Nanhua Dam Explained

Nanhua Dam
Name Official:南化水庫
Coordinates:23.0894°N 120.5378°W
Location:Nanhua, Tainan, Taiwan
Dam Type:Earthfill
Dam Height:87.5m (287.1feet)[1]
Dam Length:511m (1,677feet)
Dam Crosses:Houku River
Spillway Type:Ungated overflow, bathtub
Spillway Capacity:4332m3/s
Res Capacity Total:158e6m3
Res Catchment:512km2
Res Surface:5.37km2
Plant Operator:Taiwan Water Corporation

Nanhua Dam, originally named Houjie Dam, is a dam across the Houku River, a tributary of the Zengwen River in southern Taiwan. Located at Nanhua District, Tainan, the dam was built to provide municipal water to Tainan and Kaohsiung City and is operated by the Taiwan Water Corporation.[2] Construction work started in December 1988, and impoundment of the reservoir began in July 1993. A conduit to supply water from the reservoir to Kaohsiung was completed in October 1993 and the entire project was operational in March 1994.[3]

The curved earthfill dam is 87.5m (287.1feet) high and 511m (1,677feet) long, impounding a reservoir with a capacity of 158e6m3 and an active or useful capacity of 149.5e6m3.[1] The reservoir naturally receives water from a catchment of 104km2, which is not enough to fill it alone. Most of the water is actually diverted through a tunnel from the Qishan River to the east, adding 408km2 to the drainage area.[1] The tunnel provides an average of 160.6 million m3 (130,200 acre feet) of water to the reservoir each year.[3]

Because of its location in a mountainous region, Nanhua is prone to heavy sediment accumulation. A small upstream diversion weir was built to send water laden with silt through a bypass tunnel and allow the remaining clear water to enter the reservoir.[4] However, large amounts of silt are still carried into the reservoir during flooding events. In 2009 alone, flooding caused by Typhoon Morakot dumped 17 million m3 (14,000 acre feet) of silt into the reservoir.[5] In February 2010, the Taiwan Water Corporation began the first stage of a two-year sediment removal project at Nanhua.[6]

See also

Notes and References

  1. Book: Reservoirs and Weirs in Taiwan. Taiwan Water Resources Agency, Ministry of Public Affairs. Chinese. 335.
  2. Web site: Nanhua Reservoir (南化水庫). 煞車轉舵再加速. Fagan, Michael. 2012-05-05. 2012-07-13.
  3. Web site: Nanhua Reservoir. Museum of Major Engineering Project Models. 2012-07-13.
  4. Web site: Owens, Phil . Collins, Alison . Planning and Decision Making: Opportunities for River Basin Planning of Sediment Management. SedNet. March 2003. 2012-07-13.
  5. Web site: Impending Flood Season County Magistrate Su Urges for Acceleration in the Dredging of Dams . Tainan Public Works Bureau . 2010-04-13 . 2012-07-13 . dead . https://web.archive.org/web/20150322144841/http://web1.tainan.gov.tw/NewEnglish/PDA/HotNewsDetail.aspx?SN=22344 . 2015-03-22.
  6. News: Date set for Nan-Hua Reservoir desilting plan. The China Post. 2009-12-29. 2012-07-13.