Sabo Projects and Our Approach

The Arakawa River Sabo Project

The Arakawa River has its sources in Mt. Higashi-azuma (elevation 1,975 m), Mt. Issaikyo (elevation 1,949 m), Mt. Tetsuzan (elevation 1,710 m) and others of the Ou Mountains, and flows through hilly country creating deep gorges. The river merges with other small branches, including the Nishi-karasugawa River, the Higashi-karasugawa River, and the Shionokawa River, en route to the Jizohara Dam. The river runs through the alluvial fan with a radius as large as about 8 kilometers, and merges with its branch, the Sugawa River, and finally with the Abukumagawa River in the south of the urban Fukushima area.

The sabo project of the Arakawa River was launched in 1900 by Fukushima Prefecture as part of the engineering work on the mountainside. In 1936, the area was designated under the direct control of the government of Japan. In 1941, 13 sabo dams were completed in the Arakawa-honkawa River, 13 in the Higashi-karasugawa River including the riverbed reinforcement works, 5 in the Shionogawa River; total 30 sabo dams were completed.

These facilities stop debris flows from the upper river, thereby preventing a disaster downstream. The first reinforced riverbed is designed to stabilize the watercourse in the sediment retarding basins. It includes nine culverts with a radius of 3 m, which help fish go up the river while preventing the landslide disaster.