Step 4: Developed Site – Model Results - VOSWMM

Hydrographs

We can view the summary results in the Result Summary Tables in the same fashion as for the pre-development condition. Click the header of NHYD to sort the table by subcatchment NHYD.

Pre- and Post-Development Comparison

To compare hydrographs of pre- and post-development, select the outfall node and then click the Scenario Comparison button in the Simulation toolbar. In the pop-up window, select the Run to be compared and choose Total Inflow in the Variables.

Unlike the pre-development case, the post-development hydrographs show a more rapid decline once the rainfall ceases. This behavior can be attributed to the much larger amount of imperviousness under the post-development condition (57%) as compared to pre-development (5%).

Step 1: Undeveloped Site – Model Setup

Summary