Typhoon No. 12 of 2011 caused large-scale sediment disasters accompanied by river channel clogging in the Kii Mountains. In the Kumano District, a hillside collapsed for a width of 450 m and a length of 650 m, making 4.1 million m3 of collapsed sediment clog the river channel. For this reason, in order to control the outflow of sediment from the slops and prevent surface erosion, surface drainage works were constructed, and emergency measures such as installation of erosion control dams and widening and reinforcement of drainage channels were implemented.
In this project, EJEC designed the downstream flow/riverbed consolidation, upstream wood debris capture works and sedimentation works, slope protection works and surface drainage works at the collapsed site and road works on the right, in addition to the main check dams.