NUMERICAL SIMULATIONS OF RAINFALL-RUNOFF AND FLOOD INUNDATION FLOWS BASED ON RADAR RAINFALL IN THE KAGETSU RIVER BASIN ON KYUSHU-HOKUBU HEAVY RAIN IN 2017

Abstract

Numerical simulations of flooding event in the Kagetsu river basin on Kyushu-hokubu heavy rain in 2017 was performed by a numerical model for rainfall-runoff in watershed and flood inundation flows. The rain-fall runoff was simulated by a distributed hydrological model using radar rainfall. The flood flow in rivers and inundation flows on the ground were simulated simultaneously by the 2D flow model. The simulated results compared with the observed water level, flood marker and maximum inundation area. It shows that the model has ability to reproduce runoff, flooding and inundation process with reasonable accuracy. A inundation process was also examined through numerical result and filed survey.