2021 年 26 巻 2 号 p. 15-25
Japan experienced significant rainfall particularly from western Japan to the Tokai region in the Heavy Rain Event of July 2018. This caused extensive human casualties and tremendous property damage due to landslides and river flooding, particularly in Hiroshima, Okayama, and Ehime Prefectures. Agricultural facilities were no exception, with damage to farmland and hydraulic facilities. In this study we summarized the rainfall and Soil Water Index (SWI) mainly in areas where serious damage occurred in Ehime. The damage to agricultural infrastructure was also reported and the relationship between the damage and the rainfall characteristics including SWI was investigated. Furthermore, the behavior of the phreatic surface was traced using runoff analysis and saturated–unsaturated seepage flow analysis for the two irrigation tanks that were seriously damaged, and the factors related to collapse were investigated.
