Akihiro Nagai

Evaluation of the storage function model parameter characteristics

Abstract The storage function hydrograph model is one of the most commonly used models for flood runoff analysis in Japan. This paper studies the generality of the approach and its application to Japanese basins. Through a comparison of the basic equations for the models, the storage function model parameters, K , P , and T 1 , are shown to be related to the terms, k and p , in the kinematic wave model. This analysis showed that P and p are identical and K and T 1 can be related to k , the basin area and its land use. To apply the storage function model throughout Japan, regional parameter relationships for K and T 1 were developed for different land-use conditions using data from 22 watersheds and 91 flood events. These relationships combine the kinematic wave parameters with general topographic information using Hacks Law. The sensitivity of the parameters and their physical significance are also described.