RUNOFF PREDICTION BY SIMPLE TANK MODEL USING RECESSION CURVES

A simple water-tank model is constructed to simulate the rainfall-runo ff process ina catchment. The water tank has a horizontal cross-sectio nal area, which is a function of the water depth and which may be dete rmined from the recession curves of flood hydrographs. The total verti cal depth of the water tank and the infiltration velocity, which gover n the time lag between rainfall and runoff, are computed from the risi ng limbs of the flow hydrograph: The model is applied to two catchment s, one in Japan and the other in the United States for predicting floo d response to rainfall events. The results found from the tank model a re in good agreement with the observed data. The parameters of the tan k model have physical meanings of the catchment.