Subject:   3 Types of Subcatchment Flow in SWMM 5

There are three types of Subcatchment flow in SWMM 5 (Figure's 1 and 2)

1.   Impervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation occurs based on the depth of water in the subarea of the Subcatchment.

2.   Impervious area without depression storage in which the runoff from precipitation is NOT delayed.  Evaporation does occur based on the depth of water in the subarea of the Subcatchment.

3.   Pervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation and Infiltration occurs based on the depth of water in the subarea of the Subcatchment.