Migrating SOBEK 2 models to SOBEK 3

The modeling concepts, codes and features of SOBEK 2 have been revised to form the SOBEK 3 modeling environment. This means that some of the features  are not supported in SOBEK 3 and some objects are modeled in a different way. The following table gives an overview of the most prominent differences. Please note that this is a document in progress.

SOBEK 2 SOBEK 3
Control of structures  in CF and RTC module in D-Real-Time Control module only
Hydraulic structures in CF and RR module in D-Flow 1D module only
Open water node in RR module D-Rainfall Runoff has no open water node, it contains only rainfall-runoff processes
Rational method in CF (lateral station node) and RR module The rational method is available in D-Rainfall Runoff only
Storage and lateral node in CF module D-Flow 1D does not contain storage or lateral nodes

General procedure:

  1. SOBEK 2 1DFLOW module
    1. Modify the SOBEK 2 model
    2. Compare SOBEK 2 and SOBEK 3 simulation results
    3. Finalize the SOBEK 3 model manually
  2. SOBEK 2 Rainfall-Runoff (RR) module
  3. SOBEK 2 Water Quality (WQ) module

Modify the SOBEK 2 model

Clean up the SOBEK 2 model with the Cleanup Utility.

SobekCleanUp

Now revise the SOBEK 2 model, so that it can be handled by SOBEK 3. This is an iterative process, consisting of the following steps:

Adapt the model, regarding the aspects stated in the table above ‘prominent differences’

Import your SOBEK 2 model using the DeltaShell Import Tool in SOBEK 3

  • Choose ‘File’ and ‘Import’
  • Select ‘SOBEK Model (Flow 1D, RTC, RR, WAQ)’

DeltaShell_import_tool

The ‘SOBEK hydro model importer’ window opens

  • Select case after opening CASELIST.CMT

SOBEK 3 import window

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

  • water flow 1d
  • real-time control

Check the import log messages. Modify your SOBEK 2 model accordingly; delete features that are not supported in SOBEK 3 and deal with values that are modified by the import tool. Repeat these steps until there are no model differences between the SOBEK 3 model and the SOBEK 2 model.

The following list contains examples for necessary modifications:

  • 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. These need to be adapted.
  • Open water nodes are not imported in D-Flow 1D. They have to 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 of 0 (or: 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 not define an initial value of the PID. Therefore the initial structure settings are used as initial value.
  • Case setting CrestlevelOpeningsHeight, StructureDynamicsFactor or 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 present in the model since it has been deleted earlier by a user.
  • Friction BDFR <id> is linked to branch definition <“id”> without any tabulated, standard or river profiles or friction BDFR <“id”> is linked to branch that does not exist (id 0): to be ignored.
  • No location with id = <“id”> found: to be ignored.

 Compare SOBEK 2 and SOBEK 3 simulation results

Change the numerical parameters Iadvec1D from 4 to 1 and change the numerical parameter Limtyphu1D from 100 to 0. See SOBEK 3 user manaual, section 5.10.2.10 ‘Parameter set for comparison with SOBEK 2’, Deltares Systems, 2013.

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

Validate your SOBEK 3 model with the validation feature. Acces the feature via right-mouse click on a model and choose “Validate…”

validation feature

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

  • Add grid points
  • Re-generate grid

Run a simulation with the corresponding SOBEK 3 model and compare the results. Results may differ due to changes in the model approach. The following table gives an overview of 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. 1. Change the controller time series in such a way that pump shows the same behaviour in both models.
2. Check the initial water level

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).

Finalize the SOBEK 3 model manually

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 modeled 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 and 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.

If your SOBEK 2 1D-Flow model contains lateral stations that get inflow from rainfall-runoff features (like
the rational method or the rational method with intensity from rainfall station), these features must be added manually within the rainfall-runoff (D-RR) model.

lateral station

Add a new model to the project: right mouse-click on the project, choose ‘New Model…’.

add new model

Select ‘Rainfall Runoff Model’ and ‘Move into integrated model’

move 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 and choose the appropriate Rainfall Station, corresponding to the precipitation data and 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.; 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

Jeuken, M. (2014): Tips bij het converteren van DUFLOW modelschematisaties naar SOBEK 3. Deltares-memo.