NUMERICAL SIMULATION OF RAINFALL-RUNOFF AND FLOOD INUNDATION FLOWS IN THE YAMAKUNI RIVER BASIN AT KYUSHU-HOKUBU HEAVY RAIN IN 2014

Abstract

Numerical simulations of flooding event in the Yamakuni river basin at Kyushu-hokubu heavy rain in2014 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. The flood flow in rivers andinundation flows on the ground were simulated simultaneously by the 2D free-surface flow model. Thesimulated results compared with the observed discharge into the Yabakei dam, water level of floodmarker and maximum inundation area. It shows that the model has ability to reproduce runoff, floodingand inundation process, but the more improvement is needed to predict the runoff, flooding andinundation process with reasonable accuracy.