SIMULATION OF THE DIRECT RUNOFF HYDROGRAPH AT BASIN OUTLET

A simple model describing the transformation of effective rainfall to direct runoff through the overland flow mechanism is presented. The mo del is based on the classical representation of a watershed by a combi nation of planes and channels. The dynamics of overland flow in each p lane is simulated by the non-linear kinematic wave, but the outflow fr om a given plane is concentrated in the middle of the corresponding dr ainage channel. The water routing in the channels is carried out by a piece-wise linearized formulation in space of the kinematic wave appro ximation. Using synthetic events on 10 watersheds, the model was teste d by comparing it with results obtained by applying the non-linear kin ematic wave to all the elements of the watershed. The model was found to be adequate, even in a form that simplifies the geometric features of the planes through an averaging procedure based on the Horton-Strah ler ordering scheme of the watershed. (C) 1998 John Wiley & Sons, Ltd.