The Okutadami Dam (奥只見ダム) is a 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 to oppose the horizontal pressure of water pushing against it. ...
on the
Tadami River
The is a major tributary of the Agano River in Japan. Its basin covers and its main stem is extensively regulated and developed for hydroelectric power. The river is located within Niigata, Gunma and Fukushima Prefectures.
Dams
Starting from t ...
, east of
Uonuma
is a city located in Niigata Prefecture, Japan. , the city had an estimated population of 35,027 in 13,289 households, and a population density of 37 persons per km2. Its total area is . The city is famous for its ''koshihikari'' rice, which comm ...
on the border of
Niigata and
Fukushima Prefecture
Fukushima Prefecture (; ja, 福島県, Fukushima-ken, ) is a prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,810,286 () and has a geographic area of . Fukushima Prefecture borders Miya ...
s, Japan. The primary purpose of the dam is
hydroelectric
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 ...
power generation and it supports a 560 MW power station which is the largest conventional hydroelectric power station in Japan.
[ The dam also forms the second largest reservoir in Japan, next to that of the ]Tokuyama Dam
The is an embankment dam near Ibigawa, Ibi District, Gifu Prefecture in Japan. The dam was completed in 2008 and will support a 153 MW hydroelectric power station that is expected to be fully operational in 2015. Currently, Unit 1 at 23 M ...
.
Background
Construction on the dam began and its original 390 MW power station was commissioned 2 December 1960. The rest of the project was complete in 1961. Between 1999 and 2003, the power station was expanded, adding 200 MW in installed capacity. In addition, a 2.7 MW generator was added to ensure a flow of downstream for environmental purposes.Kaplan turbine
The Kaplan turbine is a propeller-type water turbine which has adjustable blades. It was developed in 1913 by Austrian professor Viktor Kaplan, who combined automatically adjusted propeller blades with automatically adjusted wicket gates to ach ...
-generator was added to the tall Otori Dam's power station downstream at . This generator has an 87 MW capacity in addition to the existing 95 MW unit, for an installed capacity of 182 MW.
36 houses were submerged.
Design
The Okutadami Dam is a tall and long concrete gravity dam with a structural volume of . Sitting at the head of a catchment area
In human geography, a catchment area is the area from which a location, such as a city, service or institution, attracts a population that uses its services and economic opportunities. Catchment areas may be defined based on from where people are ...
, the dam creates a 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 contro ...
with a capacity of which is active (or "useful") storage. The reservoir has a surface area of . The power station is underground and located on the right bank of the river next to the dam's abutment. It consists of two caverns, one for the original power station and another adjacent for the expansion. After being received by the dam's intake, water supplied to the original power plant travels down three penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills.
H ...
s in length before reaching an individual 120 MW Francis turbine
The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency.
The proces ...
-generator. The 200 MW Francis turbine-generator receives water via a long penstock. After water is processed through the generators, it travels down two tailrace tunnels before being discharged over downstream at the upstream edge of the Otori Reservoir.
Access
Minami Echigo Kankō Bus ( ''Okutadami Dam Line'' and ''Express Okutadami Dam Line'' )
*Ginzan Daira bus stop
** For Urasa Station
is a railway station in Minamiuonuma, Niigata, Japan, operated by the East Japan Railway Company (JR East).
Lines
Urasa Station is a station on the Joetsu Shinkansen high-speed line and also the Joetsu Line. It is located 123.9 kilometers fro ...
*** It takes to 2h35m from Tokyo Station
Tokyo Station ( ja, 東京駅, ) is a railway station in Chiyoda, Tokyo, Japan. The original station is located in Chiyoda's Marunouchi business district near the Tokyo Imperial Palace, Imperial Palace grounds. The newer Eastern extension is ...
to Urasa Station
is a railway station in Minamiuonuma, Niigata, Japan, operated by the East Japan Railway Company (JR East).
Lines
Urasa Station is a station on the Joetsu Shinkansen high-speed line and also the Joetsu Line. It is located 123.9 kilometers fro ...
.
*** It takes 1h40m from Niigata Station
is a major railway station in Chūō-ku, Niigata, Japan, operated by East Japan Railway Company (JR East). The station is at the centre of Niigata city, the largest city on the Sea of Japan coast in Honshu. It forms the central station for the ...
to Urasa Station
is a railway station in Minamiuonuma, Niigata, Japan, operated by the East Japan Railway Company (JR East).
Lines
Urasa Station is a station on the Joetsu Shinkansen high-speed line and also the Joetsu Line. It is located 123.9 kilometers fro ...
.
Aizu Bus
is the westernmost of the three regions of Fukushima Prefecture, Japan, the other two regions being Nakadōri in the central area of the prefecture and Hamadōri in the east. As of October 1, 2010, it had a population of 291,838. The princip ...
(''Nakayama Tōge and Oze Line - No.011'')
*Ozeguchi bus stop
** For Oze-Oike bus stop or Numayama toge bus stop
***When passengers want to go to Aizukōgen-Ozeguchi Station
is a railway station in Minamiaizu, Minamiaizu District, Fukushima Prefecture, Japan, operated by the Aizu Railway.
Lines
Aizukōgen-Ozeguchi Station is served by the Aizu Line, and is located 56.4 rail kilometers from the official starting ...
you must transfer onto route bus at Numayama Tōge bus stop or Oze-Oike bus stop.Commercialized this route by Tobu Railway
/ref>
*** It takes 2h40m from Asakusa Station
is a railway station in the Asakusa district of Taitō, Tokyo, Japan, operated by Tobu Railway, Tokyo Metro, and Toei Subway. It formed one terminus of the original subway line in Tokyo, now the Ginza Line.
Station layout
There is a connect ...
to Aizukōgen-Ozeguchi Station
is a railway station in Minamiaizu, Minamiaizu District, Fukushima Prefecture, Japan, operated by the Aizu Railway.
Lines
Aizukōgen-Ozeguchi Station is served by the Aizu Line, and is located 56.4 rail kilometers from the official starting ...
, when you use Tobu Limited Express ''Revaty Aizu''.
References
{{Commons category, Okutadami Dam
Dams in Fukushima Prefecture
Dams in Niigata Prefecture
Hydroelectric power stations in Japan
Gravity dams
Dams completed in 1961
Dams on the Tadami River
1961 establishments in Japan
Energy infrastructure completed in 1961