2001 Volume 45 Pages 79-84
This paper deals with a method for estimating the main model parameters of SWMM, i.e. the imperviousness ratio: F, the equivalent roughness coefficient of impervious area: Ni and the depression storage of impervious area: dpi at a small urban basin.
First, by using the single basin model, we optimized the values of the model parameters. The optimum values of F are distributed in the wide range, and they are lager than the value of the imperviousness ratio obtained from the land-utilization map. The optimum values of Ni have also the wide range of distribution according to the hyetograph patterns. On the other hand, the optimum values of dpi are nearly constantfor various rainfall events. Second, by using the separated basin model, we examined the optimum values of Ni. The results of runoff simulations showed that the value of Ni optimized for the heavy rainfall was well applicable to runoff forecasting for the other rainfalls.
