長短期両用貯留型流出モデルとその最適同定

Abstract

A storage model for analyzing both flood and long term runoff is developed as a clue forestimating the effective rainfall in the flood runoff analysis. The model is examined and improvedstep by step. The model, M3, expected to be the best form is composed of three tanks. Theupper tank of the model has three runoff holes, each of which corresponds to surface runoff of theManning's type, prompt and delayed subsurface runoff of linear type, respectively. Each of themiddle and lower tanks has one runoff hole corresponding to short and long term groundwaterrunoff, respectively. In the upper tank, the infiltration rate of rain water is assumed to bepropotional to the effective porosity of subsurface soil. This assumption allows the existence ofthe Horton's infiltration theory under the some special condition.The applicability of the model is examined for the data observed at the Kama Valley basin forthe period of 1975-1982, the first four years' data of which are used for the identification of themodel parameters and the rest for the runoff forecasting. For the identification of the parameters, the SP method which is one of the mathematical optimization techniques is applied under the chi-square criterion of errors. The model shows good agreement with observed hydrographs forboth flood and long term runoff in the forecasting period.