01/20;00:00:00’ 7.31 <
...
...
’1995/11/10;00:00:00’ 9.88 <
’1995/11/11;00:00:00’ 12.61 <
’1995/11/12;00:00:00’ 12.88 <
’1995/11/13;00:00:00’ 12.18 <
’1995/11/14;00:00:00’ 9.65 <
’1995/11/15;00:00:00’ 7.41 <
’1995/11/16;00:00:00’ 7.81 <
’1995/11/17;00:00:00’ 6.70 <
’1995/11/18;00:00:00’ 8.21 <
’1995/11/19;00:00:00’ 7.15 <
’1995/11/20;00:00:00’ 13.20 <
tble
gebr
GEBR id ’Low kasgebruik data’ PDIN 1 0 pdin TBLE
’1951/01/01;00:00:00’ 2.17 <
’1951/01/02;00:00:00’ 1.84 <
’1951/01/03;00:00:00’ 2.09 <
’1951/01/04;00:00:00’ 1.84 <
’1951/01/05;00:00:00’ 1.84 <
’1951/01/06;00:00:00’ 1.84 <
’1951/01/07;00:00:00’ 2.01 <
’1951/01/08;00:00:00’ 1.84 <
’1951/01/09;00:00:00’ 2.45 <
’1951/01/10;00:00:00’ 1.96 <
’1951/01/11;00:00:00’ 2.67 <
’1951/01/12;00:00:00’ 3.97 <
...
...
’1995/12/07;00:00:00’ 2.11 <
’1995/12/08;00:00:00’ 2.86 <
’1995/12/09;00:00:00’ 2.24 <
’1995/12/10;00:00:00’ 1.82 <
’1995/12/11;00:00:00’ 1.65 <
’1995/12/12;00:00:00’ 1.94 <
’1995/12/13;00:00:00’ 1.73 <
’1995/12/14;00:00:00’ 2.23 <
’1995/12/15;00:00:00’ 1.93 <
’1995/12/16;00:00:00’ 2.38 <
’1995/12/17;00:00:00’ 2.11 <
’1995/12/18;00:00:00’ 1.56 <

SOBEK, User Manual

SOBEK input file formats

’1995/12/19;00:00:00’ 1.48 <
’1995/12/20;00:00:00’ 2.18 <
’1995/12/21;00:00:00’ 1.69 <
’1995/12/22;00:00:00’ 1.43 <
’1995/12/23;00:00:00’ 1.60 <
’1995/12/24;00:00:00’ 2.75 <
’1995/12/25;00:00:00’ 2.42 <
’1995/12/26;00:00:00’ 1.83 <
’1995/12/27;00:00:00’ 3.30 <
’1995/12/28;00:00:00’ 3.79 <
’1995/12/29;00:00:00’ 3.16 <
’1995/12/30;00:00:00’ 2.56 <
’1995/12/31;00:00:00’ 1.61 <
tble
gebr
GEBR id ’Periodic kasgebruik data’ PDIN 1 1 ’31536000’ pdin TBLE
’1995/01/01;00:00:00’ 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 <
’1995/02/01;00:00:00’ 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 <
’1995/03/01;00:00:00’ 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 <
’1995/05/01;00:00:00’ 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 <
’1995/07/01;00:00:00’ 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 7.00 <
’1995/09/01;00:00:00’ 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00 <
’1995/10/01;00:00:00’ 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 <
’1995/11/15;00:00:00’ 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 <
’1995/12/31;23:59:00’ 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 <
tble
gebr

Optional: New format crop data <..\fixed\3B\NewCropData.dat> This file contains the
crop data (names and crop factors) in a new format, which allows extensions by the user. The
file contains 3 type of records:

CRPD records, containing the general crop definitions (id, name, number of crops, and
references to the crop name definition and crop factor definition)

NAME records, containing the crop name definitions.
CRF records, containing a time table with crop factors.
An example file is given below,
with
id
nm
nc
cn
cf

id
name
number of crops
crop name definition
crop factor definition

PDIN pdin = as in other SOBEK time tables: interpolation and periodicity options
TBLE tble = as in other SOBEK time tables
BBB2.2
CRPD id ’Default’ nm ’Nederlandse gewasdefinitie’ nc 16 cn ’Dutch Crops’ cf ’Dutch Crop

SOBEK, User Manual

factors’ crpd
CRPD id ’Example’ nm ’Example crop definition’ nc 1 cn ’Example Crops’ cf ’Example Crop
factors’ crpd
CRPD id ’Taiwan’ nm ’Taiwan crop definition’ nc 7 cn ’Taiwan Crops’ cf ’Taiwan Crop factors’
crpd
NAME id ’Dutch Crops’ nm
’grass ’
’corn ’
’potatoes ’
’sugarbeet’
’grain ’
’miscellaneous ’
’non-arable land’
’greenhouse area’
’orchard ’
’bulbous plants’
’foliage forest’
’pine forest ’
’nature ’
’fallow ’
’vegetables ’
’flowers ’
name
NAME id ’Taiwan Crops’ nm ’paddy1’ ’paddy2’ ’fishpond’ ’upland1’ ’upland2’ ’upland3’ ’fallow’
name
NAME id ’Example Crops’ nm ’all crops’ name
CRF id ’Dutch Crop factors’ nm ’Dutch Crop factors’ PDIN 1 1 ’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 <
’1994/01/11;00:00:00’ 0.35 0.40 0.40 0.40 0.40 0.40 0.40 0.00 0.35 0.40 0.35 0.40 0.35 0.40
0.35 0.00 <
’1994/01/21;00:00:00’ 0.49 0.56 0.56 0.56 0.56 0.56 0.56 0.00 0.49 0.56 0.49 0.56 0.49 0.56
0.49 0.00 <
’1994/02/01;00:00:00’ 0.56 0.64 0.64 0.64 0.64 0.64 0.64 0.00 0.56 0.64 0.56 0.64 0.56 0.64
0.56 0.00 <
’1994/02/11;00:00:00’ 0.70 0.80 0.80 0.80 0.80 0.80 0.80 0.00 0.70 0.80 0.70 0.80 0.70 0.80
0.70 0.00 <
’1994/02/21;00:00:00’ 0.70 0.70 0.70 0.70 0.70 0.80 0.70 0.00 0.70 0.70 0.70 0.80 0.70 0.80
0.70 0.00 <
’1994/03/01;00:00:00’ 0.84 0.72 0.72 0.72 0.72 0.96 0.72 0.00 0.84 0.48 0.84 0.96 0.84 0.96
0.84 0.00 <
’1994/03/11;00:00:00’ 0.91 0.65 0.65 0.65 0.65 1.04 0.65 0.00 0.91 0.65 0.91 1.04 0.91 1.04
0.91 0.00 <
’1994/03/21;00:00:00’ 0.91 0.52 0.52 0.52 0.52 1.04 0.52 0.00 0.91 0.78 0.91 1.04 0.91 1.04
0.91 0.00 <
’1994/04/01;00:00:00’ 1.04 0.52 0.52 0.52 0.52 1.04 0.52 0.00 1.04 0.91 1.04 1.04 1.04 1.04
1.04 0.00 <
’1994/04/11;00:00:00’ 1.04 0.39 0.39 0.39 0.65 1.04 0.39 0.00 1.04 0.91 1.04 1.04 1.04 1.04
1.04 0.00 <
’1994/04/21;00:00:00’ 1.04 0.26 0.26 0.26 0.78 1.04 0.26 0.00 1.04 0.91 1.04 1.04 1.04 1.04
1.04 0.00 <
’1994/05/01;00:00:00’ 1.04 0.52 0.52 0.52 0.91 1.04 0.13 0.00 1.04 1.04 1.04 1.04 1.04 1.04
1.04 0.00 <
’1994/05/11;00:00:00’ 1.04 0.65 0.65 0.65 1.04 1.04 0.13 0.00 1.04 1.04 1.04 1.04 1.04 1.04

SOBEK input file formats

1.04 0.00 <
’1994/05/21;00:00:00’ 1.04 0.78 0.78 0.78 1.17 1.04 0.13 0.00 1.04 1.04 1.04 1.04 1.04 1.04
1.04 0.00 <
’1994/06/01;00:00:00’ 1.05 0.92 0.92 0.92 1.31 1.05 0.13 0.00 1.05 1.05 1.05 1.05 1.05 1.05
1.05 0.00 <
’1994/06/11;00:00:00’ 1.05 1.05 1.05 1.05 1.31 1.05 0.13 0.00 1.05 1.05 1.05 1.05 1.05 1.05
1.05 0.00 <
’1994/06/21;00:00:00’ 1.05 1.18 1.18 1.18 1.18 1.05 0.13 0.00 1.05 0.92 1.05 1.05 1.05 1.05
1.05 0.00 <
’1994/07/01;00:00:00’ 1.03 1.16 1.16 1.16 1.16 1.03 0.13 0.00 1.03 0.77 1.03 1.03 1.03 1.03
1.03 0.00 <
’1994/07/11;00:00:00’ 1.02 1.14 1.14 1.14 1.14 1.02 0.13 0.00 1.02 0.64 1.02 1.02 1.02 1.02
1.02 0.00 <
’1994/07/21;00:00:00’ 0.99 1.12 1.12 1.12 0.99 0.99 0.12 0.00 0.99 0.50 0.99 0.99 0.99 0.99
0.99 0.00 <
’1994/08/01;00:00:00’ 0.97 1.09 1.09 1.09 0.73 0.97 0.12 0.00 0.97 0.12 0.97 0.97 0.97 0.97
0.97 0.00 <
’1994/08/11;00:00:00’ 0.95 1.07 0.95 1.07 0.36 0.95 0.12 0.00 0.95 0.12 0.95 0.95 0.95 0.95
0.95 0.00 <
’1994/08/21;00:00:00’ 0.94 1.06 0.83 1.06 0.24 0.94 0.12 0.00 0.94 0.12 0.94 0.94 0.94 0.94
0.94 0.00 <
’1994/09/01;00:00:00’ 0.94 1.05 0.70 1.05 0.23 0.94 0.23 0.00 0.94 0.23 0.94 0.94 0.94 0.94
0.94 0.00 <
’1994/09/11;00:00:00’ 0.94 1.05 0.59 1.05 0.35 0.94 0.35 0.00 0.94 0.35 0.94 0.94 0.94 0.94
0.94 0.00 <
’1994/09/21;00:00:00’ 0.94 1.05 0.47 1.05 0.47 0.94 0.47 0.00 0.94 0.47 0.94 0.94 0.94 0.94
0.94 0.00 <
’1994/10/01;00:00:00’ 0.70 0.40 0.40 0.40 0.40 0.80 0.40 0.00 0.70 0.40 0.70 0.80 0.70 0.80
0.70 0.00 <
’1994/10/11;00:00:00’ 0.63 0.45 0.45 0.45 0.45 0.72 0.45 0.00 0.63 0.45 0.63 0.72 0.63 0.72
0.63 0.00 <
’1994/10/21;00:00:00’ 0.56 0.48 0.48 0.48 0.48 0.64 0.48 0.00 0.56 0.48 0.56 0.64 0.56 0.64
0.56 0.00 <
’1994/11/01;00:00:00’ 0.56 0.56 0.56 0.56 0.56 0.64 0.56 0.00 0.56 0.56 0.56 0.64 0.56 0.64
0.56 0.00 <
’1994/11/11;00:00:00’ 0.49 0.56 0.56 0.56 0.56 0.56 0.56 0.00 0.49 0.56 0.49 0.56 0.49 0.56
0.49 0.00 <
’1994/11/21;00:00:00’ 0.42 0.48 0.48 0.48 0.48 0.48 0.48 0.00 0.42 0.48 0.42 0.48 0.42 0.48
0.42 0.00 <
’1994/12/01;00:00:00’ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 <
’1994/12/31;23:59:00’ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 <
tble
crf
CRF id ’Taiwan Crop factors’ nm ’Taiwan Crop factors’ PDIN 1 1 ’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 0.60 0.00 1.20 0.20 0.00 0.80 0.40 <
’1994/01/11;00:00:00’ 0.80 0.60 1.20 0.20 0.40 1.00 0.40 <
’1994/01/21;00:00:00’ 1.00 0.80 1.20 0.20 0.40 1.10 0.40 <
’1994/02/01;00:00:00’ 1.10 1.00 1.20 0.50 0.60 0.00 0.40 <
’1994/02/11;00:00:00’ 1.00 1.10 1.20 1.10 0.80 0.00 0.40 <
’1994/02/21;00:00:00’ 1.10 1.10 1.20 1.10 1.00 0.00 0.40 <
’1994/03/01;00:00:00’ 1.15 1.10 1.20 1.10 1.10 0.00 0.40 <
’1994/03/11;00:00:00’ 1.15 1.15 1.20 0.90 1.10 0.00 0.40 <

SOBEK, User Manual

’1994/03/21;00:00:00’ 1.15 1.15 1.20 0.90 0.80 0.00 0.40 <
’1994/04/01;00:00:00’ 1.00 1.00 1.20 0.70 0.80 0.00 0.40 <
’1994/04/11;00:00:00’ 1.00 1.00 1.20 0.60 0.60 0.00 0.40 <
’1994/04/21;00:00:00’ 1.00 0.80 1.20 0.60 0.60 0.00 0.40 <
’1994/05/01;00:00:00’ 1.00 0.80 1.20 0.40 0.60 0.00 0.40 <
’1994/05/11;00:00:00’ 0.80 0.60 1.20 0.40 0.40 0.00 0.40 <
’1994/05/21;00:00:00’ 0.80 .04 1.20 0.40 0.00 0.00 0.40 <
’1994/06/01;00:00:00’ 0.80 .05 1.20 0.40 0.00 0.00 0.40 <
’1994/06/11;00:00:00’ 0.80 .00 1.20 0.40 0.00 0.00 0.40 <
’1994/06/21;00:00:00’ 0.80 .00 1.20 0.40 0.00 0.00 0.40 <
’1994/07/01;00:00:00’ .00 .00 1.20 0.00 0.00 0.00 0.40 <
’1994/12/31;23:59:00’ .00 .00 1.20 0.00 0.00 0.60 0.40 <
tble
crf
CRF id ’Example Crop factors’ nm ’Example Crop factors’ PDIN 1 1 ’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 0.90 <
’1994/06/11;00:00:00’ 0.90 <
’1994/12/31;23:59:00’ 0.90 <
tble
crf
Optional: New format open water crop factor data <..\fixed\3B\NewCropOWData.dat>
This file contains the open water crop factors in a new format, which allows extensions by the
user. This file is similar to the new format crop data file, but somewhat simpler because there is
only 1 ‘crop’, i.e. open water. There are two type of records, the CROW and the CRFO records.
The file can contain several CROW and CRFO records. Selection of the actual records used
is done by using the options NewFormatCropFactors=-1 and OpenWaterCropDefinition= in
the Delft_3B.Ini file. An example input file:
CROW ’Default’ nm ’Nederlandse openwaterverdamping’ nc 1 cn ’Open water Netherlands’
cf ’Dutch Open water crop factors’ crow
CROW id ’Example’ nm ’Example open water evaporation’ nc 1 cn ’Open water Example’ cf
’Example Open water crop factors’ crow
CROW id ’Taiwan’ nm ’Taiwan open water evaporation’ nc 1 cn ’Open water Taiwan’ cf ’Taiwan
Open water crop factors’ crow
CRFO id ’Dutch Open water crop factors’ nm ’Dutch Open water Crop factors’ PDIN 1 1
’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 0.00 <
’1994/01/11;00:00:00’ 0.50 <
’1994/01/21;00:00:00’ 0.70 <
’1994/02/01;00:00:00’ 0.80 <
’1994/02/11;00:00:00’ 1.00 <
’1994/02/21;00:00:00’ 1.00 <
’1994/03/01;00:00:00’ 1.20 <
’1994/03/11;00:00:00’ 1.30 <
’1994/05/21;00:00:00’ 1.30 <
’1994/06/01;00:00:00’ 1.31 <
’1994/06/21;00:00:00’ 1.31 <
’1994/07/01;00:00:00’ 1.29 <
’1994/07/11;00:00:00’ 1.27 <
’1994/07/21;00:00:00’ 1.24 <
’1994/08/01;00:00:00’ 1.21 <
’1994/08/11;00:00:00’ 1.19 <
’1994/08/21;00:00:00’ 1.18 <

SOBEK input file formats

’1994/09/01;00:00:00’ 1.17 <
’1994/09/21;00:00:00’ 1.17 <
’1994/10/01;00:00:00’ 1.00 <
’1994/10/11;00:00:00’ 0.90 <
’1994/10/21;00:00:00’ 0.80 <
’1994/11/01;00:00:00’ 0.80 <
’1994/11/11;00:00:00’ 0.70 <
’1994/11/21;00:00:00’ 0.60 <
’1994/12/01;00:00:00’ 0.00 <
’1994/12/31;23:59:00’ 0.00 <
tble
crfo
CRFO id ’Taiwan Open water crop factors’ nm ’Taiwan Open water Crop factors’ PDIN 1 1
’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 1.00 <
’1994/02/01;00:00:00’ 1.05 <
’1994/03/01;00:00:00’ 1.10 <
’1994/04/01;00:00:00’ 1.15 <
’1994/05/01;00:00:00’ 1.10 <
’1994/06/01;00:00:00’ 1.05 <
’1994/07/01;00:00:00’ 1.00 <
’1994/08/01;00:00:00’ 0.95 <
’1994/09/01;00:00:00’ 0.95 <
’1994/10/01;00:00:00’ 1.00 <
’1994/12/31;23:59:00’ 1.00 <
tble
crfo
CRFO id ’Example Open water crop factors’ nm ’Example Open water Crop factors’ PDIN 1 1
’31536000’ pdin TBLE
’1994/01/01;00:00:00’ 1.2 <
’1994/12/31;23:59:00’ 1.2 <
tble
crfo
Optional: New format soil data <..\fixed\3B\NewSoilData.dat>

This file contains the soil data in a new format, which allows extensions by the user. The file
contains several type of records, and is used to specify data on the soil types (both with or
without Capsim).

SLDF records: containing general definitions and references to other records.
NAME records, containing the names of the soil types (both with or without Capsim)
(the names are actually only relevant for the user interface)

SDEF records, containing the drainage depths (for use without Capsim)
STAB records, containing the tables with storage coefficients for use without Capsim;
values are specified for the number of specified soil types (from the SLDF record) and the
number of drainage depths (from the STAB record)
SCNV records, containing conversion tables from soil types to use without Capsim to
Capsim soil types.
An example is given below.
SLDF id ’Default’ nm ’Dutch default soils no Capsim’ ns 12 sn ’Default soil names’ nd 12 sd
’Default soil depths’ st ’Default table soil storage coefficients’ nsc 21 snc ’Capsim soil names’

SOBEK, User Manual

cv ’Default conversion’ sldf
SLDF id ’BergcoefARS4633’ nm ’Dutch default soils no Capsim’ ns 12 sn ’Default soil names’
nd 12 sd ’Default soil depths’ st ’Soil storage coefficients ARS4633’ nsc 21 snc ’Capsim soil
names’ cv ’Default conversion’ sldf
with
id of soil definition
name of soil definition
number of soil types, no Capsim
aantal bodemtypen, Capsim
soil names definition, no Capsim
soil names definition Capsim
number of drainage depths in table SDEF record
soil storage coefficient table for ns soil types and sd drainage depths (no Capsim)
id conversion tables

NAME id ’Default soil names’ nm

id
nm
ns
nsc
sn
snc
nd
st

’loamy, humous fine sand (µ=0.115 per m)’
’peat (µ=0.103 per m)’
’heavy clay (µ=0.089 per m)’
’humous clay and peat (µ=0.085 per m)’
’light loamy, medium coarse sand (µ=0.084 per m)’
’loamy silt (µ=0.072 per m)’
’humous clay and peat with silty top layer (µ=0.069 per m)’
’clay and light clay (µ=0.062 per m)’
’loamless, medium coarse and coarse sand (µ=0.060 per m)’
’silt (µ=0.058 per m)’
’very light clay (µ=0.048 per m)’
’sand with a silty top layer (µ=0.044 per m)’

NAME id ’Capsim soil names’ nm
’Veengrond met veraarde bovengrond’
’Veengrond met veraarde bovengrond, zand’
’Veengrond met kleidek’
’Veengrond met kleidek op zand’
’Veengrond met zanddek op zand’
’Veengrond op ongerijpte klei’
’Stuifzand’
’Podzol (Leemarm, fijn zand)’
’Podzol (zwak lemig, fijn zand)’
’Podzol (zwak lemig, fijn zand op grof zand)’
’Podzol (lemig keileem)’
’Enkeerd (zwak lemig, fijn zand)’
’Beekeerd (lemig fijn zand)’
’Podzol (grof zand)’
’Zavel’
’Lichte klei’

SOBEK input file formats

’Zware klei’
’Klei op veen’
’Klei op zand’
’Klei op grof zand’
’Leem’
name
with
id
nm

name definition id
crop names for all crops
(the number of names should match with the number specified in the SLDF
record for this name definition id)

SDEF id ’Default soil depths’ dp -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -0.8 -0.9 -1.0 -1.2 -1.5 SDEF
with

soil drainage depth definition id
drainage depths (corresponding with nd drainage depths as specified in the
SLDF record)

STAB id ’Default table soil storage coefficients’ nm ’Default ns*nd storage coefficient values’
sc
0.0050 0.0080 0.0230 0.0070 0.0030 0.0070 0.0060 0.0130 0.0020 0.0050 0.0070 0.0030
0.0145 0.0195 0.0385 0.0175 0.0100 0.0155 0.0150 0.0235 0.0085 0.0125 0.0140 0.0080
0.0243 0.0313 0.0497 0.0273 0.0190 0.0243 0.0243 0.0310 0.0157 0.0200 0.0200 0.0130
0.0342 0.0433 0.0585 0.0370 0.0290 0.0325 0.0338 0.0375 0.0225 0.0268 0.0252 0.0178
0.0486 0.0544 0.0654 0.0462 0.0390 0.0400 0.0414 0.0430 0.0292 0.0330 0.0300 0.0226
0.0635 0.0652 0.0713 0.0548 0.0490 0.0472 0.0480 0.0477 0.0360 0.0390 0.0342 0.0273
0.0777 0.0754 0.0766 0.0630 0.0580 0.0540 0.0540 0.0519 0.0424 0.0444 0.0380 0.0317
0.0910 0.0851 0.0810 0.0709 0.0678 0.0604 0.0596 0.0556 0.0486 0.0495 0.0415 0.0360
0.1034 0.0944 0.0850 0.0783 0.0763 0.0663 0.0649 0.0590 0.0547 0.0543 0.0447 0.0401
0.1148 0.1031 0.0887 0.0852 0.0845 0.0719 0.0697 0.0621 0.0605 0.0588 0.0476 0.0440
0.1350 0.1193 0.0950 0.0983 0.0992 0.0820 0.0786 0.0676 0.0713 0.0670 0.0529 0.0513
0.1595 0.1409 0.1027 0.1155 0.1182 0.0951 0.0902 0.0745 0.0858 0.0777 0.0597 0.0611
stab
STAB id ’Soil storage coefficients ARS4633’ nm ’Default ns*nd storage coefficient values’ sc
0.0074 0.0077 0.0094 0.0063 0.0046 0.0049 0.0049 0.0048 0.0027 0.0029 0.0025 0.0013
0.0183 0.0153 0.0166 0.0134 0.0124 0.0103 0.0118 0.0092 0.0098 0.0066 0.0052 0.0032
0.0302 0.0226 0.0226 0.0206 0.0220 0.0158 0.0181 0.0132 0.0162 0.0105 0.0079 0.0052
0.0419 0.0305 0.0278 0.0279 0.0323 0.0211 0.0237 0.0171 0.0228 0.0145 0.0107 0.0074
0.0532 0.0387 0.0323 0.0350 0.0427 0.0262 0.0289 0.0206 0.0294 0.0186 0.0134 0.0096
0.0664 0.0467 0.0363 0.0420 0.0528 0.0310 0.0339 0.0240 0.0359 0.0226 0.0160 0.0120
0.0805 0.0545 0.0399 0.0486 0.0625 0.0364 0.0386 0.0271 0.0422 0.0265 0.0185 0.0143
0.0938 0.0621 0.0431 0.0551 0.0715 0.0416 0.0430 0.0300 0.0484 0.0303 0.0210 0.0167
0.1061 0.0702 0.0461 0.0613 0.0801 0.0466 0.0472 0.0328 0.0542 0.0341 0.0235 0.0191
0.1173 0.0784 0.0489 0.0673 0.0880 0.0514 0.0512 0.0355 0.0598 0.0377 0.0258 0.0214
0.1372 0.0939 0.0538 0.0786 0.1024 0.0605 0.0586 0.0404 0.0704 0.0446 0.0303 0.0261
0.1614 0.1158 0.0600 0.0941 0.1208 0.0729 0.0685 0.0470 0.0845 0.0541 0.0366 0.0329
stab
with

SOBEK, User Manual

soil storage coefficient table id
name
storage coefficient vales (for nd drainage depths and ns soil types)

SCNV id ’Default conversion’ nocap ’Default soil names’ cap ’Capsim soil names’
c1 10 1 17 18 9 11 6 16 8 21 15 12 c2 2 2 7 7 7 7 9 9 1 1 1 12 1 5 11 8 3 4 12 12 6 scnv
with

Greenhouse layer
Data file: Greenhse.3b

soil conversion tabel id
soil names definitie zonder Capsim
soil names definitie met Capsim
conversion table of soil type (no Capsim) to soil type Capsim
conversion table of soil type Capsim to soil type (no Capsim)

id
nocap
cap
c1
c2

This file contains the data for the nodes of model type 3 (greenhouse or glasshouse area)
GRHS id ’1’ na 10 ar 1000. 0. 0. 3000. 0. 0. 0. 0. 0. 0. sl 1.0 as 0. sd ’roofstor_1mm’ si
’silo_typ1’ ms ’meteostat1’ is 50.0 grhs
With
id
na
ar
as
sl
sd
si
ms
is

node identification
number or areas (default=10)
area (in m2) as a table with areas for all greenhouse classes (na values)
greenhouse area connected to silo storage [m2 ]
surface level in m NAP
storage definition on roofs
silo definition
identification of the meteostation
initial salt concentration ([mg/l])

Roof storage file: Greenhse.rf

This file contains the roof storage definitions for the nodes of model type 3 (greenhouse area)
STDF id ’roofstor_1mm’ nm ’roof_1mm’ mk 1. ik 0. stdf
Where:
id
nm
mk
ik

storage identification
name (optional)
maximum storage on roofs (in mm). Default 1 mm. Initial value is zero by
default.
initial storage on roofs (in mm). Default 0. NOT READ. Default value zero
used.

Silo definition file: Greenhse.sil
This file contains the silo definitions for the nodes of model type 3 (greenhouse or glasshouse

SOBEK input file formats

area)
SILO id ’silo_typ1’ nm ’silo_200m3’ sc 200.0 pc 0.2 silo
With:
id
nm
sc
pc

dat=industry.dat
This file contains the data for the nodes of model type 15: industrial demands and/or discharges.
INDU id ’1’ dm ‘Qdemand’ ds ‘Qdis’ rf 90. sc. 100. co 1 indu
With
id
dm
ds
rf
sc
co

silo identification
name (optional)
silo capacity (m3/ha). Default 0.
silo pump capacity (m3/s). Default 0.

node identification
name of demand table (refer to tbl file)
name of discharge table (refer to tbl file)
return flow percentage
salt concentration of discharge
computation option: discharge as a table, of a percentage of allocation
1 = discharge and salt concentration as a table (ds field)
2 = fixed percentage and fixed salt concentration (rf and sc fields)

Optional fields:
redow

redlv
redbnlv
redrf

reduction level open water specified as absolute level (0) or relative to target
level (1)
level at open water node below which industrial abstraction is reduced
level at boundary node below which industrial abstraction is reduced
return flow reduction option
(0=same ratio as demand reduction; otherwise no reduction of return flow)

tab=industry.tbl

Contains demand flow and discharge flow and salt concentration tables
DISC id ’Qdis’ PDIN 1 1 ’1;00:00:00’ pdin
TBLE
1997/01/01;00:00:00 0.50 1000.0 <
1997/12/31;00:00:00 0.50 1000.0 <
tble
disc
DEMD id ’Qdemand’ PDIN 1 1 ’1;00:00:00’ pdin
TBLE
1997/01/01;00:00:00 0.60 <
1997/12/31;00:00:00 0.60 <

SOBEK, User Manual

tble
demd
With
id
nm

table identification
table name

PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period

0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss
1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss

After the date and time fields in the table of the DISC record, the first value is the discharge
(m3/s), the second value is the salt concentration (g/m3).
The table of the DEMD records only contains a demand (m3/s).
D.19.6

Data file: Pluvius.3B

This file contains the data for the nodes of model type 7 (NWRW rainfall-runoff nodes for
Sobek-Urban)
NWRW id ’1’ sl 2.0 ar 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. np 3 dw ’125_lcd’ ms ’meteostat1’
nwrw
or

NWRW id ’1’ sl 2.0 na 2 aa 123 456 nw ‘special1’ ‘special2’ ar 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
11. 12. np 3 dw ’125_lcd’ ms ’meteostat1’ nwrw
With
id
sl
ar

node identification
surface level (in m) (optional input data)
area (12 types) as combination of 3 kind of slopes (with a slope, flat, flat stretched)
and 4 types of surfaces (closed paved, open paved, roofs, unpaved)
a1=closed paved, with a slope
a2=closed paved, flat
a3=closed paved, flat stretched
a4=open paved, with a slope
..
a7=roofs, with a slope
..
a10=unpaved, with a slope
number of people
dry weather flow identification
identification of the meteostation

SOBEK input file formats

number of special areas with special inflow characteristics
special area in m2 (for number of areas as specified after the na keyword)
reference to definition of special inflow characteristics (for na special areas)

Remarks:
- Number of areas (3 type of slopes, 4 types of surfaces, 12 possible combinations) is
hard-coded.
- Salt concentrations are not implemented for this type of node.
DWA file: Pluvius.Dwa

DWA id ’125_lcd’ nm ’125_liters per day’ do 1 wc 12. wd 125. wh 1.5 1.5 1.5 1.5 1.5 3.0 4.0
5.0 6.0 6.5 7.5 8.5 7.5 6.5 6.0 5.0 5.0 5.0 4.0 3.5 3.0 2.5 2.0 2.0 dwa

dwa identification
name
dry weather flow computation option
1 = nr. of people * constant DWA per capita per hour
2 = nr. of people * variable DWA per capita per hour
3 = 1 * constant DWA per hour
4 = 1 * variable DWA per hour
5 = using a table
water use per capita as a constant value per hour (l/hour)
water use per capita per day (l/day)
water use per capita per hour (24 percentages, total should be 100%)
dwa table id

NWRW table file: Pluvius.Tbl

This file contains the DWA discharges as a function of time. The lay-out is similar to other
time tables.
DW_T id ’DWA_table’ nm ’DWA_table’ PDIN 1 0 ’ ’ pdin
TBLE
1997/01/01;00:00:00 0.5 <
1997/05/01;00;00;00 0.55 <
1997/10/01;00:00:00 0.5 <
1997/12/31;23:59:00 0.50 <
tble
dw_t
With
id
nm

table identification
name of table

PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period
0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss

SOBEK, User Manual

1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss
TBLE .. tble contains the table, first column is the date (year month day hour minute second),
second column the DWA discharge in m3/s.
General data: Pluvius.Alg
This file contains the general data for the nodes of model type 7 (NWRW rainfall-runoff nodes)
PLVG id ’-1’ nm ’ ’ ru 0.5 0.2 0.1 ms 0.0.5 1.0 0 0.5 1.0 0. 2. 4. 2. 4. 6. ix 0. 2.0 0. 5.0
im 0. 0.5 0. 1.0 ic 0.0 0.1 0.0 0.1 dc 0.0 3.0 0.0 3.0 od 0 or 0 plvg

identification (default id –1; this record is the default general definition)
name
runoff-delay factor for 3 types of slopes (with a slope, flat, flat stretched)
maximum storage (in mm per m2) for 12 types of area (see plv file)
maximum infiltration capacities in mm/hour for 4 types of surface
(closed paved, open paved, roofs, unpaved)
minimum infiltration capacities in mm/hour for 4 types of surface
(closed paved, open paved, roofs, unpaved)
decrease in infiltration capacity (1/hour) for 4 types of surface
increase in infitration capacity (1/hour) for 4 types of surface
option for infiltration from depressions (1=yes, 0=no)
option for infiltration from runoff (1=yes, 0=no)

PLVA id ’Special1’ nm ’Special1’ ru .5 ms 1 ix 3 im 1 ic .5 dc .2 ef 1 od 1 or 0 plva
With:
id
nm
ru
ms
ix
im
ic
dc
ef
od
or

identification definition for special inflow areas
name
runoff-delay factor
maximum storage (in mm per m2)
maximum infiltration capacities in mm/hour
minimum infiltration capacities in mm/hour
decrease in infiltration capacity (1/hour)
increase in infitration capacity (1/hour)
evaporation factor (default=1.0)
option for infiltration from depressions (1=yes, 0=no)
option for infiltration from runoff (1=yes, 0=no)

SOBEK input file formats

Open water layer
Data file: Openwate.3b
This file contains the data for the nodes of model type 4 (open water area)
OPWA id ’1’ ml 0.0 rl 0.0 al 2 na 6 ar 10000. 110000. 120000. 130000 140000. 150000.
lv -1. -0.8 -0.6 -0.4 -0.2 0. bl -2.0 tl 0 -0.9 sp ’seep_1’ ms ’meteostat1’ is 75.0 opwa
With

na
ar
lv
ml
rl
bl
sp
ms
is
tl

node identification
area-level relation (only used by ModelEdit)
1 = constant area, 2=interpolation, 3=lineair
number of area/level combinations. Default 6. NOT READ.
6 values of area (in m2)
6 corresponding values of level (m NAP) in increasing order
maximum allowable level (m NAP)
reference level (m NAP)
bottom level (m NAP)
Default 1 meter below lowest value from area-level relation.
seepage definition.
identification of the meteostation
initial salt concentration (mg/l)
target level; constant or reference to a table.
tl 0 -0.9 = initial groundwater level as a constant, with value -0.9 m NAP.
tl 1 ’Tlv-Table’ = target open water levels as a table, with table id Tlv-Table.

Seepage definition file: Openwate.sep

This file contains the seepage definitions for the nodes of model type 4 (open water)
SEEP id ’seep_1’ nm ’constant seepage_1mm’ co 1 sp 1. ss 500. seep
SEEP id ’seep_2’ nm ’simple variable seepage’ co 2 cv 3.0 h0 ‘H0Table’ ss 500. seep
SEEP id ’seep_3’ nm ’variable seepage using coupling with Modflow’ co 3 cv 3.0 ss 500. seep
With:
id
nm
co

seepage identification
name
computation option seepage
1 = constant seepage (default)
2 = variable seepage, using C and a table for H0
3 = variable seepage, using C and H0 from Modflow
If the co field is missing, co 1 will be assumed.
Seepage or percolation (mm/day)
Positive numbers represent seepage, negative numbers represent percolation.
Default 0.
salt concentration seepage (mg/l). Default 500 mg/l.
This value is only important for positive seepage values.
Resistance value C for aquitard
reference to a table with H0 values

Remark: File could be combined with similar file from unpaved layer.

SOBEK, User Manual

Open water table file: Openwate.tbl
This file contains the tables for target levels and variable H0 values for the open water nodes.

OW_T id ’targetlevel table1’ PDIN 1 0 ’1;00:00:00’ pdin
TBLE
1995/01/01;00:00:00 0.3 <
1995/04/15;00:00:00 0.4 <
1995/09/14;23:00:00 0.4 <
1995/09/15;00:00:00 0.3 <
1995/12/31;23:59:00 0.3 <
tble
ow_t
With
table identification
name of table

Table input of the target open water level as function of time.

PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period

0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss
1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss

TBLE .. tble contains the table, first column is the date (year month day hour minute second),
second column the target level in m NAP. The < sign is a separator.
H0 table definitions:

H0_T id ’H0table’ PDIN 1 1 ’1;00:00:00’ pdin
TBLE
1995/01/01;00:00:00 0.4 <
1995/02/01;00:00:00 0.5 <
1995/03/01;00:00:00 0.5 <
1995/04/01;00:00:00 0.4 <
1995/05/01;00:00:00 0.3 <
1995/06/01;00:00:00 0.2 <
1995/07/01;00:00:00 0.1 <
1995/08/01;00:00:00 0.0 <
1995/09/01;00:00:00 0.0 <
1995/10/01;00:00:00 0.1 <
1995/11/01;00:00:00 0.2 <
1995/12/01;00:00:00 0.3 <
tble
h0_t
With:

SOBEK input file formats

table identification

PDIN .. pdin = period and interpolation method (for description see above)
Paved area layer
Data file: Paved.3B
This file contains the data for the nodes of model type 1 (paved or impervious area)

The keyword PAVE is used to mark the beginning of a record, and in lower case characters
it marks the end of a record. The keywords within the record may appear in any order (same
for other files). Some keywords within the records may be missing; in that case defaults will
be used. If essential keywords (e.g. the id) are missing, error message will follow.
PAVE id ’1’ ar 100000. lv 1.0 sd ’stor_1mm’ ss 0 qc 0 0.2 0 qo 1 1 so 0.5 0.5 si 0 0 ms
’meteostat1’ is 100. np 5000 dw ’1’ ro 1 ru 0.5 qh ‘Qhrelation’ pave
With
id
ar
lv
sd
ss
qc

node identification
area (in m2)
street level (m NAP)
storage identification
sewer system type (0=mixed, 1=separated, 2=improved separated)
capacity of sewer pump (m3/s)
qc 0 0.2 0.0 = capacity as a constant, with value 0.2 (mixed/rainfall sewer) and
0.0 (DWA in separated or improved separated systems). So, first value is for
mixed/rainfall sewer, second value for the dry weather flow (DWA) sewer.
qc 1 ’qctable1’ = capacity as a table, with table identification qctable1.
1 1 = both sewer pumps discharge to open water (=default)
0 0 = both sewer pumps discharge to boundary
0 1 = rainfall or mixed part of the sewer pumps to open water,
DWA-part (if separated) to boundary
1 0 = rainfall or mixed part of the sewer discharges to boundary,
DWA-part (if separated) to open water
2 2 = both sewer pumps discharge to WWTP
2 1 = rainfall or mixed part of the sewer pumps to open water,
DWA-part (if separated) to WWTP
etc.
Note: first position of record is allocated to DWA sewer, second position
is allocated to mixed/rainfall sewer; 0=to boundary, 1= to openwater, 2=to
WWTP. In all other keywords the order is just the other way around!!!!
sewer overflow level (first value for RWA/Mixed sewer, second value for DWA
sewer). If missing, the surface level will be used. The level is used to verify whether sewer overflows can occur (no overflows can occur if the related
boundary or open water level is higher)
sewer inflow from open water/boundary possible yes/no (1=yes,0=no); first value
for RWA/Mixed sewer, second value for DWA sewer). Default value is 0, meaning that no external inflow is possible.
identification of the meteostation by a character id
If this id is missing in the rainfall file, data from the first station in the rainfall file
will be used.
initial salt concentration (g/m3). Default 0.

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number of people
dry weather flow identification
runoff option
0 = default, no delay (=previous situation)
1 = using runoff delay factor (as in NWRW model)
2 = using Qh relation
runoff delay factor in (1/min) (as in NWRW model)
(only needed and used if option ro 1 is specified)
reference to Qh-relation
(only needed and used if option ro 2 is specified)

Storage Definition file: Paved.Sto

Spilling of paved area sewers occurs to the downstream open water node (if existing), otherwise to the downstream boundary. In case no downstream open water node and no downstream boundary exists, an error message will be given.

This file contains the storage definitions for the nodes of model type 1 (paved or impervious
area)
STDF id ’stor_1mm’ nm ’storage 1mm’ ms 1. is 0. mr 7.0 0.0 ir 0.0 0.0 stdf
With
id
nm
ms
is
mr
ir

storage identification
name (optional)
maximum storage on streets (mm). Default 1 mm.
initial storage on streets (mm). Default 0.
maximum storage sewer (mm). Default 7 mm.
initial storage in sewer (mm). Default 0.

For mr and ir different sewer systems are distinghuished (mixed systems, separated systems,
improved separated system). The first value is for mixed and rainfall sewer, the second value
for DWA sewer.
DWF definition file: Paved.dwa

This file defined the dry weather flow for paved area. It is similar to the DWA file for the NWRW
rainfall-runoff model.
DWA id ’125_lcd’ nm ’125 liter per capita per day’ do 1 wc 12. wd 125. wh 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 sc 50. dwa
id
nm
do
wc
wd
wh
sc

dwa identification
dwa name
dwa computation option
see NWRW dwa description.
water use per capita as a constant value per hour (l/hour)
water use per capita per day (l/day)
water use per capita per hour (24 percentages, total should be 100%)
salt concentration (mg/l) of DWA. Default 400 mg/l.
sc keyword is NOT READ. Default value always used.

Table definition file: Paved.tbl

SOBEK input file formats

For table input of the sewer pump capacity as function of time.
QC_T id ’qctable1’ nm ’Test’ PDIN 1 0 ’ ’ pdin
TBLE
1997/01/01;00:00:00 1.0 0.0 <
1997/12/31;00:00:00 1.0 0.0 <
tble
qc_t
With
id
nm

table identification
table name

0 0 ’ ’ = interpolation continuous, no period

1 0 ’ ’ = interpolation block, no period

PDIN ..pdin = period and interpolation method

0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss
1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss

TBLE .. tble contains the table, first column is the date (year month day hour minute second),
second and third column the capacity in m3/s. Third column is default zero, can only be used
for separated sewer systems. The < sign is used to separate the rows.
Period can be indicated in DDD;HH:mm:ss indicates a yearly period, for example 365;00:00:00.
This option is especially useful for open water target levels as a table.
The period is indicated within quotes; this is also done in the SOBEK-CF modeldatabase.
For a Qh-table the following lay-out is used:

QHTB id ’Qhrelation’ nm ‘Qhrelation table’ TBLE
0.0 0.0 <
0.01 0.5 <
0.03 1.0 <
0.05 1.5 <
0.07 2.0 <
tble qhtb
With the keywords:
id
nm

reference to Qh-relation
name of Qh-relation

TBLE . . . tble = table, with
1st column = Q in mm/s,
2nd column = h in mm.

SOBEK, User Manual

Runoff layer
Data file (sacrmnto.3b)
This file contains the data for the nodes Sacramento, HBV, SCS, NAM and external timeseries
SACR id ’5’ ar 319000000 ms ’1’ ca ’Capacities&Contents’ uh ’UnitHydrograph’ op ’OtherParameters’ sacr
EXTR id ‘nodeid’ ar 7010324 rs ‘rs7001’ ms ‘ms7001’ Extr
HBV id ‘nodeid’ ar 7010324 sl 300 snow ‘1’ soil ‘1’ flow ‘2’ hini’3’ ts ‘Moezeltemperature’ ms
‘Moezel’ aaf 0.9 hbv

SCS id ‘nodeid’ ar 7010324 slp 0.530683 le 2650.826 cn 50 ms ‘7001’ uh 1 amc 1 scs
SCS id ‘nodeid2’ ar 7010324 slp 0.530683 le 2650.826 cn 50 ms ‘7001’ uh 0 tl 1.0 scs
SCS id ‘nodeid3withbaseflow’ ar 7010324 slp 0.530683 le 2650.826 cn 50 ms ‘7001’ uh 0 tl
1.0 amc 1 bu 1 gsmax 100 gsinit 50 kr 0.01 scs
With
id
ar
ca
uh
op
rs
ms
ts
sl
snow
soil
flow
hini
slp
le
cn
uh

amc
aaf
bu
gsmax
gsinit
kr

node identification
area in m2
name of capacity and content definition (refer to sacrmnto.cap file)
name of unit hydrograph definition (refer to sacrmnto.uh file)
name of definition of other parameters (refer to sacrmnto.oth file)
runoff station
meteo station
temperature station
surface level (altitude)
reference to snow definition in SNOW record
reference to soil definition in SOIL record
reference to flow definition in FLOW record
reference to initial water contents definition in HINI record
average basin slope (m/m)
flow path length to outlet (m)
SCS curve number
SCS unit hydrograph option (optional)
default value uh 0 = HEC-HMS unit hydrograph; other option uh 1 = SCS dimensionless unit hydrograph.
SCS time lage (hours), optional input
(if not specified, computed using SCS time lag formula from SCS curve number,
average basin slope and flow path length)
antecedent moisture condition. 1=dry, 2=average, 3=wet.
The keyword is optional, if missing a default value of 2 is assumed.
area adjustment factor. Optional keyword, default value 1.
Value should be >=0.
baseflow used; 0=no, 1=yes. Default 0
groundwater storage, maximum value (mm)
groundwater storage, initial value (mm)
recession coefficient Kr (1/day)

In the SACR, HBT and SCS record also the aaf keyword is optionally present to specify area

SOBEK input file formats

adjustment factor. There are no other changes in the SACR, HBV, EXTR, SNOW, SOIL,
FLOW, HINI records in the Sacrmnto.3B file.
Capacities and contents definition file (sacrmnto.cap)
This file contains the definitions of the capacities, initial contents, and reservoir coefficients of
the Sacramento soil storage reservoirs.
CAPC id ’Capacities&Contents’ uztwm 50 uztwc 50 uzfwm 150 uzfwc 100 lztwm 150 lztwc
150 lzfsm 200 lzfsc 100 lzfpm 150 lzfpc 150 uzk .08 lzsk .05 lzpk .003 CAPC
With

identification
upper zone tension water storage capacity (maximum content)
upper zone tension water initial content
upper zone free water storage capacity (maximum content)
upper zone free water initial content
lower zone tension water storage capacity
lower zone tension water initial content
lower zone supplemental free water storage capacity
lower zone supplemental free water initial content
lower zone primary free water storage capacity
lower zone primary free water initial content
upper zone drainage rate
lower zone secondary drainage rate
lower zone primary drainage rate

id
uztwm
uztwc
uzfwm
uzfwc
lztwm
lztwc
lzfsm
lzfsc
lzfpm
lzfpc
uzk
lzsk
lzpk

Unit hydrograph definition file (sacrmnto.uh)

UNIH id ’UnitHydrograph’ uh 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 dt 1 unih
With
id
uh
dt

identification
unit hydrograph components
step size to be applied on unit hydrograph components

other data file (sacrmnto.oth)
Other Sacramento parameters:

OPAR id ’OtherParameters’ zperc 5.0 rexp 9.0 pfree 0.2 rserv 0.95 pctim 0 adimp 0.5 sarva
0.0 side 0.0 ssout 0.0 pm 0.1 pt1 500 pt2 500 opar
With
id
zperc
rexp
pfree
rserv
pctim
adimp

identification
proportional increase in percolation from saturated to dry conditions
exponent in percolation equation
fraction of percolated water directly to lower zone free water
fraction of lower zone free water unavailable for transpiration
permanently impervious fraction of basin
fraction of basin which becomes impervious as all tension water

SOBEK, User Manual

requirements are met
fraction of basin covered by streams, channels
portion of baseflow not observed in the stream channel
sub-surface outflow
time interval increment parameter
rainfall threshold 1
rainfall trheshold 2

sarva
side
ssout
pm
pt1
pt2

For an explanation of the Sacramento concepts and parameters, reference is made to the
HYMOS manual.
NAM rainfall runoff model

1 NAM database record (Main record)

The SOBEK graphical user interface writes all D-NAM input parameters (see section 5.4.13)
into six different type of NAM database records, that are stored in the
database file.

NAM id ’1’ nm ’1’ ar 5000000 sp ’##1’ lwd ’##1’ sr ’##1’ bf ’##1’ gw ’##1’ ms ’Station1’ aaf
1 nam

where:
id
nm
ar
sp

ID of D-NAM node
NAME of D-NAM node (optional)
Catchment area [m2 ]
Reference to NAMS database record with id=##1, containing the soil parameters definition
Reference to NAML database record with id=##1, containing the levels and
initial water depth definition
Reference to NAMR database record with id=##1, containing the surface
runoff parameters definition
Reference to NAMB database record with id=##1, containing the base flow
parameters definition
Reference to NAMG database record with id=##1, containing groundwater
pump definition
Meteo-station
Area adjustment factor [-]

2 NAMS database record (Soil parameters definition)

NAMS id ’##1’ nm ’SoilDef01’ infcap 11 sfc 0.8 syrz 0.9 syss 0.4 capo 0 capc 12 capt
PDIN 0 0 ” pdin
TBLE
.2 15 <
.5 12 <
1 10 <
2 10 <
tble
pero 0 perc 8 pert PDIN 0 0 ” pdin
TBLE
01<
15<
28<

SOBEK input file formats

4 16 <
tble
nams
where:

nm
infcap
sfc
syrz
syss
capo
capc
capt

ID of this NAMS database record, containing a particular soil parameter
definition
Name of this NAMS database record, containing a particular soil parameter
definition (shown in GUI)
Maximum infiltration capacity (IN F Cap) [mm/hr]
Field capacity of root zone layer (sf c ) [-]
Specific yield of root zone layer (sy,rz ) [-]
Specific yield of subsoil layer (sy,ss ) [-]
Option for capillary rise (CR), 0 = Constant, 1 = Table
Capillary rise (CR) [mm/day] as a Constant
Capillary rise (CR) [mm/day] as Function of groundwater table depth in
default SOBEK format
Option for Percolation capacity (G), 0 = Constant, 1 = Table
Percolation Capacity (G) as a Constant [mm/day]
Percolation Capacity (G) as Function of groundwater table depth [mm/day]
in default SOBEK format

3 NAML database record (Levels and initial water depth definition)

NAML id ’##1’ nm ’IniValDef01’ sl 6.66 rzbl 4 gwsbl 3 ui 25 li 400 gwsdi 45 naml
where:
id

sl
rzbl
gwsbl
ui
li
gwsdi

ID of this NAML database record, containing a particular level and initial
water depth definition
Name of this NAML database record, containing a particular level and initial
water depth definition (shown in GUI)
Surface level (SL) [m AD]
Bed level of the root zone layer (RZBL) [m AD].
Bed level of the subsoil layer or groundwater storage (GW SBL) [m AD]
Initial water depth in the surface storage (Ui ) [mm]
Initial water depth in lower zone storage (Li ) [mm]
Initial water depth in groundwater storage (GW SDi ) [mm]

4 NAMR database record (Runoff parameters definition)

NAMR id ’##1’ nm ’Runoff’ cl 5000 ss 0.001 man 0.02 utof 5 ckif 1000 utif 1 ltif 5 namr
where:
id
nm
cl
ss
man
utof

ID of this NAMR database record, containing a particular runoff parameters
definition
Name of this NAMR database record, containing a particular runoff parameter definition (shown in GUI)
Catchment length (CL) [m]
Averaged slope of the catchment surface area towards its overland outflow
point (S ) [-]
Manning value (n) for the roughness of the surface catchment area [s/m1/3 ]
Threshold, used in determining if water in the surface storage may flow out

SOBEK, User Manual

as overland flow [mm]
Reservoir coefficient used in routing interflow [days]
Threshold, used in determining if water in the surface storage may flow out
as interflow [mm]
Lower-zone-storage-threshold, used in determining if water in the surface
storage may flow out as interflow [mm]

5 NAMB database record (Base flow parameters definition)
NAMB id ’##1’ nm ’BaseFlow’ ckfastbf 1500. ckslowbf 2500. ckgwinf 3000. ltp 10. tfastbf
-1.0 tslowbf -5.0 namb
where:

ckfastbf
ckslowbf
ckgwinf

ID of this NAMB database record, containing a particular base flow parameter definition
Name of this NAMB database record, containing a particular base flow parameter definition (shown in GUI)
Reservoir coefficient used in routing fast base flow (CKF astBF ) [days]
Reservoir coefficient used in routing slow base flow (CKSlowBF ) [days]
Reservoir coefficient used for the inflow of external (ground)water
(CKGWInflow ) [days]
Threshold, used in determining if water in the lower zone storage may percolate to the groundwater storage (LT P ) [mm]
Threshold for fast base flow (TF astBF ) [m AD]. Only water in the groundwater storage above TF astBF can flow out as fast base flow]
Threshold for slow base flow (TSlowBF ) [m AD]. Only water in the groundwater storage above TSlowBF can flow out as slow base flow

Note: CKGWInflow ≥ CKSlowBF ≥ CKFastBF ≥ 1 .

6 NAMG database record (Groundwater pump definition)

NAMG id ’##1’ nm ’GWPump’ po 0 pu 0.1 pt PDIN 0 1 ’365;00:00:00’ pdin
TBLE
’2001/01/01;00:00:00’ 0.0 <
’2001/03/31;23:59:00’ 0.0 <
’2001/04/01;00:00:00’ 0.1 <
’2001/09/30;23:59:00’ 0.1 <
’2001/10/01;00:00:00’ 0.0 <
’2001/12/31;00:00:00’ 0.0 <
tble
namg
where:
id
nm
po
pu
pt

ID of this NAMG database record, containing a particular groundwater pump
definition
Name of this NAMG database record, containing a particular groundwater
pump definition (used in GUI)
Pumping option, 0 = Constant, 1 = Time Series
Discharge of the groundwater pump (GW P ump) as a Constant [m3 /s]
Discharge of the groundwater pump (GW P ump) as a Time series [m3 /s]
in default SOBEK format

SOBEK input file formats

Walrus rainfall runoff model

The file:
The file contains switch (UseWalrusorWagmod=ModelName):

SOBEK 2: Switch set as UseWalrusorWagmod=WALRUS, means that the Walrus model

is run. Switch set as UseWalrusorWagmod=WAGMOD, means that the WAGMOD model
is run. Limitation, the Walrus and Wagmod model cannot jointly be used during a simulation.
SOBEK 3: Switch is default set as UseWalrusorWagmod=WALRUS, since the Wagmod
model cannot be run in SOBEK 3.
Following five numerical parameters can be specified in the file, which control
the Walrus internal timestep (i.e. possible reductions of the user-defined timestep):
1 Walrus_min_deltime: minimum timestep in seconds (default=60.0)
2 Walrus_maxhchange: maximum change in the water depth of the surface water reservoir
and/or quickflow reservoir in 1 internal timestep in mm (default =10.0).
3 Walrus_minh: minimum water depth in the the surface water reservoir and/or quickflow
reservoir in mm (default =0.001).
4 Walrus_max_pstep: maximum precipitation in 1 internal Walrus timestep in mm (default
=10.0).
5 Walrus_max_substeps: maximum number of internal timesteps in 1 computation timestep
(default=288)

Note: For more information on the Walrus time step reduction procedure, reference is made
to section "Possible time step reductions and applied threshold values" in the technical reference manual.

Walrus database records in the file

DeltaShell (graphical user interface) writes the input parameters of a Walrus catchment into
six different type of Walrus database records, that are stored in the database
file. These Walrus database records are:
1 The WALR database record (main record):

WALR id ‘node id’ nm ‘node name’ ar 1000 sl 20.1 wa 0 cw 200 wit ‘wetness index table’ cv 4 cg 5000000 cq 10 va 0 vit ‘Veq table’ ba 0 bit ‘evaporation reduction table’ qa 0
qit ‘Qh interpolation table’ cs 4 xs 1.5 as 0.01 cd 1500 hst 0 hsmin 0 hstable ‘1’ st 21 b
4.05 psi_ae 121 theta_s 0.395 hs0 0 hq0 0 dg0 0 dv0 0 q0 1 ms ‘meteostation’ msevap
‘evap’ fxs ‘sw supply/extraction’ fxg ‘seepage’ aaf 1.0 walr
where:
id
nm
ar
sl
wa

Walrus node id
Walrus node name
Catchment surface area [m2 ]
Surface level of the catchment area (optional) [m AD]
-1 (wetness index is determined, applying the Walrus analytical formulation

SOBEK, User Manual

for wetness index and value for parameter cw), or
0 (wetness index is determined, applying the user-defined interpolation table for wetness index).
Wetness index parameter [mm] (default=200). Value for cw is only used if
wa=-1.
id of a user-defined interpolation table for the wetness index, which is to be
specified on a WETN database record. This interpolation table is only used
if wa=0.
Vadose zone relaxation time constant [hours] (default=4).
Constant parameter applied in computing groundwater drainage or infiltration [mm hour] (default=5000000).
Quickflow constant reservoir coefficient [hours] (default=10).
-1 (equilibrium storage deficit is determined, applying the Walrus analytical
formulation for equilibrium storage deficit), or
0 (equilibrium storage deficit is determined, applying the user-defined interpolation table for equilibrium storage deficit).
id of a user-defined interpolation table for equilibrium storage deficit, which
is to be specified on a VEQD database record. This interpolation table is
only used if va=0.
-1 (transpiration reduction factor β is determined, applying the Walrus analytical formulation for β ), or
0 (transpiration reduction factor β is determined, applying the user-defined
interpolation table for β ).
id of a user-defined interpolation table for the transpiration reduction factor
β , which is to be specified on a BETA database record. This interpolation
table is only used if ba=0.
-1 (discharge Q flowing out of the surface water reservoir is determined,
applying the Walrus analytical formulation for Q), or
0 (discharge Q flowing out of the surface water reservoir is determined,
applying the user-defined interpolation table for Q).
id of a user-defined interpolation table for discharge Q flowing out of the
surface water reservoir, which is to be specified on a WQH database record.
This interpolation table is only used if qa=0.
Bankfull discharge of the surface water reservoir [mm/hour] (default=4).
Value for cs is only used if qa=-1.
Exponent in Walrus analytical formulation for computing discharge (Q) flowing out of the surface water reservoir (default=1.5). Value for xs is only used
if qa=-1.
Surface water area fraction, ratio of the area of the surface water reservoir
and the catchment surface area [-] (default=0.1)
Channel depth or bed level of the surface water reservoir [mm below SL]
(default=1500).
-1 (value of hS,min in the Walrus analytical formulation for discharge (Q)
flowing out of the surface water reservoir is defined as a time table), or
0 (a constant value is defined for hS,min in the Walrus analytical formulation
for discharge (Q) flowing out of the surface water reservoir).
For a water depth in the surface water reservoir equal to hS,min , the outflow
of the surface water reservoir Q equals zero. Value for hsmin is only used
if qa=-1.
id of the user-defined time table for hsmin, which is to be specified on a
HSTT database record. This time table is only used if qa=-1 and hst=-1.
Soil type (default; st=22 loamy sand). For soil types st=21 up to st=33 yields
that values for b, ψae and θS are read from Table D.1. For soil type st=34
(custom) yields that the values for b, ψae (or psi_ae) and θS (or theta_s) are

SOBEK input file formats

psi_ae
theta_s
hs0
hq0
dg0
dv0
q0
ms
msevap

applied, that are specified hereunder.
Pore size distribution parameter [-]. This value for b is only used if soil type
st=34 (custom) is selected.
Air entry pressure [mm]. This value for psi_ae is only used if soil type st=34
(custom) is selected.
Soil moisture content at saturation [-]. This value for theta_s is only used if
soil type st=34 (custom) is selected.
Initial water depth in surface water reservoir [mm]
Initial water level in quickflow reservoir [mm]
Initial groundwater table depth [mm]
Initial water-storage deficit (or availabe water storage capacity in vadose
zone of soil water reservoir [mm]
Initial discharge flowing out of the surface water reservoir [mm/hour]
Reference (or id) to meteo-station with rainfall time-series in [mm/timestep]
Reference (or id) to meteo-station with potential evapotranspiration timeseries in [mm/timestep] (to give the option to specify evaporation not only
as daily values, but in detail)
Reference (or id) to surface water supply or extraction time-series in [mm/timestep] (from rainfall file)
Reference (or id) to groundwater seepage or extraction time-series in [mm/timestep] (from rainfall file)
Area adjustment factor for rainfall (default 1.0)

Please note that:

Input parameters ar, cw, cv, cg, cq, cs, cd, xs, hsmin, as, hs0, hq0, dg0, dv0 and q0
should be larger than or equal to zero.

For input parameters hsmin and cd should yield that hsmin < cd. Since, the q = 0
level (coinciding with hsmin) should be smaller than the channel depth (cd).

The groundwater reservoir area fraction (aG ) is not defined in the WALR database
record, since aG = 1-as.
If a restart file is used, the values for hs0, hq0, dg0, dv0 and q0 are read from the
restart file. So the values specified in the WALR database record are neglected.

Time-series for precipitation (P ), potential evapotranspiration (ETpot ), groundwater
seepage and extraction (fxg) and external surface water supply or extraction (fxs) are
assigned to a particular meteo-station (ms). The id of this meteo-station as well as the
time-series data is read from a particular rainfall file.
Table D.1: Soil types and related Walrus parameter values.

Walrus
soil type

Pore-size
distribution
parameter

Air entry
pressure

Soil moisture
content at
saturation

21
22
23
24
25
26
27
28

sand
loamy_sand
sandy_loam
silt_loam
loam
sandy_clay_loam
silt_clay_loam
clay_loam

4.05
4.38
4.9
5.3
5.39
7.12
7.75
8.52

121
90
218
786
478
299
356
630

0.395
0.410
0.435
0.485
0.451
0.42
0.477
0.476

SOBEK, User Manual

29
30
31
32
33
34

sandy_clay
silty_clay
clay
cal_Hupsel
cal_Cabauw
custom

10.4
10.4
11.4
2.63
16.77
User defined

153
490
405
90
9
User defined

0.426
0.492
0.482
0.418
0.639
User defined

Note: Soil type descriptions "cal_Hupsel" and "cal_Cabauw" are respectively the calibrated dataset for the Hupselse Beek catchment and the Cabauw catchment in the Netherlands.

2 The WETN database record (Wetness index (W ) interpolation table)
WETN id ‘wetness index table’ nv 4 dv 0 100 200 300 wi 1.0 0.7 0.1 0.0 wetn
where:

Table id (matching with id given after keyword wit in the WALR database
record)
Number of values (length of table)
Water-storage deficit (dV ) values [mm]. For dv should yield dv ≥ 0; consecutive values for dv should be increasing.
Wetness index (W ) [-] For wi should yield 0 ≤ wi ≤ 1; consecutive values
for wi should be non-increasing.

3 The BETA database record (Transpiration reduction (β ) interpolation table)
BETA id ‘evaporation reduction table’ nv 5 dv 0 100 200 300 400 er 1.0 0.99 0.9 0.75
0.0 beta
where:
id
nv
dv
er

Table id (matching with id given after keyword bit in the WALR record)
Number of values (length of table)
Water-storage deficit (dV )values [mm]. For dv should yield dv ≥ 0; consecutive values for dv should be increasing.
Transpiration reduction factor (β ) [-]. For er should yield 0 ≤ er ≤ 1; consecutive values for er should be non-increasing.

4 The VEQD database record (Equilibrium water-storage deficit (dV,eq ) interpolation table)
VEQD id ‘Veq table’ nv 6 dg 0 250 500 1000 1500 2000 veq 0.0 0.0 100 250 500 900
veqd
where:
id
nv
dg
veq

Table id (matching with id given after keyword vit in the WALR record)
Number of values (length of table)
Groundwater table depth (dG ) [mm]. For dg should yield dg ≥ 0; consecutive values for dg should be increasing.
Equilibrium water-storage deficit (dV,eq ) [mm]. For veq should yield veq
≥ 0; consecutive values for veq should be non-decreasing.

SOBEK input file formats

5 The WQH database record (Discharge relationship (Q = f (hS ) interpolation table)
WQH id ‘Qh interpolation table’ nv 4 hs 0 1000 1500 2000 q 0.0 1.0 2.0 3.0 wqh
where:
id
nv
hs

Table id (matching with id given after keyword qit in the WALR record)
Number of values (length of table)
Surface water depth (hS ) [mm]. For hs should yield hs ≥ 0; consecutive
values for hs should be increasing.
Discharge (Q) flowing out of the surface water reservoir [mm/hour]. For q
should yield q ≥ 0; consecutive values for q should be non-decreasing.

HSTT id ’1’ nm ’table hsmin’
PDIN 1 0 ’365;00:00:00’ pdin
TBLE
’2016/01/01;00:00:00’ 0.0 <
’2016/04/01;00:00:00’ 20.0 <
’2016/10/01;00:00:00’ 0.0 <
’2016/12/31;23:59:00’ 0.0 <
tble
hstt

6 The HSTT database record (Time-series for hS,min )

Table id (matching with id given after keyword hstable in the WALR database
record)
nm
Name of table
PDIN 1 0 ‘365;00:00:00’ pdin
First value: 0 (linear interpolation) / 1(block interpolation)
Second value: 0 (no periodicity) / 1 (periodic)
Third value: period in ‘days;hh:mm:ss’ (only used if second value equals 1)
TBLE . . . tble
Free number of sub-records allowed. Each sub-record consecutively contains: date ‘YYYY/MM/DD;hh:mm:ss’, value and <, denoting the end of a
sub-record.

Structure layer

Data file: Struct3b.dat

STRU id ’pomp1’ dd ’pomp1’ ca 0 0 0 0 cj ’-1’ ’-1’ ’-1’ ’-1’ STRU
With:
id
dd
ca
cj

node identification
structure definition
controller active (1=yes, 0=no.). To be consistent with the SOBEK modeldatabase 4 controllers are allowed. Only the first is used at the moment.
controller id’s (-1 for no controller). Only the first is used.

Structure table file: Struct3b.Tbl

SOBEK, User Manual

Contains the tables of switch on/off levels for pumps (including inlet pumps), weir or gate
settings as a function of time, switch-on/off levels for inlet weirs and gates.
Switch-on and -off levels for a pump:

SWLV ’on-off_levels’ nm ’ pump1’ PDIN 0 0 ’1;00:00:00’ pdin
TBLE
1997/01/01;00:00:00 0.03 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
1997/04/01;00:00:00 0.04 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
1997/05/01;00:00:00 0.05 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
1997/08/01;00:00:00 0.05 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
1997/10/01;00:00:00 0.04 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
1997/11/01;00:00:00 0.03 -0.03 0.10 0. 0.03 -0.05 0.10 0.02 <
tble
swlv

The first column in the table indicates the date, the second 4 values are the switch-on and off
levels relative to the related open water target levels during the day (on low, off low, on high,
off high), the next 4 values are the switch-on and off levels relative to the related open water
target levels during the night (on low, off low, on high, off high)
For a normal pump the switch-on levels will be higher than the switch-off levels; for an inlet
pump it will be just the other way around.
Switch-on and -off levels for a weir or gate:

For a weir or gate the table contains only 2 values per line, viz. the switch-on and off level
relative to the related open water target levels. The switch-on level for inlet weirs or gate will
be smaller than the switch-off level.
SWLV ’on-off_levels’ nm ’ weir1’ PDIN 0 0 ’1;00:00:00’ pdin
TBLE
1997/01/01;00:00:00 -0.05 0.03 <
1997/05/01;00:00:00 -0.03 0.05 <
1997/08/01;00:00:00 -0.05 0.03 <
1997/12/31;00:00:00 -0.05 0.03 <
tble
swlv
Consistency checks for normal pumps: (dn 1)

switch on levels >=switch off levels,
switch-on level low capacity <= switch-on level high capacity
switch-off level low capacity <= switch-off level high capacity
for dn 2 (inlet pump) just the other way around.
Initial weir or gate settings:
INST ’init_weir_setting’ nm ’ name1’ PDIN 0 0 ’1;00:00:00’ pdin
TBLE
1997/01/01;00:00:00 -1.5 <
1997/04/01;00:00:00 -1.45 <
1997/05/01:00:00:00 -1.40 <

SOBEK input file formats

1997/09/01:00:00:00 -1.45 <
1997/10/01:00:00:00 -1.50 <
tble
inst
In previous versions of Sobek-RR always block interpolation was assumed, but since version
2.06.000.35g the data specified for PDIN .. pdin is used.
Controller definition file: Contr3B.Def
This file contains the definition of the controllers of RR-structures.

11 = 3B -PID controller (not yet available)
12 = 3B -fixed upstream level controller

13 = 3B -fixed level difference controller

The following type of controllers are distinguished (type numbering starts at 11, to prevent
confusion with Sobek-controllers):

14 = 3B -minimum level difference controller
15 = 3B -time controller

PID controller not yet defined and implemented
CNTL id ’1’ nm ’3B_PID’ ty 11 cntl
....

All controllers can at the moment only be defined for normal weirs, except for the time
controller. The time controller is also available for normal RR-pumps and RR-orifices.
Fixed upstream level controller with flow limitation:

CNTL id ’1’ nm ’target level controller’ ty 12 mf 1.0 ml -0.5 md -0.7 zmin -2.75 zmax -2.0 cntl
with

id
nm
ty
mf
ml
md
zmin

controller definition identification
name
controller type (12=fixed upstream level controller)
maximum flow
maximum level above which the maximum flow may be exceeded
maximum downstream level
minimum crest level in m w.r.t. reference level (optional keyword);
(if this is not specified, the lowest crest level is taken equal to the bottom level
of
the boundary or the RR-open water; this keyword provides a way to specify a
higher lowest level)
maximum crest level in m w.r.t. reference level (optional keyword);
(if this is not specified, the maximum crest level is taken equal to 9999.99;
this keyword provides a way to specify a lower maximum crest level)

SOBEK, User Manual

This controller tries to maintain the upstream target level as long as the flow over the structure does not exceed the maximum flow; if the flow equals the maximum flow, the level may
increase up to the maximum level; at that time the maximum flow may also be exceeded. If
the downstream level exceeds the specified maximum downstream level, a more strict flow
limitation is used.
Firstly, it is verified that this flow can be physically realised by lowering the weir to the specified
lowest value zmin (either bottom level, or a higher user defined level).

Fixed level difference controller:

CNTL id ’1’ nm ’3B_fixed level difference’ ty 13 cntl

Secondly, there may be a maximum crest level zmax which limits the operation of the weir.
If not specified, the controller operates such that negative weir flows are not allowed (this is
equivalent with specifying zmax very high). If a zmax is specified, negative flows may occur (if
the downstream level is higher than the upstream level; and also either the downstream level
is above the zmax level or the upstream level is below target level)

controller definition identification
name
controller type (13=fixed level difference controller)

This controller requires no extra input data; the fixed level difference is taken as the difference
of the upstream and downstream target levels.
Minimum level difference controller:

CNTL id ’1’ nm ’3B_minimum level difference’ ty 14 ml 0.1 cntl
with
id
nm
ty
ml

controller definition identification
name
controller type (14=minimum level difference controller)
minimum level difference. NOT READ; minimum level difference is defined
as difference in upstream and downstream target levels.

Time controller:

CNTL id ’1’ nm ’3B_time controller’ ty 15 ts ’TimeTable’ cntl
With:
id
nm
ty
tb

controller definition identification
name
controller type (15=time controller)
name of controller table

This controller requires a table with the time settings of the crest level (weir), opening height
(gates), or capacity (pumps). All tables are specified in the Structure Table using the INST
records. This has the advantage that the table for the initial settings of weirs/gates and the
tables for the time controller can be the same.

SOBEK input file formats

Equal filling controller:
** To be completed **
CNTL id ’1’ nm ’3B_equal filling controller’ ty 16 mf 1.0 mf2 5.0 zmin 0. zmax 1. cntl
with

controller definition identification
name (optional)
controller type (16=equal filling controller)
maximum flow at target level (from upstream open water)
maximum flow at maximum level (from upstream open water)
minimum crest level in m w.r.t. reference level (optional keyword);
(if this is not specified, the lowest crest level is taken equal to the bottom level
of
the boundary or the RR-open water; this keyword provides a way to specify a
higher lowest level)
maximum crest level in m w.r.t. reference level (optional keyword);
(if this is not specified, the maximum crest level is taken equal to 9999.99;
this keyword provides a way to specify a lower maximum crest level)

id
nm
ty
mf
mf2
zmin

Structure definition file: Struct3b.def

This file contains the data for the nodes of Sobek-RR-model type 8 to 12 (various types
of structures: pump, weir, gate, Manning resistance, Q-h relation). The following type of
structures are present in Sobek-RR:
8=pump
9=weir

11=Manning resistance
12= Q-h relation

Where possible, the keywords are chosen equal as in the Sobek-modeldatabase, to enable
using the same conventions and routines.
The definition for a pump:

STDS id ’1’ nm ’3B-pomp’ ty 8 in 0 dn 1 nc 2 pc 0.5 0.2 so ’on-off_levels’ stds
With:
id
nm
ty
in
dn

id van de structure definition definition
name of pump (optional)
type of structure (8=3B-pomp)
inlet pump (0=no, 1=yes). Default 0.
Direction and type of control
1 : Check upstream level only (normal pump). Default.
2 : Check downstream level only (inlet pump)
Number of capacities. Default = 2. NOT READ. Default value 2 used.

SOBEK, User Manual

Pump capacities (in m3/s).
First value low capacity, second value extra capacity at high capacity.
In the future maybe more values, depending on nc.
switch-on and switch-off levels. Reference to a table.

The definition for a weir:
STDS id ’1’ nm ’3B-overlaat’ ty 9 in 0 wt 1 dc 1.1 cl -1.5 cw 3.0 cp 1.5 rt 0 ws ’init_weir_setting’
fl 0. stds
or

STDS id ’1’ nm ’3B-overlaat’ ty 9 in 1 wt 2 sl 1.0 dc 1.1 cl -1.5 cw 3.0 cp 2.5 rt 0 ws
’init_weir_setting’ so ‘table2’ fl 0. stds
or

With:
id
nm
ty
in
wt
sl
dc
cl
cw
cw2
cl2

STDS id ’23’ nm ’3B-overlaat’ ty 9 wt 3 dc 1 cw 1 cw2 9 cl 1.1 cl2 1.3 cp 1.5 ws ” in 0 rt 0 stds

structure definition identification
name
structure type (9=3B-weir)
inlet weir (0=no, 1=yes). Default 0.
weir type (1=rectangular weir, 2=V-shape weir, 3=2-stage weir)
slope (only for V-shape type of weir)
discharge coefficient. Default 1.0
crest level (m NAP)
crest width (m)
(additional) crest width 2nd stage (m)
crest level 2nd stage (m NAP)
The keywords cl2 and cw2 are only needed for 2-stage weirs.
The second crest level (cl2) should be higher than the first crest level (cl).
power coefficient. Default 1.5, for V-notch 2.5.
0 = flow in both directions possible (default for normal weirs)
1 = only positive flow possible (default for inlet weirs)
2 = only negative flow possible
3 = no flow possible
Initial weir setting table as a function of time; if not present the initial weir setting
will default be equal to crest level;
Inlet flushing flow. Default 0. Only used for inlet weirs.
table of switch-on and off levels. Only for inlet weirs.

For a gate:
STDS id ’1’ nm ’3B-onderlaat’ ty 10 in 0 dc1 cl -1.5 cp 0.5 cw 2.0 gh 1.0 mu 0.63 rt 0 gs
’init_setting’ fl 0. stds
With:
id
nm
ty
in

structure definition identification
name
structure type (10=3B-gate)
inlet gate (0=no, 1=yes). Default 0.

SOBEK input file formats

contraction coefficient. Default 0.63
discharge coefficient. Default 1.0
(bottom) crest level (m NAP); default=bottom level of upstream open water
node,
if available.
crest width (m)
power coefficient; default 0.5 NOT READ. Always value 0.5 used.
gate height (opening height) in m NAP.
0 = flow in both directions possible (default for normal weirs)
1 = only positive flow possible (default for inlet weirs)
2 = only negative flow possible
3 = no flow possible
Initial gate setting table as a function of time; if not present the initial gate setting
will default be equal to crest level;
Inlet flushing flow. Default 0. Only used for inlet gates.
table of switch-on and off levels. Only for inlet gates.

For a Manning resistance:

With:
id
nm
ty
mn
cl
dp
bw
ss

STDS id ’1’ nm ’3B- weerstand’ ty 11 mn 0.02 cl 1000.0 dp 1.0 bw 3.0 ss 1.0 stds

structure definition identification
name
structure type (11=3B-Manning resistance)
Manning coefficient n
characteristic length (m)
depth wrt upstream reference level (in m)
bottom width (m)
slope talud (0=rectangular cross section, 1=slope of 45 degrees)

For a Q-h relation:

STDS id ’1’ nm ’3B-Q-h_relatie’ ty 12 qv -1.0 0. 0.5 1. 1.5 2. hv -0.1 0. 0.1 0.2 0.3 0.4 0.5 hr
0 stds
id
nm
ty
qv
hv
hr

structure definition identification
name
structure type (12=3B-Q-h relation)
6 values for Q (m3/s)
6 corresponding values of h (m NAP)
0 = use upstream level in Q-h relation
1 = use downstream level in Q-h relation
2 = use level difference in Q-h relation

SOBEK, User Manual

Topography layer
[Topography layer]
The topography layer consists of three files which describe the topography of the network.
The first file contains the list of all the nodes in the schematisation, the second file the list of
links (connections) between these nodes. The third file is only used in case of Sobek-Urban
models using the NWRW node type. The Topography layer in fact defines all the network
objects of which the attribute data are described in the other layers.
Node file: 3b_nod.tp

This file contains the node definitions for Sobek-Rural applications. The header line of this
file contains in the first positions the string ‘BBB2.2’. The keyword NODE is used to mark the
beginning of a record, and in lower case characters it marks the end of a record.
NODE id ’3B72’ nm ’Node1’ ri ’2’ mt 1 ‘6’ nt 23 ObID ‘SBK_SBK-3B-REACH’ px 11404.2 py
123768.5 node
With
id
nm
ri
mt
nt
ObID
px
py

node identification
name of the node
branch identification
model nodetype
netter nodetype
Object id
position X (X coordinate)
position Y (Y coordinate)

Remark 1: no weather station in this file!

Remark 2: For aggregation purposes it is very well possible that this file should be extended
with fields such as
au = administrative unit
rb = river basin

so that e.g. total areas or total waste loads can be determined later on by administrative unit
and/or river basins. Also a ‘multi-select’ option of changing some input data for all nodes
within one administrative unit, or setting default values per river basin, could be nice options
for a user.
Remark 3: Another suggestion is to include a second name in the file, to be able to have the
node names in two languages.
Remark 4: the following model types are available:
1=Paved area
2=Unpaved area

SOBEK input file formats

3=Greenhouse
4=Open water
(5=Internally reserved for all structures)
6=Boundary
7=NWRW
8=pump

10=orifice
11=Manning resistance

12=Q-h relation

14=WWTP (RWZI)
15=Industry

16=Sacramento (ObId ’3B_SACRAMENTO’)
23= Wagmod/Walrus

Remark 5: the Object id is used by RR to distinguish RR-boundaries from RR-CF connection
nodes. The RR model type of these different objects is the same (mt 1 ‘6’) , but there Netter
types and Object id’s are different.
Link file: 3B_Link.Tp

This file contains the link definitions for Sobek-Rural applications. The header line of this file
contains in the first positions the string ‘BBB2.2’.
BRCH id ’1’ nm ’Tak1’ ri ’-1’ mt 1 ‘0’ bt 11 ObID ‘3B-LINK’ bn ’1’ en ’2’ brch
With:

id
nm
ri
mt
bt
ObID
bn
en

link identification
name of the link
branch identification
model type
branch type
Object identification
identification of begin node (‘from’ node)
identification of end node (‘to’ node)

The branch identification is only used for special (aggregation) purposes of the NWRW rainfallrunoff model which is used in Sobek-Urban applications.
The branch type and Object Id are not used by the RR-computational core, but are used

SOBEK, User Manual

by user-interface programs (Netter). The model type of the links is used to check whether
RR-routing links are used or not.
Runoff file: 3B_Runoff.Tp
This file contains the NWRW node definitions for Sobek-Urban applications.
NODE id ’0-28’ ri ’1’ mt 1 ’7’ nt 3 ObID ’SBK_CONN&RUNOFF’ px 198002.5 py 457582.5
node

node identification
name of the node
branch identification
model nodetype
netter nodetype
Object id
position X (X coordinate)
position Y (Y coordinate)

id
nm
ri
mt
nt
ObID
px
py

The branch identification is only used for special (aggregation) purposes of the NWRW rainfallrunoff model which is used in Sobek-Urban applications.
D.19.14

RR-Routing link layer

Data file (3B_Rout.3b)

This file contains the data for the links of model type 30: RR-Routing links.
The file contains two type of records, ROUT and RDEF records. The ROUT records contain
for each routing link a reference to the routing definition, while the RDEF records contain the
routing definition.
ROUT id ’l_8’ di ’1’ rout

ROUT id ’link_id’ di ’def-id’ rout
With
id
di

link identification
definition of routing id to be used

RDEF id ’1’ nm ’Donau’ nl 2 x 0.3 0.12 k 2.7 4.06 qm 4000 qi 2400 qo 2750 rdef
With
id
nm
rt
nl
x
k
qm
qi

routing definition id
routing definition name
routing type, type 0 = Muskingum
number of layers
x coefficient per layer; there are as many coefficients as layers
k coefficient per layer; there are as many coefficients as layers
maximum discharge Q per layer, except for the last layer
initial link inflow

SOBEK input file formats

Unpaved area layer
Data file: Unpaved.3B
This file contains the data for the nodes of model type 2 (pervious or unpaved area)
UNPV id ’1’ na 16 ar 1. 0. 3. 0. 0. 6. 0. 0. 0. 10. 11. 12. 13. 14. 15. 16. lv 1.0 ga 110.
co 1 su 0 sd ’ovhstor_1mm’ ad ’alfa_1’ sp ’seepage_1’ ic ’infcap_5’ bt 1 0 ig 0 0.5
mg 0.8 gl 1.5 ms ’meteostat1’ is 100. Unpv
With

sd
ad
ed
sp
ic
bt
ig

node identification
number of areas (at the moment fixed at 16)
area (in m2) for all crops. In the user interface either the total area can be
specified, or the different areas per crop. In case the total area is specified, it is
put at the first crop (grass).
area for groundwater computations. Default = sum of crop areas.
surface level (=ground level) in m NAP
computation option (1=Hellinga de Zeeuw (default), 2=Krayenhoff van de Leur,
3=Ernst)
reservoir coefficient (for Krayenhoff van de Leur only);
Indicator Scurve used
su 0 = No Scurve used (Default)
su 1 ‘Scurve-id’ = Scurve used; Unpaved.Tbl contains defniition of table with id
‘Scurve-id’.
storage identification
alfa-level identification (for Hellinga de Zeeuw drainage formula only)
Ernst definition (for Ernst drainage formula only)
seepage identification.
infiltration identification
soil type (from file BERGCOEF or BergCoef.Cap)
Indices >100 are from Bergcoef.Cap.
initial groundwater level; constant, or as a table
ig 0 0.2 = initial groundwater level as a constant, with value 0.2 m below the
surface.
ig 1 ’igtable1’ = initial groundwater level as a table, with table identification
igtable1.
maximum allowed groundwater level (in m NAP)
initial depth of groundwater layer in meters (for salt computations)
identification of the meteostation
initial salt concentration (mg/l) Default 100 mg/l

initial link outflow

Alfa definition file: Unpaved.alf
This file contains the definitions of alfa-factors and related levels for the nodes of model type
2 (unpaved or pervious area). Also the Ernst definitions are included in this file.
ALFA id ’alfa_1’ nm ’set1 alfa factors’ af 5.0 0.9 0.7 0.6 0.3 0.03 lv 0. 1.0 2.0 alfa
ERNS id ’Ernst_1’ nm ’Ernst definition set1’ cvi 300 cvo 30 30 30 cvs 1 lv 0. 1.0 2.0 erns

SOBEK, User Manual

alfa-factors identification
name
alfa factors (say a1 to a6) for Hellinga-de Zeeuw formula (1/day).
a1 = alfa factor surface runoff
a2 = alfa factor drainage to open water, top soil layer
a3 = alfa factor drainage to open water, second layer
a4 = alfa factor drainage to open water, third layer
a5 = alfa factor drainage to open water, last layer
a6 = alfa factor infiltration
Resistance value (in days) for infiltration from open water into unpaved area
Resistance value (in days) for drainage from unpaved area to open water, for 3
layers
Resistance value (in days) for surface runoff
three levels below surface (say lv1, lv2, lv3), separating the zones with various
alfa-factors (or Ernst resistance values) for drainage.
a2 is used between surface level and lv1 m below the surface.
a3 is used between lv1 and lv2 m below the surface.
a4 is used between lv2 and lv3 m below the surface
a5 is used below lv3 m below surface.

Storage definition file: Unpaved.sto

This file contains the storage definitions for the nodes of model type 2 (unpaved or pervious
area)
STDF id ’ovhstor_1mm’ nm ’1 mm storage’ ml 1. il 0. STDF
With:
id
nm
ml
il

storage identification
name
maximum storage on land (mm). Default 1 mm.
initial storage on land (mm). Default 0.

Seepage definition file: Unpaved.sep

This file contains the seepage definitions for the nodes of model type 2 (unpaved or pervious
area)
SEEP id ’seep_1’ nm ’constant seepage_1mm’ co 1 sp 1. ss 500. seep

SEEP id ’seep_2’ nm ’simple variable seepage’ co 2 cv 3.0 h0 ‘H0Table’ ss 500. seep
SEEP id ’seep_3’ nm ’variable seepage using coupling with Modflow’ co 3 cv 3.0 ss 500. seep
With:
id
nm
co

seepage identification
name
computation option seepage
1 = constant seepage (Default)
2 = variable seepage, using C and a table for H0
3 = variable seepage, using C and H0 from Modflow

SOBEK input file formats

If the co field is missing, co 1 will be assumed.
Seepage or percolation (mm/day)
Positive numbers represent seepage, negative numbers represent percolation.
Default 0.
salt concentration seepage (mg/l). Default 500 mg/l.
This value is only important for positive seepage values.
Resistance value C for aquitard
reference to a table with H0 values
Remark 1: This file has similar structure as a file of the open water layer.

Infiltration file: Unpaved.inf

INFC id ’infcap_5’ nm ’inf_5mm’ ic 5. INFC
With:

infiltration identification
name
infiltration capacity of the soil, constant. (mm/hour)
Remark: no variable infiltration capacity implemented yet.

This file contains the infiltration definitions for the nodes of model type 2 (unpaved or pervious
area)

Table file: Unpaved.tbl

This file can contain three kinds of tables:

initial groundwater level as a function of time
S curve definitions
H0 definitions for variable seepage

Table input of the initial groundwater level as function of time.
IG_T id ’igtable1’ PDIN 1 1 ’0;10:00:00’ pdin
TBLE
1995/01/01;00:00:00 0.3 <
1995/03/01;00:00:00 0.2 <
1995/05/01;00:00:00 0.3 <
1995/07/01;00:00:00 0.4 <
1995/09/01;00:00:00 0.5 <
1995/11/01;00:00:00 0.4 <
tble
ig_t
With
id

table identification

PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period
0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss

SOBEK, User Manual

1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss
TBLE .. tble contains the table, first column is the date (year month day hour minute second),
second column the initial groundwater level in m below surface. The < sign is a separator.
S-curve definitions:
This table is not time depending, so different from the other types of tables in this file.

H0 table definitions:

SC_T id ’ScurveTable’ nm ’ScurveTable1’ PDIN 1 1 ’0’ pdin
TBLE
0 -5.1 <
10 -5.0 <
80 -4.9 <
90 -4.2 <
100 -4.0 <
tble
sc_t

H0_T id ’H0table’ PDIN 1 1 ’1;00:00:00’ pdin
TBLE
1995/01/01;00:00:00 0.4 <
1995/02/01;00:00:00 0.5 <
1995/03/01;00:00:00 0.5 <
1995/04/01;00:00:00 0.4 <
1995/05/01;00:00:00 0.3 <
1995/06/01;00:00:00 0.2 <
1995/07/01;00:00:00 0.1 <
1995/08/01;00:00:00 0.0 <
1995/09/01;00:00:00 0.0 <
1995/10/01;00:00:00 0.1 <
1995/11/01;00:00:00 0.2 <
1995/12/01;00:00:00 0.3 <
tble
h0_t
With:
id

table identification

PDIN ..pdin = period and interpolation method (for description see above at IG_T record)

SOBEK input file formats

WWTP layer
The RWZI layer represents nodes of model type 14 (WWTP’s or waste water treatment plants).
Table file (WWTP.Tbl)

MEAS id ’WWTPTable’ nm ’Test’ PDIN 0 0 ’ ’ pdin
TBLE
1997/01/01;00:00:00 -1.0 <
1997/01/01;00:00:01 0.5 <
1997/01/02;00:00:00 0.55 <
1997/01/06;00:00:00 0.55 <
1997/01/06;00:00:01 0.5 <
1997/01/08;00:00:00 0.6 <
1997/01/10;00:00:00 0.6 <
1997/01/11;00:00:00 -1.0 <
1997/01/20;00:00:00 -1.0 <
1997/01/20;00:00:01 0.5 <
1997/01/30;00:00:00 0.54 <
1997/02/01;00:00:00 -1.0 <
tble
meas
With
id
nm

Contains measured WWTP discharge flow (m3/s)

table identification
table name

PDIN ..pdin = period and interpolation method
0 0 ’ ’ = interpolation continuous, no period
1 0 ’ ’ = interpolation block, no period

0 1 ’365;00:00:00’ = interpolation continuous, period in DDD;HH:mm:ss
1 1 ’1;00:00:00’ = interpolation block, period in DDD;HH:mm:ss

Convention: Missing data is indiciated with -1. In that case the discharge of the WWTP is
equal to the computed inflow of the WWTP.
No salt concentration included in input table, is derived from inflow.
Data file (WWTP.3b)
This file contains the data of the WWTP node (RR model type 14).
WWTP id ’1’ tb 0 wwtp
With
id
tb

node identification
table used yes/no

SOBEK, User Manual

tb 0 = no table of measured data; the WWTP outflow is equal to the sum of the
inflows.
tb 1 ‘WWTPTable’ = table of measured data with id ‘WWTPTable’
RTC (Real Time Control)
General
This document only describes the files of Real-time Control which can be edited by the user.
These files are indicated with an asterisk in the table.

File description

The rainfall and wind files other input files which are editable by the user. These files are
described in the Rainfall-Runoff and Water Flow model database description.
Input/
Output
file

INI file with options

File with Water Flow data locations available for Real-time Control

File with Rainfall-Runoff data locations
available for Real-time Control

File with data locations for rainfall prediction

File with other data locations (e.g. wind
prediction)

Not used anymore

Not used anymore

Decision parameter definitions

Water Flow measure definitions

Rainfall-Runoff measure definitions

Communication file with results from Water Flow data locations to Real-time Control

Communication file with results from
Rainfall-Runoff data locations to Realtime Control

Communication file with results from
Sobek-Predict data locations to Realtime Control.

SOBEK input file formats

File description

Input/
Output
file

Communication file with results from
other data locations to Real-time Control

File with available WQ monitoring locations

Communication file with results from WQ
monitoring locations to Sobek-RTC

Communication file with results from
Real-time Control to Rainfall-Runoff

Communication file with results from
Real-time Control to Water Flow

Communication file with results from Water Flow data locations to Real-time Control

All output to Rainfall-Runoff

All output to Water Flow

All values of decision parameters

Debug file of Real-time Control

Meteo
task
block

Meteo
task
block

Rainfall prediction HIS file

Wind prediction HIS file

Ini file for control module to enable online coupling of Real-time Control with
other SOBEK modules.

rtc.ini-file (Control layer)
This file contains some general options in a Windows-ini file type structure. The file contains
general options such as version number, date, options indicating how Real-time Control is
used in combination with other modules, the time control of Real-time Control, etc. An example
file looks like this:
[General]
Version=1.00

SOBEK, User Manual

Date = June 1997
[Options]
3B=-1 (with SOBEK-Rural RR)
-1=On;
0=Off;
input either by 0,-1,or On or Off.
Precipitation=-1
Extern=-1
Sobek=-1 (-1 = with a SOBEK 1DFLOW module)
WQ = -1 (-1 = with the SOBEK-Rural 1DWAQ module)
Control=INI
!available options:
3B=Event dates/times from Rainfall file;
INI = time control via this INI file
3Bformat=ASC
!options:
HIS = HIS format,
ASC = ASCII format .
Sbkformat=HIS
WQformat=HIS
ModePrecipitation=Actual
Available option:
!Actual = prediction is equal to actual precipitation according to rainfall file
ModeWind=Actual
Available option:
Actual = prediction is equal to actual wind data
PrecipTimeHorizon=5
Max. number of time steps ahead precipitation prediction
WindTimeHorizon=5
Max. number of time steps ahead for wind prediction
DecisionHorizon=720
Max. number of time steps memory for decision
parameters. Default=720
Debug=0
0=no debug file;
-1=debug file is generated.
DebugTime=1 2
DebugFromTimestep, DebugToTimestep
DebugTime2=101 102
DebugFromTimestep2, DebugToTimestep2
OutputTimestep=1
Output every x timesteps; default OutputTimestep=1
WriteRtcHisFiles=0
0=only writes overall HIS files for event 1
-1=writes overall his files for all events (default)
SetSequenceDecisionParameters=0
0 = (default) = by order in input file
-1 = determined by RTC
WindUseTableModule=-1
0=no (default),
-1=yes
ReduceWindTable=-1
0=no,
-1=yes (default); only reads part of the wind table within the specified
simulation period + time horizon prediction.
NLocHis=99
Maximum number of locations in on-line HIS files, default 9999.
NTimHis=99
Maximum number of timesteps from external HIS files, default 365*50*24.
NParQ=99
Maximum number of on-line available Water Quality parameters, default value 500.
FormatMeasureFiles209003=-1
0=False (Default), measure files are read according to the new format
-1=true, measure files are read according to the old 2.09.003 format
ReservoirMaxIterations=10
Maximum number of reservoir iterations, default value 10.

SOBEK input file formats

ReservoirVolumeConvergenceCriterion=0.1
Volume convergence criterion for reservoir, default value 0.1 m3.
ReservoirFlowConvergenceCriterion=0.001
Flow convergence criterion for reservoir, default value 0.001 m3/s.
[Control]
Time step size etc.\ always through this data block;
Event data either here or through 3B Rainfall file.
NumberofEvents=1
Number of events
NumberofStepsperkeer=1
Should be 1
Deltat=0.010000
(Time step size; cf. definition of Time start below)
Timestart=19940901.000000
Start time per event
(year*10000+month*100+day+ ihour/100.+iminute/10000.+isecond/100000.)
LastTimeStep=8
Last time step of event
[CouplingMatlab]
MatlabMFileDir=Matlabdir
Matlab directory containing the input file
MatlabMFileName=matlabfile
Matlab input file name
MatlabDebugMode=1
Debug option (1=true)
MatlabRRData=0
0 = False (default);
1 = also RR open water levels are passed to MATLAB.
MatlabRainData=0
0 = False (default)
1 = also Rainfall data are passed to MATLAB.
MatlabWQData=0
Default 0=False.
If =1 then a selection of WQ data are passed to MATLAB.
MatlabNrWqPar=
Number of WQ parameters passed to MATLAB.
MatlabWQPar1= id of WQ parameter 1 to be passed to MATLAB
MatlabWQPar2= id of WQ parameter 2 to be passed to MATLAB
etc.\ up to the number of WQ parameters passed to MATLAB.

MatlabWithSobekCString=0

0= False. In each RTC time step the MATLAB set points will be used and transferred to the
SOBEK Water Flow and Rainfall-Runoff modules (default).
1= True. RTC will also request the SobekC en RRC strings from MATLAB. SobekC and RRC
can be used to specify whether the MATLAB values should be used or not, giving the option
for controlling at other time intervals. In RTC versions before March 2001 this option was
default.
MaxCountGeneral=100
Maximum number of items (RR data, WQ data, precipitation data) to be passed in 1 string to
Matlab.
MaxCountStructures=15
Maximum number of Flow-structures for which Sobek-Flow data is passed in 1 string to Matlab.
MaxCountBranchSegments=50

SOBEK, User Manual

Maximum number of Sobek-branchsegments for which data is passed in 1 string to Matlab.
MaxCountNodes=50
Maximum number of Sobek-nodes for which data is passed in 1 string to Matlab.
MaxCountBiLcLocations=30
Maximum number of Sobek-branch id point locations for which data is passed in 1 string to
Matlab.
MaxCountMeasLocations=30

Data Locations layer
sbk_loc.rtc-file (Data locations layer)

Maximum number of Sobek-Measurement stations for which data is passed in 1 string to
Matlab.

This file specifies the locations containing SOBEK data. These locations can subsequently
be used in specifying decision parameters in the RTC module.
The general format of available data records are:

SBKO id ’Sobek-id’ nm ’Sobekname’ bi ’branch-id’ lc 25.5 sbko
SBKO id ’meetid’ nm ’name’ in ’Node_id’ sbko
SBKO id ’meetid’ nm ’name’ ir ’Branchsegment_id’ sbko
SBKO id ’meetid’ nm ’name’ is ’Structure_id’ sbko
SBKO id ’meetid’ nm ’name’ ml ’MeasLoc_id’ sbko
SBKO id ’meetid’ nm ’name’ hl ’2DHistory location’ sbko
SBKO id ’meetid’ nm ’name’ db ’2D Breaking dam location’ sbko where:
id
nm
bi
lc
in
ir
is
ml
hl
db

id of data location
name, which can be used as additional comment
SOBEK-branch id
location on the branch (in meters)
node id
branch-id
] structure-id
measurement location-id
2D-history location-id
2D-breaking dam location-id

Notice that ‘in’ can only be used to measure a water level (on nodes or calculation points),
‘ir’ can only be used to measure a discharge (on branch segments), ‘is’ can only be used to
measure the control structure parameter of a structure (crest level for weir, opening height for
orifice, discharge for pump and valve opening for culvert) and ‘ml’ can be used te measure a
discharge and/or water level, depending on the type of measurement station.
However, the user should still specify the correct variable (1=water level, 2=discharge, 3=structure parameter) in the definition of the decision parameter (see file description decision parameter file).

SOBEK input file formats

Notice that ’ir’ is focused on the id of the first part of the branch segment.
Optionally, the data file may contain a header record. A header record either starts with an
asterisk ‘*’ or with the 3 characters ‘RTC’.
An example file:
RTC1.0
SBKO id ’Sbk_meas_id1’ nm ’Sobek_lokatie_1’ bi ’branch_id_1’ lc 25.5 sbko
SBKO id ’Sbk_meas_id2’ nm ’Sobek_lokatie_2’ bi ’branch_id_2’ lc 0. sbko
SBKO id ’meetid’ nm ’name’ is ’Structure_id’ sbko
3b_loc.rtc-file (Data locations layer)

The general format of a record is as follows:

This file contains the data-locations of Rainfall-Runoff module which are available in Realtime Control. These locations can be used in the definition of Real-time Control decision
parameters.

3BO id ‘3B-id’ nm ‘3B-name’ 3bo
where:
id
nm

id of data location
name

Optionally, the data file may contain a header record. A header record either starts with an
asterisk ‘*’ or with the 3 characters ‘RTC’.
An example file:

RTC1.0
3BO id ’3B_id1’ nm ’3B_naam_1’ 3bo
3BO id ’3B_id2’ nm ’3B_naam_2’ 3bo
3BO id ’3B_id3’ nm ’3B_naam_3’ 3bo

prec_loc.rtc-file (Data locations layer)

This file contains the data-locations of SOBEK-RR which are available in SOBEK-RTC. These
locations can be used in the definition of SOBEK-RTC decision parameters.
The general format of a record is as follows:

PREC id ’precipitation-id’ nm ’precipitation-name’ prec where:
id
nm

id of precipitation location
name

Optionally, the data file may contain a header record. A header record either starts with an
asterisk ‘*’ or with the 3 characters ‘RTC’).
An example file:
RTC1.0

SOBEK, User Manual

PREC id ’Neerslag1’ nm ’Neerslag1’ prec
PREC id ’Neerslag2’ nm ’Neerslag2’ prec
ext_loc.rtc-file (Data locations layer)
This file contains the other external data locations. The file can contain the wind predictions
computed in the Real-time Control module, and locations related to external HIS files. Wind
information concerns wind direction and wind velocity.
These external data locations can be used to define decision parameters.
The general format of a data record is:

EXT id ’external-id’ nm ’external-name’ ext
HEXT id ’BoezemlastDZV_Sacr’ nm ’BoezemlastDZV_Sacr’ hf ’..\fixed\Sacrmnto.His’ hl ’1427’
hp ’ChannelInflow [m3 /s]’ hext where:
id of external data location
name
external HIS filename
location from external HIS file
parameter from external HIS file

Optionally, the data file may contain a header record. A header record either starts with an
asterisk ‘*’ or with the 3 characters ‘RTC’.
An example file:

RTC1.0
EXT id ’Global wind’ nm ’global wind data’ ext
EXT id ’Extern2’ nm ’Extern serie2 for temperature’ ext
monstat.wq-file (Data locations layer)

This file contains the monitoring data locations defined in the water quality module. The file
may be empty or non-existent. The format is different from other data location files, since an
already existing input file of the water quality module is used.
The file contains a header with the lines:
MON1.0

# Monitoring area’s
Branch = 0
The next line contains the number of monitoring locations. Then, for each monitoring location
some lines are included. First, a line with:
Area nr Name: id
where:
nr

number of the monitoring location

SOBEK input file formats

id of WQ monitoring location

and then some lines with additional data, not used by RTC.

MON1.0
# Monitoring area’s
Branch = 0
5
Area 1 Name: WVO006
1,"l_307"
0
Area 2 Name: WVO023
1,"l_317"
0
Area 3 Name: BLV002
1,"l_255"
0
Area 4 Name: GHC002
1,"l_159"
0
Area 5 Name: WVO001
1,"l_389"
0

An example file:

The decision parameter file contains the definition of the decision parameters. There are four
possible ways of defining decision parameters:

A first possible definition of a decision parameter is a linear combination of Water Flow results, Rainfall-Runoff results, predicted rainfall or other external (wind) data, on-line water
quality data, and other decision parameters.
A second option is to define decision parameters as a non-linear function of other decision
parameters.
A third option is to define decision parameters as SOBEK tables.
The fourth option is to define SOBEK reservoirs.
Furthermore, there are some standard predefined decision parameters which can be used to
define other decision parameters or measures. These predefined decision parameters are:

Year
Month
Day
Hour (an integer between 0 and 23)
Minute (an integer between 0 and 59)
Second (an integer between 0 and 59)
Date (a number defined as 10000*year+100*month+day)
Time (a number defined as 10000*hour+100*minute+second)
Date_Time (the number defined as date + time/10000)
Day of Week
0=Sunday;
1=Monday;

SOBEK, User Manual

..
6=Saturday;
DECISPAR.RTC-file (Decision layer)
Function Decision Parameters
The value of decision parameters is based on data locations and also may be dependent of
other decision parameters. These decision parameters are specified in the PAR2 records.
In the User Interface these records are presented under Decision Parameters as Function
Parameters.

PAR2 id ’beslispar_1’ nm ’para_1’ iv 1 do ‘None’

These data records may look like:

DATA ty ‘ExtLoc’ lo ’Extern_id’ va 1 ca 0.1 cb -1 cn 0 data par2

or
PAR2 id ’beslispar_2’ nm ’para_2’ do ’Interpolate’

DATA ty ’2DFlowLoc’ lo ’2D_Weurt’ va 1 ca 1 cb 0 cn 0 data

DATA ty ’InterpolationTable’ lo ’InpTable_1’ va 1 ca 0 cb 0 cn 0 data par2
or

PAR2 id ’beslispar_3’ nm ’para_3’ do ‘multiply’

DATA ty ‘FlowLoc’ lo ’Sobek-id1’ va 1 ca 1. cb 0. cn 0 data
DATA ty ‘RRLoc’ lo ’3b-stuw’ va 3 ca 1. cb 0. cn 0 data

DATA ty ‘PrecipLoc’ lo ’Neerslag-id’ va 1 ca 1. cb 0. cn 0 data
DATA ty ‘RRLoc’ lo ’3B-ow’ va 1 ca 0.5 cb 0. cn 0 data

DATA ty ‘ParLoc’ lo ’beslispar_1’ va 1 ca 0 cb -1 cn -1 data
DATA ty ‘ExtLoc’ lo ’Extern_id’ va 1 ca 0.1 cb -1 cn 0 data

DATA ty ‘FlowLoc’ lo ’Sobek-id2’ va 2 ca. 2. cb. 1. cn -1 data par2 where:
id
nm
iv

id of decision parameter
name of decision parameter
initial value to be used at beginning of simulation when parameter is used in
computations with negative time shift; the default initial value is 0 for all parameters
mathematical actions or functions on location value[s]

The following functions (or mathematical actions) can be defined in PAR2 records:
Functions that can be applied using one argument only:

SOBEK input file formats

Arccosine (result in degrees)
Arccosine (result in radians)
Arcsine (result in degrees)
Arcsine (argument in radians)
Arctangent (result in degrees)
Arctangent (result in radians)
Ceiling (smallest integer >= x)
Cosine (input argument in degrees)
Cosine (argument in radians)
Exponent
Floor (largest integer <= x)
Hyperbolic cosine
Hyperbolic sine
Hyperbolic tangens
Logarithm with base 10
Natural logarithm
Nearest integer
None (no function is applied)
Sine (input argument in degrees)
Sine (argument in radians)
Square
Square root
Tangent (input argument in degrees)
Tangent (argument in radians)
Functions that can be applied for two arguments only:
Interpolate (determine values using an Interpolation table)
Functions that can be applied for two or more arguments:
Add
Average
Divide
Max
Min
Multiply
Power
Subtract

The PAR2 record contains DATA sub-records with data for the specified locations. The data
items will appear in the same order as specified in the PAR2-record, so the order may influence the results, depending on the specified action function.
The DATA sub-record contains the following keywords:
ty

Type of location, which can be:
‘FlowLoc’ = Water Flow Location in 1D schematization
‘RRLoc’ = Rainfall-Runoff Location
‘ExtLoc’ = External data from file
‘PrecipLoc’ = Precipitation Prediction Location
‘DateTimLoc’ = Date Time
‘ParLoc’ = (Other) Decision Parameter
‘WQLoc’ = Sobek-WQ Monitoring Location
’2DFlowLoc’ = Water Flow Location in 2D schematization
’InterpolationTable’ = Interpolation Table
Location-id (defined in RTC on the “Data Location” Tab)
Selected variable, which has different values for the different data types:

SOBEK, User Manual

Water Flow Location in 1D schematization:
Node:
1 = Water Level
4 = Water Depth
Reach Segment:
2 = Discharge
Structure:
5 = Crest Level
6 = Crest Width
7 = Gate Lower Level
8 = Opening Height
9 = Structure Flow Area
10 = Discharge Structure
11 = Structure Velocity
12 = Water Level Up
13 = Water Level Down
14 = Head
15 = Pressure Difference
16 = Pump Capacity
Measurement Location:
1D Flow Measurement Station:
1 = Water level
2 = Discharge
3 = Storage Surface Area
4 = Water Depth
Manhole Measurement Station:
1 = Water level
3 = Storage Surface Area
4 = Water Depth
Pipe Measurement Station:
2 = Discharge
Reach Location:
1 = Water level
2 = Discharge
3 = Storage Surface Area
4 = Water Depth
Water Flow Location in 2D schematization:
2D History Station & 2D Breaking - Dam:
1 = Water level
4 = Water depth
17 = Bed level
18 = U-velocity
19 = V-velocity
√
20 = C-Abs. flow velocity [= U 2 + V 2 ]
Rainfall-Runoff Location
1 = Open Water Level
2 = Groundwater Level
External data
From HIS-file
1 = Value
In case of Public Wind
1 = Wind Direction
2 = Wind Velocity
Precipitation Prediction Location

SOBEK input file formats

Year(yyyy),
Month(mm),
Day(dd),
Hour(hh),
Minute(mm),
Second(ss),
Date(yyyymmdd),
Time(hhmmss),
Day_of_week(day no)

1 . . . n = Prediction period in number of time steps
Decision Parameter
1 = Parameter Value
Date Time
1 = Actual Value, that can be
Integer value of:

Date+Time(yyyymmdd.hhmmss)
CompTimeStep (Timestep as defined in RTC settings)

Sobek-WQ Monitoring Location
SOBEK WQ variable (series id as character string)
coefficient for multiplication
constant for addition
time shift: integer values
1 represents: t+1
0 represents: t
-1 represents: t-1
-2 represents: t-2
etc.
When using negative time shifts, the value used for the first time steps will be
equal to the initial value of that parameter (see the iv keyword).

The value of the decision parameter is determined by executing the specified action over the
calculated values of all locations.
The time indexes are t, t − 1, t − 2. At the moment the time shift is limited to at most 720
time steps (based on 5 days memory of a computation time step of 10 minutes). This can be
specified in the INI file (keyword DecisionHorizon).
By using different time indices, a moving average or a trend can be determined. For instance,
by defining as a decision parameter: the water level at time step t minus the water level in time
step t − 1, in fact the increase in water level will be determined. If the water level rises quickly,
you may want to take some measure. Real-time Control will remember the data values of all
data locations of the previous time steps; the communication with the other modules is such
that it only receives the values for the current time steps.
When you are using SOBEK-RTC in combination with WQ, you could define the decrease in
O2 concentration, or the (increase) in fraction of WWTP water in the system as decision parameters, and define measures to set structure set points in the SOBEK Water Flow modules,
based on these (water quality based) decision parameters.
The coefficients for multiplication and addition can be positive, negative or zero. This gives

SOBEK, User Manual

many possibilities in the definition of decision parameters. Even the definition of a constant
decision parameter is possible (specify zero for the multiplication value, and set the proper
addition value)
The time shifts can be zero or negative, meaning that the decision parameter is depending on
current or previous values of variables at data locations. If a decision parameter is depending
on other decision parameters, it should depend on values of previous time steps (since the
values for the current time step may not yet be defined). In that case only negative values for
the time shift are allowed.
PAR2 records may refer to decision parameter values for the current timesteps or for previous timesteps. When defining decision parameters depending on values of other decision
parameters in the same timesteps, dependency loops should be avoided.

The first set of functions can accommodate multiple arguments; in case of 1 argument (only
1 input decision parameter), the result is equal to that decision parameter. In case of 2 input
decision parameters a and b, the result is obvious. In case of 3 input decision parameters a,b,
and c, the result for the maximum operation will be: max (max(a,b),c)) which is the same as
max(a,b,c); the result of the power operation will be ((a**b)**c).
The result of the computations is as the name suggests; using the short notation d1 for decision parameter 1, being equal to di1 ∗ dc1 + da1 , the results are:
multiply: d1*d2
divide : d1 / d2
add: d1 + d2
subtract: d1 - d2
max: max (d1, d2)
min: min (d1, d2)
average: average (d1, d2) = add (d1, d2) / 2
power: power(d1,d2) = d1 ** d2

The generalisation to more than 2 arguments is obvious, e.g.
subtract (d1, d2, d3, d4) = d1- d2 - d3 - d4
divide (d1, d2, d3, d4) = ((( d1 / d2) / d3) / d4 )
average (d1, d2, d3) = add (d1, d2, d3) / 3 = (d1+d2+d3) / 3
Some example records:

PAR2 id ’PreviousLvlShimen’ nm ” do ’none’
DATA ty ’FlowLoc’ lo ’Lvl Lower Shimen’ va 1 ca 1 cb 0 cn -1 data par2
PAR2 id ’ExpectedRain402001_7’ nm ” do ’add’
DATA ty ’PrecipLoc’ lo ’402001_7’ va 1 ca 0.166 cb 0 cn 0 data
DATA ty ’PrecipLoc’ lo ’402001_7’ va 2 ca 0.166 cb 0 cn 0 data
DATA ty ’PrecipLoc’ lo ’402001_7’ va 3 ca 0.166 cb 0 cn 0 data
DATA ty ’PrecipLoc’ lo ’402001_7’ va 4 ca 0.166 cb 0 cn 0 data
DATA ty ’PrecipLoc’ lo ’402001_7’ va 5 ca 0.166 cb 0 cn 0 data
DATA ty ’PrecipLoc’ lo ’402001_7’ va 6 ca 0.166 cb 0 cn 0 data par2
PAR2 id ’ExpectedInflowShimen’ nm ” do ’max’
DATA ty ’ParLoc’ lo ’PreviousInflowShimen’ va 1 ca 1 cb 0 cn 0 data
DATA ty ’ParLoc’ lo ’ExpectedRunoffShimen’ va 1 ca 0.5 cb 0 cn 0 data par2
PAR2 id ’Downstream demands Shimen’ nm ” do ’add’
DATA ty ’ParLoc’ lo ’DemandTaoYuan’ va 1 ca 1 cb 0 cn 0 data

SOBEK input file formats

DATA ty ’ParLoc’ lo ’PWS Shimen’ va 1 ca 1 cb 0 cn 0 data
DATA ty ’ParLoc’ lo ’Irr Demand Shimen’ va 1 ca 1 cb 0 cn 0 data par2
As the example indicates, records may be more than one line long. The beginning of a record
is indicated by PAR2 in capitals (upper case), and the end of a record is indicated by par2 in
lower case.
Time Decision Parameters

The tables are defined using the PAR3 record.

A third way for defining decision parameters is by defining SOBEK time-tables. In this way, a
decision parameter is simply defined as a standard SOBEK time-table. SOBEK-RTC allows
tables for one decision parameter at a time only. The table can contain interpolation and
periodicity switches.

PAR3 id ’MaxFlowOutlet2TimeTable’ PDIN 1 1 365;00:00:00 pdin
TBLE
’1995/01/01;00:00:00’ 9999. <
’1995/02/15;00:00:00’ 500. <
’1995/03/01;00:00:00’ 9999. <
’1995/06/01;00:00:00’ 750. <
’1995/12/31;23:59:00’ 750. <
tble par3

PAR3 id ’Cons.DemandOutlet1TimeTable’ PDIN 1 1 365;00:00:00 pdin
TBLE
’1995/01/01;00:00:00’ 0. <
’1995/03/01;00:00:00’ 60. <
’1995/12/31;23:59:00’ 60. <
tble par3
Where:
id

id of decision parameter

PDIN .. pdin= option for interpolation and periodicity

= 1 1 365;00:00:00 means block functions, periodicity one year
= 0 0 means linear interpolation, no periodicity

= 0 1 365;00:00:00 means linear interpolation, period one year
= 1 0 means block function, no periodicity

TBLE .. tble = the table, containing date; time string, value, and
Interpolation Tables
Interpolation tables can be applied by an “Interpolate” function, that determines the values of
a particular “Interpolate Function Decision Parameter”. Values for the independent variable
are contained in the first column of an interpolation table, while values for the dependent
variable are contained in the second column. For the interpolation table given below yields

SOBEK, User Manual

that an input (independent) value of 0.15 results in an output (dependent) value of 0.025.
Independent values may be contained in any data series defined in RTC. The dependent
values will be assigned to the concerning “Interpolate Function Decision Parameter.
Note that:
1 Independent values in the Interpolation Table (i.e. the values in the first Table column)
should be given in ascending order,
2 If the independent value is less than the independent value on first Table row, than the
dependent value will be equal to the dependent value on the first Table row,
3 If the independent value is larger than the independent value on the last Table row, than
the dependent value will be equal to the dependent value on the last Table row.

where:
id
nm
v1
v2

INTP id ’InpTable1’ nm ’InterpolationTable1’ v1 ’Heading_v1’ v2 ’Heading_v2’
TBLE
0.0 0.0 <
0.1 0.0 <
0.2 0.05 <
0.3 0.15 <
0.4 0.25 <
0.5 0.25 <
tble intp

id of interpolation table
name of interpolation table
heading of column 1 (Independent input variable)
heading of column 2 (Dependent variable)

SOBEK reservoir

SOBEK offers functionality of modelling reservoirs. This is done by defining a RSVP record in
the decision parameter file, and detailed reservoir information in the reservoir input file. An example of the RSVP record is described in this subsection and the reservoir file (Reservoi.Rtc)
is described in the next subsection.
An example of the RSVP record:

RSVP id ’Res1’ nm ’ ’ nb 2 nq 5 nt 2 ns 1 hav ’HeadVolumeReservoir1’
rule ’RuleCurveRsv1’ hedg ’HedgingRule’

bg ’Bottom gate Definition’ tg ’Turbine gate Definition’ sg ’Spillway gate Definition’
dp ’RsvRes1BotGate1’ ’RsvRes1BotGate2’ ’RsvRes1TurbGate1’
’RsvRes1TurbGate2’ ’RsvRes1SpillGate1’
no 2 gb 1 2 gt 1 2 gs 2 dm ’Cons.DemandOutlet1TimeTable’
’Cons.DemandOutlet2’
mf ’9999’ ’MaxFlowOutlet2TimeTable’ il ’Initial RsvLvl1’ ei ’Expected Inflow1’ rsvp

SOBEK input file formats

Where:
id
nm
nq
nb
nt
ns

dp
hav
rule
hedg
il

ei
no
gb
gt
gs
mf
dm

reservoir id
name of the reservoir
total number of gates
number of bottom gates
number of turbine gates
number of spillway gates
SOBEK will check that nq=nb+nt+ns
id’s of decision parameters (flows over individual gates)
reference to head-area-volume curve definition
reference to rule curve definition
reference to hedging rule definition
reference to decision parameter representing initial reservoir level in
m (initial= at begin of time step)
reference to decision parameter representing expected inflow
(in m3/s)
number of outlet links (check: no <= ng)
assignment of bottom gates to outlet links
assignment of turbine gates to outlet links
assignment of spillway gates to outlet links
reference to maximum flow definition for each outlet link
reference to demand definition for each outlet link

Combination of different type of decision parameters
In the decision parameter file, all type of decision parameters (PARA, PAR2, PAR3, and RSVP)
records can be used. There is no specific order of specification required. It is possible to use
decision parameters inRSVP records (i.e. the discharges over the different gates) as ’input’
decision parameters in PAR2 records.
Also the RSVP decision parameters may depend on other parameters (initial reservoir level,
expected inflow, consumptive demands on each downstream outlet) which itself may be defined as decision parameters in PARA, PAR2, PAR3, or even other RSVP records.
Default RTC will compute the decision parameters in the order in which they are specified
in the input file. However, SOBEK-RTC can also determine the order of computations itself
(use the option SetSequenceDecisionParameters=-1 in the Ini file RTC.DAT). RTC will check
whether cyclic definitions of decision parameters occur. It is not allowed to define decision
parameter A depending on decision parameter B, decision parameter B depending on C,
and C on A for the same time step. Such cyclic chains of dependencies are only allowed
if somewhere a time delay is introduced (like the value of decision parameter A at time t is
depending on the value of decision parameter B at time t − 1).
reservoi.rtc-file (Decision layer)
This file contains the detailed information of the SOBEK-reservoirs. The information is related
to the RSVP records in the decision parameter file (DECISPAR.RTC). The information in the
reservoir input file consists of:

level-area-volume curve of the reservoir (HAVC record)
reservoir rule curves (RULE record)
bottom gate data (BOTG record)
turbine data (TURB record)
spillway data (SPIL record)
Q-h relation data for individual gates (QHRE record)

SOBEK, User Manual

maximum flow data for individual gates (MAXF record)
flow demands (for energy generation) for individual turbine gates (ENGD record)
hedging rule (HEDG record)
Each of these records is described below.

HAVC id ’HeadVolumeReservoir1’
TBLE
0100000000
1010000000100000000
2010000000200000000
3010000000300000000
4010000000400000000
5010000000500000000
tble havc

An example of each record with a description:

id of the head-area-volume curve relation

TBLE .. tble contains the relation;

the first column is the level (in m with respect to reference level),
the second column is the area [m2 ]
the third column is the volume (m3)

RULE id ’RuleCurveRsv1’ PDIN 0 1 365;00:00:00 pdin
TBLE
’1995/01/01;00:00:00’ 50. 45. 40.
’1995/02/01;00:00:00’ 50. 45. 40.
’1995/03/01;00:00:00’ 50. 45. 40.
’1995/04/01;00:00:00’ 50. 45. 35.
’1995/05/01;00:00:00’ 50. 40. 30.
’1995/06/01;00:00:00’ 45. 35. 25.
’1995/07/01;00:00:00’ 40. 30. 20.
’1995/08/01;00:00:00’ 35. 30. 20.
’1995/09/01;00:00:00’ 35. 30. 20.
’1995/10/01;00:00:00’ 40. 35. 25.
’1995/11/01;00:00:00’ 45. 40. 30.
’1995/12/01;00:00:00’ 50. 45. 35.
’1995/12/30;00:00:00’ 50. 45. 40.
tble rule
Where:
id

id of the rule curve

TBLE .. tble contains the rule curve time table;
the first column is the flood control level;

SOBEK input file formats

the second column is the target level;
the third column is the firm level;
(all levels in m with respect to reference level)
the flood control level >= the target level >= the firm level
BOTG id ’Bottom gate Definition’ lv 0 10 qh ’Q-NetHead bottom gate’ ’Q-NetHead bottom
gate’
mf ’Max.Flow 999’ ’Max.Flow 999’ botg

id of the bottom gate definition
intake levels for the number of bottom gates
(this number is defined in the RSVP record in DECISPAR.RTC)
reference to Q-h relations for all bottom gates
maximum flow definition for each individual bottom gate

TURB id ’Turbine gate Definition’ lv 20 15 qh ’Q-NetHead turbine gate’ ’Q-NetHead turbine
gate’
ed ’Energy demands’ ’Energy demands 2nd turbine’ mf ’Max.Flow turbine gate’ ’Max.Flow
turbine gate’ turb
Where:
id
lv
qh
mf
ed

id of the turbine gate definition
intake levels for the number of turbines
(this number is defined in the RSVP record in DECISPAR.RTC)
reference to Q-h relations for all turbine gates
maximum flow definition for each individual turbine gate
energy demand definition for each individual turbine gate
(energy demands can of course only be defined for the turbine gates, not for
bottom gates or spillway gates)

SPIL id ’Spillway gate Definition’ lv 50 qh ’Q-NetHead spillway gate’ mf ’Max.Flow 999’ spil
Where:
id
lv
qh
mf

id of the spillway gate definition
intake levels for the number of spillways
(this number is defined in the RSVP record in DECISPAR.RTC)
reference to Q-h relations for all spillways
maximum flow definition for each individual spillway gate

MAXF id ’Max.Flow turbine gate’ PDIN 1 1 365;00:00:00 pdin
TBLE
’1995/01/01;00:00:00’ 31.25
’1995/01/15;00:00:00’ 27.
’1995/02/01;00:00:00’ 24.5
’1995/02/15;00:00:00’ 19.
’1995/03/01;00:00:00’ 50.

SOBEK, User Manual

id of the maximum flow definition

PDIN .. pdin = option for interpolation and periodicity

’1995/05/01;00:00:00’ 50.5
’1995/06/01;00:00:00’ 59.5
’1995/06/15;00:00:00’ 59.5
’1995/07/01;00:00:00’ 50.
’1995/07/15;00:00:00’ 50.
’1995/08/01;00:00:00’ 50.
’1995/08/15;00:00:00’ 50.
’1995/09/01;00:00:00’ 50.
’1995/10/01;00:00:00’ 50.
’1995/11/01;00:00:00’ 50.
’1995/12/01;00:00:00’ 50.
’1995/12/15;00:00:00’ 50.
’1995/12/31;23:59:00’ 50.
tble maxf

= 1 1 365;00:00:00 means block functions, periodicity one year
= 0 0 means linear interpolation, no periodicity

= 0 1 365;00:00:00 means linear interpolation, period one year
= 1 0 means block function, no periodicity

TBLE .. tble = the table, containing date;time string, value, and
QHRE id ’Q-NetHead bottom gate’
TBLE
0 999
10 999
20 999
30 999
40 999
45 999
50 999 tble qhre
Where:
id

id of Q-h relation

TBLE .. tble contains the relation;
the first column is the flow (m3/s)
the second column is the water level h (m)
ENGD id ’Energy demands’ PDIN 1 1 365;00:00:00 pdin
TBLE
’1995/01/01;00:00:00’ 31.25

SOBEK input file formats

’1995/01/15;00:00:00’ 27.
’1995/02/01;00:00:00’ 24.5
’1995/02/15;00:00:00’ 19.
’1995/03/01;00:00:00’ 12.5
’1995/04/01;00:00:00’ 12.5
’1995/05/01;00:00:00’ 12.5
’1995/06/01;00:00:00’ 12.5
’1995/10/01;00:00:00’ 12.5
’1995/11/01;00:00:00’ 12.5
’1995/12/31;23:59:00’ 12.5
tble engd
Where:
id of the energy demand definition

PDIN .. pdin = option for interpolation and periodicity

= 1 1 365;00:00:00 means block functions, periodicity one year
= 0 0 means linear interpolation, no periodicity

= 0 1 365;00:00:00 means linear interpolation, period one year
= 1 0 means block function, no periodicity

TBLE .. tble = the table, containing date;time string, value, and <
The values specified in the table are flows in m3/s.
HEDG id ’HedgingRule’
TBLE
100 100
90 100
70 75
50 50
30 25
10 0 tble hedg
Where:
id

id of hedging rule relation

TBLE .. tble contains the relation;
the first column is the level percentage (between 0 and 100)
( 0 corresponds with the level at dead storage (=the level at the lowest outlet);
100 corresponds with the firm level).
the second column is the release percentage (between 0 and 100)

SOBEK, User Manual

Measures layer
sbk_meas.rtc-file (Measures layer)
In this file, the user can specify the measures related to structures/controllers in the Flow
module.
The measures are specified in an FLCM record for each controller which is controlled by RTC.
Each FLCM record contains one or more SBMS sub-records in which the measures for the
regarding controller are specified.
The general format of a data record is:

FLCM id ’Ctrl_id’ nm ’Comment’ na 0 iv 41.
SBMS pr 1 ty 5 nv 1 bp ’Decispar1’ cv 71.35 ch ’>’ sp 41.05 sbms
flcm
or

FLCM id ’Ctrl_id’ nm ’Comment’ na 0 iv 1.0
SBMS pr 1 ty 2 bp ’Decispar1’ nv 3 cv 1.0 2.0 sp 0.0 1.0 2.0 sbms
flcm

FLCM id ’Sbk-Cntrl-id’ nm ’Comment’ na 0 iv 41.
SBMS pr 1 ty 7 nv 1 bp ’Decispar1’ cp ’Decispar2’ ch ’>’ sp 41.05 sbms flcm
SBMS pr 2 ty 9 mi ‘Matlabid’ dv 18.0 sbms flcm
or

FLCM id ’Ctrl_1’ nm ’Comment’ na 0 iv 41.
SBMS pr 1 ty 8 nv 1 bp ’Decispar1’ cp ’Decispar2’ ch ’>’ psp ’Decispar3’ sbms
flcm
or

FLCM id ’Sobek1D2D_BottomLevel controller location X’ nm ’Comment’ na 0 iv 12.75
SBMS pr 1 ty 10 psp ’Bottom Level at location X’ sbms
flcm
where: in the FLCM record:
id
nm
na
iv

Water Flow controller-id on which the measure is working
name of the controller, which can be used as additional comment
option not active, 0 = active, <> 0 means not active. This option can be used
to switch off RTC for this pump while keeping the definition
initial set point value, and

in the SBMS sub-record:
pr
ty

priority
type of measure; the format of the record is depending on the type
2 = table with n check values, n set points
5 = record with n decision parameters, n check values and 1 set point (number);

SOBEK input file formats

6 = record with n decision parameters, n check values and 1 set point as a
decision variable
7 = record with n decision parameters, n check parameters, 1 set point (number)
8 = record with n decision parameters, n check parameters and a set point as a
decision parameter
9 = MATLAB measure
10 = record with 1 setpoint decision parameter only
12 = external TCN measure
id of decision parameter
number of values or decision parameters (only for type ty 2, 5,6,7,8)
check value (only for type 2,5,6; nv values for type 2,5,6)
check to be carried on on the check value (not for type 2)
check decision parameter (only for measure type 7, 8)
set point of the controller (PID or interval controller) or the controlled parameter
(hydraulic controller or time controller) controlling the Flow-structure.
parameter set point (only for ty 6, 8, 10)
Matlab communication id, the id which is used in Matlab for this measure
TCN-id, the id which is used in TCN for this measure

bp
nv
cv
ch
cp
sp
psp
mi
ti

The following table gives a concise overview of the measure types:
Measure
Description

Decision
parameters

Check
Setpoint
Measure
value/parameters value/parameter Type No.

Interpolation Table

For measure type 5-8, the value of n may also be equal to 1.
It is possible to define multiple measures at one Flow controller. These measures can be
linked to the same decision parameter as well, but that is not required. If one of the defined measures is active, the set point of local controller controlling the Flow structure will be
adjusted to that measure.
In defining measures of type 5 to type 8, the multiple condition check is performed using ‘AND’
logic: only of all conditions hold, the set point will be set according to the decision rule.
An example file:

SOBEK, User Manual

FLM2.0
FLCM id ’Sobek_cntrlid1’ nm ’Comment’ na 0 iv 0.0
SBMS pr 2 ty 2 bp ’BesComment blispar1’ nv 3 cv 3.0 3.54 4.0 sp 3.5
3.52 3.99 sbms
SBMS pr 1 ty 5 bp ’Decispar2’ ’Decispar5’ nv 2 cv 3.0 5.0 ch ’<’ ’>’ sp 5.0 sbms
SBMS pr 1 ty 6 bp ’Decispar2’ ’Decispar5’ nv 2 cv 3.0 5.0 ch ’<’ ’>’ psp ’Decispar1’ sbms
SBMS pr 1 ty 7 bp ’Decispar2’ ’Decispar5’ nv 2 cp ’Decispar4’ ’Decispar3’ ch ’>’ ’<’
sp 5.0 sbms
SBMS pr 1 ty 8 bp ’Decispar2’ ’Decispar5’ nv 2 cp ’Decispar3’ ’Decispar4’ ch ’<’ ’>’
psp ’Decispar1’ sbms flcm

FLCM id ’10-68’ nm ’Comment’ na 0 iv 5.25
SBMS pr 1 ty 12 sbms flcm

FLCM id ’0-68’ nm ’Comment’ na 0 iv 18.0
SBMS pr 2 ty 9 sbms flcm

FLCM id ’Sobek1D2D_BottomLevel controller location X’ nm ’Comment’ na 0 iv 12.75
SBMS pr 1 ty 10 psp ’Bottom Level at location X’ sbms
flcm
With the exception of the MATLAB and TCN measures of types 9 and 12 respectively, all
measure types are related to a decision parameter (‘bp’ field in the data record). For the
MATLAB and TCN measure types, everything has to be defined in the MATLAB m-file or the
TCN csv-files.
Note:
It is possible to define multiple measures operating on the same controller, by giving them
the same id. If multiple measures with the same priority are defined and active on the same
controller, the last active one will define the setting of the controller.
3bmeas.rtc-file (Measures layer)

The Rainfall-Runoff measures are limited to structures (pumps, weirs, orifices, friction, Q-h
relations) in Rainfall-Runoff. A typical application is pump operation. In normal conditions the
pump operation in Rainfall-Runoff is based on water levels of open waters in Rainfall-Runoff
only. In a combined Water Flow - Rainfall-Runoff calculation, pumps in Rainfall-Runoff can be
switched off, based on the water levels in Water Flow. This is done using the Real-time Control
module. A typical application is for a combined ’polder-boezem’ network, using Rainfall-Runoff
for ’polder’ and Water Flow for the ’boezem’ network: polder pumps are switched off if the
‘boezem’ water level is too high. This is called a pumpstop measure.
Pumpstop measures for Rainfall-Runoff are specified using two types of records. First, a
measure is defined using a decision parameter and switch-on and off-levels. This allows to
determine whether a measure is active or not. Second, a pump in Rainfall-Runoff can be
linked to a measure. If the measure is active, Real-time Control will pass on to Rainfall-Runoff
that the pump should be switched off. If the measure is not active, Real-time Control will pass
on to Rainfall-Runoff that the pump may be switched on again. Whether the Rainfall-Runoff
pump is indeed switched on, is determined by the pump operation rules in Rainfall-Runoff.
Several pumps can be linked to the same measure. In fact, this is the main reason to use two
different data records: you only have to define the measure or decision rule once, and you
can link as many Rainfall-Runoff pumps to that measure as you like.

SOBEK input file formats

Also it is possible that a Rainfall-Runoff pump is linked to several measures. The measure
with the highest priority determines what happens. If there are several measures of the same
priority, the following rules apply: if one of the measures is active, the Rainfall-Runoff pump
will be switched off. It can only be switched on again if all measures related to that pump are
inactive again.
This set-up of measures also allows to take measures on RR-weirs and RR-orifices. A pump
stop is then interpreted as a forcing to set Q=0; whereas with no pumpstop the discharge over
the weir or orifice is determined by the normal discharge formula. At the moment there is not
yet an option to distinguish the different high and low capacities of the Rainfall-Runoff pump:
a pumpstop applies to the full capacity.

The general format of data-records is as follows:

Since August 2000 an extra option is available to operate the RR-pumps using MATLAB. With
MATLAB the user can change the switch-on and -off levels for the RR-pump at both the low
and high capacity.

MLST id ’Measure2’ nm ’Comment 2’ bp ’trend_ow’ on -1 of 0 cn ’<’ cf ’>’ mlst
RRST id ’38’ nm ’Comment 3’ na 0
RRMS ty 9 pr 1 rrms
RRMS ty 10 ms ’Measure2’ pr 2 rrms rrst
where:

MLST record:
Id
nm
bp
on
of
cn
cf
and:

id of measure (MLST record)
name of the measure, which can be used as additional comment
id of decision parameter
switch-on level measure
switch-off level measure
check on switch-on level
check on switch-off level

RRST record:
id
nm
na

id of Rainfall-Runoff pump
name of RR-Pump, which can be used as additional comment
option not active, 0 = active, <> 0 means not active.

This option can be used to switch off RTC for this pump while keeping the definition
The RRST record contains one or more RRMS sub-records with the specification of the used
measure[s].
RRMS sub-record:
ty

measure type,
9= MATLAB,
10= normal measure.
measure id, only applicable for type 10
priority

SOBEK, User Manual

An example input file:
RRM2.0
MLST id ’Measure1’ nm ’Comment 1’ bp ’peil_ow’ on -595 of -605 cn ’<’ cf ’>’ mlst
MLST id ’Measure2’ nm ’Comment 2’ bp ’trend_ow’ on -1 of 0 cn ’<’ cf ’>’ mlst
MLST id ’Measure3’ nm ’Comment 3’ bp ’trend2’ on 1 of 0 cn ’>’ cf ’<’ mlst

RRST id ’2’ nm ’Comment 2’ na 0
RRMS ty 10 ms ’Measure3’ pr 1 rrms
rrst

RRST id ’38’ nm ’Comment 3’ na 0
RRMS ty 9 pr 1 rrms
RRMS ty 10 ms ’Measure2’ pr 2 rrms
rrst

RRST id ’111’ nm ’Comment 111’ na 0
RRMS ty 10 ms ’Measure1’ pr 1 rrms
RRMS ty 10 ms ’Measure2’ pr 1 rrms
rrst

E Error Messages
E.1

Error Messages on Startup
Run-time Error ’53’: File not found: wlauth40.dll
This error will occur when the DS_Flex license manager has not been installed. SOBEK can
only be used when the license manager is installed, even the Free Trial mode. It is possible
to install the DS_Flex license manager by opening the SOBEK setup and following the default (recommended) installation options. For more information on installing the license manager, see https://publicwiki.deltares.nl/display/LMADMIN/Deltares+

License+Management
E.2

General error messages or unexpected results

Decimal and digit grouping symbols
SOBEK uses the comma (,) as digit grouping symbol, and the dot (.) as decimal symbol.
The SOBEK user interface will ensure the correct symbols are written to the data files. When
directly editing the SOBEK data files (not recommended) incorrect use of the digit grouping
symbol as decimal symbol will result in unexpected behaviour that may cause error messages,
software crashes or unexpected results.
Error Messages Model data editor

Run time Error 62, Input past end of file.
This error may occur when you open the data editor for a 2D grid. It means that your 2D grid
file does not entirely comply to the ASCII standards. We have encountered 2D grid files made
by customers where the lines did not end with the obligatory "carriage linefeed" (Hexadecimal
code 0D 0A, ASCII character codes 13 and 10). These files had been made with MATLAB.
Read here how to create a correct 2D grid file from MATLAB: How to write a correct 2D-Grid
file from MATLAB:
If you use the command "open" in MATLAB for Windows, to start writing the grid file, you
should not use the -w option (write), but the -wt option (write text). Using the -wt option
means that MATLAB will write the text file platform dependently. In the case of a Windows
environment, it will write a "carriage linefeed" at the end of each line.
E.4

Error Messages SOBEK-Rural / Urban 1DFLOW
Fatal
Node x is connected to itself
Network input of this node is wrong
Delete node and add it in the right way
Fatal
Missing or corrupted definition and data file
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Inquire next group failed
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Unable to close definition file
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged

SOBEK, User Manual

Unable to close data file
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Inquire group failure
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Inquire cell failure
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Inquire element failure
Network and data can not be read from file by flow module or
files might be write-protected or disk might be damaged
Fatal
Get element failure
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Unable to open definition file
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Unable to open data file
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Unknown element type
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Variable already declared
Network and data can not be read from file by flow module
or files might be write-protected or disk might be damaged
Fatal
Running out of data space
Network and data can not be read into memory by flow module
Disk might be full
Fatal
Running out of name space
Network and data can not be read into memory by flow module
Disk might be full
Fatal
Estimated time step too small
(Error message: plchdt) The time step that is necessary to compute the next solution
is smaller than 0.001s (the default minimum time step in SOBEK). This is due to an extreme condition that occurred at a location in the network. To see where the extreme
condition occurs and what the extreme condition is, check the SOBEK log files (for example: ) . For example, there might be an extreme large discharge due to
over-dimensioned structures. The description ’Estimated time step too small’ is usually
replaced with the error message ’plchdt’ in ).

In order to obtain more information on time step reductions in your model, these advanced
options are available:
In Results in Charts and Results in Maps, the output for "Simulation Info at the Branch
Segments". This output is stored in the file .
In the file. More information about time step reductions becomes available in this file after setting the option "Debug=-1" in the and running
a simulation.
In the . This file only becomes available after setting the option "UseTimers=1" in the file, under the "SimulationOptions" category. In order to
decrease the amount of additional output this setting generates, set the value for the
setting TimersOutputFrequency=1 to a higher number, for example 10. This generates
Timer output every 10 time steps instead of every time step.

For more information about time step reductions, see also Time step reductions during
the simulation.

Note: Starting with SOBEK 2.14, SOBEK will automatically reduce the calculation time
step for locations where culverts are located below the cross-section bed level. This may
result in reduced simulation performance or the plchdt error message for models that contain such inconsistencies. Besides manually ensuring culverts are not placed below the
cross-section bed level in the network, SOBEK offers an option to automatically adjust the
cross-section bed level when encountering this issue. For more information, search for
the setting Maximum Lowering of Cross-section Bed Level at Culvert in this manual.

Restart time step not found
Restart data can not be read from fileDon not use this restart file
Fatal
Nefis error
Network and data can not be read into memory by flow module
Fatal
Error while reading SobekB file. Maximum number of SobekB connections exceeded
Module is not dimensioned for this large number of communication points
Use fewer points
Fatal
Error while reading node identifiers
file is incorrect
Warning
No lateral discharges in file
Sobekb has run but no lateral discharge is written to file
Run flow module stand alone
Fatal
Error while reading SobekB file. Number of identifiers on lateral discharge file exceeds
maximum. Module is not dimensioned for this large number of communication points
Use fewer points
Fatal
Error while reading SobekB file
file is not right
might be write-protected or disk might be damaged
Warning
Lateral discharge from file not found. Lateral discharge set to zero
and file are inconsistent
Check runoff
Warning

SOBEK, User Manual

Extreme differences in bottom level in branch segment x
Difference in bed level over branch segment is more than meter
Check data
Fatal
Number of grid points from file and calculated inconsistent
There is an error in the network data
Check if all branches have a start and end node
Warning
Lateral outflow higher than half the volume in node/calculation point x
Withdrawals can cause negative water depths
Check (negative) lateral discharge near this location
Warning
Restart data at grid points inconsistent with present network. Continued with initial state
Network has changed since writing of restart file
Make new restart file
Warning
Restart data at structures inconsistent with present network. Continued with initial state
Network has changed since writing of restart file
Make new restart file
Warning
Restart data at controllers inconsistent with present network. Continued with initial state
Network has changed since writing of restart file
Make new restart file
Warning
Bed level higher than bottom connected branch in well x. Bed level moved to bottomconnected branch Wrong (too high) bed level at this node
check data at this node
Warning
Extreme differences in levels of connected branches in node x
Connected branches differ more than meter in level at this node
Check data
Warning
Well surface table with one row in node x
This one value is used as constant surface
Use constant surface
Warning
Street surface table with one row in node x
This one value is used as constant surface
Use constant surface
Warning
Mass balance not closed in branch x at calculation point x
Netto inflowing water is not equal to storage. High discharges or velocities might be computed
Check data at this location
Warning
Mass balance not closed in node x
Netto inflowing water is not equal to storage. High discharges or velocities might be computed
Check data at this location
Warning
Steady state not branched in steps. Water level stop criterion = . m. Error = x
System is not suitable for a steady state calculation
Turn of discrete action like pumps switching on
Warning

minutes not dividable by chosen time step
Results according to RIONED can not be given
Change time step
Warning
Street level lower than well depth in node x. Street level set one meter above well depth
Street level at this node is wrong
Change street level at this node
Warning
Missing tbl-files with identifiers
Might be an old .
Use new
Fatal
Error while reading branch identifiers
file is incorrect
Fatal
Error while reading structure identifiers
file is incorrect
Fatal
Error while reading lateral discharge identifiers
file is incorrect
Warning
Structure x might generate numerical oscillations due to broad crest and few storage area
around the structure.
Storage surface over one meter above crest level next to structure is less than . times the
crest width. See if oscillations occur.
If yes add storage surface
Fatal
Error while reading calculation point identifiers
file is incorrect
Fatal
Error while reading branch-segment identifiers
file is incorrect
Warning
Lateral discharge set to zero
Withdrawal is to large to be used in a computation with a time step higher than.
Change large withdrawal at this location
Fatal
Two Q-boundaries on branch segment x
No calculation point on branch on which a solution can be found.
Numerical scheme can not deal with this. Change network

Error Messages SOBEK-Rural / Urban RR (Rainfall-Runoff)
66. error
unknown meteo-id or name of node
67. error
node-id found, but inconsistent node names
71. fatal error
fatal error
902. fatal error
error in sub file is corrupt
911. fatal error
unexpected end of file
914. error

SOBEK, User Manual

923.
925.
926.
932.

incorrect number of meteo stations
error
crop factor below zero or above 2.5
error
inconsistency in data
error
basin storage (min.) should be given as a percentage
error
time coefficient not in range 0–1
error
error reading file name

F The SOBEK OpenMI interface
F.1

Introduction
The OpenMI standard defines an interface that allows time dependent models to exchange
data at runtime (Moore et al., 2005). Model components that comply with the OpenMI standard can, without any programming, be coupled to OpenMI modelling systems (Moore and
Tindall, 2005; Gregersen et al., 2007).

The intention of this chapter is to help modellers to setup OpenMI compositions with SOBEK.
The OpenMI interface of SOBEK has been applied several times for model coupling (see e. g.
Becker et al., 2012c; Becker and Talsma, 2014; Becker, 2013; Becker and Gao, 2012; Becker
et al., 2012a; Schellekens et al., 2012; Becker et al., 2012b).

To use SOBEK within an OpenMI composition requires some installation steps. These steps
are described in Becker (2013), Schwanenberg et al. (2011) and Becker and Gao (2012).
The omi file

The omi file populates the OpenMI compliant component. The main information is the location of the assembly (the computational core with OpenMI interface). Below an example for
an omi-file is given.

Different argument keys are used to let the user to specify the component more in detail:
Model specifies the name of the model, appears in the yellow box in the OpenMI editor.
ID specifies an ID for the component, appears in the yellow box in the OpenMI editor.
Directory specifies the location of the schematization file (argument key Schematization)
Sobeksim.fnm relative from the location of the omi file or absolute.
SplitSpecificElementSets defines element sets to split. By default all groups appear as one
exchange item that groups all elements (for example all calculation points) as one element
set. The element set appears in the list of available exchange items. Should elements of this
element set be addressed separately, the element list should appear under this argument key.
ExchangeItemGroup specifies a group of exchange items that are used for typical tasks. The
following groups are available (not case sensitive):

rtc can be used for coupling of SOBEK models with real-time control models based on
based on RTC-Tools (Deltares, 2013) as shown by Becker et al. (2012b) and Becker
(2013).

SOBEK, User Manual

nhi has been set up for the Dutch National Hydraulic Instrument.
sobek for coupling of multiple SOBEK models, examples given by (Becker and Gao,

Photo’s by: BeeldbankVenW.nl, Rijkswaterstaat / Joop van Houdt.

PO Box 177
2600 MH Delft
Rotterdamseweg 185
2629 HD Delft
The Netherlands

T +31 (0)88 335 81 88
F +31 (0)88 335 81 11
sales@deltaressystems.nl
www.deltaressystems.nl

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