ESTIMATION OF FLOOD HAZARD AREAS BASED ON POTENTIAL EVALUATION OF LEVEE BREACHING PROCESS FOR RIVERS IN TOYAMA PREFECTURE

Abstract

 Evacuation is promoted by using hazard maps, but there is a problem of delayed evacuation due to the unexpected flood inundation by a levee breaching arong the rivers. In this study, rainfall-runoff simulation was conducted on all rivers in Toyama Prefecture to evaluate flood hazard areas in the prefecture by evaluating their overflow, erosion and infiltration potentials of the river levees.The results of the evaluation of each potential indicate the risk of overtopping due to water level rise at the confluence and the risk of erosion at the bend. Evaluation of river flood risk areas by combining the three potentials. Erosion was highly rated in the overall evaluation, and the estimation of risk areas reflects the erosive effect of rapids, which is a characteristic of rivers in Toyama Prefecture.