A Simple Flood Hydrograph Model for Urban Catchments

Study of rainfall and runoff depths, and runoff hydrographs on 16 urban catchments, has indicated that runoff from pervious and impervious areas should be modelled separately. For small storms, runoff comes predominantly from impervious surfaces, while for the larger less frequent storms, runoff is generated on both pervious and impervious surfaces. The lag parameter for impervious runoff can be successfully estimated from hydrograph recessions. A parallel reservoir model is suggested as an adequate model for urban catchment hydrographs.