Three Gorges Dam
2007 Schools Wikipedia Selection. Related subjects: Engineering
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
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
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
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.