Akiba Dam
Encyclopedia
The is a dam
on the Tenryū River
, located in Tenryū-ku
, Hamamatsu, Shizuoka Prefecture
on the island of Honshū
, Japan
.
, and it was not until the Taishō period
that development began on the Tenryū River. Private entrepreneur Fukuzawa Momosuke founded the , which later became before it was nationalized into the pre-war government monopoly in 1938. The first dams on the main stream of the Tenryū River were built in Nagano Prefecture
. To develop of the hydroelectric potential of the river in Shizuoka Prefecture, the post-war Japanese government turned to the Electric Power Development Company
. The new company, in part through foreign aid loans from the United Nations
, and with the use of new dam technologies completed the huge Sakuma Dam
in the 1956, at the time the 10th largest in the world.
The Akiba Dam was designed as a pumped-storage hydroelectricity
facility, with the discharge from Sakuma Dam discharging through a penstock
into a lake created by the smaller Akiba Dam downstream. The reversible turbine generators at the Sakuma power plant were designed to function as either electrical power generators, or as pumps, to reverse the flow of water back into the reservoir in times of low demand. Construction began in 1954 and was completed in 1958 by the Kumagai Gumi
.
s. It supplies water to the nearby Akiba No. 1 Hydroelectric Power Station, with a rated capacity of 45,300 kW, and to the Akiba No. 2 Hydroelectric Power Station, with a rated capacity of 34,900 kW. A third station, the Akiba No. 3 Hydroelectric Power Station was added in 1989 with a rated capacity of 46,900 kW. The Akiba Dam was designed as a multipurpose dam. In addition to hydroelectric power generation, the dam provides industrial water to the city of Hamamatsu, and water for irrigation to a large area of eastern Shizuoka Prefecture.
However, as with other dams on the Tenryū and Ōi rivers, the dam has been rapidly filling with sand and silt from the mountains upstream, and the reduction of the amount of sand and silt reaching the river mouth has caused problems with coastal erosion.
, and it is located within the boundaries of the Tenryū-Okumikawa Quasi-National Park
.
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
on the Tenryū River
Tenryu River
The is a river arising from Lake Suwa in Okaya, Nagano Prefecture, grazing Aichi Prefecture and flowing through western Shizuoka Prefecture in central Honshū, Japan. With a length of , it is Japan's ninth longest river.-Geography:...
, located in Tenryū-ku
Tenryū-ku, Hamamatsu
is one of the seven wards of the city of Hamamatsu, Shizuoka Prefecture, Japan. It is bordered by Kita-ku and Hamakita-ku in Hamamatsu, the cities of Shimada and Iwata and towns of Mori and Kawanehon in Shizuoka, Shishiro, Tōei and Toyone in Aichi Prefecture and Iida and Tenryū in Nagano...
, Hamamatsu, Shizuoka Prefecture
Shizuoka Prefecture
is a prefecture of Japan located in the Chūbu region on Honshu island. The capital is the city of Shizuoka.- History :Shizuoka prefecture was formed from the former Tōtōmi, Suruga and Izu provinces.The area was the home of the first Tokugawa Shogun...
on the island of Honshū
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
History
The potential of the Tenryū River valley for hydroelectric power development was realized by the Meiji government at the start of the 20th century. The Tenryū 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. However, the bulk of investment in hydroelectric power generation in the region was centered on the Ōi RiverOi 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 peaks ranging from 2000–3000 meters, are characterized by...
, and it was not until the Taishō period
Taisho period
The , or Taishō era, is a period in the history of Japan dating from July 30, 1912 to December 25, 1926, coinciding with the reign of the Taishō Emperor. The health of the new emperor was weak, which prompted the shift in political power from the old oligarchic group of elder statesmen to the Diet...
that development began on the Tenryū River. Private entrepreneur Fukuzawa Momosuke founded the , which later became before it was nationalized into the pre-war government monopoly in 1938. The first dams on the main stream of the Tenryū River were built in Nagano Prefecture
Nagano Prefecture
is a prefecture of Japan located in the Chūbu region of the island of Honshū. The capital is the city of Nagano.- History :Nagano was formerly known as the province of Shinano...
. To develop of the hydroelectric potential of the river in Shizuoka Prefecture, the post-war Japanese government turned to the Electric Power Development Company
Electric Power Development Company
The , operating under the brand name J-POWER, formerly , is the largest electric utility in Japan. It mainly produces Electricity from Coal and Hydroelectric Power Stations. It also has a few wind farms and is currently building a nuclear plant in Ohma, Aomori prefecture, that is scheduled to...
. The new company, in part through foreign aid loans from the United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
, and with the use of new dam technologies completed the huge Sakuma Dam
Sakuma Dam
The is a dam on the Tenryū River, located on the border of Toyone, Kitashitara District, Aichi Prefecture on the island of Honshū, Japan. It is one of the tallest dams in Japan and supports a 350 MW hydroelectric power station...
in the 1956, at the time the 10th largest in the world.
The Akiba Dam was designed as a pumped-storage hydroelectricity
Pumped-storage hydroelectricity
Pumped-storage hydroelectricity is a type of hydroelectric power generation used by some power plants for load balancing. The method stores energy in the form of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps...
facility, with the discharge from Sakuma Dam discharging through a penstock
Penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
into a lake created by the smaller Akiba Dam downstream. The reversible turbine generators at the Sakuma power plant were designed to function as either electrical power generators, or as pumps, to reverse the flow of water back into the reservoir in times of low demand. Construction began in 1954 and was completed in 1958 by the Kumagai Gumi
Kumagai Gumi
is a construction company founded in Fukui, Fukui Prefecture, Japan. The company still has registered headquarters in Fukui, but the actual head office is located in Shinjuku, Tokyo.Kumagai Gumi was removed from the Nikkei 225 index on Oct...
.
Design
The Akiba Dam is a hollow-core concrete gravity dam with several central spillwaySpillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
s. It supplies water to the nearby Akiba No. 1 Hydroelectric Power Station, with a rated capacity of 45,300 kW, and to the Akiba No. 2 Hydroelectric Power Station, with a rated capacity of 34,900 kW. A third station, the Akiba No. 3 Hydroelectric Power Station was added in 1989 with a rated capacity of 46,900 kW. The Akiba Dam was designed as a multipurpose dam. In addition to hydroelectric power generation, the dam provides industrial water to the city of Hamamatsu, and water for irrigation to a large area of eastern Shizuoka Prefecture.
However, as with other dams on the Tenryū and Ōi rivers, the dam has been rapidly filling with sand and silt from the mountains upstream, and the reduction of the amount of sand and silt reaching the river mouth has caused problems with coastal erosion.
Surroundings
The Akiba Dam Reservoir is a popular attraction for canoeing and camping, due to its proximity to downtown Hamamatsu as well as the Akihasan Hongū Akiha JinjaAkihasan Hongū Akiha Jinja
The is a Shinto shrine in Tenryū-ku, Hamamatsu . The shrine is located near the summit of Mount Akiha, on the southern slopes of the Akaishi Mountains...
, and it is located within the boundaries of the Tenryū-Okumikawa Quasi-National Park
Tenryū-Okumikawa Quasi-National Park
is a quasi-national park in the Tokai region of Honshū in Japan. It is rated a protected landscape according to the IUCN. The park includes the gorges of the upper Tenryū River, Sakuma Dam and its surrounding forests, Atera Seven Falls, Chausu Mountains and Mount Horaiji. It straddles the border...
.