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Three Gorges Dam

2007 Schools Wikipedia Selection. Related subjects: Engineering

   Three Gorges Dam, downstream side, 26 July 2004
   Enlarge
   Three Gorges Dam, downstream side, 26 July 2004
   Three Gorges Dam, upstream side, 26 July 2004
   Enlarge
   Three Gorges Dam, upstream side, 26 July 2004

   The Three Gorges Dam ( Simplified Chinese: 长江三峡工开发; Traditional
   Chinese: 長江三峽工開發; pinyin: Chángjiāng Sānxiá Gōng Kāifā) spans the
   Yangtze River at Sandouping, Yichang, Hubei province, China.
   Construction began in 1994. It will be the largest hydroelectric dam in
   the world, more than five times the size of the Hoover Dam. The
   reservoir began filling on June 1, 2003, and will occupy the present
   position of the scenic Three Gorges area, between the cities of
   Yichang, Hubei; and Fuling, Chongqing. Structural work was finished on
   May 20, 2006, nine months ahead of schedule. However, several
   generators still have to be installed and the dam is not expected to
   become fully operational until 2009.

   As with many dams, there is controversy over the costs and benefits of
   the Three Gorges Dam. Although there are economic benefits from flood
   control and hydroelectric power, there are also concerns about the
   future of over 1.9 million people who will be displaced by the rising
   waters, the loss of many valuable archaeological and cultural sites, as
   well as the effects on the environment.

Dam model

   Photos of the models that were built to represent what the dam would
   look like upon completion in 2009.

   Main spillway flanked by powerhouses, ship lift at right

   Ship lift at left, double locking steps at right

   View along main dam at right. Auxiliary dam in foreground with upstream
   ship navigation weir in background

History

   1919 - originally proposed by Sun Yat-sen, the father of the modern
   China republic (see Economy 2004)
     * 1993-1997: The Yangtze River was diverted, and after four years was
       reverted in November 1997.
     * 1998-2003: The first group of generators began to generate power in
       2003, and a permanent ship lock opened for navigation the same
       year.
     * 2004-2006: The last section of dam wall was completed in May of
       2006. On 6 June 2006, the temporary construction barrier behind the
       dam was demolished . As reservoirs begin to fill, floodwaters will
       begin to displace communities. The entire project is to be
       completed by 2009, when all 26 generators (with a combined
       generating capacity of 18.2 GW) will be able to generate 84.7 TWh
       (315 PJ) of electricity annually, about one-ninth of the nation's
       electricity consumption .

Proposal and development of project

   Location of the dam and major cities on the Yangtze River
   Enlarge
   Location of the dam and major cities on the Yangtze River

   Sun Yat-sen first proposed building a dam on the Yangtze River in 1919
   for power generation purposes and the National Defense Planning
   Commission under the Kuomintang made the first survey of the proposed
   site in 1932, but the idea was shelved due to unfavorable political and
   economic conditions. Major floods resurrected the idea and the PRC
   government adopted it in 1954 for flood control.

   Vice Minister of Electric Power Li Rui initially argued that the dam
   should be multipurpose, that smaller dams should be built first until
   China could afford such a costly project, and that construction should
   proceed in stages to allow time to solve technical problems.

   Later, Li Rui concluded that the dam should not be built at all since
   it would be too costly, flood many cities and fertile farmland, subject
   the middle and lower reaches of the river to catastrophic flooding
   during construction, and would not contribute much to shipping. Sichuan
   province officials also objected to the construction since Sichuan,
   located upstream, would shoulder most of the costs while downstream
   Hubei province would receive most of the benefits.

   Lin Yishan, head of the Yangtze Valley Planning Office, who was in
   charge of the project, favored the dam construction, however. His
   optimism about resolving technical problems was further encouraged in
   1958 by the favorable political climate and the support from the late
   chairman Mao Zedong, who wanted China to have the largest hydroelectric
   dam in the world. Criticisms were suppressed. But depression resulted
   from the disastrous Great Leap Forward and ended the preparation work
   in 1960.

   The idea resurfaced in 1963 as part of the new policies to build a "
   third front" of industry in southwest China. But the Cultural
   Revolution erupted in 1966, and in 1969 the fear that the dam would be
   sabotaged by the Soviet Union, now an enemy, resulted in a construction
   delay. In 1970, work was resumed on Gezhouba, a smaller dam downstream,
   but it soon ran into severe technical problems and cost overruns that
   seemed likely to plague the Three Gorges Dam on an even larger scale.

   The economic reforms introduced in 1978 underlined the need for more
   electric power to supply a growing industrial base, so the State
   Council approved the construction in 1979. A feasibility study was
   conducted in 1982 to 1983 to appease the increasing number of critics,
   who complained that the project did not adequately address technical,
   social, or environmental issues. Further feasibility studies were then
   conducted from 1985 to 1988 by Canadian International Project Managers
   Yangtze Joint Venture, a consortium of five Canadian engineering firms.

   Leaders from Chongqing also demanded suddenly that the dam height be
   raised so substantially that it would cripple the project and free them
   from bearing the brunt of the costs. The new height and the demand for
   a more reliable study with the use of international standards resulted
   in a new feasibility study in 1986.

   Ecologist Hou Xueyu was among the few who refused to sign the
   environmental report, claiming that it falsely overstated the
   environmental benefits provided by the dam, failed to convey the real
   extent of environmental impact, and lacked adequate solutions to
   environmental concerns.

   Environmentalists internationally began to protest more vociferously.
   Human rights advocates criticized the resettlement plan. Archaeologists
   balked at the submergence of a huge number of historical sites. Many
   mourned the loss of some of the world's finest scenery.

   Increasing numbers of engineers doubted whether the dam would actually
   achieve its stated purposes. Chinese journalist/engineer Dai Qing
   published a book relentlessly criticizing the project by the Chinese
   scientists, yet many foreign construction companies continued to press
   their governments to financially support the construction in hopes of
   winning contracts.

Approval of project

   Three Gorges Dam from space
   Enlarge
   Three Gorges Dam from space

   In the face of much domestic and international pressure, the State
   Council agreed in March 1989 to suspend the construction plans for five
   years. After the Tiananmen Square protests of 1989, however, the
   government forbade public debate of the dam, accused foreign critics of
   ignorance or intent to undermine the regime, and imprisoned Dai Qing
   and other famous critics.

   Premier Li Peng crusaded for the dam and pushed it through the National
   People's Congress in April 1992 despite the opposition or abstention
   from one-third of the delegates. Such actions were unprecedented from a
   body that usually rubberstamped all government proposals.

   Resettlement soon began, and physical preparations started in 1994.
   While the government solicited technology, services, hardware and
   financing from abroad, leaders reserved the engineering and
   construction contracts for Chinese firms.

   Corruption scandals have plagued the project. It was believed that
   contractors had won bids through bribery and then skimped on equipment
   and materials to siphon off construction funds. The head of the Three
   Gorges Economic Development Corp. allegedly sold jobs in his company,
   took out project-related loans and disappeared with the money in May
   2000. Officials from the Three Gorges Resettlement Bureau were caught
   embezzling funds from resettlement programs in January 2000.

   Much of the project's infrastructure was so shoddy that Premier Zhu
   Rongji ordered some of it to be demolished in 1999 after a number of
   high-profile accidents including a collapse of a bridge. Zhu Rongji,
   who had been a harsh critic of the project, announced that the
   officials had a "mountain of responsibility on their heads". Around the
   time, a significant crack had also developed in the dam. To offset
   construction costs, project officials had quietly changed the operating
   plan approved by the NPC to fill the reservoir after six years rather
   than 10. In response, 53 engineers and academics petitioned President
   Jiang Zemin twice in the first half of 2000 to delay full filling of
   the reservoir and relocating the local population until scientists
   could determine whether a higher reservoir was viable given the
   sedimentation problems.

Debate over the dam

Cost

   Officials report that the plan is within its US$25 billion budget and
   insisted early on that the project would pay for itself through
   electricity generation. However , the project is thought to have cost
   more than any other single construction project in the history of
   China, with unofficial estimates of US$100 billion or more.

   It has been said that under the order of the biggest proponent of the
   dam, then premier Li Peng, the cost was based on 1980's prices, with
   almost no inflation included in the estimate. Opposition to the dam and
   to the fraudulent numbers being used to promote it was willfully
   ignored in the report in order to ensure its passage. One of the main
   opponents of the dam, famous Chinese activist, Li Rui, repeatedly
   voiced his concerns about rigged numbers and estimates, but the pleas
   of Li and others fell on deaf ears. As a retired senior communist
   official and Mao Zedong's former secretary, Li Rui managed to evade
   governmental prosecution. Dai Qing was not that lucky.

   However, one report from Xinhua news rebuffed those claims . The
   project would cost no more than 180 billion yuan (22.5 billion U.S.
   dollars), 20 billion yuan less than the initial budget of 203.9 billion
   yuan (25.2 billion U.S. dollars) thanks to the low inflation rate in
   recent years.

Increasing wealth disparity

   Critics see the dam as serving primarily the interests of east coast
   industrialists, since this group has the most need for hydro-electric
   power. Unfortunately, this is at the expense of millions of people
   displaced from prime arable land. Making matters worse, relocation
   compensation has been inadequate (with corrupt officials stealing from
   the fund), the number of people displaced has been grossly
   underestimated, and their new land is of poor quality. As a result, a
   significant portion of the displaced population has to resort to
   begging and garbage collecting, or even prostitution. The exact number
   of rural people whose lives have been diminished or severely disrupted
   is uncertain because of state censorship by the Chinese government, but
   domestic Chinese researchers generally agree that the impact has been
   much more severe than Chinese state organs will admit. Domestic Chinese
   human-rights groups have been able to bring some members of the
   displaced to at least one of the international conferences held in
   China on dams/reservoirs to testify about their plight, to no response
   from the Chinese government.

   The suffering of those entitled even to the best available housing,
   land, and other benefits given the displaced, is undeniable, even by
   the Chinese government. Displaced peasants face hostility from people
   in regions in which newcomers are resettled. The locals often resent
   newcomers for the benefits they have received, or suspect that those
   benefits will be at the expense of their own meagre livelihoods.

Environment

Electricity production

   The amount of power generated by the dam in 2009 was originally meant
   to supply about 10% of China's electricity needs, but with China's
   rapidly growing economy it is only projected to produce approximately
   3% at the end of 2006. In fact, the dam is predicted to produce 18,200
   MW of electrical power. According to a recent Discovery Channel special
   on the Three Gorges Dam, it will supply enough electricity to power a
   city four times larger than Los Angeles. That is a lot of energy, but,
   considering China's population and already immense cities, it will
   simply be a drop in the bucket--not considering the fact that energy
   demand will increase with all of the new, modern relocation cities and
   development from the new shipping capabilities and industry. Over 80%
   of the country's power is currently produced by coal.

Pollution

   Cities such as Shanghai need ever-increasing electricity. With 26 hydro
   turbines generating up to 18 gigawatts of electricity—the equivalent of
   roughly eighteen coal power stations or 11,000 barrels of oil per
   hour—the Dam will help reduce this power shortage. Filling this demand
   for energy with hydroelectric power will also be welcomed by
   environmentalists as China has been criticized for relying too heavily
   on fossil fuel in recent decades. While in the short term the dam will
   cause extra pollution, the dam could potentially reduce China's annual
   coal consumption by 40 to 50 million tons, thus reducing the discharge
   of two million tons of sulfur dioxide and 10,000 tons of carbon
   monoxide a year.

Greenhouse gas

   Although hydro-electric power is a renewable energy source, the
   creation of large reservoirs can generate considerable quantities of
   greenhouse gases, including substantial amounts of methane, due to
   micro-biotic activity. Compared to the greenhouse gas emissions of
   conventional natural gas power plants, emissions from northern
   reservoirs are typically about 5% of conventional power plants, while
   emissions from tropical reservoirs are typically 25%.

   Critics also argued that due to the short lifespan of the reservoir (a
   topic will be discussed further in the Flood section), the eventual
   output of the greenhouse gas will be much greater in comparison to the
   current level, because when the lifespan of the reservoir expires, the
   vegetation will need decades to recover.

Ecosystem

   Huge reservoirs by their nature alter the ecosystem and threaten some
   habitats whilst helping others. The Chinese River Dolphin and the
   Chinese paddlefish, for example, are on the edge of extinction and will
   lose habitat and suffer divided populations due to the dam. Of the
   3,000 to 4,000 remaining critically endangered Siberian Crane,
   approximately 95% currently winter in wetlands that will be destroyed
   by the Three Gorges Dam.

   While logging in the area was required for construction which adds to
   erosion, stopping the periodic uncontrolled river flooding will lessen
   erosion in the long run. The build up of silt in the reservoir will,
   however, reduce the amount of silt transported by the Yangtze River to
   the Yangtze Delta and could reduce the effectiveness of the dam for
   electricity generation and, perhaps more importantly, the lack of silt
   deposited in the river delta could result in erosion and sinking of
   coastal areas.

Local culture and aesthetic values

   The 600 km (370 mile) long reservoir will inundate some 1,300
   archaeological sites and alter the legendary beauty of the Three
   Gorges. Cultural and historical relics are being moved to higher ground
   as they are discovered but the flooding of the Gorge will undoubtedly
   cover some undiscovered relics. Many other sites cannot be moved
   because of their size or design.

   These historical sites contain remnants of the homeland of the Ba, an
   ancient people who settled in the region more than 4,000 years ago. One
   of the traditions of the Ba was to bury the dead in coffins in caves
   high on the cliff, many of which will soon be submerged. This has
   raised some strong protests from the people.

   In Chinese government's own admission, the funds provided to salvage
   the artefacts are not enough. Chinese scholars further pointed out that
   the funds provided by the government is barely 10% of what needs to be
   (and the actual funds needed is only a rough estimate), and the
   so-called experts who provided funding advise to the government were
   only accountants, engineers and architects, instead of archaeologists,
   historians, and sociologists. However, the latter were wilfully
   excluded from the advisory bodies under the order of premier Li Peng,
   and some were even forced in to exile abroad, such as the famous
   economist Qian Jiaju, who was only able to return to China under the
   direct intervention of Jiang Zemin, with the condition of silencing his
   criticism. Another strong opponent of the project, the famous rocket
   scientist Qian Weichang was able to achieve better fate by avoiding
   been exiled, and after repeated pressure from the Chinese government,
   he devoted his life in the actual work of saving the artefacts. Again,
   such criticism was allowed in China only recently, well after the
   official retirement of Li Peng, but just like the criticism on the
   budgetary tricks, it is already too late since most artefacts are
   already submerged under water, making salvaging a much more difficult
   task.

Navigation

   Ship locks for river traffic to bypass the Three Gorges Dam, May 2004
   Enlarge
   Ship locks for river traffic to bypass the Three Gorges Dam, May 2004

   The installation of ship locks is intended to increase river shipping
   from 10 million to 50 million tonnes annually, with transportation
   costs cut by 30 to 37%. Shipping will become safer, since the gorges
   are notoriously dangerous to navigate. Each ship lock is made up of 5
   stages taking around 4 hours in total to complete. Critics argue,
   however, that heavy siltation will clog ports such as Chongqing within
   a few years based on the evidence from other dam projects.

   The canal locks are designed to be 280 m long, 35 m wide, and 5 m deep
   (918 x 114 x 16.4 ft). That is 30 m longer than those on the St
   Lawrence Seaway, but half as deep. The canal locks are designed to
   handle 10,000 ton barges.

   The project also includes a ship lift, a kind of elevator, which will
   be capable of lifting ships of up to 3,000 tons. In the original plan
   the ship lift would carry 10,000 ton vessels.

   However, since its completion, the canal lock proved to be far less
   capable than the Chinese government had advertised: the official record
   indicates that due to various factors such as the dimensions of the
   ships/barges/boats, the maximum capacity actually reached is only 37%
   of what was originally claimed. Furthermore, there were numerous
   incidents of congestion, with the longest one lasting more than 5 days.
   Critics point out that 10,000 ton barges can already reach Chongqing
   without the lock, and in fact, without the dam.

Flood control and drought

   The reservoir's flood storage capacity is 22 cubic kilometres, or 18
   million acre-feet. This capacity will lessen the frequency of big
   downstream floods from once every 10 years to once every 100 years. But
   critics believe that the Yangtze will add 530 million tons of silt into
   the reservoir on average per year and it will soon be useless in
   preventing floods. Additionally, the system designed to flush out the
   silt relies on an unproven sequence of sluice gates. Increased
   sedimentation resulting from the dam could increase the already high
   flood level at Chongqing.

   There is also a contradiction between the roles of the dam as flood
   control and hydroelectricity production. Flood control requires dam
   levels to be kept low, allowing for increased flow throughout flood
   times, whereas hydroelectricity requires higher levels to allow for
   continual escape of water to produce the electricity. Probe
   International asserts that the dam does not address the real source of
   flooding, which is the loss of forest cover in the Yangtze watershed
   and the loss of 13,000 km² of lakes (which had greatly helped to
   alleviate floods) due to siltation, reclamation and uncontrolled
   development.

Potential hazards

   Concerns exist about the quality of construction materials used,
   highlighted by a major crack appearing in the dam in 2000, and have led
   some critics to fear a potential catastrophe similar to the Banqiao Dam
   failure of 1975.

   In an annual report to the United States Congress, the Department of
   Defense cited that in Taiwan, "proponents of strikes against the
   mainland apparently hope that merely presenting credible threats to
   China's urban population or high-value targets, such as the Three
   Gorges Dam, will deter Chinese military coercion." The notion that the
   ROC military would seek to destroy the Dam provoked an angry response
   from the mainland state media. PLA General Liu Yuan was quoted in the
   China Youth Daily saying that the PRC would be "seriously on guard
   against threats from Taiwanese independence terrorists". Despite a
   claim by Taiwan Deputy Defence Minister Tsai Ming Hsian to the
   contrary, most analysts believe Taiwan neither has the will nor seeks
   the technology to bomb the Three Gorges Dam, fearing that Beijing will
   respond with overwhelming force. A group of 53 Chinese engineers
   campaigned for the government to rethink plans for the dam. If the
   reservoir level is filled to 156 m, then 520,000 fewer people will have
   to be displaced, easing demands on the government. The original plan
   for the Three Gorges Dam, approved by the National People's Congress in
   1992, aimed to keep water levels behind the Three Gorges dam at 156 m
   for the first ten years. In 1997, dam officials changed the plans, to
   maximize the dam's power output.

   In September 2004 the China Times reported that heavily-armed guards
   had been deployed to the area to fend off a possible terrorist attack,
   but did not say who might want to target the dam.

   There are two hazards uniquely identified with the dam: sedimentation
   modelling is unverified and the dam sits on a seismic fault. Excessive
   sedimentation can block the sluice gates which can cause dam failure
   under some conditions. This was a contributing cause of the Banqiao Dam
   failure in 1975 that precipitated the failure of 61 other dams and
   resulted in over 200,000 deaths. Also, the weight of the dam and
   reservoir can theoretically cause induced seismicity, as happened with
   the Katse Dam in Lesotho.

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