DEVELOPMENT OF STAGE-DISCHARGE RELATIONSHIP EQUATION INCORPORATIONG SATURATED-UNSATURATED FLOW MECHANISM

A stage-discharge relationship equation incorporationg saturated-unsaturated flow mechanism is newly devised. A distribited rainfall-runoff model introducing the equation is applied at the Kamishiiba dam catchment (211 km2) in Kyushu, Japan and the model performances are compared with a distributed model using the A-layer flow-surface flow equation and the storage function method. It is shown that simulated hydrographs using the proposed equation show good agreements with observed ones not only peak discharges but also recession parts of hydrographs. The model parameters stability are also highly enhanced by introdusing the proposed stage-discharge relationship equation.