Catch Basin Inlet Capacity-Bypass Flow

I am looking for some help in modelling the volume of bypass flow with HYDROCAD 6.0, which I have calculated separately from inlet coefficients provided by grate manufacturer. I'm a little lost as to how to break out a certain percentage of flow (x-percentage of flow which is carried past the catch basin inlet and y-percentage that enters the CB). Any help would be greatly appreciated

 

[elminer]

You have to model your CB as two ponds. One on top of the grate, and the other, the CB itself. When modeling the one one top of the grate, the primary outflow is through the horizontal grate. Play with it until the flow closely approximates the manufacturer's numbers. The rest overflows the pond (bypasses the grate) and flows down the gutter.