The is a

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

on the

Ōi River The is a river in Shizuoka Prefecture, Japan. Geography The Ōi River flows from the Akaishi Mountains, the branch of the Japanese Southern Alps which form the border between Shizuoka, Nagano and Yamanashi prefectures. These mountains, with p ...

in Aoi-ku,

Shizuoka Shizuoka can refer to: * Shizuoka Prefecture, a Japanese prefecture * Shizuoka (city), the capital city of Shizuoka Prefecture * Shizuoka Airport * Shizuoka Domain, the name from 1868 to 1871 for Sunpu Domain, a predecessor of Shizuoka Prefecture ...

Shizuoka Prefecture is a prefecture of Japan located in the Chūbu region of Honshu. Shizuoka Prefecture has a population of 3,637,998 and has a geographic area of . Shizuoka Prefecture borders Kanagawa Prefecture to the east, Yamanashi Prefecture to the northea ...

on the island of

Honshū , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separa ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It was the first hollow core

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

gravity dam A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it. ...

to be constructed in Japan, and has a

hydroelectric power 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 and ...

generating station owned by the

Chubu Electric Power Company , abbreviated as Chuden in Japanese, is a Japanese electric utilities provider for the middle Chūbu region of the Honshu island of Japan. It provides electricity at 60 Hz, though an area of Nagano Prefecture uses 50 Hz. Chubu Electric ...

History

The potential of the Ōi River valley for hydroelectric power development was realized by the

Meiji government The was the government that was formed by politicians of the Satsuma Domain and Chōshū Domain in the 1860s. The Meiji government was the early government of the Empire of Japan. Politicians of the Meiji government were known as the Meiji o ...

at the start of the 20th century. The Ōi River was characterized by a high volume of flow and a fast current. Its mountainous upper reaches and tributaries were areas of steep valleys and abundant rainfall, and were sparsely populated. In 1906, a

joint venture A joint venture (JV) is a business entity created by two or more parties, generally characterized by shared ownership, shared returns and risks, and shared governance. Companies typically pursue joint ventures for one of four reasons: to acces ...

company, the was established, and began studies and design work on plans to exploit the potential of the Ōi River and Fuji River in Shizuoka Prefecture. The British interests were bought out by 1921, and electrical production nationalized under the aegis of the in 1938. The first dams on the Ōi River were completed in the late 1920s and early 1930s, but further work was suspended by the

Great Depression The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagio ...

of the 1930s, and

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

in the 1940s. However, by the early 1950s, Japan's need for electrical energy was growing exponentially, especially in the industrial belt near

Nagoya is the largest city in the Chūbu region, the fourth-most populous city and third most populous urban area in Japan, with a population of 2.3million in 2020. Located on the Pacific coast in central Honshu, it is the capital and the most pop ...

. After the breakup of Nippon Hassoden at the end of World War II into various regional power utilities, the bulk of the dams on the Ōi River came under the control of

Chubu Electric Power , abbreviated as Chuden in Japanese, is a Japanese electric utilities provider for the middle Chūbu region of the Honshu island of Japan. It provides electricity at 60 Hz, though an area of Nagano Prefecture uses 50 Hz. Chubu Electric ...

Design

Design work on the Ikawa Dam began in 1951, with construction starting in 1952 with a foreign aid grant from OCI, facilitated by the American occupation authorities. The dam design introduced the technique of hollow-core

construction to Japan, which had previously been used with success in

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

. There was initial resistance to the technique by Japanese civil engineers, who were concerned with the earthquake resistance of the design, but the number of successful applications in earthquake-prone areas of northern Italy together with the economics of using less concrete swayed the decision towards the new technology. Construction of the tall dam was facilitated by its location on the

Ōigawa Railway Ikawa Line The is a railway line of the Ōigawa Railway. It runs from Senzu Station in Kawanehon, Shizuoka, the end station of the Ōigawa Main Line, and terminates at Ikawa Station in Aoi-ku, Shizuoka. The line has 61 tunnels and 51 bridges along its 25 ...

, and was completed in 1957. The associated Ikawa Hydroelectric Power Plant produces 62,000 KW of power. As a result of the lake created by the Ikawa Dam, the village of Ikawa was submerged, and its 550 households had to be relocated. serves as an important source of

tap water Tap water (also known as faucet water, running water, or municipal water) is water supplied through a tap, a water dispenser valve. In many countries, tap water usually has the quality of drinking water. Tap water is commonly used for drinking, ...

, industrial water and

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...

water in Shizuoka Prefecture. The lake is stocked with

cherry salmon The masu salmon (''Oncorhynchus masou''), also known as masu ( ja, マス, , trout) or in Japan, is a species of salmon belonging to the genus '' Oncorhynchus'', found in the North Pacific along Northeast/East Asian coasts from the Russian Far Ea ...

carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...

and

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmoni ...

, and is a popular fishing spot. A museum established by Chubu Electric Power near the lake has exhibits relating to the history and construction of the dam, and on hydroelectric power in general.

Surroundings

Public access to the dam and its lake are by Shizuoka Prefectural Road 60, with bus connections to

Shizuoka Station is a major railway station in Shizuoka, Shizuoka Prefecture, Japan, operated by the Central Japan Railway Company (JR Central). Lines Shizuoka Station is served by the Tōkaidō Shinkansen and Tōkaidō Main Line, and is 180.2 rail km from To ...

or Shin-Shizuoka Station.

References

*Japan Commission on Large Dams. ''Dams in Japan: Past, Present and Future''. CRC Press (2009).
Ikawa Electric Museum
{{Dams in Shizuoka Prefecture Gravity dams Dams in Shizuoka Prefecture Hydroelectric power stations in Japan Dams completed in 1957 1957 establishments in Japan