Proposal of hyetograph to simulate massive flood discharge

Abstract

 Massive flood discharge is applied to design river structures or evaluate flood inundation, which is simulated by a runoff model through inputting a hyetopgaph. This study proposed two hyetographs to simulate the flood, namely, hyetograph on the basis of observed rainfall and hyetograph on the basis of historical experiment of d4PDF. These hyetographs allowed us to set the rainfall depth on the basis of extreme rainfall in a pecific return period. As a case study, we conducted runoff analyses by inputting these hyetographs corresponding to 1,000-year return period in two basins within Shogawa river. The hyetograph on the basis of observed rainfall brought flood discharge which exceeded the largest flood discharge in the observed record. On the other hand, the simulated discharge through inputting the hyetograph on the basis of the historical experiment did not exceed the largest flood discharge, which was caused by the underestimation of the historical experiment in the target basins.