RELATION ANALYSIS BETWEEN METEOROLOGICAL FIELD AND RAINFALL FOR EACH BASIN IN KYUSHU USING SELF-ORGANIZING MAP

Abstract

 In this study, we utilized a self-organizing map to analyze the relationship between the meteorological fields across the entire Kyushu region, where is increasing risk of heavy rainfall in the future, and the rainfall patterns in the first-class river basins. River basins selected in this study include the gala, Rokkaku-kawa, Ono-gawa, Shira-kawa, Kuma-gawk, Oyodo-gawa, and Sendai-gawa. As a result, it was found that the basins in the western part of northern Kyushu (Chikugo-gawa, Rokkaku-gawa, and Shira-kawa) were predominantly affected by heavy rainfall from frontal systems. Heavy rainfall events that occurred in the basins of the western part of southern Kyushu (Kuma-gawa and Sendai-gawa) were characterized by typhoons as well as frontal systems. On the other hand, in the eastern basins (Ono-gawa and Oyodo-gawa), typhoon-induced heavy rainfall was highly prevalent. Moreover, the meteorological pattern on 14 August 2021, which induced heavy rainfall in Saga Prefecture, was diagnosed by using the self-organizing map constructed in this study. As a result, it was found that this meteorological pattern indicates a high risk of heavy rainfall in Chikugo-gawa and Rokkaku-gawa river basins.