CLIMATE CHANGE RESPONSE PROJECTIONS DUE TO GLOBAL WARMING TO RIVER FLOODS CAUSED BY TYPHOON HAGIBIS

Abstract

 Typhoon Hagibis in 2019 induced river floods in various parts of eastern Japan. The precipitation of Typhoon Hagibis was reproduced by a high-resolution atmospheric model experiment, and the model showed high reproducibility. Atmospheric model experiments with the pseudo-warming method, in which the environmental air temperature increases are assumed to be 1.1 and 3.4 degrees, were applied to estimate precipitation, where the future typhoons show almost the same intensities and tracks. The increases in rainfall, which was mostly comparable to the effect of increasing water vapor, were estimated in the future typhoon experiment. Next, the river inundation in Ibaraki Prefecture was reproduced with an RRI model experiment, and its climate change responses were also investigated. It was projected that the peak discharge would increase, the peak water level would rise, the maximum inundation depth would rise, and the inundation area would expand. In particular, there was a significant difference in the impact of flood influences between the cases where the environmental air temperatures increased by 1.1 and 3.4 degrees.