TerryScan,
Thanks for the reply. Thats how I began modeling the project, but my issue is with modeling the valves so that the outflow into the canal stops once the canal is higher than the culvert (valve closed). I am using Hydrocad to do the modeling.
I have a project where I am analyzing a neighborhood for a 100 yr storm event. The current design drains each street into a canal. When the canal rises above the outfall culverts, valves close and the ditches are alowed to backwater until they spill over into a ditch on the far upstream end of...