Storm Drain Capacity Simulator

Every city street drains through a pipe sized for a specific storm — and when rainfall outruns that pipe, the street becomes the overflow channel. This simulator pits the Rational Method's estimate of stormwater inflow against Manning's equation for the storm drain pipe's real hydraulic capacity, live: dial up rainfall intensity, catchment imperviousness, pipe diameter and slope, and watch the pipe's flow-depth gauge rise toward its crown. Push inflow past capacity and the drain surcharges — the excess floods back onto the modeled street as a rising blue sheet of ponding, exactly the mechanism behind urban flash flooding in undersized or aging storm sewer networks.