SWMM5 Runoff and Depth Relationships

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.

Figure 2:  Subcatchment Runoff and Depth over time with a Subcatchment Width of 500 feet.

Figure 3:  Subcatchment Runoff and Depth in a Scatter Graph with a Subcatchment Width of 500 feet.

Figure 4:  Subcatchment Runoff and Depth in a Scatter Graph with a Subcatchment Width of 2000 feet.