EVALUATION OF THE FLOOD DAMAGE REDUCTION EFFECTS OF DIFFERENT URBAN PLANNING SCENARIOS IN THE KAKEHASHI RIVER

Abstract

 In order to realize effective watershed flood control, it is essential to establish evaluation methods for urban planning measures to reduce flood damage. In this study, the consolidation of elementary schools was assumed in the Kakehashi River basin, including Komatsu City, under a population decline, and urban structure changes in 2050 were estimated. We assumed multiple scenarios that differed in the timing and sequence of consolidations, and the number of households relocated each year within the target area. Flood economic loss under urban structure changes were also estimated based on flood analysis results using future extreme rainfall as input, and the impact of different scenarios on flood disaster mitigation were evaluated. Comparing the results with varying numbers of households relocated per year, useful information was obtained for setting the annual target number of households to be relocated in order to obtain sufficient damage reduction in the target area. It has been shown that comparisons by varying the timing and order of integration may be an effective method for selecting advantageous scenario even when the number of households relocated per year is small and sufficient damage mitigation cannot be achieved.