The estimated hydropower potential of the lower Mekong Basin (i.e. excluding China) is 30,000 MW,[1] while that of the upper Mekong Basin is 28,930 MW.[2] In the lower Mekong, more than 3,235 MW has been met through facilities built largely over the past ten years, while an additional 3,209 MW are currently under construction. An additional 134 projects are planned for the lower Mekong, which will effectively exhaust the river’s hydropower generating capacity.[3] The single most significant impact – both now and in the future – on the use of water and its management in the Mekong Region is hydropower.[4]
With development proceeding in the region’s countries, power demands are expected to rise 7% per year over the next 20 years,[1] yielding a substantial – and potentially lucrative - energy market. Hydropower is a clear and favoured energy option for the Mekong’s riparian countries, as reflected in the narratives utilised to support these interventions. Laos is being portrayed as the ‘battery of Southeast Asia’.[5] In China, hydropower is heralded as the best possible (‘clean green’) alternative to their coal-fired power stations, and will open the way to the development of the west.[2] In Thailand, they emphasise the ‘greening of Isan’, the drought-prone northeast, to legitimise the development of a spectacular ‘water grid’ that will channel water from Laos, under the Mekong mainstream,[6] and over-emphasising projected energy demands in the country.[7] In Cambodia, hydropower is central to solving the country’s energy supply problems.
Enhanced navigation of the Mekong is another important positive economic impact. Dams with locks, make a river navigable year round to efficent river barges, which is the greenest of inland transportation systems, eliminating thousands of trucks, carbon emisions, and the need for ever more highways. Navigational improvements will provide South East Asia with such a green system, and provide everyone there with the vital outlet to the sea at Vietnam.
The development of the Mekong River Basin is highly controversial, and is one of the most prominent components in the discussion about the river and its management. This debate occurs in both the academic literature, as well as the media, and is a focus for many activist groups.
Dams already constructed are presented below in Table 1:
Table 1: Commissioned dams in the Mekong River Basin (more than 10 MW)[8]
Project | Country | River | Approx Location | Commissioned | Installed capacity (MW) | Height (m) | Crest length (m) | Active storage (million m3) | Max reservoir area (km2) |
---|---|---|---|---|---|---|---|---|---|
Dachaoshan | CHN | Mekong | 2003 | 1,350 | 118 | 481 | 367 | 826 | |
Gongguoqiao | CHN | Mekong | 2008 | 750 | 130 | 120 | 343 | ||
Jinghong | CHN | Mekong | 2010 | 1,750 | 118 | 249 | 510 | ||
Manwan | CHN | Mekong | 1992 | 1,550 | 136 | 418 | 257 | 415 | |
Houayho | LAO | Houayho/Xekong | 1999 | 150 | 76.5 | 620 | |||
Nam Leuk | LAO | Nam Leuk/Nam Ngum | 2000 | 60 | 45 | 800 | 185 | ||
Nam Lik 2 | LAO | Nam Lik | 100 | 103 | 328 | 8.26 | 24.4 | ||
Nam Ngum 1 | LAO | Nam Ngum | 1971 | 148.7 | 75 | 468 | 7,000 | 370 | |
Nam Theun 2 | LAO | Nam Theun/Xe Bangfai | 2010 | 1,075 | 48 | 325 | 3,680 | 450 | |
Theun-Hinboun | LAO | Nam Theun/Nam Hinboun | 1998 | 210 | 20 | ||||
Xeset 1 | LAO | Xeset | Saravan Province, Lao PDR | 1994 | 45 | 0.5 | |||
Xeset 2 | LAO | Xeset | Saravan Province, Lao PDR | 2009 | 76 | 20 | |||
Buon Kuop | VN | Sre Pok | 2009 | 280 | 37 | ||||
Buon Tua Sra | VN | Se San/Kroong Po Ko | 2009 | 86 | |||||
Dray Hinh 1 | VN | Sre Pok | Dak Lak Province, Viet Nam | 1990 | 12 | ||||
Dray Hinh 2 | VN | Sre Pok | 2007 | 16 | |||||
Plei Krong | VN | Se San/Kroong Po Ko | 2008 | 100 | 65 | 745 | 162 | 80 | |
Sesan 3 | VN | Sesan | 2006 | 79 | 164 | 6.4 | |||
Sesan 3A | VN | Sesan | 2007 | 96 | |||||
Sesan 4 | VN | Sesan | 2009 | 360 | 60 | 54 | |||
Sre Pok 3 | VN | Sre Pok | 2009 | 220 | 52.5 | ||||
Yali Falls | VN | Sesan | 2001 | 720 | 65 | 1,460 | 1,037 | 64.5 | |
Chulabhorn | THL | Nam Phrom | 1972 | 40 | 70 | 700 | 188 | 31 | |
Pak Mun | THL | Mun | 1994 | 136 | 17 | 300 | |||
Sirindhorn | THL | Lam Dom Noi | 1971 | 36 | 42 | 940 | 1967 | 288 | |
Ubol Ratana | THL | Nam Pong | 1966 | 25.2 | 35.1 | 885 | 2,263 | 410 | |
Hua Na | THL | Huay Kaosan | 1994 | 17 | 207 | ||||
Lam Phra Phloeng | THL | Lam Phra Phloeng | 1967 | 11 | 145 | ||||
Lam Ta Khong | THL | Lam Ta Khong | 2002 | 500 | 40.3 | 251 | 291 | 1,430 |
The Xiaowan Dam (simplified Chinese: 小湾坝; traditional Chinese: 小灣壩; pinyin: Xiǎowān Bà) is a large hydroelectric arch dam on the Lancang (Mekong) River in Yunnan Province, southwest China, which is currently under construction. Construction commenced in January 2002 and the river dammed in October, 2004. Construction is expected to be complete in 2013. The dam site is at located . When complete, it will be the world's highest arch dam and the second largest hydroelectric power station in China after the Three Gorges Dam.[9][10] The dam will be 292 m (958 ft) high, a head of 248 m (814 ft), and a crest length of 920 m (3,018 ft). It will have an installed capacity of 3,600 MW, spread over six turbines. All turbines are currently operational.[11] Mean annual energy production is 18,207 GWh. The dam reservoir has a maximum capacity of 14.56 km3 (5.14×1011 cu ft), and active storage 9.9 km3 (3.5×1011 cu ft). The reservoir will cover an area of more than 190 km2 (73 sq mi).[12] The cost of the Xiaowan hydropower station is estimated at ¥32 billion (nearly US$3.9 billion).[10] The project is being constructed, and will be operated, by Huaneng Power International.[13]
Nuozhadu Dam (simplified Chinese: 糯扎渡大坝; traditional Chinese: 糯扎渡大壩; pinyin: Nuòzhādù Dàbà) is a central core rock fill dam, presently under construction at . It is sometime also known as the "Ruzhadu". The dam will be 261.5 m (858 ft) tall, the tallest dam of this type in China, and the third tallest in the world.[14] It will create a reservoir with a normal capacity of 21,749,000,000 m3 (17,632,000 acre·ft) at a level of 812 m (2,664 ft) asl. It will be the largest hydropower dam in the Mekong River Basin.[15] The purpose of the dam is hydroelectric power production along with flood control and navigation. The dam will support a power station with nine generators, each with generating capacity of 650 MW. The total generating capacity of the project is 5,850 MW.[16] The construction and management of the project is being implemented by Huaneng Power International Ltd., which has a concession to build, own and operate hydroelectric dams on China's stretch of the Mekong River.
The Lower Se San 2 Dam is a proposed hydroelectric dam on the Se San River in the Stung Treng Province of Northeastern Cambodia. The dam site is at . The dam is planned to be a run-of-the-river facility. It will be 75 m (246 ft) high, and will create a reservoir that will cover 355 km2 (137 sq mi). It will have an installed capacity of 400MW with an average output of 1,998 GWh per year.[17] Electricity will be routed to Vietnam, and then half of its generated output sold back to Cambodia.[18] Construction is expected to commence in 2011, and completed in 2016. The dam will be located 25 km (16 mi) west of the confluence between the Sesan River and the Mekong. The dam will be developed by a joint venture between Electricity of Vietnam (51%) and a Cambodian firm, the Royal Group (49%).[19]
A memorandum of understanding between Cambodia's Ministry of Industry, Mines and Energy (MIME) and Electricity of Vietnam was signed in 2007 outlining and authorising an initial feasibility study, and an environmental impact assessment. In January 2011, the Vietnamese Ministry of Planning and Investment licensed Electricity of Vietnam to make a US$800 million investment into the project.
The project's environmental impact assessment has drawn criticism from some groups.[20] The dam's reservoir is expected to inundate numerous villages upstream from the dam. Up to 2,000 people will be displaced, with claims that at least 38,675 people, including a large number of indigenous peoples, resident in at least 86 villages located along the Sesan and Srepok Rivers and in the reservoir area would lose access to a considerable proportion fisheries resources as a consequence of the dam impeding fish migration routes[21]
Prek Liang 1 Dam is a dam planned for the Prek Liang River, a tributary of the Mekong, in the Ratanakiri Province of Cambodia. The proposed dam site is at . It is understood to be a seasonal storage dam, and is intended to be 90 m (300 ft) high and 300 m (980 ft) long. It will have an installed capacity of 64MW and will generate 300GWh annually. Its reservoir will have a live storage capacity of 110,000,000 m3 (3.9×109 cu ft). The dam will be both developed and operated by a Korean company, KTC Cable.[22]
The dam is based inside the Virachey National Park. The park is one of only two Cambodian ASEAN Heritage Parks [11] and is one of the top priority areas for conservation in Southeast Asia. The dam is under pre-feasibility study.
The Sambor Dam would be the lowest dam of the Mekong's mainstream dams, and largest in Cambodia. It is planned to be a concrete gravity dam and an earth rockfill dam.[23] If commissioned, the dam will extend across the Mekong mainstream as well as the mouth of the inflowing Sre Pok, Sesan and Se Kong Rivers.[24] The dam site is located near the village of Sambor, upstream of Kratie at , and would inundate the river channel to just south of Stung Treng town. It is being developed by the China Southern Power Grid Company at an estimated cost of US$4,947 million. Associated transmission lines would cost a further US$312.9 million.[23] 70% of the power it generates is destined for Vietnam, while the balance is intended for domestic Cambodian markets.[23] It would have an installed capacity of 2,600MW, and a dam over 18 km (11 mi) and 56 m (184 ft) high, with a rated head of 33 m (108 ft).[25] If built, its reservoir would be 620 km2 (240 sq mi) with an active storage of 463 km3 (375,000,000 acre·ft).[25] Construction and inundation will displace an estimated 19,034 people.[23] The dam's earliest potential commissioning date is 2020.
Like other mainstream (and tributary) dams planned for the Mekong, the Sambor Dam has given rise to numerous social and environmental concerns. It is expected that the dam, together with the Stung Treng Dam (see below) will have significant negative impacts on the Mekong's fisheries,[26] its hydrology and regional and national economies[25]
Stung Battambang 1 Dam (also known as 'Battambang 1') is planned to be an earth core rockfill dam that will impound the Battambang River in Cambodia. The river is a major tributary of the Tonle Sap. The dam will be located east of Pailin District, in the Battambang Province of Cambodia. Of the two dams planned for this river, the larger is the Stung Battambang 1. It is planned to be 38 m (125 ft) high, to have an installed capacity of 24MW, and an annual electricity output of 120GW. A letter of commitment has been issued by the Cambodian authorities for a pre-feasibility study of the dam by an unknown Korean company[27]
Surrounding the dam site is the Bannan Irrigation project, covering some 20,000 ha (77 sq mi), and the dam is understood to play a role in the irrigation of this area, as well as generating hydropower.[28] There is little data available about reservoir size or number of people who will be displaced. The dam is one of three possible dams in the Stung Battambang basin; the other two would block two of the Battambang River's tributaries: the Mongkol Borey River and the Sangker River.
The Stung Treng Dam is a proposed earth core rockfill gravity dam hydroelectric project over the Mekong River in Stung Treng Province, Cambodia. If completed, the dam's crest will be 10,844 m (35,577 ft) long, and 22 m (72 ft) high. Its rated head is 15.2 m (50 ft). If commissioned, it will have an installed capacity of 980MW, and will, on average, generate 4,870GWh a year. The dam's reservoir, which will extend well beyond the mainstream canal, will have an active storage of 70,000,000 m3 (2.5×109 cu ft), and will inundate an area of 211 km2 (81 sq mi), and 50 km (31 mi) long[23] The proposed dam site is located at . An MoU for its development had been signed with a Russian company, but when this lapsed, the Song Da company from Viet Nam agreed to carry out feasibility studies.[25] At this stage it is not known where the power is destined for.[25] Multiple independent agencies, including International Rivers,[29] the Save the Mekong campaign (www.savethemekong.org) and others have all raised concerns about the dam’s construction. The dam site lies within the Stung Treng Ramsar Site (Ramsar site No. 999),[30] which effectively obliges the Royal Cambodian Government to ‘actively support' the three 'pillars' of the Ramsar Convention: 1) ensuring the conservation and wise use of wetlands it has designated as Wetlands of International Importance, 2) including as far as possible the wise use of all wetlands in national environmental planning, and 3) consulting with other Parties about implementation of the Convention, especially in regard to transboundary wetlands, shared water systems, and shared species.[25] If it and the Sambor Dam (see above) are constructed, it is expected that fish migration routes (which support the Tonle Sap fisheries, the world's largest inland fishery) will be more or less wholly impeded.[25] The two proposed dams of the Sambor and the Stung Treng would have the Mekong river basin's highest sediment trapping efficiencies of all the Lower Mekong Basin's proposed mainstream projects, destabilising downstream channels and between Kratie and Phnom Penh and cutting overbank siltation in the Cambodian floodplain.[25]
If built, an estimated 21 villages with 2,059 households and 10,617 people will be displaced with the construction of the dam.[23] "Stung Treng and Sambor would create a situation of extreme crisis for the populations of affected provinces, and could provoke an emergency food security situation for the poor".[25]
The "Tuoba Hydropower Plant" is a planned concrete gravity dam, which will planned to be the fifth of China's 'cascade dams' on the Mekong (or Lancang) River. It will be located in Zhonglu Township, Weixi County, Diqing Prefecture, in China's Yunnan Province at . At the damsite, it will draw on a catchment are of 88,700 km2 (34,200 sq mi), and a mean annual discharge of 810m3/s. It will be 138 m (453 ft) high, with a total installed capacity of 900MW, a firm output of 375MW, and an annual output of 4630GWh.[31]
Table 2: Proposed Dams on the Mekong Mainstream[23]
Project | Country | Approx Location | Commissioning | Installed capacity (MW) | Height (m) | Crest length (m) | Active storage (million m3) | Max reservoir area (km2) |
---|---|---|---|---|---|---|---|---|
Nuozhadu | CHN | 2016 | 5,850 | 261.5 | 608 | 21.749 | 320 | |
Pak Beng | Lao PDR | 2016 | 1,230 | 76 | 943 | 442 | 87 | |
Luang Prabang | Lao PDR | 2016 | 1,410 | 68 | 1,106 | 734 | 90 | |
Xayaburi | Lao PDR | 2016 | 1,260 | 32 | 810 | 225 | 32 | |
Pak Lay (Option 1) | Lao PDR | 2016 | 1,320 | 35 | 630 | 384 | 108 | |
Pak Lay (Option 2) | Lao PDR | 2016 | 1,320 | 35 | 630 | 384 | 108 | |
Sanakham | Lao PDR | 2016 | 700 | 38 | 1,144 | 106 | 81 | |
Pakchom | Lao PDR/Thailand | 2017 | 1,079 | 1,200 | 55 | 12 | 74 | |
Ban Koum | Lao PDR/Thailand | 2017 | 1,872 | 53 | 780 | 0 | 133 | |
Lat Sua | Lao PDR | 2018 | 686 | 27 | 1,300 | 0 | 13 | |
Don Sahong | Lao PDR | 2016 | 240 | 10.6 | 1,820 | 115 | 2.9 | |
Stung Treng | Cambodia | 980 | 22 | 10,884 | 70 | 211 | ||
Sambor | Cambodia | 2020 | 2,600 | 56 | 18,002 | 465 | 620 |