FLOOD RISK ANALYSIS BY HISTORICAL LANDUSE CHANGE IN THE KUROKAWA RIVER BASIN, ASO

Abstract

 The purpose of this study is to obtain knowledge of relationships between landuse change and flood risk to prepared for the increase of flood disasters caused by climate change in the Kurokawa basin, Aso. We show the change in the number of houses from 1902 to 2003, and predict the number of inundated houses and the inundation depth induced by the 2012 northern Kyushu heavy rain its 1.4 times heavy rain. As a result, the number of inundated houses increase due to the increase of houses especially in the bottom plain and the lower terraces. In the case of the 1.4 times heavy rain, it is predicted that the inundation depth exceeding about 3.0 m would occur in the valley bottom plain and the lower terrace surface, which is not induced by the 2012 northern Kyushu heavy rain. It is predicted that exposure to these floods can be reduced or avoided in the valley bottom plain where the distance from the river is more than about 600 m, and in the natural embankments where the relative height is higher than about 1.8 m.