ESTIMATION OF THE RISK OF INLAND FLOOD BASED ON EXTREME PRECIPITATION DATA CONSIDERING CLIMATE CHANGE IN JAPAN

Abstract

 This study estimated the damage cost and exposed population caused by inland flood in Japan modeled by extreme precipitation data. We used two inundation scenarios (natural drainage scenario and poor drainage scenario) based on the presence or absence of drainage by gravity to rivers. In the current climate, in the natural drainage scenario, the expected damage cost and exposed population were estimated to be 618 billion JPY/year and 52,695 people/year, respectively. On the other hand, in the poor drainage scenario, the expected damage cost and exposed population were estimated to be 9,422.4 billion JPY/year and 870,388 people/year, respectively. We then estimated the damage cost and exposed population in the nearfuture climate (2031-2050) using the poor drainage scenario. As a result, the damage cost increased about 2-fold and exposed population (considering population change) increased about 1.6-fold from current climate to near-future climate. The increase rate of the damage cost tended to be higher on the Japan Sea side. The increase rate of exposed population was higher in Hokuriku region, Tokyo and Saitama prefecture.