Technical Tour: Reconstruction sites affected by the Northern Kyushu torrential rainfall in 2017.

On July 5, 2017, heavy rainfall occurred from noon until night in the North Kyushu area, and emergency warnings were issued for Fukuoka Prefecture and Oita Prefecture. Measured 24 hours precipitation was 1,000 mm for Asakura City in Fukuoka Prefecture and 600 mm for Hita City in Oita Prefecture. The record-breaking torrential rainfalls caused numerous landslides upstream of the Chikugo River, and a large amount of driftwood washed into the river along with debris. The large quantities of driftwood made the consequential damage worse. How the areas affected by the torrential rainfall disaster have been recovering, and how reconstruction works have been implemented will be covered in this trip.

Site 1: Reconstruction Work on Steep Slope in Miyano District

Summary: A steep slope in Miyano district was affected by the Northern Kyushu torrential rainfall in 2017. The slope is composed of colluvial deposits and schist, and the failure occurred within the colluvial deposits and heavily weathered schist.

Site 2: Landslide Reconstruction Project upstream of Funadani River

Summary: The Northern Kyushu torrential rainfall in 2017 resulted in landslides in the crystalline schist rock slope upstream of the Funadani River, a tributary of the Chikugo River. This area also experienced landslides and riverbank erosion during the heavy rainfall in July 2018, July 2020, and August 2021.