I am trying to model a stormsewer system that discharges to a tidal water body. The stomwater pipe systems has sever catchbasins which drain a roadway. I want to model a scenario in which a storm event runoff, say 25 year, coindes with high tide tailwater which closes a tideflex at the downstream end of the stormwater pipe. With the tide gate close under high tide, one will expect the roadway runoff water that has been building in the pipe (because it can discharged from the closed tide gate) to backup from downstream to upstream of the pipe system. Can I model this scenarios as reverse flow in HydroCAD? Also, will HydroCAD reverse flow fill up all the pipe network (pressure flow) before catchbasin reverse flow could occur? Thank you very much for your support.