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Shihmen Dam

Shihmen Dam (Chinese: 石門水庫; lit. 'Stone Gate Dam'; also spelled Shimen or Shihman) is a major rock fill dam across the Dahan River in northern Taoyuan City. It forms the Shihmen Reservoir (石門水庫), Taiwan's third largest reservoir or artificial lake. It provides irrigation in Taoyuan, flood control for the Taipei Basin, and hydroelectricity and domestic water supply for more than three million people in northern Taiwan.

Shihmen Dam
View from below the dam, showing the main rock fill dam (right) and the spillway.
Official name石門水庫
LocationFuxing, Taoyuan City, Taiwan
Coordinates24°48′38″N 121°14′39″E / 24.81056°N 121.24417°E / 24.81056; 121.24417
Construction beganJuly 1955;
68 years ago
 (1955-07)
Opening dateJune 14, 1964;
59 years ago
 (1964-06-14)
Construction costNT$1.4 billion
Owner(s)Taiwan Water Resources Agency
Dam and spillways
Type of damRolled rockfill
ImpoundsDahan River
Height133.1 m (437 ft)[1]
Length360 m (1,180 ft)[1]
Spillway typeGated overflow
Spillway capacity11,400 m3/s (400,000 cu ft/s)[2]
Reservoir
CreatesShihmen Reservoir
Total capacity309,120,000 m3 (250,610 acre⋅ft) (nominal)
251,880,000 m3 (204,200 acre⋅ft) (1997)[1]
Catchment area763.4 km2 (294.8 sq mi)[1]
Surface area8.0 km2 (2,000 acres)[1]
Power Station
Turbines2x 45 MW[3]
Installed capacity90 MW[3]
Annual generation200 million KWh[4]

Completed in 1964 after nine years of construction, Shihmen was Taiwan's first multi-purpose water project and a major step towards the island's economic independence after World War II. Year-round water releases from the dam enabled additional rice harvests and doubled Taoyuan's annual agricultural output, while the reservoir became a tourist destination due to its scenery and plentiful fisheries.[citation needed] However, the project was criticized for its high cost and its impact on local communities, as more than 2,000 people were displaced to make way for the reservoir.

Like some other reservoirs in Taiwan, Shihmen has suffered from sedimentation, reducing its capacity by over a third. Efforts to reduce the rate of sediment accumulation, including dredging, check dam construction and watershed restoration work, have had a limited effect. This has diminished both the Shihmen Dam's capability to contain floods and provide water during droughts.

History edit

Background edit

The Dahan River is the main river in northwestern Taiwan and is one of two tributaries that join in Taipei to form the Tamsui, Taiwan's largest river system. Originating in the Xueshan Range, the river begins life as a fast-flowing mountain stream prone to flooding during typhoons. The Dahan skirts, but does not cross, the Taoyuan Plateau, which lacks a reliable water supply of its own. The plateau has been farmed since 1680 using thousands of artificial ponds to capture rainfall;[5] in 1928, when Taiwan was under Japanese rule, the Taoyuan Canal was dug to divert water from the Dahan (then known as the Takekan River) onto the plateau.[6] River water enabled the irrigation of an additional 20,000 hectares (49,000 acres) of land in the Taoyuan area.[7] Due to the limited storage capacity of the small Taoyuan ponds, there was often not enough water for irrigation in the November–April dry season, demonstrating the need for a large reservoir.[7]

A dam at the "stone gates" (Shihmen), a deep canyon formed where the Dahan river exits the mountains, was proposed as early as 1938, but plans were dropped at the beginning of World War II with the strain on industrial resources. After the war, the Republic of China was faced with food shortages and a rapidly increasing population. By the 1960s, the annual population growth had reached 350,000.[8] In order to improve its economic self-sufficiency, the government initiated the construction of Shihmen Dam, Taiwan's first multi-purpose water project. The Shihmen Development Commission was established to oversee the project. The initial budget for the dam was NT$1.4 billion, with approximately half of that as low-interest aid loans from the United States through the Agency for International Development.[7]

Construction edit

 
Shihmen Dam site before construction, looking upstream at the "stone gates".

Starting in July 1955, access roads and worker facilities were constructed at the dam site, and the area of the future reservoir was prepared to accommodate flooding. About 2,000 people (416 families) living in the Dahan River valley would be displaced by the project; they were relocated starting in 1956 to areas along Taiwan's northwest coast. Although the government built new homes, schools and other infrastructure as well as providing land compensation to families, the resettlement programme was the subject of bitter controversy.[9]

The dam was designed by Tippetts-Abbett-McCarthy-Stratton, with construction overseen by Morrison-Knudsen (known previously for its work on Hoover Dam). Heavy construction began in late 1959 when large equipment arrived at the dam site. Although work was interrupted several times by typhoon flooding, the river was successfully diverted into a tunnel in December 1960.[3] The concrete cofferdam, later to serve as the core of the dam, was finished in 1962; notably, it was the first use of roller-compacted concrete in dam construction.[10] About 120 hectares (300 acres) of nearby farmland were purchased by the government to provide 6,675,000 cubic metres (235,700,000 cu ft) of earth and rock needed to build the dam.[7]

With the dam only partially complete in May 1963, the diversion tunnel was plugged, allowing the reservoir to begin storing water.[9] In July 1963, Typhoon Wendy struck Taiwan, causing massive flooding; the new reservoir was able to reduce the flood crest on the Dahan River by 25 percent.[9] The embankment was topped out in June 1964, at a final cost of NT$ 4.85 billion.[11] The dam was dedicated on June 14, 1964 by Vice President Chen Cheng, to a crowd of more than four thousand people.[7] A total of 7,500 people were employed in the construction of the dam, with as many as 6,000 workers on the site at one time. Thirty-two people were killed during construction; out of 2,881 injured, 87 were left permanently disabled.[7]

Later history edit

 
The spillway, nearing completion in 1964

Engineers estimated that the natural sedimentation rate would give the reservoir a useful life of at least 71 years without any sediment removal. However, just four months after the reservoir began filling, Typhoon Gloria struck Taiwan, and the resulting floods washed 19 million cubic metres (670 million ft3) of sediment[12] into the reservoir – taking 23 years off its expected lifespan.[13] As the reservoir filled, it also inundated several historic landmarks, including the former summer villa of Chiang Kai-shek, the Amuping Stone Bridge and a nearby Earth God shrine.[14][15]

Irrigation was the primary goal of the Shihmen reservoir; about 22,000 hectares (54,000 acres) of new farmland came into production after the dam was built, bringing the total to 57,000 hectares (140,000 acres). The annual crop was more than doubled due to an increased water supply for pre-existing farmland. Individual farmers' income rose by almost 20 percent.[16] About 27 kilometres (17 mi) of canals were added to the existing irrigation system, including the new Shihmen Canal, bringing the total to 175 kilometres (109 mi), and a treatment plant with 30,000 tons per day capacity was constructed to provide municipal water supply.[9] Despite the scale of the project, the increase in agricultural production was estimated to feed 500,000 people, or less than two years of population growth.[8] The importance of the dam for irrigation has been decreasing since the 1990s as Taoyuan County saw significant urbanization; in the meantime, demand for cleaner domestic water has risen.[6]

The government allocated NT$21 million to develop the Shihmen Reservoir as a recreational area. Boating facilities and about 31 kilometres (19 mi) of new roads were constructed to improve access to the reservoir. The reservoir would also be stocked with game fish, and its shores would eventually be developed with "temples, museums, monuments, pagodas, hostels and residences."[9] After the dam was completed, it brought prosperity via tourism to this rural area, helping to diversify its economy from one solely reliant on agriculture.[17] However, due to the project's high capital cost, the actual annual return on investment was only 1.5 percent: "It stands as an engineering monument of which the Chinese people may be proud. But it was purchased at far too high a cost in terms of tens of millions of dollars of alternative developmental opportunities foregone."[18]

Dam details edit

 
View from a nearby mountain, showing the main dam (center) and spillway (lower left).

Embankment and spillways edit

Shihmen Dam is a rolled rockfill embankment dam 133.1 metres (437 ft) high and 360 metres (1,180 ft) long, constructed over a 70-metre (230 ft) high concrete core.[1] The main body of the dam contains some 7.06 million cubic metres (9.23 million yd3) of material.[1] At the crest, the dam is 11.5 metres (38 ft) wide, with an elevation of 252.1 metres (827 ft) above sea level. The normal water level is 245 metres (804 ft), with a maximum flood level of 249.7 metres (819 ft).[19]

The concrete spillway is located to the east of the dam and is controlled by six radial gates, each 10 metres (33 ft) high and 14 metres (46 ft) wide.[19] The maximum water release is 11,400 cubic metres per second (400,000 cu ft/s).[2] There is also a river outlet works used for normal releases, with a capacity of 34 cubic metres per second (1,200 cu ft/s).[20] The dam also has two additional flood tunnels which were completed in 1978, in order to allow faster evacuation of reservoir storage prior to typhoons. Each tunnel is 375.4 metres (1,232 ft) long, 1.372 metres (4.50 ft) in diameter, with a combined capacity of 2,400 cubic metres per second (85,000 cu ft/s).[19]

Power station edit

 
View across the spillway showing Shihmen Power Station

The dam's hydroelectric power station is located on the left bank of the Dahan River at the base of the dam. Two steel 4.57-metre (15.0 ft) diameter penstocks, each 318.8 metres (1,046 ft) long, feed water to two Francis turbines. The maximum water flow through the power plant is 137.2 cubic metres per second (4,850 cu ft/s).[20] Each generator has a capacity of 45,000 kilowatts (KW), for a total capacity of 90,000 KW.[3] The plant produces about 200 million kilowatt hours per year.[4]

Reservoir edit

The impounded water behind the dam forms Shihmen Reservoir, one of Taiwan's largest reservoirs with a length of 16 kilometres (9.9 mi) and more than 800 hectares (2,000 acres) of water at full pool. The reservoir had an original total capacity of 309,120 megalitres (250,610 acre⋅ft), with an active or useful capacity of 251,780 ML (204,120 acre⋅ft). Sedimentation reduced the total storage capacity to 251,880 ML (204,200 acre⋅ft) by 1997 – a nearly 20 percent reduction – and the active capacity was decreased to 233,800 ML (189,500 acre⋅ft).[1] As of a 2017 study, the total capacity had been reduced to 216,000 ML (175,000 acre⋅ft).[21]

The Shihmen afterbay reservoir, located below the main dam, regulates the water release into the Dahan River and provides the intake point for the Taoyuan and Shihmen Canals. The afterbay is formed by a 317.5-metre (1,042 ft) long weir and can store up to 2,200,000 cubic metres (1,800 acre⋅ft). The headworks for the Taoyuan Canal have a capacity of 18.6 cubic metres per second (660 cu ft/s), and the Shihmen Canal can carry up to 18.4 cubic metres per second (650 cu ft/s).[19]

Operations and usage edit

Water from Shihmen Dam is distributed to 28 districts in Taoyuan City, Hsinchu County and New Taipei, with a combined population of some 3.4 million people and more than 36,500 hectares (90,000 acres) of irrigated land.[11][22] Each year, Shihmen furnishes 181.6 million m3 (147,200 acre feet) of water for irrigation and industrial uses and about 127.4 million m3 (103,300 acre feet) for residential use in downstream areas. In addition, an annual minimum river release of 299.6 million m3 (242,900 acre feet) is maintained to provide a baseflow in the lower Dahan River. About 386.3 million m3 (313,200 acre feet) of the aforementioned releases are utilized for hydroelectric generation.[23] The dam's power station generates roughly 200 million kilowatt hours annually and is integral in meeting peaking power demands in northern Taiwan's electricity grid.[11] Hydroelectric power releases peak in late July and August, largely because of air-conditioning usage in Taiwan's northern cities.[23]

 
 
Taoyuan Canal (Left: In Taoyuan City; Right: Intake at Shihmen Afterbay Dam)

Shihmen is one of several key reservoirs in the Tamsui River system used to cut peak flood flows during typhoon events. Dam releases are coordinated with those from Feitsui Dam to the east in order to reduce the severity of flooding.[24] However, sediment accumulation in the reservoir has reduced its effectiveness on large flooding events. As a result, the "frequency with which the Shih-men Dam discharges water down its spillway ranks first among Taiwan's reservoirs. The phrase 'the Shihmen Reservoir is releasing flood water' has become a euphemism for 'your fly is open'."[25] Additionally, large flooding events can cause turbidity levels in the reservoir to increase by over 3,000 times of average, forcing authorities to shut down water supplies.[26] This problem has been exacerbated by the increasing percentage of Shihmen water going to residential and industrial users, who generally demand clearer water than the agricultural users Shihmen was originally intended to supply.[27]

 
Flood release in June 2017

The reduction in storage capacity has also affected Shihmen's ability to provide water during droughts. Demand often exceeds stored water in Shihmen Reservoir during the dry season, forcing frequent water-supply cuts. For several weeks in 1994, the drought-stricken Shihmen Dam service area was limited to one day of running water in three.[25] This has been further exacerbated by global climate change reducing the length of the rainy season in Taiwan, while increasing the intensity of rainfall when storms do strike the island. In 2015, Taiwan recorded its lowest winter rainfall since 1947, and the Shihmen reservoir fell to a record low of 24.5 percent of capacity, again forcing the government to enact water rationing.[28]

Among the other benefits of the dam and reservoir is recreation. More than 160,000 tourists visit the dam each year, especially during floodwater releases.[14] The reservoir, its surrounding recreation area and towns are visited by a further 1.7 million people each year.[29] It is said that "after its grand opening to the public in 1964, the Shihmen Reservoir has remained one of the top spots on Taiwan's sight-seeing billboards".[30] Recreational and commercial fishing on the reservoir produces about 80,000 kilograms (180,000 lb) of fish each year, generating an annual revenue of NT$29.33 million.[30]

Environmental issues edit

 
Shihmen Reservoir

Poor land use and construction practices in the catchment area of Shihmen Dam have contributed to a severe sedimentation problem in the reservoir. This sediment mainly comes from landslides and other erosion-related issues in the steep, rugged drainage basin, which have been exacerbated by deforestation, land-clearing for agriculture, and the opening of roads into mountainous areas.[25] The reservoir, which originally had a maximum depth of over 100 metres (330 ft), is estimated to be no more than 40 metres (130 ft) deep today.[25] The textbook The Hydraulics of Open Channel Flow by Hubert Chanson describes the dam as having "become a vast sediment trap with an inappropriate storage capacity to act as a flood control or water supply reservoir."[31]

In 1981 it was estimated that 2.9 million tonnes of sediment flow into the reservoir each year, or a watershed erosion rate of 3,789 tonnes/km2.[12] According to a 2017 Taipei Times report, the amount of sediment flowing into the reservoir was 3.42 million tonnes per year. About 1.17 million tonnes were sluiced through the dam's outlets and another 900,000 tonnes were removed by excavation and dredging. The government has proposed to construct a sediment bypass tunnel, which would prevent another 640,000 tonnes from entering the reservoir.[32] This technology has already been employed at reservoirs in Japan and Switzerland, and would essentially allow river water to be diverted around the reservoir instead of flowing into it during periods of high sediment runoff, such as after typhoons.[33]

Sediment prevention projects edit

 
The destroyed Baling Dam, showing severe riverbed erosion typical in the watershed

A number of measures have been taken to try and reduce the amount of sediment flowing into Shihmen Reservoir. Because of the construction of hundreds of sediment-trapping dams or sabo dams, the upper reaches of the Dahan and its tributaries are now among the most heavily impounded river systems in Taiwan, with at least 123 such dams along the main stem alone.[25] The largest 24 sabo dams have collectively prevented some 36 million cubic metres (29,200 acre feet) of sediment from reaching Shihmen Reservoir.[34] Only one, the Junghua Dam, is still collecting sediment, although its 16 million cubic metre (13,000 acre foot) capacity is nearly full.[13] These sediment catching dams have also failed on several occasions causing even more debris and silt to wash into Shihmen. Among these was the failure of Baling Dam during Typhoon Wipha (2007), which caused 10 million cubic metres (8,000 acre feet) of sediment to wash downstream, destroying the village of Baling.[35] Dredging efforts on Shihmen Reservoir have also been only partly successful. Beginning in 1985, seven dredging companies removed more than 10 million cubic metres (8,000 acre feet), but the reservoir continued filling with sediment faster than it could be excavated. The capacity of the silt disposal areas was exhausted in 1995.[25] Other measures taken to decrease sediment flow include the construction of retaining walls and the reforestation of clear-cut areas.

In more recent years, the Taiwanese government has revived the idea of constructing more mega-dams in the Dahan River to increase water retention capacity and trap silt. The Gaotai Reservoir (高台水庫) near the indigenous community of Jianshi would consist of a dam 190 metres (620 ft) high with a 171 million cubic metre (139,000 acre-foot) storage capacity. This project could be built in conjunction with the Bilin Reservoir (比麟水庫) which would divert some water from the Dahan drainage to the Da'an River, increasing the water supply available for Hsinchu County.[36] The dam projects have been strongly criticized as an expensive, yet only marginally effective solution to the problem, and for their effects on local communities.[37]

Water quality edit

The large amount of sediment flowing into the reservoir has also caused unusually high nutrient levels, which leads to frequent eutrophication and algae blooms in the summer. As a result, Shihmen is often considered to be among the worst in water quality among all Taiwan's reservoirs.[25] A large water-quality monitoring system is in place, installed circa 2005 at two points in Shihmen Reservoir. Called "Vertical Profiling System" or "YSI 6600EDS", the system measures a series of water quality factors by depth at intervals of 5 metres (16 ft). The turbidity, chlorophyll content, pH level, and dissolved oxygen levels in the reservoir are sent to the operator of the dam every three hours. A future plan for the system is to record algae growth, allowing action to be taken to prevent hypoxic events in the water.[38] In 2008, the Taiwanese Environmental Protection Agency allocated NT$200 million for eutrophication control projects at Shihmen, Feitsui, Zengwun and Kinmen Reservoirs.[39]

 
Shihmen Reservoir (right) and afterbay (left), seen from the crest of Shihmen Dam.

See also edit

References edit

  1. ^ a b c d e f g h Reservoirs and Weirs in Taiwan (in Chinese). Taiwan Water Resources Agency, Ministry of Public Affairs. p. 322.
  2. ^ a b "Outline of Shihmen Reservoir". Shihmen Reservoir and its Catchments Management Project. Taiwan Water Resources Agency. Retrieved 2012-07-14.
  3. ^ a b c d "I. Economic Development". Taiwan Review. Ministry of Foreign Affairs, Republic of China (Taiwan). 1963-07-01. Retrieved 2012-07-14.
  4. ^ a b "Main Facilities: Shihmen Reservoir". Northern Region Water Resources Office. Taiwan Water Resources Agency. 2009. Retrieved 2012-07-14.
  5. ^ (PDF). Archived from the original (PDF) on 2016-09-15. Retrieved 2016-08-29.{{cite web}}: CS1 maint: archived copy as title (link)
  6. ^ a b "Taiwan Today". taiwantoday.tw. Retrieved 2017-02-17.
  7. ^ a b c d e f Yuan, Lorraine (1964-06-21). . Taiwan Today. Archived from the original on 2013-12-24. Retrieved 2012-07-14.
  8. ^ a b Li, Guoding; Ranis, Gustav; Fei, John C. H. (1995). The Evolution of Policy Behind Taiwan's Development Success. World Scientific. p. 137. ISBN 978-981-02-1838-6.
  9. ^ a b c d e Ministry of Foreign Affairs, Republic of China (Taiwan). "Year of the Big Dam - Taiwan Today". taiwantoday.tw. Retrieved 2017-02-17.
  10. ^ Penman, A.D.M. "18.4.3: Rollcrete dams" (PDF). Ethiopian Civil Service University Libraries. Retrieved 2012-07-14.
  11. ^ a b c "Shimen reservoir". library.taiwanschoolnet.org. Retrieved 2012-07-14.
  12. ^ a b Sidle, Roy C. (2002). Environmental Change and Geomorphic Hazards in Forests. CABI. p. 60. ISBN 978-0-85199-598-4.
  13. ^ a b Lin, Rebecca (2010-07-09). "Shihmen Reservoir; A Time Bomb Waiting to Explode". CommonWealth Magazine. No. 450. Retrieved 2014-04-22.
  14. ^ a b "A Cultural Map of Taoyuan". Taoyuan County Government Department of Cultural Affairs. Retrieved 2009-05-09.
  15. ^ Kelly, Robert; Bender, Andrew; Brown, Joshua Samuel (2007). Taiwan. Lonely Planet.
  16. ^ "Irrigation in Shihmen Area Boosts Rice Field Acreage". Taiwan Info. 1966-09-25. Retrieved 2016-08-28.
  17. ^ Peng, Jenny (2015-05-25). "Lessons From the Drought: Following last month's prolonged drought, Taiwan should seize the opportunity to reinvent and modernize itself for a sustainable future". Thinking Taiwan. Retrieved 2016-08-28.
  18. ^ Maddison, Angus (2013). Economic Progress and Policy in Developing Countries. Routledge. p. 145. ISBN 978-1-13454-511-7.
  19. ^ a b c d (in Chinese (Taiwan)). 經濟部水利署北區水資源局. Archived from the original on 2015-06-04. Retrieved 2014-06-25.
  20. ^ a b Tan, Yih-Chi=; Lee, Fong-Zuo; Lai, Jihn-Sung (October 2011). Complex Disaster Damage to Water Resources in Taiwan (PDF). 21st International Congress on Irrigation and Drainage. Tehran, Iran. R.56.5/Poster/18.
  21. ^ Cheng, Wen-Ming; Huang, Chien-Lin; Hsu, Nien-Sheng; Wei, Chih-Chiang (2017-02-03). "Risk Analysis of Reservoir Operations Considering Short-Term Flood Control and Long-Term Water Supply: A Case Study for the Da-Han Creek Basin in Taiwan". Water. 9 (424): 424. doi:10.3390/w9060424.
  22. ^ Pao, William C. "Shimen Dam water shortage shows no sign". The China Post. Retrieved 2009-05-08.
  23. ^ a b Chaves, Paulo; Chang, Fi-John (June 2008). "Intelligent reservoir operation system based on evolving artificial neural networks" (PDF). Advances in Water Resources. 31 (6): 926–936. Bibcode:2008AdWR...31..926C. doi:10.1016/j.advwatres.2008.03.002.
  24. ^ "Reservoir Operations". Taipei Feitsui Reservoir Administration. 2012-05-30. Retrieved 2012-07-14.
  25. ^ a b c d e f g Chang, Chin-ju (November 1996). "A Tale of Two Reservoirs – Greater Taipei's Water Woes". Taiwan Panorama. Retrieved 2014-04-22.
  26. ^ "CEPD Approves Plan to Renovate Shihmen Reservoir". Taiwan Soil and Water Conservation Bureau. 2006-05-16. Retrieved 2012-07-14.
  27. ^ "Searching for Water: Reservoirs continue to play a role, but Taiwan is looking for alternative ways to quench its thirst". Taiwan Review. 2009-02-01. Retrieved 2012-07-14.
  28. ^ "Taiwan launches water rationing to fight drought | World news | The Guardian". theguardian.com. Retrieved 2017-02-17.
  29. ^ van Harssel, Jan; Jackson, Richard H.; Hudman, Lloyd E. (2014). National Geographic Learning's Visual Geography of Travel and Tourism. Cengage Learning. p. 460. ISBN 978-1-13395-126-1.
  30. ^ a b "Shihmen Tourist Festival". Cultural Tourism Taiwan. Retrieved 2012-07-14.
  31. ^ Chanson, Hubert (25 May 2004). Hydraulics of Open Channel Flow. Butterworth-Heinemann. p. 147. ISBN 978-0-08-047297-3.
  32. ^ Lee, Jung-ping (2017-09-07). "Reservoir upgrade to help stabilize tap water supply". Taipei Times. Retrieved 2017-10-01.
  33. ^ Kondolf, G. Mathias; et al. (2014). "Sustainable sediment management in reservoirs and regulated rivers: Experiences from five continents". Earth's Future. 2 (5): 256–280. Bibcode:2014EaFut...2..256K. doi:10.1002/2013EF000184.
  34. ^ Chen, Su-Chin; Lai, Yi-Cheng; Wang, Chin-Lun (2008). Typhoons' Effects on Long-Term Watershed Sediment Management in Shihmen Reservoir in Taiwan (PDF). Interpraevent 2008. Retrieved 2012-07-14.
  35. ^ Tseng, W.H.; Shieh, C.L.; Lee, S.P.; Tsang, Y.C. (April 2009). "A study on the effect of a broken large sabo dam on the sediment transportation in channel – an example of Baling-sabo-dam". EGU General Assembly 2009. 11. The Smithsonian/NASA Astrophysics Data System, Harvard University: 3554. Bibcode:2009EGUGA..11.3554T.
  36. ^ "高台水庫環境調查評估" [Environmental Investigation and Assessment of Kaotai Reservoir] (PDF) (in Chinese (Taiwan)). 水利署水利規劃試驗所. February 2011. Retrieved 2014-01-09.
  37. ^ Hsu, Jenny W. (2010-03-13). "Demonstrators slam government plans to build new dams". Taipei Times.
  38. ^ Dumont, Danielle. "Monitoring Reservoir Water Quality in Taiwan Tames Turbidity after Typhoon". WaterWorld. Retrieved 2009-05-08.
  39. ^ "EPA to spend NT$200 million on eutrophication control at reservoirs". Taiwan Headlines. 2008-01-09. Retrieved 2009-05-10.

External links edit

  • Goodbye to Water Shortages?
  • (in Chinese)
  • The View from Taiwan: Rain = Silt
  • What are the problems presently faced by the Shihmen Reservoir?
  • Current water levels at Taiwan reservoirs (Chinese)

shihmen, district, taipei, city, shimen, district, chinese, 石門水庫, stone, gate, also, spelled, shimen, shihman, major, rock, fill, across, dahan, river, northern, taoyuan, city, forms, shihmen, reservoir, 石門水庫, taiwan, third, largest, reservoir, artificial, lak. For the district in New Taipei City see Shimen District Shihmen Dam Chinese 石門水庫 lit Stone Gate Dam also spelled Shimen or Shihman is a major rock fill dam across the Dahan River in northern Taoyuan City It forms the Shihmen Reservoir 石門水庫 Taiwan s third largest reservoir or artificial lake It provides irrigation in Taoyuan flood control for the Taipei Basin and hydroelectricity and domestic water supply for more than three million people in northern Taiwan Shihmen DamView from below the dam showing the main rock fill dam right and the spillway Official name石門水庫LocationFuxing Taoyuan City TaiwanCoordinates24 48 38 N 121 14 39 E 24 81056 N 121 24417 E 24 81056 121 24417Construction beganJuly 1955 68 years ago 1955 07 Opening dateJune 14 1964 59 years ago 1964 06 14 Construction costNT 1 4 billionOwner s Taiwan Water Resources AgencyDam and spillwaysType of damRolled rockfillImpoundsDahan RiverHeight133 1 m 437 ft 1 Length360 m 1 180 ft 1 Spillway typeGated overflowSpillway capacity11 400 m3 s 400 000 cu ft s 2 ReservoirCreatesShihmen ReservoirTotal capacity309 120 000 m3 250 610 acre ft nominal 251 880 000 m3 204 200 acre ft 1997 1 Catchment area763 4 km2 294 8 sq mi 1 Surface area8 0 km2 2 000 acres 1 Power StationTurbines2x 45 MW 3 Installed capacity90 MW 3 Annual generation200 million KWh 4 Completed in 1964 after nine years of construction Shihmen was Taiwan s first multi purpose water project and a major step towards the island s economic independence after World War II Year round water releases from the dam enabled additional rice harvests and doubled Taoyuan s annual agricultural output while the reservoir became a tourist destination due to its scenery and plentiful fisheries citation needed However the project was criticized for its high cost and its impact on local communities as more than 2 000 people were displaced to make way for the reservoir Like some other reservoirs in Taiwan Shihmen has suffered from sedimentation reducing its capacity by over a third Efforts to reduce the rate of sediment accumulation including dredging check dam construction and watershed restoration work have had a limited effect This has diminished both the Shihmen Dam s capability to contain floods and provide water during droughts Contents 1 History 1 1 Background 1 2 Construction 1 3 Later history 2 Dam details 2 1 Embankment and spillways 2 2 Power station 2 3 Reservoir 2 4 Operations and usage 3 Environmental issues 3 1 Sediment prevention projects 3 2 Water quality 4 See also 5 References 6 External linksHistory editBackground edit The Dahan River is the main river in northwestern Taiwan and is one of two tributaries that join in Taipei to form the Tamsui Taiwan s largest river system Originating in the Xueshan Range the river begins life as a fast flowing mountain stream prone to flooding during typhoons The Dahan skirts but does not cross the Taoyuan Plateau which lacks a reliable water supply of its own The plateau has been farmed since 1680 using thousands of artificial ponds to capture rainfall 5 in 1928 when Taiwan was under Japanese rule the Taoyuan Canal was dug to divert water from the Dahan then known as the Takekan River onto the plateau 6 River water enabled the irrigation of an additional 20 000 hectares 49 000 acres of land in the Taoyuan area 7 Due to the limited storage capacity of the small Taoyuan ponds there was often not enough water for irrigation in the November April dry season demonstrating the need for a large reservoir 7 A dam at the stone gates Shihmen a deep canyon formed where the Dahan river exits the mountains was proposed as early as 1938 but plans were dropped at the beginning of World War II with the strain on industrial resources After the war the Republic of China was faced with food shortages and a rapidly increasing population By the 1960s the annual population growth had reached 350 000 8 In order to improve its economic self sufficiency the government initiated the construction of Shihmen Dam Taiwan s first multi purpose water project The Shihmen Development Commission was established to oversee the project The initial budget for the dam was NT 1 4 billion with approximately half of that as low interest aid loans from the United States through the Agency for International Development 7 Construction edit nbsp Shihmen Dam site before construction looking upstream at the stone gates Starting in July 1955 access roads and worker facilities were constructed at the dam site and the area of the future reservoir was prepared to accommodate flooding About 2 000 people 416 families living in the Dahan River valley would be displaced by the project they were relocated starting in 1956 to areas along Taiwan s northwest coast Although the government built new homes schools and other infrastructure as well as providing land compensation to families the resettlement programme was the subject of bitter controversy 9 The dam was designed by Tippetts Abbett McCarthy Stratton with construction overseen by Morrison Knudsen known previously for its work on Hoover Dam Heavy construction began in late 1959 when large equipment arrived at the dam site Although work was interrupted several times by typhoon flooding the river was successfully diverted into a tunnel in December 1960 3 The concrete cofferdam later to serve as the core of the dam was finished in 1962 notably it was the first use of roller compacted concrete in dam construction 10 About 120 hectares 300 acres of nearby farmland were purchased by the government to provide 6 675 000 cubic metres 235 700 000 cu ft of earth and rock needed to build the dam 7 With the dam only partially complete in May 1963 the diversion tunnel was plugged allowing the reservoir to begin storing water 9 In July 1963 Typhoon Wendy struck Taiwan causing massive flooding the new reservoir was able to reduce the flood crest on the Dahan River by 25 percent 9 The embankment was topped out in June 1964 at a final cost of NT 4 85 billion 11 The dam was dedicated on June 14 1964 by Vice President Chen Cheng to a crowd of more than four thousand people 7 A total of 7 500 people were employed in the construction of the dam with as many as 6 000 workers on the site at one time Thirty two people were killed during construction out of 2 881 injured 87 were left permanently disabled 7 Later history edit nbsp The spillway nearing completion in 1964 Engineers estimated that the natural sedimentation rate would give the reservoir a useful life of at least 71 years without any sediment removal However just four months after the reservoir began filling Typhoon Gloria struck Taiwan and the resulting floods washed 19 million cubic metres 670 million ft3 of sediment 12 into the reservoir taking 23 years off its expected lifespan 13 As the reservoir filled it also inundated several historic landmarks including the former summer villa of Chiang Kai shek the Amuping Stone Bridge and a nearby Earth God shrine 14 15 Irrigation was the primary goal of the Shihmen reservoir about 22 000 hectares 54 000 acres of new farmland came into production after the dam was built bringing the total to 57 000 hectares 140 000 acres The annual crop was more than doubled due to an increased water supply for pre existing farmland Individual farmers income rose by almost 20 percent 16 About 27 kilometres 17 mi of canals were added to the existing irrigation system including the new Shihmen Canal bringing the total to 175 kilometres 109 mi and a treatment plant with 30 000 tons per day capacity was constructed to provide municipal water supply 9 Despite the scale of the project the increase in agricultural production was estimated to feed 500 000 people or less than two years of population growth 8 The importance of the dam for irrigation has been decreasing since the 1990s as Taoyuan County saw significant urbanization in the meantime demand for cleaner domestic water has risen 6 The government allocated NT 21 million to develop the Shihmen Reservoir as a recreational area Boating facilities and about 31 kilometres 19 mi of new roads were constructed to improve access to the reservoir The reservoir would also be stocked with game fish and its shores would eventually be developed with temples museums monuments pagodas hostels and residences 9 After the dam was completed it brought prosperity via tourism to this rural area helping to diversify its economy from one solely reliant on agriculture 17 However due to the project s high capital cost the actual annual return on investment was only 1 5 percent It stands as an engineering monument of which the Chinese people may be proud But it was purchased at far too high a cost in terms of tens of millions of dollars of alternative developmental opportunities foregone 18 Dam details edit nbsp View from a nearby mountain showing the main dam center and spillway lower left Embankment and spillways edit Shihmen Dam is a rolled rockfill embankment dam 133 1 metres 437 ft high and 360 metres 1 180 ft long constructed over a 70 metre 230 ft high concrete core 1 The main body of the dam contains some 7 06 million cubic metres 9 23 million yd3 of material 1 At the crest the dam is 11 5 metres 38 ft wide with an elevation of 252 1 metres 827 ft above sea level The normal water level is 245 metres 804 ft with a maximum flood level of 249 7 metres 819 ft 19 The concrete spillway is located to the east of the dam and is controlled by six radial gates each 10 metres 33 ft high and 14 metres 46 ft wide 19 The maximum water release is 11 400 cubic metres per second 400 000 cu ft s 2 There is also a river outlet works used for normal releases with a capacity of 34 cubic metres per second 1 200 cu ft s 20 The dam also has two additional flood tunnels which were completed in 1978 in order to allow faster evacuation of reservoir storage prior to typhoons Each tunnel is 375 4 metres 1 232 ft long 1 372 metres 4 50 ft in diameter with a combined capacity of 2 400 cubic metres per second 85 000 cu ft s 19 Power station edit nbsp View across the spillway showing Shihmen Power Station The dam s hydroelectric power station is located on the left bank of the Dahan River at the base of the dam Two steel 4 57 metre 15 0 ft diameter penstocks each 318 8 metres 1 046 ft long feed water to two Francis turbines The maximum water flow through the power plant is 137 2 cubic metres per second 4 850 cu ft s 20 Each generator has a capacity of 45 000 kilowatts KW for a total capacity of 90 000 KW 3 The plant produces about 200 million kilowatt hours per year 4 Reservoir edit The impounded water behind the dam forms Shihmen Reservoir one of Taiwan s largest reservoirs with a length of 16 kilometres 9 9 mi and more than 800 hectares 2 000 acres of water at full pool The reservoir had an original total capacity of 309 120 megalitres 250 610 acre ft with an active or useful capacity of 251 780 ML 204 120 acre ft Sedimentation reduced the total storage capacity to 251 880 ML 204 200 acre ft by 1997 a nearly 20 percent reduction and the active capacity was decreased to 233 800 ML 189 500 acre ft 1 As of a 2017 study the total capacity had been reduced to 216 000 ML 175 000 acre ft 21 The Shihmen afterbay reservoir located below the main dam regulates the water release into the Dahan River and provides the intake point for the Taoyuan and Shihmen Canals The afterbay is formed by a 317 5 metre 1 042 ft long weir and can store up to 2 200 000 cubic metres 1 800 acre ft The headworks for the Taoyuan Canal have a capacity of 18 6 cubic metres per second 660 cu ft s and the Shihmen Canal can carry up to 18 4 cubic metres per second 650 cu ft s 19 Operations and usage edit Water from Shihmen Dam is distributed to 28 districts in Taoyuan City Hsinchu County and New Taipei with a combined population of some 3 4 million people and more than 36 500 hectares 90 000 acres of irrigated land 11 22 Each year Shihmen furnishes 181 6 million m3 147 200 acre feet of water for irrigation and industrial uses and about 127 4 million m3 103 300 acre feet for residential use in downstream areas In addition an annual minimum river release of 299 6 million m3 242 900 acre feet is maintained to provide a baseflow in the lower Dahan River About 386 3 million m3 313 200 acre feet of the aforementioned releases are utilized for hydroelectric generation 23 The dam s power station generates roughly 200 million kilowatt hours annually and is integral in meeting peaking power demands in northern Taiwan s electricity grid 11 Hydroelectric power releases peak in late July and August largely because of air conditioning usage in Taiwan s northern cities 23 nbsp nbsp Taoyuan Canal Left In Taoyuan City Right Intake at Shihmen Afterbay Dam Shihmen is one of several key reservoirs in the Tamsui River system used to cut peak flood flows during typhoon events Dam releases are coordinated with those from Feitsui Dam to the east in order to reduce the severity of flooding 24 However sediment accumulation in the reservoir has reduced its effectiveness on large flooding events As a result the frequency with which the Shih men Dam discharges water down its spillway ranks first among Taiwan s reservoirs The phrase the Shihmen Reservoir is releasing flood water has become a euphemism for your fly is open 25 Additionally large flooding events can cause turbidity levels in the reservoir to increase by over 3 000 times of average forcing authorities to shut down water supplies 26 This problem has been exacerbated by the increasing percentage of Shihmen water going to residential and industrial users who generally demand clearer water than the agricultural users Shihmen was originally intended to supply 27 nbsp Flood release in June 2017 The reduction in storage capacity has also affected Shihmen s ability to provide water during droughts Demand often exceeds stored water in Shihmen Reservoir during the dry season forcing frequent water supply cuts For several weeks in 1994 the drought stricken Shihmen Dam service area was limited to one day of running water in three 25 This has been further exacerbated by global climate change reducing the length of the rainy season in Taiwan while increasing the intensity of rainfall when storms do strike the island In 2015 Taiwan recorded its lowest winter rainfall since 1947 and the Shihmen reservoir fell to a record low of 24 5 percent of capacity again forcing the government to enact water rationing 28 Among the other benefits of the dam and reservoir is recreation More than 160 000 tourists visit the dam each year especially during floodwater releases 14 The reservoir its surrounding recreation area and towns are visited by a further 1 7 million people each year 29 It is said that after its grand opening to the public in 1964 the Shihmen Reservoir has remained one of the top spots on Taiwan s sight seeing billboards 30 Recreational and commercial fishing on the reservoir produces about 80 000 kilograms 180 000 lb of fish each year generating an annual revenue of NT 29 33 million 30 Environmental issues edit nbsp Shihmen Reservoir Poor land use and construction practices in the catchment area of Shihmen Dam have contributed to a severe sedimentation problem in the reservoir This sediment mainly comes from landslides and other erosion related issues in the steep rugged drainage basin which have been exacerbated by deforestation land clearing for agriculture and the opening of roads into mountainous areas 25 The reservoir which originally had a maximum depth of over 100 metres 330 ft is estimated to be no more than 40 metres 130 ft deep today 25 The textbook The Hydraulics of Open Channel Flow by Hubert Chanson describes the dam as having become a vast sediment trap with an inappropriate storage capacity to act as a flood control or water supply reservoir 31 In 1981 it was estimated that 2 9 million tonnes of sediment flow into the reservoir each year or a watershed erosion rate of 3 789 tonnes km2 12 According to a 2017 Taipei Times report the amount of sediment flowing into the reservoir was 3 42 million tonnes per year About 1 17 million tonnes were sluiced through the dam s outlets and another 900 000 tonnes were removed by excavation and dredging The government has proposed to construct a sediment bypass tunnel which would prevent another 640 000 tonnes from entering the reservoir 32 This technology has already been employed at reservoirs in Japan and Switzerland and would essentially allow river water to be diverted around the reservoir instead of flowing into it during periods of high sediment runoff such as after typhoons 33 Sediment prevention projects edit nbsp The destroyed Baling Dam showing severe riverbed erosion typical in the watershed A number of measures have been taken to try and reduce the amount of sediment flowing into Shihmen Reservoir Because of the construction of hundreds of sediment trapping dams or sabo dams the upper reaches of the Dahan and its tributaries are now among the most heavily impounded river systems in Taiwan with at least 123 such dams along the main stem alone 25 The largest 24 sabo dams have collectively prevented some 36 million cubic metres 29 200 acre feet of sediment from reaching Shihmen Reservoir 34 Only one the Junghua Dam is still collecting sediment although its 16 million cubic metre 13 000 acre foot capacity is nearly full 13 These sediment catching dams have also failed on several occasions causing even more debris and silt to wash into Shihmen Among these was the failure of Baling Dam during Typhoon Wipha 2007 which caused 10 million cubic metres 8 000 acre feet of sediment to wash downstream destroying the village of Baling 35 Dredging efforts on Shihmen Reservoir have also been only partly successful Beginning in 1985 seven dredging companies removed more than 10 million cubic metres 8 000 acre feet but the reservoir continued filling with sediment faster than it could be excavated The capacity of the silt disposal areas was exhausted in 1995 25 Other measures taken to decrease sediment flow include the construction of retaining walls and the reforestation of clear cut areas In more recent years the Taiwanese government has revived the idea of constructing more mega dams in the Dahan River to increase water retention capacity and trap silt The Gaotai Reservoir 高台水庫 near the indigenous community of Jianshi would consist of a dam 190 metres 620 ft high with a 171 million cubic metre 139 000 acre foot storage capacity This project could be built in conjunction with the Bilin Reservoir 比麟水庫 which would divert some water from the Dahan drainage to the Da an River increasing the water supply available for Hsinchu County 36 The dam projects have been strongly criticized as an expensive yet only marginally effective solution to the problem and for their effects on local communities 37 Water quality edit The large amount of sediment flowing into the reservoir has also caused unusually high nutrient levels which leads to frequent eutrophication and algae blooms in the summer As a result Shihmen is often considered to be among the worst in water quality among all Taiwan s reservoirs 25 A large water quality monitoring system is in place installed circa 2005 at two points in Shihmen Reservoir Called Vertical Profiling System or YSI 6600EDS the system measures a series of water quality factors by depth at intervals of 5 metres 16 ft The turbidity chlorophyll content pH level and dissolved oxygen levels in the reservoir are sent to the operator of the dam every three hours A future plan for the system is to record algae growth allowing action to be taken to prevent hypoxic events in the water 38 In 2008 the Taiwanese Environmental Protection Agency allocated NT 200 million for eutrophication control projects at Shihmen Feitsui Zengwun and Kinmen Reservoirs 39 nbsp Shihmen Reservoir right and afterbay left seen from the crest of Shihmen Dam See also edit nbsp Taiwan portal nbsp Water portal nbsp Renewable energy portal List of power stations in Taiwan Feitsui Dam List of dams and reservoirs in Taiwan Electricity sector in TaiwanReferences edit a b c d e f g h Reservoirs and Weirs in Taiwan in Chinese Taiwan Water Resources Agency Ministry of Public Affairs p 322 a b Outline of Shihmen Reservoir Shihmen Reservoir and its Catchments Management Project Taiwan Water Resources Agency Retrieved 2012 07 14 a b c d I Economic Development Taiwan Review Ministry of Foreign Affairs Republic of China Taiwan 1963 07 01 Retrieved 2012 07 14 a b Main Facilities Shihmen Reservoir Northern Region Water Resources Office Taiwan Water Resources Agency 2009 Retrieved 2012 07 14 Archived copy PDF Archived from the original PDF on 2016 09 15 Retrieved 2016 08 29 a href Template Cite web html title Template Cite web cite web a CS1 maint archived copy as title link a b Taiwan Today taiwantoday tw Retrieved 2017 02 17 a b c d e f Yuan Lorraine 1964 06 21 Huge Shihmen Dam Completed After Eight Years Of Hard Work Taiwan Today Archived from the original on 2013 12 24 Retrieved 2012 07 14 a b Li Guoding Ranis Gustav Fei John C H 1995 The Evolution of Policy Behind Taiwan s Development Success World Scientific p 137 ISBN 978 981 02 1838 6 a b c d e Ministry of Foreign Affairs Republic of China Taiwan Year of the Big Dam Taiwan Today taiwantoday tw Retrieved 2017 02 17 Penman A D M 18 4 3 Rollcrete dams PDF Ethiopian Civil Service University Libraries Retrieved 2012 07 14 a b c Shimen reservoir library taiwanschoolnet org Retrieved 2012 07 14 a b Sidle Roy C 2002 Environmental Change and Geomorphic Hazards in Forests CABI p 60 ISBN 978 0 85199 598 4 a b Lin Rebecca 2010 07 09 Shihmen Reservoir A Time Bomb Waiting to Explode CommonWealth Magazine No 450 Retrieved 2014 04 22 a b A Cultural Map of Taoyuan Taoyuan County Government Department of Cultural Affairs Retrieved 2009 05 09 Kelly Robert Bender Andrew Brown Joshua Samuel 2007 Taiwan Lonely Planet Irrigation in Shihmen Area Boosts Rice Field Acreage Taiwan Info 1966 09 25 Retrieved 2016 08 28 Peng Jenny 2015 05 25 Lessons From the Drought Following last month s prolonged drought Taiwan should seize the opportunity to reinvent and modernize itself for a sustainable future Thinking Taiwan Retrieved 2016 08 28 Maddison Angus 2013 Economic Progress and Policy in Developing Countries Routledge p 145 ISBN 978 1 13454 511 7 a b c d 設施概況 in Chinese Taiwan 經濟部水利署北區水資源局 Archived from the original on 2015 06 04 Retrieved 2014 06 25 a b Tan Yih Chi Lee Fong Zuo Lai Jihn Sung October 2011 Complex Disaster Damage to Water Resources in Taiwan PDF 21st International Congress on Irrigation and Drainage Tehran Iran R 56 5 Poster 18 Cheng Wen Ming Huang Chien Lin Hsu Nien Sheng Wei Chih Chiang 2017 02 03 Risk Analysis of Reservoir Operations Considering Short Term Flood Control and Long Term Water Supply A Case Study for the Da Han Creek Basin in Taiwan Water 9 424 424 doi 10 3390 w9060424 Pao William C Shimen Dam water shortage shows no sign The China Post Retrieved 2009 05 08 a b Chaves Paulo Chang Fi John June 2008 Intelligent reservoir operation system based on evolving artificial neural networks PDF Advances in Water Resources 31 6 926 936 Bibcode 2008AdWR 31 926C doi 10 1016 j advwatres 2008 03 002 Reservoir Operations Taipei Feitsui Reservoir Administration 2012 05 30 Retrieved 2012 07 14 a b c d e f g Chang Chin ju November 1996 A Tale of Two Reservoirs Greater Taipei s Water Woes Taiwan Panorama Retrieved 2014 04 22 CEPD Approves Plan to Renovate Shihmen Reservoir Taiwan Soil and Water Conservation Bureau 2006 05 16 Retrieved 2012 07 14 Searching for Water Reservoirs continue to play a role but Taiwan is looking for alternative ways to quench its thirst Taiwan Review 2009 02 01 Retrieved 2012 07 14 Taiwan launches water rationing to fight drought World news The Guardian theguardian com Retrieved 2017 02 17 van Harssel Jan Jackson Richard H Hudman Lloyd E 2014 National Geographic Learning s Visual Geography of Travel and Tourism Cengage Learning p 460 ISBN 978 1 13395 126 1 a b Shihmen Tourist Festival Cultural Tourism Taiwan Retrieved 2012 07 14 Chanson Hubert 25 May 2004 Hydraulics of Open Channel Flow Butterworth Heinemann p 147 ISBN 978 0 08 047297 3 Lee Jung ping 2017 09 07 Reservoir upgrade to help stabilize tap water supply Taipei Times Retrieved 2017 10 01 Kondolf G Mathias et al 2014 Sustainable sediment management in reservoirs and regulated rivers Experiences from five continents Earth s Future 2 5 256 280 Bibcode 2014EaFut 2 256K doi 10 1002 2013EF000184 Chen Su Chin Lai Yi Cheng Wang Chin Lun 2008 Typhoons Effects on Long Term Watershed Sediment Management in Shihmen Reservoir in Taiwan PDF Interpraevent 2008 Retrieved 2012 07 14 Tseng W H Shieh C L Lee S P Tsang Y C April 2009 A study on the effect of a broken large sabo dam on the sediment transportation in channel an example of Baling sabo dam EGU General Assembly 2009 11 The Smithsonian NASA Astrophysics Data System Harvard University 3554 Bibcode 2009EGUGA 11 3554T 高台水庫環境調查評估 Environmental Investigation and Assessment of Kaotai Reservoir PDF in Chinese Taiwan 水利署水利規劃試驗所 February 2011 Retrieved 2014 01 09 Hsu Jenny W 2010 03 13 Demonstrators slam government plans to build new dams Taipei Times Dumont Danielle Monitoring Reservoir Water Quality in Taiwan Tames Turbidity after Typhoon WaterWorld Retrieved 2009 05 08 EPA to spend NT 200 million on eutrophication control at reservoirs Taiwan Headlines 2008 01 09 Retrieved 2009 05 10 External links edit nbsp Wikimedia Commons has media related to Shimen Dam Goodbye to Water Shortages Taiwan Water Resources Agency in Chinese The View from Taiwan Rain Silt What are the problems presently faced by the Shihmen Reservoir Current water levels at Taiwan reservoirs Chinese Retrieved from https en wikipedia org w index php title Shihmen Dam amp oldid 1216045071, wikipedia, wiki, book, books, library,

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