Catchment geometry lost when importing model prepared in InfoSWMM

Product(s): SewerGEMS, CivilStorm
Version(s): 10.XX.XX.XX, 08.11.XX.XX
Area: Other


When importing a model prepared in InfoSWMM catchments lose their defined shape (geometry) in SewerGEMS or CivilStorm.


This is a known issue when importing models exported from InfoSWMM. To import a model prepared in InfoSWMM the model must be first be brought in the proper format such as .inp (an EPA-SWMM) format which can then be imported to re-create the model.

The model exported from InfoSWMM, when opened in EPA-SWMM would look like this;

The grey shaded areas are the catchments with the black box shaped catch-basins.

When this model (.inp) file is directly imported in SewerGEMS or CivilStorm (File > Import > SWMM v5) then the model appears like this;

As seen, the geometry of the catchments is lost. However, the parameters defining the catchment such as area (if user defined), SWMM properties etc. would be imported and assigned to the respective catchments.

Along with the catchments losing their geometry a user notification also appears informing that the geometry is missing, and a default polygon shape will be assigned.


To fix this the following workflow can be adopted;

1. Open the .inp file in EPA-SWMM software. (EPA-SWMM v5 and above is recommended)

2. Do a “Save-As” in EPA-SWMM. Go to File > Save-As and store the .inp under a different name. Do not overwrite the original model file.

3. Now, in SewerGEMS or CivilStorm, import the newly created .inp file. Go to File > Import > SWMM v5.

4. The geometry of the catchments will be corrected.

When the new .inp file is imported, with the corrected geometry of the catchments, the model would appear as below when imported in SewerGEMS or CivilStorm;

From the above image it can be seen that the catchment geometry is now corrected.

Another alternative to this is importing shapefiles via ModelBuilder. If the shapefiles for all the elements viz. catch-basins, manholes, catchments, conduits etc. are available, then the model can be built using ModelBuilder.

See Also

How to import or Open a InfoSWMM, Mike Urban, LandXML, or other competitor product?

Troubleshooting problems with importing EPANET or EPASWMM files