ESTIMATIONS OF FLOOD FLOW DISCHARGE BY USING OBSERVED WATER LEVEL AND OPTIMIZATION OF RAINFALL-RUNOFF AND FLOOD INUNDATION FLOW ANALYSIS

Abstract

 Estimations of flood flow discharge and model parameter optimization such as roughness coefficient were performed by flood inundation analysis using water levels as boundary conditions for the Kagetsu river during North Kyushu heavy rain in 2017. The optimization of model parameters of rainfall-runoff and flood inundation flow analysis was also performed based on the estimated flow discharge. It showed that the method proposed in this study enables optimization of model parameters of rainfall-runoff and flood inundation flow analysis even when flow discharge was unknown, and also was confirmed to improve the reproduction accuracy of flow and water level hydrograph while maintaining the same degree of accuracy in the maximum flooded area.