Runoff Over Pond Surface

Question

Hello, 
 I am simulating a storm water network in SewerGEMS platform. In my model there is pond which spreads over a large area. 
 My question is, does the software calculate the rainwater getting over the pond surface area? or do we have to assigned a dummy catchment which is equal to Pond surface area and connect with the pond with high runoff coefficient (0.9)? 
 
 Thanks 
 Nishadi

Holly Herring · Answer

I recommend posting this question in this forum: (+) OpenFlows | Water Infrastructure Forum - OpenFlows | Water Infrastructure - Bentley Communities .

Jesse Dringoli · Answer

Nishadi, 
 SewerGEMS will not automatically have the rain fall over the pond area. 
 So, indeed, if you have a pond with a significant top surface area and need to account for rain that falls directly into the pond, lay out a separate catchment overlapping the pond catchment and set the pond as the "outflow element". Or, to help prevent difficulties associated with overlapping polygons, consider laying out a schematic catchment (for example hold CTRL and click to lay out a pentagon shaped catchment) with a user defined area set equal to the pond top surface area, and direct that to the pond. 
 I see you asked the same question in August: Runoff generated over a waterbody