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 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:
SOBEK 2 | SOBEK 3 |
---|---|
Hydraulic structures in channel flow module and rainfall runoff module | Hydraulic structures in D-Flow 1d module only |
Control of structures in channel flow module and RTC module | All control of structures in D-RTC module |
Rainfall-runoff module contains open water node | D-RR has no open water node, RR contains only rainfall-runoff processes. |
Rational method in channel flow module (lateral station node) and rainfall-runoff module | No rational method in D-Flow 1d. The rational method is only available in D-RR |
Storage and lateral node available in channel flow module | D-Flow 1D does not contain a storage and lateral node (planned feature) |
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 produce the same results, or that all differences in results can be explained.
Continue with the rainfall-runoff module.
Continue with the water quality module.
Finalize the model by manual modifications.
1D flow
First clean up the SOBEK 2 model with the Cleanup Utility:
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.
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
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 therefor 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 therefor 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
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:
issue | SOBEK 2 | SOBEK 3 | Modification in SOBEK 2 |
---|---|---|---|
Controller operations on pumps, handling of initial value | When the initial waterlevel is in the range of the deadband between switch on and switch off level, in SOBEK2 the pump is on | When the initial waterlevel is in the range of the deadband between switch on and switch off level, in SOBEK2 the pump is on. |
|
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).
Rainfall measurement stations in 1D-Flow
Finalization
Add features that could not be imported from the original SOBEK 2 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.
References
Meijer, D. (2015): Results acceptance test FLOW 1D and RTC SOBEK 3. Deltares draft report 1205718-000-DSC-0124-v1.
Velner, R.; Meijers, E.; Ketelaat, 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