SWMM 5 Subcatchment Runoff and Depth Relationship

Note: The surface runoff is a non linear function of the independent depth in both the pervious and impervious areas of the subcatchments. No surface runoff occurs until the depth over either the impervious or pervious area is greater than the respective depression storage (Figure’s 1, 2, 3 and 4).
Figure 1: Surface Runoff, Depth and Depression Storage Relationship.