Subject:  How to Edit the Subcatchment Polygons in InfoSWMM with Arc Map

You can edit the polygon boundaries of the Subcatchments in Arc GIS by using the Editor command and either editing the vertices or by using the Reshape Feature Tool to adjust the boundaries or snap to the polygon lines or vertex points.    You should start the editing session by right mouse clickining on the Subcatchment Feature layer

Vertex Editing and Reshape Feature Tool

via Blogger http://www.swmm5.net/2013/08/how-to-edit-subcatchment-polygons-in.html