Classification of rivers in Japan

[1][2] Rivers are classified by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT).

At the beginning of the Meiji era, river construction mainly consisted of low water construction such as securing water for boat transportation and irrigation, but after the middle of the Meiji era, boat transportation declined with the spread of railways, and on the other hand, development of river coasts exacerbated damage from floods.

However, due to the background of its enactment, the old River Law had strong overtones of control by state power, and, reflecting the social situation at the time, placed more emphasis on flood control than water utilization.

[3] Over the following 70 years, due to post-war social and economic development, the use of river water for hydroelectric power generation and industrial water increased rapidly[3] and because of inconsistencies that had arisen in the system implemented by the old River Act, the new River Act was enacted in 1962, with the following changes: The River Act was amended in 1997, changing its text to have a greater emphasis on conservation of natural environments, and the consultation and participation of local residents in forming water management plans.

[5] Especially post-1997 amendment, there is now greater community involvement when formulating plans regarding rivers and water management.

[4] Class A river system (一級水系, Ikkyū suikei) is a designation applied to rivers systems deemed to be important to the economy of the nation as a whole, as well as those deemed important to the conservation of nature within Japan.

[7] Generally speaking, areas surrounding Class A rivers will suffer greater damage in the event of a flood.