Author(s): Yasuyuki Maruya; Shinichiro Yano; Satoshi Watanabe
Linked Author(s): Shinichiro Yano
Keywords: No Keywords
Abstract: In previous studies, it has been demonstrated that the frequency of localized heavy rainfall and extreme flood events have been increased by climate change. Especially, the number of flood disasters by heavy rainfall has been increasing such as in Kyushu, Japan, flood damage has been caused several times in recent years, such as the heavy rainfall in July 2020. Therefore, this study aims to analyze the precipitation patterns that induce floods and assess the impact of climate change on the change in precipitation patterns and the frequency of floods in the Chikugo River and Kuma River basins in Kyushu, Japan. In this study, we used d4PDF (Present climate: HPB, Future climate: +2K scenario and +4K scenario, we called them F2K and F4K, respectively) which has 1500 (30 years x 50 ensembles), 3240 (6 sst x 9 ensembles x 60 years), and 5400 (6 sst x 15 ensembles x 60 years) years of data, respectively, as the GCM simulation data to assess the climate change impact on the precipitation patterns and flood discharge in the present and future scenarios. We used the catchment mean precipitation which was calculated by the Thiessen method with AMeDAS (Automated Meteorological Data Acquisition System) measured by Japan Meteorological Agency and MLIT (Ministry of Land, Infrastructure, Transport and Tourism) observed stations around the Chikugo River and Kuma River Basins. Moreover, to analyze precipitation patterns that induce floods, we calculated river discharge by the distributed hydrological model (DHM) that inputted precipitation and temperature. Here, temperature was used to estimate evapotranspiration by the Thornthwaite method. As a result, it was shown that short-term precipitation such as the annual maximum 1 hourly and 2 hourly precipitations in the future (F2K and F4K), although there are some differences in basins, especially 1-12 hourly precipitations might be more increased in the future (F2K and F4K) relative to the present (HPB) in both of the Chikugo River and Kuma River basins. In addition, precipitation duration time tends to decrease in the future (F2K and F4K) compared with the present (HPB). Furthermore, it was found that accumulated 72 and 24 hours of precipitation before the occurrence of monthly maximum discharge had the greatest impact on the discharge in the Chikugo River and Kuma River basins, respectively. Therefore, it was suggested that the flood discharge in the future would be caused by the increase in short-term precipitation.
Year: 2024