A Quick Micro-Computer Urban Runoff Model

The Penn State Direct Hydrograph Model PSDH described in this paper uses watershed and rainfall data to generate a synthetic unit hydrograph and a runoff hydrograph, both gamma-distributed. This allows an analytic derivation of gamma distribution parameters which define the resulting runoff hydrograph, avoiding the traditional and more tedious stepwise summation of incremental rainfall effects. The model can handle relatively large watersheds with up to 100 subareas on a microcomputer in a much shorter execution time than most of the presently available micro-computer models.