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, aqua ...

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 ...

, located in Kawanehon Town, Haibara District,

Shizuoka Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Shizuoka Prefecture has a population of 3,555,818 and has a geographic area of . Shizuoka Prefecture borders Kanagawa Prefecture to the east, Yamanashi Pref ...

on the island of

Honshū , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

History

The potential of the Ōi River valley for

hydroelectric power Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

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 ...

at the start of the twentieth 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 acce ...

company, the was established, and began studies and design work on plans to exploit the potential of the Ōi River and

Fuji River The is a river in Yamanashi Prefecture, Yamanashi and Shizuoka Prefectures of central Japan. It is long and has a drainage basin, watershed of . With the Mogami River and the Kuma River (Japan), Kuma River, it is regarded as one of the three mos ...

in Shizuoka Prefecture. The British interests were bought out by 1921, and the company was renamed . By the mid-1950s, several dams had been completed on the upper reaches of the Ōi River and its tributaries. In September 1954, a

typhoon A typhoon is a tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere and which produces sustained hurricane-force winds of at least . This region is referred to as the Northwestern Pacific Basin, accounting for a ...

caused flooding in the downstream reaches of the Ōi River, leading to plans being drawn by the central government in Tokyo for a new dam, which was justified as a "multipurpose" dam to provide industrial water, agricultural water in addition to flood control. Work was delayed due to lack of budget in the 1960s, with the construction of the

Tōkaidō Shinkansen The is a Japanese high-speed rail line that is part of the nationwide Shinkansen network. Along with the San'yō Shinkansen, it forms a continuous high-speed railway through the Taiheiyō Belt, also known as the Tokaido corridor. Opening in 19 ...

and

Tōmei Expressway The is a national expressway on the island of Honshū in Japan. It is operated by Central Nippon Expressway Company. The expressway is designated as E1 under the "2016 Proposal for Realization of Expressway Numbering", because it parallels Na ...

, but was given additional impetus due to the "Tanabata Flood" of July 1974 which flooded most of downtown Shizuoka. Nagashimachosa-s-r1

Construction work began on the Nagashima Dam in 1972 and was completed by 2002 by a consortium of the

Maeda Corporation is a Japanese corporation which was established in 1919. Its main areas of business are building construction and civil engineering. Maeda has domestic offices in eleven Japanese cities, and overseas offices in Thailand, Hong Kong, and India. ...

Shimizu Corporation is an architecture, architectural, civil engineering and General contractor, general contracting firm. It has annual sales of approximately US$15 billion and has been widely recognized as one of the top 5 contractors in Japan and among the top 2 ...

and the

Takenaka Corporation is one of five major general contractors in Japan. Takenaka provides architectural, engineering, and construction services and has its headquarters located in Chūō-ku, Osaka, Osaka Prefecture. Takenaka has eight domestic offices in Japan with ...

. Work was facilitated by the proximity of the dam to the

Ōigawa Railway is a railway company in Shizuoka Prefecture, Japan, which first opened in 1927. The company is commonly known as . The company belonged to the Meitetsu Group until 2015, when it was sold to Eclipse Hidaka, a food and hotel company headquarte ...

Design

The Nagashima Dam is a hollow core concrete

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. Gravity dams are designed so that each section of the dam is ...

with central

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

s. It is not equipped with any hydroelectric generation capability. It is now operated and maintained by the

Ministry of Land, Infrastructure, Transport and Tourism The , abbreviated MLIT, is a ministry of the Japanese government.国土交通省設置法

. In order to avoid silting problems as was experienced with the Senzu Dam, the Nagashima Dam is equipped with a large secondary

check dam A steel check dam A check dam is a small, sometimes temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity. Check dams themselves are not a type of new technology; rather, t ...

upstream, the first in Japan to be constructed with the cemented sand and gravel method. This dam reduces the current, causing most of the sand and silt to settle before it reaches the main Nagashima Dam. Under normal conditions, this check dam is completely underwater and cannot be seen from the surface. Nagashima Dam lake

Surroundings

The Nagashima Dam Reservoir is a popular attraction for canoeing, fishing and camping, and for its proximity to hot spring resorts and the

steam locomotives A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...

operated by the Ōigawa Railway. The nearest train station is the Nagashima Dam Station. The area is popular with mountain climbers heading towards the high peaks of the

Minami Alps National Park is a national park in the Akaishi Mountains, Chūbu region, Honshū, Japan. The Minami Alps National Park was established on June 1, 1964. It extends along the border of Shizuoka, Yamanashi and Nagano Prefectures for a length of , and a maxim ...

References

*Berger, Luis. ''Roller Compacted Concrete Dams''. Technology and Engineering (2003). *Japan Commission on Large Dams. ''Dams in Japan: Past, Present and Future''. CRC Press (2009).
photo page with data''Dredging News'', Feb 2002 issue
{{Dams in Shizuoka Prefecture Gravity dams Dams in Shizuoka Prefecture Dams completed in 2002 2002 establishments in Japan Shimizu Corporation