Okutadami Dam
{{Use dmy dates|date=November 2019}}
{{Infobox dam
| name = Okutadami Dam
| name_official =
| image = Okutadami Dam 001.jpg
| image_size =
| image_caption =
| image_alt =
| location_map = Japan
| location_map_size =
| location_map_caption =
| coordinates = {{coord|37|09|12|N|139|15|00|E|type:landmark|display=inline,title}}
| country = Japan
| location = Uonuma
| status =
| construction_began = 1953
| opening = 1961
| demolished =
| cost =
| owner = Electric Power Development Company
| dam_type = Gravity
| dam_height = {{Convert|157|m|ft|0|abbr=on}}
| dam_height_thalweg =
| dam_height_foundation=
| dam_length = {{Convert|475|m|ft|0|abbr=on}}
| dam_width_crest =
| dam_width_base =
| dam_volume = {{Convert|1636000|m3|cuyd|0|abbr=on}}
| dam_elevation_crest =
| dam_crosses = Tadami River
| spillway_count =
| spillway_type =
| spillway_capacity =
| res_name = Lake Okutadami
| res_capacity_total = {{Convert|601000000|m3|acre.ft|0|abbr=on}}
| res_capacity_active ={{Convert|458000000|m3|acre.ft|0|abbr=on}}
| res_capacity_inactive=
| res_catchment = {{Convert|595|km2|sqmi|0|abbr=on}}
| res_surface = {{Convert|1150|ha|acre|0|abbr=on}}{{cite web|title=Okutadami Dam|url=http://damnet.or.jp/cgi-bin/binranA/All.cgi?db4=0500|publisher=Japan Dam Handbook|access-date=14 August 2011}}
| res_elevation ={{Convert|750|m|ft|0|abbr=on}}
| res_max_depth =
| res_max_length =
| res_max_width =
| plant_hydraulic_head = 120 MW units: {{Convert|170|m|ft|0|abbr=on}}
200 MW unit: {{Convert|164.2|m|ft|0|abbr=on}}
| res_tidal_range =
| plant_operator =
| plant_commission = 1960, 2003
| plant_decommission =
| plant_type =
| plant_turbines = 3 x 120 MW, 1 x 200 MW Francis-type
| plant_capacity = 560 MW
| plant_annual_gen =
| website =
| extra =
}}
The Okutadami Dam (奥只見ダム) is a concrete gravity dam on the Tadami River, {{Convert|26|km|mi|0|abbr=on}} east of Uonuma on the border of Niigata and Fukushima Prefectures, Japan. The primary purpose of the dam is hydroelectric 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.{{cite web|title=Dam Okutadami|date=7 June 2004 |url=http://dammania.net/niigata/okutadami.html|publisher=DamMania|access-date=14 August 2011|language=ja}}
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 {{Convert|2.5|m3/s|ft3/s|0|abbr=on}} downstream for environmental purposes.{{cite web|title=Start of Commercial Operation of the Okutadami (Extension) and Otori (Extension) Hydropower Plants and of the Okutadami-dam Ecological Flow Hydropower Plant|url=http://www.jpower.co.jp/english/news_release/news/news176.pdf|publisher=J-Power|access-date=14 August 2011}} Along with the same power plant upgrade, a second Kaplan turbine-generator was added to the {{Convert|83|m|ft|0|abbr=on}} tall Otori Dam's power station downstream at {{Coord|37|12|53|N|139|12|50|E|name=Otori Dam}}. This generator has an 87 MW capacity in addition to the existing 95 MW unit, for an installed capacity of 182 MW.{{cite web|last=Sato|first=Asami|title=Commissioning of 87,000-kW Kaplan Turbine and Generator for Otori Power Statio|url=http://www.hitachi.com/ICSFiles/afieldfile/2004/09/07/r2004_03_104.pdf|publisher=Hitachi|access-date=14 August 2011|author2=Keiichi Got0}}
36 houses were submerged.
Design
The Okutadami Dam is a {{Convert|157|m|ft|0|abbr=on}} tall and {{Convert|475|m|ft|0|abbr=on}} long concrete gravity dam with a structural volume of {{Convert|1636000|m3|cuyd|0|abbr=on}}. Sitting at the head of a {{Convert|595|km2|sqmi|0|abbr=on}} catchment area, the dam creates a reservoir with a {{Convert|601000000|m3|acre.ft|0|abbr=on}} capacity of which {{Convert|458000000|m3|acre.ft|0|abbr=on}} is active (or "useful") storage. The reservoir has a surface area of {{Convert|1150|ha|acre|0|abbr=on}}. 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 penstocks {{Convert|185|-|189|m|ft|0|abbr=on}} in length before reaching an individual 120 MW Francis turbine-generator. The 200 MW Francis turbine-generator receives water via a {{Convert|280|m|ft|0|abbr=on}} long penstock. After water is processed through the generators, it travels down two tailrace tunnels before being discharged over {{Convert|3|km|mi|0|abbr=on}} downstream at the upstream edge of the Otori Reservoir.{{cite web|title=Case study 01-02: Biological Diversity - Okutadami and Ohtori Expansion Hydropower Project, Japan|url=http://www.ieahydro.org/reports/Annex_VIII_CaseStudy0102_Okutadami_Ohtori_Japan.pdf|work=IEA Hydropower Implementing Agreement Annex VIII: Hydropower Good Practices: Environmental Mitigation Measures and Benefit|publisher=New Energy Foundation|access-date=14 August 2011|year=2006|url-status=dead|archive-url=https://web.archive.org/web/20111003104335/http://www.ieahydro.org/reports/Annex_VIII_CaseStudy0102_Okutadami_Ohtori_Japan.pdf|archive-date=3 October 2011}}
Access
Minami Echigo Kankō Bus ( Okutadami Dam Line and Express Okutadami Dam Line )
- Ginzan Daira bus stop
- For Urasa Station[https://trafficnews.jp/post/99669/3 Commercialized this route by Tobu Railway]
- It takes to 2h35m from Tokyo Station to Urasa Station.
- It takes 1h40m from Niigata Station to Urasa Station.
Aizu Bus (Nakayama Tōge and Oze Line - No.011)Reservation system bus
- Ozeguchi bus stop
- For Oze-Oike bus stop or Numayama toge bus stop
- When passengers want to go to Aizukōgen-Ozeguchi Station you must transfer onto route bus at Numayama Tōge bus stop or Oze-Oike bus stop.[https://trafficnews.jp/post/99669/1 Commercialized this route by Tobu Railway]
- It takes 2h40m from Asakusa Station to Aizukōgen-Ozeguchi Station, when you use Tobu Limited Express Revaty Aizu.
References
{{reflist}}
{{stack|{{Portal|Japan|Water|Renewable energy}}}}
{{GeoGroup}}
{{Dams in Niigata Prefecture}}
{{Dams in Fukushima Prefecture}}
{{Commons category|Okutadami Dam}}
Category:Dams in Fukushima Prefecture
Category:Dams in Niigata Prefecture
Category:Hydroelectric power stations in Japan
Category:Dams completed in 1961
Category:Dams on the Tadami River