The Tone-gawa River: the largest river basin in Japan

Before the 17th century, the Tone-gawa River and its tributaries, the Watarase and Kinu Rivers, followed distinct paths. The Tone-gawa flowed south through the center of the Kantō Plain, running into the Arakawa River and emptying into Tokyo Bay through the modern-day area of the Sumida River. In 1590, with Tokugawa Ieyasu's entry in Edo (now Tokyo), redirection works began and, as a result, its course was altered to empty directly into the Pacific Ocean. This series of works is known as the “Tone-gawa River's Direction Eastward” (Tone-gawa Tōsen Jigyō), constituting its current configuration.

The redirection of the Tone-gawa River and river transportation

The Tone-gawa River redirection project created a vast network of canals in the Kantō Plain. This infrastructure transformed the river into an important internal transport hub for Japan, driving commerce even in more distant areas, such as Tsugaru, where the western part of Aomori Prefecture is currently located, and the city of Sendai, in Miyagi Prefecture.

Several river ports for unloading goods, known as kashi, were installed along the tributaries and the main river, bringing prosperity to the warehouse owners and vendors who operated along on the banks of the rivers. In 1890, the Tone-gawa River Canal was opened, significantly shortening the route and travel time to Tokyo and resulting in reduced freight costs. In 1891, over 37,000 vessels crossed the canal, proving the importance of this access.

Although river transportation remained relevant in the supply chain of goods up until the early 1890s, the development of land transportation and the expansion of the railway network, especially the Takasaki Line in 1884 and the Tsuchiura Line (today, the Jōban Line) in 1896, in addition to the improvement of roads, led to its gradual decline. Nowadays, the Tone-gawa River can no longer be navigated for commercial transportation purposes.

Reference: Japan Ministry of Land, Infrastructure, Transport and Tourism Official Website.
 

Tone-gawa River System: World Heritage of Irrigation

Tengu-iwa Yōsui Canal (cities of Maebashi, Takasaki and Tamamura in Gunma Prefecture)

Built in cooperation with farmers between 1602 and 1604.

Bizen-kyo Yōsui Irrigation Canal (cities of Honjō, Fukaya and Kumagaya in Saitama Prefecture)

Built in one year starting in 1604, it is one of the oldest irrigation canals in Saitama Prefecture.

Jyukkoku-bori Canal (city of Kitaibaraki, Ibaraki Prefecture)

Built in 1669, it is an irrigation structure of about 15 kilometers.

Minuma-dai Yōsui Canal (cities of Gyōda, Hanyū, Kazo, Kōnosu, Kuki, Okegawa, Ageo, Hasuda, Shiraoka, Kasukabe, Saitama, Koshigaya, Kawaguchi, Sōka, Toda, Ina and Miyashiro in Saitama Prefecture)

Built in 1728, it is considered one of the three largest agricultural irrigation canals in Japan.

Ogawa Dam (city of Kanra, Gunma Prefecture)

It is believed to have been built about 400 years ago, functioning as a water supply canal for the castle city, samurai residences and rice paddies in the river's lower-lying region.