Author(s): Hisanori Kusuhara; Kohji Tanaka; Ryoukei Azuma
Linked Author(s):
Keywords: Global warming projection; Spatial resolution; Frequency; Simultaneous occurrence
Abstract: In recent years, Japan has been hit by an increasing number of water-related disasters, including extreme rainfall and powerful typhoons. In response to this increase in extreme weather events, there has been a lot of research into risk assessment using global warming prediction data (d4PDF; 20 km resolution). Recently, a higher resolution version (5 km) has been released, and it is now possible to apply future predictions to tributary river basins. In this study, we focused on the Kumano River basin in the Shingu River system, which has a high number of flood damage cases. When examining the main river basin and tributary river basins using future prediction data, it is necessary to understand the hydrological characteristics due to differences in spatial resolution. Therefore, the aim of this study was to understand the future rainfall and runoff characteristics and the tendency for simultaneous occurrence of main river water levels and tributary river basin rainfall due to differences in the resolution of the global warming prediction values (20 km) and the higher resolution (5 km). As a result, the 20 km tended to underestimate the amount of rainfall and flow in the basin compared to the 5 km. In addition, since the rainfall in the tributary rivers is also underestimated when the water level in the main river is high, it is suggested that 5 km is appropriate when using future prediction values within this basin. In addition, as a result of examining the case of simultaneous occurrence of the main and tributary rivers that actually occurred during Typhoon No. 21 in October 2017 on the global warming prediction values, it was confirmed that it was an extremely rare event regardless of the resolution, and the uniqueness of the flood at that time was confirmed.
DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1979-cd
Year: 2025