Using SWMM Hydrology during Flood simulation

Product(s): OpenFlows FLOOD
Area: Modeling

For who performs flood simulation by connecting 1D networks models, there is an option that allows modelers to use the hydrology calculation from the 1D model, where subcachments are placed as polygons.

To bring the subcatchment polygons into consideration during the flood analysis, the 1D network model needs to be saved in the SWMM INP file format.

Figure 1 – SWMM INP Example with Subcatchments

If you have the 1D network modeled in CivilStorm or SewerGEMS, the subcatchments (Catchment element) should be modeled using the option “EPA-SWMM Runoff” as Runoff method. See picture below that shows an example of a polygon catchment set up using the preferred option.

Figure 2 – SewerGEMS/CivilStorm model with Subcatchments

Once having model’s catchment polygons set up, the model needs to be exported to INP (File > Export > SWMM v5).

Please also check your exported model to see if data and results are consistent.

Having the INP file, we can couple the 1D model to FLOOD using the tool Urban Floods > Connect SWMM model to MOHID Land model.

Figure 3 – FLOOD’s toolbox to couple SWMM model file

Check the option to “Keep SWMM Hydrology” to consume the subcatchment polygons and rainfall data from the SWMM model.

Figure 4 – FLOOD’s toolbox to couple SWMM model file

The tool also asks to select the project’s DTM, coordinates projection system and the file path to place the output files.

Figure 5 – FLOOD’s toolbox to couple SWMM model file

Consider that simulations that use hydrology calculation from SWMM model don´t need to have the rainfall modeled in the 2D, then check the atmosphere module of your simulation has the Precipitation option toggled as False:

Figure 6 – Simulation’s atmosphere module

To learn more about this tool and the overall OpenFlows tools for Flood modeling, please see our training materials below:

OpenFlows FLOOD - Generic Start Guide

OpenFlows FLOOD - Quick Start Urban Flood Simulation – SWMM

See more

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