An isolated event model based upon direct runoff calculations using an implicit source area concept

Abstract

An isolated event flood model is described that is based upon the concept of expanding source areas using an S-curve function to relatethe proportion of rainfall that becomes stormflow to the moisture status of the catchment.Some features of the Flood Studies Team IEM4 model (NERC, 1975) are included in the modelpresented here. The model has been calibrated on a number of observed flood events in semiarid and sub-humid catchments of South Africa.In reviewing the results, the paper assesses not only the level of correspondence between observed and simulated stormflows, but also the stability of the parameters between stormson the same catchment as well as the differences in parameter values between catchments with different physiographic and climatic characteristics. The results are promising and indicate that the model is able to simulate double or multi-peaked hydrographs. Further work is required to test the wider applicability of the model and to investigate the question of parameter estimation when calibration is not possible. © 1984 Taylor & Francis Group, LLC.