SYNTHETIC STORAGE ROUTING MODEL COUPLED WITH LOSS MECHANISMS

摘要

Flood runoff analysis by the storage function models normally requires an estimate of the effective rainfall as an input, which is computed by use of runoff coefficient or filtering of runoff-component separations. The present study proposes a new storage routing model that can accommodate a nonlinear relationship between the storage and discharge as well as loss mechanisms. The model can produce a hydrograph from the observed rainfall instead of using the effective rainfall. The loss mechanisms take accounts of infiltration, evaporation and transpiration from a river basin. An unknown parameter of the loss component is identified at the same time as the other parameters involved in the storage function model. The proposed model has the advantage of the real-time flood forecasting, because the hydrologic data are directly processed. The model developed in this study was applied to more than 70 flood records from the rivers in Hokkaido. The Newton-Raphson method was used to optimize the model parameters in which the sensitivity coefficients were theoretically derived and the technique of the lower triangular Cholesky factorization was employed to search the optimized values as fast as possible. The results clearly show that the proposed model appears to provide better reproduction of the hydrograph than the model using the hyetograph of effective rainfall patterns.