:Okukubi Dam

File:OkukubiDamCornerStone1.jpg

Construction on the dam had originally begun in 1978. At that time, it was designed as a concrete gravity dam. Construction was halted soon after it began though.{{cite web|title=Dams in Okinawa: Okukubi|url=http://pcpulab.dip.jp/main/okukubidam.htm|publisher=PCPulap|accessdate=24 July 2011|language=Japanese|archive-date=28 March 2012|archive-url=https://web.archive.org/web/20120328035505/http://pcpulab.dip.jp/main/okukubidam.htm|url-status=dead}} The dam was redesigned over the next few decades and after the new project was approved, preliminary construction for the dam began in late 2003. Principal construction began on March 24, 2009 and there was a groundbreaking ceremony on June 5, 2009.{{cite web|title=Construction progress|url=http://www.okukubi-dam.com/kotei.html|publisher=TAISEI Corporation|accessdate=24 July 2011|language=Japanese|archive-date=23 January 2012|archive-url=https://web.archive.org/web/20120123034531/http://www.okukubi-dam.com/kotei.html|url-status=dead}} To divert the river, a cofferdam did not need to be constructed. The existing Kinmu Dam {{Convert|100|m|ft|0|abbr=on}} upstream was modified to divert the river on the left bank of the river.{{cite web|title=Schedule|url=http://www.dc.ogb.go.jp/hokudamu/jigyou/kakudamu/okukubi/yotei/index.html|publisher=North Dam Construction Office|accessdate=24 July 2011|language=Japanese|url-status=dead|archiveurl=https://web.archive.org/web/20110927062444/http://www.dc.ogb.go.jp/hokudamu/jigyou/kakudamu/okukubi/yotei/index.html|archivedate=27 September 2011}}{{cite web|title=River Diversion|url=http://www.dc.ogb.go.jp/hokudamu/jigyou/kakudamu/okukubi/kansei/tenryukou/index.html|publisher=North Dam Construction Office|accessdate=24 July 2011|language=Japanese}} In May 2010, the river was diverted and by August of the same year, over {{Convert|1042000|m3|cuyd|0|abbr=on}} of rock and stone had been excavated from the site.{{cite web|title=Okukubi Dam|url=http://cmed.jp/sekou2011/okukubi.html|publisher=CMED|accessdate=24 July 2011|language=Japanese}} On February 26, 2011, a ceremony was held to bury the cornerstone of the dam prior to beginning the fill of the dam's body. It was attended by Japanese and U.S. officials (due to the dam's location within the U.S. Marine Central Training Area).{{cite news|last=Baez|first=Dengrier M.|title=Ceremony marks completion of Dam|url=http://www.marines.mil/Pages/NewsStoriesItemDetails.aspx?ItemUrl=http%3A%2F%2Fwww.marines.mil%2Funit%2Fmcbjapan%2FPages%2F2011%2F110304-dam.aspx|accessdate=24 July 2011|newspaper=Marines.mil|date=4 March 2011}} It will cost ¥3 billion (US$38.2 million) and it was completed in March 2013.{{cite web|title=Managing a wild horse with a rotten rope: A contemporary history of Okinawa|url=http://www.niraikanai.wwma.net/pages/wildhorse/chap3-12.html|publisher=The Ryukyu-Okinawa History and Culture Website|accessdate=24 July 2011}}{{cite web|title=億首 （ おくくび ） ダム|url=http://cmed.jp/sekou/okukubi.html|publisher=The Association of Certified Chief Managing Engineer Dam Construction|accessdate=7 February 2013|language=Japanese}}

File:OkukubiDamConstruction3.jpg

The dam is a {{Convert|39|m|ft|abbr=on|adj=mid|-tall|0}} and {{Convert|462|m|ft|0|abbr=on}} long trapezoidal CSG-type with a structural volume of {{Convert|339000|m3|cuyd|0|abbr=on}}. The cemented, sand and gravel (CSG) design is a mixture of a concrete gravity dam and an embankment dam. Essentially, it is a sand and gravel embankment coated in concrete. This design is cheaper because it uses less fill and concrete when compared to a gravity or embankment dam. Its wide base provides the required strength while the concrete coating seals the embankment and adds to its durability. The dam's crest lies at an elevation of {{Convert|29|m|ft|0|abbr=on}} and sits at the head of a {{Convert|14.6|km2|sqmi|0|abbr=on|adj=on}} catchment. The dam's main spillway is a labyrinth weir-type over its main crest. It has a design discharge capacity of {{Convert|430|m3/s|ft3/s|0|abbr=on}}. The dam is equipped with an emergency spillway as well, which will have a capacity of {{Convert|160|m3/s|ft3/s|0|abbr=on}}.{{cite web|title=The design of the spillway of the dam neck billion (adoption of the labyrinth weir)|url=http://www.dc.ogb.go.jp/hokudamu/jimusyo/katudo/happyou/img/ronbun15.5.pdf|publisher=North Dam Construction Office|accessdate=24 July 2011|language=Japanese}} It impounds a reservoir with a capacity of {{Convert|8560000|m3|acre.ft|0|abbr=on}}, of which {{Convert|7860000|m3|acre.ft|0|abbr=on}} is active (or "useful") capacity. The reservoir's surface area is {{Convert|0.61|km2|sqmi|abbr=on}}.{{cite web|title=Key Features of Dams in Okinawa|url=http://www.dc.ogb.go.jp/hokudamu/e/element.html|publisher=North Dam Construction Office|accessdate=24 July 2011|url-status=dead|archiveurl=https://web.archive.org/web/20110927062557/http://www.dc.ogb.go.jp/hokudamu/e/element.html|archivedate=27 September 2011}}

{{Reflist|30em}}

{{Commons category}}

• [http://www.okukubi-dam.com/index.html Official website] {{Webarchive|url=https://web.archive.org/web/20120123013212/http://www.okukubi-dam.com/index.html |date=2012-01-23 }} (Japanese)

{{Dams in Okinawa Prefecture}}

Category:Dams in Okinawa Prefecture

Category:Dams completed in 2013

Category:2013 establishments in Japan