COMPARISON OF 6 RAINFALL-RUNOFF MODELING APPROACHES

Six rainfall-runoff modelling approaches - simple polynomial equation, simple process equation (tanh equation), simple time-series equation (Tsykin equation), complex time-series model (IHACRES), simple concept ual model (SFB) and complex conceptual model (MODHYDROLOG) - are compa red in this paper with the models used to simulate daily, monthly and annual flows in eight unregulated catchments. The complex conceptual m odel gives, by far, the best simulation of daily high and low flows, a nd can estimate adequately daily flows for the wetter catchments. It c an provide satisfactory estimates of monthly and annual catchment yiel ds in almost all catchments. However, the time-series approaches and t he simple conceptual model can also provide adequate estimates of mont hly and annual yields in the wetter catchments. As it is much easier t o use these approaches than the complex conceptual model, the simpler methods may be used to estimate monthly and annual runoff in the wette r catchments.