Characteristics of Flood Disaster in Saga Prefecture by Heavy rainfall of Autumnal Rain Front in 2019

Abstract

The autumnal rain front became active, and precipitation reached nearly 400 mm in 24 hours in Takeo in the upper Rokkaku River area of West Saga Prefecture from the early morning of August 27, 2019 until the early morning of the 28th. The precipitation was observed to be particularly heavy in the early morning hours of August 28th, with 210 mm falling in 3 hours. As a result, the water level of the Rokkaku River rose, and “driving adjustment” to turn off a pump to prevent the collapse and overflow of the embankment was carried out. Inland flooding occurred since rainwater in the city area inside of the dikes could not drain. The heavy rain caused the water level of the Ushitsu River, a tributary of the Rokkaku River, to rise, and flood damage occurred in farmlands and in the city area from water that overflowed the dikes. In addition, inland flooding occurred in the city of Saga, and damages within the prefecture extended to 6,060 buildings.