Author(s): Norihito Takahashi, So Kazama
Linked Author(s): So Kazama
Keywords: Flood-disaster; Mountainous-river; Antecedent-Rainfall; Strong coupling simulation;
Abstract: The Typhoon No.10 in 2016 that caused a massive flood disaster at Omoto river had several antecedent rainfalls. Thus, we assumed that the river basin had been considerably saturated, which has led to exacerbating the flood disaster. This paper describes the effects of antecedent rainfall on a flash flood in a mountainous river using a physical-based rainfall-runoff model that employs a strong coupling simulation of surface-water flow and ground-water flow. The results of the simulation indicated that infiltration of the antecedent rainfall lead to a change of pressure head distribution across the entire basin. The pressure rise has occurred across the basin, except the area directly under the river channel. This clearly shows that antecedent rainfalls make ground-water easy to be pushed out to the surface and increase the flood-flow.