Category: Inside SWMM5

The Link Time Step in SWMM 5, InfoSWMM and H2OMap SWMM

Introduction:  This set of blogs uses the 1000 year rainfall/runoff/hydraulics model that you can download at to show the inner workings of SWMM 5 and by extension InfoSWMM and H2oMap SWMM using a QA/QC version of SWMM 5 with extended graphics.   I always hope that seeing the inner workings
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The Non Linear Term in the Saint Venant Equation of SWMM 5

Subject: Non Linear Term in the Saint Venant Equation of SWMM 5

The flow equation has six components that have to be in balance at each time step:

1. The unsteady flow term or dQ/dt

2. The friction loss term (normally based on Manning's equation except for full force mains),Read the rest

Hysteresis Effect in the Link Flow versus Depth Relationship in SWMM 5

Subject:  Hysteresis Effect in the Link Flow versus Depth Relationship in SWMM 5
You can often get a hysteresis effect for the Flow versus Depth relationship in SWMM 5 due to the five component St. Venant equation used
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Time Step Selection in InfoSWMM, ICM SWMM Networks and SWMM5

1st The time step you use in SWMM 5 is controlled from the top by the rainfall interval (Figure 1): 

1.   All of your time steps should be less than the rainfall interval,

2.   The hydrology time step should be less … Read the rest

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