EVALUATION OF CLIMATE CHANGE IMPACTS ON WATER LEVEL, DISCHARGE, AND INUNDATION IN KINU AND KOKAI RIVER BASINS USING RRI MODEL

In order to evaluate risks of river disasters due to global warming, rainfall data of super-high resolution numerical simulation estimated by a regional climate model were given to the Rainfall-Runoff-Inundation (RRI) model simulations in Kinu and Kokai river basins. We evaluated the impact of climate change on the risks of river floods with the three viewpoints of water level, discharge, and inundation area. As a result, the excess frequency for the lower-risk water level significantly increased, whereas the increase for the higher-risk water level was unclear. Water discharge amount mostly increased, whereas drought-flow amount did not significantly change. Furthermore, the frequency with which innundation areas expand remarkably increased, suggesting an increased risk of floods. However, the 31-year-experiments in this study involve large uncertainties with the narrow target areas such as the Kinu and Kokai River basins. It is necessary to further increase the number of cases in the future.