亀岡盆地の流出・氾濫解析に基づく日吉ダムの治水操作手法の検討

Abstract

Heavy rainfall caused severe flood disasters across the western Japan in July 2018. In order to decrease frequent inundation in the downstream reaches where river improvement works have never been completed, some reservoir dams are often operated to control small and/or medium floods by releasing a less discharge than originally designed. However, this operation can increase a risk of severe flood inundation in case of large floods, because the water level of the reservoir increases faster to the full storage level and eliminates the flood control function of the reservoir. This study aims at analyzing impacts of different flood control operations for floods of various scales including large flood events using rainfall runoff inundation analysis in order to identi fy an effective operation rule for flood risk reduction.Heavy rainfall caused severe flood disasters across the western Japan in July 2018. In order to decrease frequent inundation in the downstream reaches where river improvement works have never been completed, some reservoir dams are often operated to control small and/or medium floods by releasing a less discharge than originally designed. However, this operation can increase a risk of severe flood inundation in case of large floods, because the water level of the reservoir increases faster to the full storage level and eliminates the flood control function of the reservoir. This study aims at analyzing impacts of different flood control operations for floods of various scales including large flood events using rainfall runoff inundation analysis in order to identi fy an effective operation rule for flood risk reduction.