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 which can accommodate a nonlinear relationship between the storage and discharge as well as loss mechanisms.The model can calculate the total hydrograph from the observed rainfall instead of using the effective rainfall . The loss mechanisms take into account infiltration, evaporation and transpiration from the 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 hyetograph of effective rainfall patterns is used.

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The possibility is considered of effective riverbank stabilization using a combination of vegetation and nonwoven fabric to make the bank and fabric strong enough, in such combination, to withstand damages caused by flowing water, rainwater and wild animals. This reinforcement eventually would make it possible to lessen the frequency of weedings presently done in riverbank maintenance and management. As a result, improved safety of the riverbank and reduced maintenance costs are expected, as well as diversification of vegetation toward fostering a grassland ecosystem.This research seeks to verify the expected effects of the use of nonwoven fabric as a reinforcing material for riverbanks through experiments to examine the applicability of the material.The effectiveness of the nonwoven fabric was confirmed in two experiments. One concerned the behavior of the fabric under the condition of maximum water velocity of 3m/s in a straight, 3-m wide, 40-m long waterway with 1/50 gradient. The other concerned characteristics of the permeability of the same fabric under the condition of a rainfall intensity of 60 mm using a one-meter-high experimental bank.