Subject: How is the Soil Saturated Conductivity Used in SWMM 5 Green-Ampt?
How sensitive is the infiltration loss and rate to the Soil Saturated Conductivity parameter in the SWMM 5 Green-Ampt infiltration method (Figure 1). Figure 2 shows how the total infiltration loss and total loss rate vary as you change the soil saturated conductivity from 1 to 0.1 to 0.01 inches/hour. Internally, Ks is used to check saturation and in the computation of the soil infiltration rate. Two of the checks are:
· In low rainfall everything infiltrates as irate less than Infil>Ks and
· In the check to see if the soil is already saturated.
Figure 1. The three parameters for Green-Ampt Infiltration in SWMM 5
Figure 2. The sensitivity of the total infiltration loss to the soil saturated conductivity in a continuous simulation