FLOOD RISK EVALUATION FOR URBAN CONSOLIDATION

Abstract

Recently urban consolidation is thought to save variable social cost (for maintenance of infrastructure, disaster risk and so on). To maintain the flood risk cost or reduce social costs lower in compacting city, the technique to evaluate and show expected flood damage is needed. In this study, the spatial distribution and total value of the flood damage cost by flood in An-ei River basin as example, which includes urban area of Toyota, are evaluated. Yahagi River is the big river going through Toyota and may cause extensive damage when the levee is destructed by flood, but the probability of flood levee failure is low. Therefore, flood of tributary rivers, which happen more frequently, was considered. Calculated results show that frequent smaller flood is more effective for expected disaster damage, and contribution to expecting value by tributary flood disaster is much more than big river’s flood.