The Asuwagawa Irrigation Canal consists of seven main canals drawing water from the Asuwagawa Headworks in the southeast area of Fukui City. The canal extends for a total length of 22 kilometres, providing irrigation water for 1,997 hectares of agricultural paddy fields.
The Asuwa-gawa river is one of several rivers flowing through the plains of Fukui. In the past this river often overflowed because of drainage problems, but after the formation of an alluvial fan drainage pattern about 2,000 years ago, paddy rice cultivation began in the area.
In the seventh century, a large-scale river improvement construction was carried out on the Asuwa-gawa river by Fukui’s powerful ruling family. The primitive irrigation system that was created led to the beginning of paddy rice cultivation in the extended area surrounding the river.
The irrigation system took its current form after 1688, when the wooden mattress division weir and the irrigation canals were built to unify water intake, creating a large irrigation canal drawing water from the Asuwa-gawa river.
The Asuwagawa Irrigation Canal was affected by several historic disasters over the years including the great flood of 1807 and the deluge of 1881, but was repaired after each event. However, the canal was destroyed when a major earthquake struck suddenly in June 1948, greatly hindering paddy rice cultivation due to the resulting shortage of water.
With a stable water supply being one of the most important factors in paddy rice cultivation, water disputes between villages were renewed following the destruction of the irrigation canal. Although it required a great deal of labour and expense, in 1963 the Asuwagawa Headworks was built to solve these problems, and the Asuwagawa Irrigation Canal once again became a stable source of irrigation water that still survives to this day.
The irrigation canal also greatly contributed to revitalization of the local community, with its construction leading to the recreation of old city landscapes, the creation of a biotope made by drawing irrigation water into a schoolyard, and more. Today, the Asuwagawa Irrigation Canal is overseen by a water management organization and irrigates a paddy field area of 1,997 hectares.
A remote control system in a management office is used to control the division works and headworks, distributing water appropriately into the seven main canals. With this stable water supply, this land is now a prosperous area for paddy rice cultivation.