The storied Shimanto River rises in the Koban area in western Kochi. The river heads south then west into the mountains. As it enters the Hata area, it loops back and flows into the Pacific in the southwest of Kochi Prefecture. Its watershed reaches into Ehime. The river is 196 km long, with a watershed covering 2,270 km². In Shikoku, it’s second only in size to the mighty Yoshino River.

An NHK television documentary in the 1980s noted that the Shimanto was Japan’s last major river without a dam, and since then, this point has been made endlessly, often with unfortunate results in English; “Japan’s last limpid stream” and other such nonsense. The Shimanto is also renowned for its chinkabashi — simple bridges without parapets that can be submerged entirely in the regular floods and not get washed away. They present a rustic and beautiful sight. In the days before concrete, the river was crossed on little wooden ferries powered by hand. Long, gently sloping ramps went down the banks of the river where a boatman would have a hut. When the chinkabashi were built, the huts were demolished, but the ramps remain as they were.

Some of the chinkabashi are quite tall and it’s hard to imagine the river rising that much. But several times a year, the river covers them completely, and in years of heavy rainfall, the river can rise to fill nearly the whole valley. Consequently, the houses in the settlements are built high above the river. The rice paddies are made closest to the river and the villagers’ vegetable plots are arranged on higher ground. Since rice was originally a commodity grown for sale and not immediate consumption, the paddies were somewhat expendable if there was serious flooding, whereas the vegetable plots were more important to survival.