Why schools visit the Nikaryo yosui canals – a trip back to Edo bakufu’s foundations

Yesterday, my daughter went on her elementary school field trip to visit the Nikaryo yosui or the Nikaryo canals. The Nikaryo yosui is a network system of irrigation canals siphoning off the 138-km-long Tama River in Kawasaki city, Kanagawa Prefecture. The irrigation system is at the root of Kawasaki’s heartland traditional agricultural industries, but its historical significance penetrates regions beyond Kawasaki city itself.

Nikaryo canal, Shukugawara

Ever since the advent of railroads and modern transportation systems, many of the nation’s historically important ancient waterways or canal systems have become increasingly irrelevant and forgotten. In Kanagawa prefecture, many schools however, still conduct field trips to study the Nikaryo yosui waterway or canals.

Now the Nikaryo waterway canals really aren’t much to look at. Even if they’re nowhere as romantic or picturesque as the Grand Canals of Venice or Amsterdam’s canals, we’d still like to examine below why the canals should  merit a field trip.
The Nikaryo waterway canals, completed in 1611, are described as  “the most important regional definer” – and “the single biggest economic change in the Kawasaki region during the Edo period”  according to Neil L. Waters, author of the book “Japan’s local pragmatists: the transition from Bakumatsu to Meiji in the Kawasaki region
At the watershed, the Nikaryo yosui Kuji Ento-Bunsui Water Aqueduct

Built on the orders of Tokugawa Ieyasu, and under the supervision of the daikan (=magistrate), Koizumi Jidaiyu, the waterway system channeled water to more than 60 villages in the Kawasaki region and irrigated 2,007 hectares of paddy rice land.

The Tama River and the vast irrigation network built from the river was a big key to the commercial prosperity of the region and a pivotal factor for Kawasaki’s transition into the Meiji era.  The Edo bakufu supported the efforts of the villagers in Kawasaki as it benefited from the prosperity of the region. The kumiai system that it had established had become a key pillar contributing to its economic foundation and the basis for driving the local economy.
The dam at the Kuji watergate

The waterway goes to the heart of the social structure of Japanese society as well.  In order to manage the water allocation and distribution rights, the Inage-Kawasaki Nikaryo-yosui-kumiai was set up, village heads were appointed to become its leaders.  The kumiai included representatives of 60 villages and was led by a few leaders elected by the village heads. This formed the apex of a hierarchical group of smaller irrigation kumiai composed of 3 to 19 villages sharing the same canal branch.

Membership in the Nikaryo-kumiai-coop system was thus an indicator of real power in the Kawasaki region. The farming coop or community was self-governing according to the principles of the Nomin no kyoryoku code (The cooperation of farmers), a code drafted by Koizumi.

For the most part, the Nikaryo waterway system dealt with problems of maintenance and distribution of water with remarkable efficiency with most of the conflicts resolved without interference from authorities above… . The one exception was the siege that took place during the drought of 1821. The villagers who lived in the some 20 villages downstream of the Kuji watergate rebelled when the water gate was shut to conserve water.
At Mizonokuchi is the main switch for the irrigation channel's water-diversion.

Kawasaki was traversed by four major highways in addition to the Tokaido (the most important of the Five Routes of the Edo Period), Kawasaki’s shugo post-town prospered – driven by increasing traffic of rural merchants to Edo’s markets.  Due to the strategic crossroad advantage of Kawasaki’s location (the roads eased communications between villages) and its proximity to Edo (a.k.a. Tokyo today), the Kawasaki post-town provided many opportunities for Kawasaki’s inhabitants to develop trade and commerce and cottage industries, in addition to the agricultural activities of the villages. The second half of the Tokugawa period was marked by economic growth so the Kawasaki post-town and its supporting irrigation-works were important to the Tokugawa regime’s prestige.

Kawasaki’s inhabitants benefited from the many commercial and mercantile opportunities that presented themselves from Kawasaki’s strategic convergence of the highways location – so that most of Kawasaki’s inhabitants did not subsist on rice growing activities alone. Life was however also very hard, because the villagers had to contribute corvee labor for the maintenance of the post-town.

Nevertheless, Kawasaki villages and town were prosperous at least relative to the rest of the Kanto region due to the security of the Nikaryo waterway system and kumiai‘s efficiency. It created a unique situation where Kawasaki’s inhabitants did not join the yonaoshi peasant class uprisings that were sweeping through the rest of the Kanto region. Instead, Kawasaki’s inhabitants sought to insulate themselves from those unruly uprisings, preferring the order and the security of living off the Nikaryo-irrigated lands and the dependent cottage industries that supported travelers to their post-town.

In 1725, a major expansion of the Nakaryo yosui irrigation system was undertaken. The maintenance and allocation of labor thereafter was left to the locals. However, the corvee labor and levies needed to maintain the post-town that were imposed upon Kawasaki’s farming villages constituted a severe hardship, one that was alleviated only when ferry services were started across the Tama River, and when the fares collected were used to offset those requirements.

The Tama ward flanking the Nikaryo canal area today.

The area, once famous nationwide for its production of the Tama River Pear, is witnessing a reduction in the amount of cultivated land for fruit in the face of the recent wave of urbanization. Many farms still operate along the Nikaryo Yosui Canal today, and are open to the public visits. The source of Tamagawa River lies within Mt. Kasatori in Yamanashi Prefecture. The 138-km long Tamagawa is known as Kawasaki’s “mother river. The Tama Ward area, fed by the Tama River and sustained by the natural environment of Tama Hills, is one of few pockets of land where satoyama and traditional farming lifestyles can still be glimpsed.


Getting there for a visit: Get off at the Shukugawa Station on the JR Nambu Line, nearby is the walkway that allows you to walk along the banks of the Nikaryo yosui.

Do combine your field trip with a visit to the Ecomuseum. Use the computers here to learn about the history of the Tamagawa Ecomuseum Project, Tama River, or the Nikaryo Yosui Canal. View the Shukugawara Dam exhibit and the laser disk presentation of Tama River’s natural history.

Access: 1-5-1 Shukugawara, Tama-ku, Kawasaki city, Kanagawa. Phone: 044-900-8386

By Aileen Kawagoe


Source of images: Wikimedia Commons

For marvellous photos of the Nikaryo yosui, go to this Flicker page.


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