Problem

When using the Explicit (SWMM) solver in SewerGEMS or CivilStorm, some results such as climatology or washoff appear to be different when compared to running the same model in EPASWMM itself (V5.X).

Solution

Be sure that you are using the latest versions of SewerGEMS or CivilStorm. You can download the latest version of the products using the steps in this link. To get the latest patch set, contact Bentley Technical Support.

In addition, the default solver uses a "Bentley-enhanced" version of the SWMM solver (see more at the bottom of the article further below), so for comparable results be sure to choose the appropriate EPA version from the "Solver Compatibility" calculation option. Lastly, be sure that the solver version matches the one used by EPA-SWMM itself. See the compatibility chart in the article below. For example the initial SewerGEMS and CivilStorm CONNECT Edition release uses the same solver as EPA-SWMM v5.1010. The version number is also noted in the text of the dropdown entry in the "Solver Compatibility" calculation option. If you are comparing results from SewerGEMS and CivilStorm to a different version of EPA-SWMM, it is possible you could see different results.

Lastly, please check the following key areas where there have been known issues in the past with this information not being included during import/export:

• Flap gates on pressure pipes
• Weekend patterns

See Also

EPA SWMM solver versions used by SewerGEMS and CivilStorm