Horizontal 2D flood simulation on flooding and vehicle stability at car accidents

Vehicle deaths is one of the causes of human deaths due to flood disaster. In order to understand the flooding situation related this accident, we analyze the actual vehicle sweeping away case by the numerical calculation. In this study, we conducted 1D river flow and 2D inundation simulations in the Hata River basin, Tochigi Prefecture, Japan during typhoon Hagibis in 2019. The calculated results indicated that a rapid increase of flow velocity and inundation depth was confirmed immediately after the floodwaters reached at the vehicle sweeping away location. We evaluated the fluid force and frictional force on the vehicle by the results of the inundation simulation. As a result, the time when the sweeping away of the vehicle was almost comparable to the time when the vehicle sweeping away actually occured. It is found that the area for vehicle sweeping away were locally limited and agreed with the inundation depth distribution affected by the topography of railway embankments.