Overland Flow from Time-Distributed Rainfall

The influence of time-varying rainfall on overland flow is investigated. The kinematic wave equations for turbulent flow (across a plane, impermeable surface) are solved using a time-varying rainfall appropriate for thunderstorms. The peak discharge is shown to be a function of surface length, total precipitation, storm duration, and time to equilibrium for rainfall of constant intensity. For rainfall durations equal or less than the time-of-concentration, there is little difference between peak discharges estimated using time-varying rainfall and rainfall of constant intensity. For rainfall of long relative duration, the thunderstorm distribution gives much higher peak discharges.