Estimation of the mitigation and the adaptation for the flood in Japan caused by climate change

Abstract

 This study shows and compares the effect of the mitigation and the adaptation for the flood caused by climate change. It was estimated that the flood depth and the damage using 2D non-uniform flow model and the flood control economy investigation manual . Furthermore, it was estimated that the future flood damage using GCM(Global Climate Model)s and two RCP(Representative Concentration Pathways) scenarios. And we considered the land use regulation as the adaptation. We consider the reduction if we withdraw the land based on the 100 year return period flood depth as the effect of the land use regulation.

 The results shows that the estimated current annual average flood damage is 1.39 trillion JPY, and aruound 2050 damages are 1.43 trillion JPY on RCP2.6, and1.45 JPY trillion on RCP8.5. Therefore the effect of the mitigation is 19.2 billion JPY. On the other hand, the effect of the adaptation is 57.6 billion JPY. The cost-benefit ratio was also considered. The ratio of the mitigation is 0.056, and the cost of the adaptation need keep under 28.8 billion JPY in order to keep the ratio over 2.0.