SWMM5 Runoff Method in XPSWMM, ICM-SWMM and ICM

  • The runoff volume model: calculate the rainfall losses
  • The routing model: route the water through the subcatchment to calculate the shape of the runoff hydrograph

Example Model

The challenge with using the SWMM5 runoff method is that depending on the software of choice, the user interface can look quite different. Next, we’ll set up a sample model in SWMM5, XPSWMM, ICM and ICM SWMM. The model is downloaded from the official application manual. Refer to the manual for more information about the predevelopment model in example 1.

  • % Imperv: 5% is impervious area
  • %Zero-Imperv: 25% of the impervious area is without depression storage
  • Pervious area is implied: 1–5%=95%
  • Evaporation is 0
  • Infiltration seems to reach its limit during the peak of the storm


To setup the same hydrology in XPSWMM will require working through a few windows.

  • The runoff is pretty much the same
  • XPSWMM shows slightly higher infiltration rate after the peak

InfoWorks ICM

To setup the same hydrology in ICM will take some work and can be quite confusing. We’ll first go through the general steps, then we’ll get into the details.

  1. Define a land use, which has a collection of different landcovers called runoff areas
  2. Define the area for each type of runoff area



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