The is a dam located between the cities of Ena and

Nakatsugawa Magome-juku on the Nakasendō is a city located in Gifu, Japan. , the city had an estimated population of 78,930, and a population density of 120 persons per km2 in 30,788 households The total area of the city was . Geography Nakatsugawa is in ...

Gifu Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Gifu Prefecture has a population of 1,991,390 () and has a geographic area of . Gifu Prefecture borders Toyama Prefecture to the north; Ishikawa Prefecture ...

, Japan. It was built to produce electricity for the surrounding area. The

Agi River The is a river in Japan which flows through Gifu Prefecture. It is part of the Kiso River system. Geography The river originates from Mount Yaki on the border of Nakatsugawa and Ena and flows west. It flows through the Akigawa Dam and the Ōi ...

flows through the dam. Built in 1924, the Ōi Dam was the first dam built anywhere on the

Kiso River The is a river in the Chubu region of Japan roughly long, flowing through the prefectures of Nagano, Gifu, Aichi, and Mie before emptying into Ise Bay a short distance away from the city of Nagoya.Nussbaum, Louis Frédéric ''et al.'' (2 ...

system. It is also the first

hydroelectric dam Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

built in Japan. At tall, it is the largest gravity dam in Japan after the Taishakugawa Dam in

Hiroshima Prefecture is a prefecture of Japan located in the Chūgoku region of Honshu. Hiroshima Prefecture has a population of 2,811,410 (1 June 2019) and has a geographic area of 8,479 km² (3,274 sq mi). Hiroshima Prefecture borders Okayama Prefecture to the ...

. In 1983, the New Ōi Dam (新大井ダム ''Shin-Ōi Damu'') was built just downstream. Combined, they produce 80,000 kW of power.

History

The upper portions of the Kiso River have a strong flow in terms of speed and volume, making it an ideal location for hydroelectric dams. Interest in hydroelectric dams in Japan grew greatly in 1911 when a hydroelectric law was passed. Given the technologies of the time, though, building a dam along the Kiso River was too difficult because floods often occurred.

Surrounding area

The

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...

created by the dam was named

Ena Gorge is a river valley located at the mid reaches of the Kiso River, which runs through the cities of Ena and Nakatsugawa in Gifu Prefecture, Japan. Ena Gorge was so named by Shiga Shigetaka, a geographer of that time who praised the harmony of the ...

. More than , the gorge is lined by rocky walls on both sides. Along with the lake created by the Maruyama Dam downstream, the area has been designated the Hida-Kisogawa Quasi-National Park.

References

External links

{{DEFAULTSORT:Oi Dam Dams in Gifu Prefecture Dams completed in 1924