A runoff model named KWST model(Runoff Model combined Kinematic Wave and Storage Tanks) is developed as a clue for estimating the effective rainfall in the flood runoff analysis.
The upper zone of the model is composed by kinematic wave runoff model.The lower zone is the same with the storage model proposed by Kadoya and Nagai. The estimation method of the effective rainfall concerned in the surface runoff and/or subsurface runoff is shown in the model. It is possible to calculate by the model that the runoff component of the slope flow consists of either surface runoff or both surface and subsurface runoff. The applicability of the model is exaimined for the data observed at the River Hii, the area ofland reclamation in Masuda and Shimokari river basin. For the identification of the parameters, the SP method which is one of the mathematical optimization techinques is applied under the chi-square criterion of errors. The model agrees well with observed hydrographs for flood runoff. And the practical formulae for estimating the optimum model parameters are obtained.