How Does the Green Ampt Initial Moisture Defiict Work in InfoSWMM and SWMM 5?

Subject:   How Does the Green Ampt Initial Moisture Defiict Work in InfoSWMM and SWMM 5?


This graph shows the values of the internal SWMM 5 parameters for Green Ampt Infiltration for the pervious area of a Subcatchment during a simulation.  The parameters are:


·         Soil Moisture = IMD Max – (FUMax – FU)/Upper Soil Zone Depth

·         FU or current moisture content of the upper zone of the of the soil

·         FUMax which is the saturated moisture content of the upper zone in feet and stays constant during the simulation

·         IMD Max is the user defined Initial soil moisture deficit and is a fraction



Figure 1.  How Soil Moisture changes over time.


Figure 2.  Soil Moisture and IMD are related – the Soil Moisture has a maximum of IMDMax.

via Blogger http://www.swmm5.net/2013/08/how-does-green-ampt-initial-moisture.html

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