Read this article when you have a SOBEK 2 model and you want to convert it to SOBEK 3. If you want to import a DUFLOW model, see reference Jeuken (2014).

Preface

SOBEK 3 is refaced against SOBEK 2 in terms of modeling concept and features. This means that some features in SOBEK 2 are no longer supported and some objects are modelled in a different way.

The following table gives an overview about differences in the modelling concepts between SOBEK 2 and SOBEK 3:

Approach

Import the SOBEK 2 model into SOBEK 3 and choose features

Procedure:

• Start with the SOBEK 2 channel flow module.
  • Modify the SOBEK 2 model in such a way that the corresponding SOBEK 3 model produces the same results, or that all differences in results can be explained.
  • Finalize the 1D flow model by manual modifications.
• Continue with the rainfall-runoff module.
• Continue with the water quality module.

1D flow

Clean up the SOBEK 2 model

First clean up the SOBEK 2 model with the Cleanup Utility:

Import to SOBEK 3

Now create a SOBEK 2 model that can be imported in such a way that there is no difference between the SOBEK 2  model and the SOBEK 3 model with regards to the contents.

This is an iterative process:

• Import your SOBEK 2 model with the help of the import feature in SOBEK 3.
• Check the import log messages. Are there any features that are not supported, any values that are modified by the import tool?
• Modify your SOBEK 2 model accordingly: delete features that are not supported in SOBEK 3.
• Repeat the three steps above until there are no model differences between the SOBEK 3 model and the SOBEK 2 model.

To import the model, use the SOBEK 3 import tool:

SOBEK 3 import window. Choose "SOBEK Model (Flow 1D, RTC, RR, WAQ)". This window is accessible via File --> Import

Select case after opening CASELIST.CMT

Dependent from the choices you make, you receive an integrated model with the following sub-models:

• water flow 1d
• real-time control

The following list gives examples for modifications that might be necessary:

• The rational method on lateral inflow is not supported, lateral inflow must be accounted for in a different way, for example with a set of time series.
• Infeasible bottom levels for culverts must be changed.
• Open water nodes are not imported into D-Flow 1D. They must be deleted in the SOBEK 2 model. 
• Structures in the rainfall-runoff module must be deleted.

The following warning messages do not require any modifications in the model, but can explain different model results:

• The initial value 0 of PID controller <id> will not be used. The defined structure dimension is the initial value:
  • In SOBEK 3 you can’t define an initial value of the PID, therefore the initial structure setting are used as initial value.
• The initial value -5.37 of PID controller <id> will not be used. The defined structure dimension is the initial value
  • In SOBEK 3 you can’t define an initial value of the PID, therefore the initial structure setting are used as initial value.
• Case setting CrestlevelOpeningsHeight cannot be imported, model parameter setting not available.
• Case setting StructureDynamicsFactor cannot be imported, model parameter setting not available.
• Case setting Steady cannot be imported, model parameter setting not available.
• Computational grid import: 1 grid points were skipped in branch '<id>' because there are structures defined at these locations.
  • There is no longer a gridpoint on structures necessary.
• Friction data of definition <id> of cross-section <id> has not been found. The main bed of branch <id> is used as roughness data.
  • This warning is related to a network element that is no longer available in the model after it has been deleted by a user.
• Friction BDFR <id> is linked to branch definition <id> without any tabulated, standard or river profiles; ignored.
• Friction BDFR <id> is linked to branch that does not exist (id 0); ignored.
• No location with id = <id> found

Compare simulation results and modify model data

Change the numerical parameters Iadvec1D from 4 to 1 and Limtyphu1D from 100 to 0 according to SOBEK 3 user manual, section 5.10.2.10 (Parameter set for comparison with SOBEK 2, Deltares Systems, 2013).

Run a simulation with your modified SOBEK 2 model with the channel flow module only.

Validate your SOBEK 3 model with the validation feature.

Validate model tool. This tool is available after right-mouse click on a model. Choose "Validate...".

Check the warning messages and make the necessary changes. Possible necessary changes are:

• Add grid points
• Re-generate grid

Run a simulation with the corresponding SOBEK 3 model. Compare the results. Results may differ due to changes in the model approach. The following table gives an overview about the differences in model approach between SOBEK 2 and SOBEK 3:

Modify the SOBEK 2 model in such a way that the corresponding SOBEK 3 model produces the same results. This is not possible in all cases (Meijer, 2015).

Finalization 1D-Flow

Preface

Within the finalization phase, features that could not be imported from the original SOBEK 2 model must be added:

• For lateral stations where the inflow is computed with the rational method, corresponding objects must be modelled in a Rainfall-Runoff model.
• Open water nodes from the rainfall-runoff module must be schematized in the D-Flow 1D network.
• Hydraulic structures from the rainfall-runoff module must be added to the D-Flow 1D network. 

If the model has a long history, modify your model according to good modeling practice:

• Remove so-called "Preismann-slots" from all cross-sections.

Consider to use the scripting feature of SOBEK 3. Example scripts are delivered with SOBEK 3.

Lateral stations in 1D-Flow with rational method

If your SOBEK 2 1D-Flow model contains lateral stations that get inflow from rainfall-runoff features like

• rational method
• rational method with intensity from Rainfall Station

these features must be added manually within a rainfall-runoff (D-RR) model.

• Add a new model to the project: 
  • right mouse-click on the project, choose "New Model...": 
  • 
• Select "Rainfall Runoff Model"
• Move it to integrated model 
  • 
• Import precipitation data (a *.bui file) from your SOBEK 2 model
• Create catchments
• modify the open water property
  • fill in the catchment area
  • choose the appropriate Rainfall Station (corresponds to the precipitation data)
• connect the catchment to the corresponding lateral node in the water flow 1d network.

References

Deltares Systems (2013): 1D/2D modelling suite for integral water solutions / SOBEK Suite / D-Flow 1D and D-Real Time Control in Delta Shell / User manual. Version: 3.0.1.29328, 30 July 2013 Deltares: Delft, The Netherlands.

Meijer, D. (2015): Results acceptance test FLOW 1D and RTC SOBEK 3. Deltares draft report 1205718-000-DSC-0124-v1.

Velner, R.; Meijers, E.; Ketelaar, H.; Heeringen, J.-J.; Stout, J.; van Putten, H. (2013): Pilot: testen van SOBEK3.1 o.b.v. DeltaShell bij Waterschap Rivierenland. Eindrapport. Waterschap Rivierenland. file: PilotSobekDeltaShellWSRL_Groeidocument_v09_final.doc

Related articles

• Page:
  [intermediate] Using MATLAB to plot SOBEK output
• Page:
  [beginner] Running batch computations
• Page:
  [intermediate] Using Python to plot SOBEK output
• Page:
  [advanced] Scripting a full modelling workflow
• Page:
  [intermediate] How to migrate SOBEK 2 models to SOBEK 3