These changes are likely the result of releases to create storage space in the reservoir in anticipation of the upcoming flood season.
This modified flow regime is significantly less effective in stimulating spawning behavior of the carps. Thus, since the completion of the Three Gorges Dam, the change of the flow pattern and the decline of the average flooding period are the key factors affecting the natural spawning of the four carp species Yangtze River Fisheries Research Institute, It is possible that these pressures have acted synergistically to impact fish populations.
The number of egg and larvae in surveys had already dropped from 7 to 8 billion in the to 1—2 billion by the s and s Survey Team of Spawning Grounds of Domestic Fishes in Chanjiang River, ; Yi et al. The number of egg and larval fell from 1.
The social and environmental impacts of the Three Gorges Dam received considerable attention—both within China and globally—since the dam's planning stages in the s. Subsequently, the dramatic decline of the four carp species, described above, received widespread media attention within China, prompting the public and conservation organizations to apply pressure to regulators and CTG to find solutions to address the issue.
Evolving regulatory requirements for environmental protection provided the strongest driver for dam operators to seeks solutions to mitigate impacts on the carp. Following decades of rapid economic growth, the Chinese government has begun to strengthen environmental protections to address the negative impacts of that growth. In , China's State Environmental Protection Administration the precursor to the Ministry of Environmental Protection required that hydropower projects release environmental flows to support a range of other downstream resources and values, including social and environmental benefits.
This has included releases to support fisheries and to maintain water quality. Scientists understanding of the carps' spawning requirements suggested that an environmental flow should mimic the Yangtze's natural flood pulse to promote spawning.
However, the Three Gorges Dam is a multi-purpose project that has major functions of flood control, electricity production, navigation, and drought alleviation. The implementation of environmental flows needed to be integrated into the operational requirements that encompass these multiple purposes and thus required engagement with diverse stakeholders.
This consultation process addressed barriers to reoperation, complemented by a research program. For example, the MOA which is responsible for fishery resources management in China and CTG funded a research program, including field surveys, analyses of hydrologic and fish biology data, and modeling of operations. The research focused on the relationship between flows and spawning, including identifying hydrologic indicators and thresholds, and how changes to flows would affect other major purposes, such as flood control.
This research program is ongoing to monitor the effects of environmental flow operation and analyze further potential improvements to operations. The information gained from the research program was then integrated into the decision processes for the operation of the Three Gorges Dam. The operational plan is drafted based on a structured decision-making SDM process involving relevant agencies Gregory et al. A number of government agencies are consulted during this process, including CWRC and YFRC, and those concerned with environmental protection, land and resources, the electricity grid, and navigation.
The operational guidelines for the dam clearly stipulate that flood control takes priority over water resources operation water released for downstream economic production, human needs, and environmental needs , which has priority over electricity production and navigation. For example, in order to cope with salt water intrusion in the Yangtze River estuary in , the reservoir released more water 1. The evolving regulatory requirements for dam operators to maintain river health along with a period of stakeholder consultation and research resulted in changes to the operations of the Three Gorges Dam in Operational changes included both those aimed at water management to benefit social and economic values downstream flow releases to mitigate droughts and saltwater intrusion and flows to promote carp spawning.
Dam operation was first modified in , for two purposes: drought mitigation during the early part of the year; followed by a flow release in May to mimic the Yangtze's natural flood pulse and promote carp spawning. Flow releases to promote carp spawning have been made in the early flood period late May to June , and have lasted for 3—10 days, continuously increasingly the flow during the spawning period of the carps.
These environmental flow releases have now been implemented for seven consecutive years. Examples of environmental flow releases from Three Gorges Dam in and were shown in Figure 3. Figure 3. A monitoring program samples carp eggs and larval fish in the water column below the dam before, during and after the period of environmental flow release. Monitoring results available to date indicate that carp reproduction has increased with these new flow releases.
The average number of carp eggs and larvae sampled at Jianli station was million per year between and before implementation of environmental flows and million between and , during the period that environmental flows have been implemented data from Yangtze River Fisheries Research Institute, Figure 2. In June , the average density of eggs and larvae in the reach from Yichang to Yidu was three times higher after the environmental flow release than before, and the density on the third day of operation was seven times higher than before the release began Chen and Li, While these results show that carp reproduction appears to be increasing after a period of significant decline between and , it is not yet possible to fully attribute that increase to the environmental flow program.
The relevant authorities would need to publish more rigorous statistical analyses that control for other factors water quality, habitat, fishing pressure, background hydrology before firm conclusions can be drawn on the extent to which the environmental flows can explain the increases. Although the full analysis of impacts has yet to be published, the re-operation of Three Gorges Dam to promote carp spawning provides an important example of how regulations, stakeholder engagement, and science can be combined to inform re-operation of a major dam and to broaden the range of objectives for dam management in China and, potentially, beyond.
A combination of environmental, socio-economic, and political pressures and opportunities stimulated policies, processes and institutional interactions that led to the re-operation program. An understanding of how this situation unfolded can provide insights that might be useful in other contexts. This case study is particularly valuable as it involved one of the largest dams in the world and occurred within a country with extremely limited examples of environmental flow implementation.
The environmental flows program of the Three Gorges Dam can serve as a precedent for the re-operation of other dams in China—the country with the most dams in the world. Further, Chinese companies and investors have achieved substantial market shares in the construction of hydropower dams around the world. A high-profile example of dam management for environmental objectives could influence how dams are planned, designed and operated in other countries.
The public, conservation organizations, and various agencies recognized that Three Gorges Dam had caused considerable adverse environmental impacts and they advocated for solutions to mitigate these impacts. China's evolving environmental regulations reflected and amplified the concerns described above. The State Environmental Protection Agency published policies requiring hydropower projects to release environmental flows to support downstream resources and these requirements were supported by further guidance from the MWR and the MOA.
These agency actions provided a regulatory driver for CTG to pursue reoperation of Three Gorges Dam to support an expanded range of management objectives. The spawning requirements of carp are relatively well known and the environmental flow program has included considerable investment in further research. The new reservoir, typical of facilities in gorges, will not have a so-called "big-belly" section similar to other facilities built on lakes. Charm of Three Gorges to Remain The Three Gorges, one of the world's most famous scenic sites around Qutang, Wuxian and Xiling, features breathtaking scenery which attracts hundreds of thousands of tourists from at home and abroad each and every year.
The charming scenery will be left untouched following the damming of the mid-section of the Xiling Gorge. The high-water mark once the dam is completed will stand at However, the rise in the water level will have little impact on scenery in the Three Gorges which sit at an elevation of some 1, meters above sea level.
The charm of the famous landmark will remain unchanged the year when the high-water mark will rise by some meters. A spectacular waterfall formed by the steep incline of the Three Gorges dike will offer a new site expected to attract an incessant stream of tourists.
Preliminary Success Scored in Three Gorges Resettlement Drive Some 90, local residents are expected to move out of the reservoir area of the Three Gorges Project by the end of this year, leading to a favorable start of the massive resettlement drive.
The Three Gorges Project will relocate 1. To this end, China will inject approximately billion yuan into the relocation of the reservoir residents by the year when the whole project is completed. And the sum will increase continuously in the future," according to an official with the Bureau of Resettlement and Development under the Three Gorges Project Construction Commission. Along with the resettlement drive, the State also plans to invest more than 20 billion yuan on the upgrading of local infrastructure and construction of major industrial projects.
The Three Gorges Dam makes perfect sense within this tradition, as does the equally ambitious South-North Water Transfer Project which aims to transport water from the humid Yangtze valley along canals a thousand kilometres long to the water-strapped northern plains. There was no greater compliment a ruler could receive than to be compared to the virtuous Da Yu. Even today, Chinese still mark Mao's crossing of the Yangtse - underlining the river's importance to the nation Credit: Getty Images.
A massive dam on the Yangtze has been the ambition of every leader of the modern era, starting with the first president of the Republic of China, Sun Yat-sen. In his poem composed to mark his swimming of the Yangtze , Mao Zedong announced the vision like this:. The gorges themselves — the Wushan mountains loom over the middle one — are filled with legend; every peak and crag seems to have some story attached to it.
A smaller dam — a pilot project of sorts — was begun further downriver at Gezhouba in Yichang, and the time seemed ripe for the main objective. Contrary to common impression, the dam was not bulldozed through by an implacable state.
Protestors such as the writer Dai Qing, who was jailed in after publishing a book of essays criticising the dam scheme, were victims of the post-Tiananmen Square crackdown, rather than of disapproval of opposition to the dam itself.
Even critics have to admit that since the dam was built, there have been no catastrophic floods on the Yangtze like the one that claimed 3, lives in But the outcomes of the massive relocation programme are more contentious.
It is surely true that some of the flooded Yangtze towns were grim, under-developed places that few residents were sad to leave, and some are content to have been rehoused in new apartments with heating and running water. Others have struggled to adapt to a new life, perhaps hundreds of miles from their ancestral homes, where the local dialect is incomprehensible to them. And there have been complaints of inadequate compensation and embezzlement of resettlement funds. A country like China, with plenty of fast-flowing rivers and an immense demand for energy, would be unwise not to make use of its natural renewable resources to sustain economic growth.
China theoretically has more hydroelectric resources — around gigawatts, equivalent to hundreds of medium-sized nuclear power stations — than anywhere in the world, but is still exploiting barely a quarter of that.
The Three Gorges Dam has so far prevented the kind of flood that has killed millions over the ages Credit: Getty Images. It was built during the Mao era half-a-century ago.
The contrast with the brash, tightly orchestrated, high-security visitor experience at the Three Gorges Dam was striking — and telling. Historically, the Yellow River has left even deeper impressions on the Chinese national psyche than the Yangtze. China's Three Gorges Dam is one of the largest ever created. Was it worth it? The Three Gorges Dam was designed to tame China's longest river.
But this summer's record rains reveal its limited ability to control floods. Three Gorges Dam is the largest hydropower project ever built. When construction began in , it was designed not only to generate electricity to propel China's breakneck economic growth, but also to tame China's longest river, shield millions of people from fatal floods and, as a symbol of technological prowess, become a searing point of national pride.
But it hasn't quite worked out that way. And while the government promised the dam would be able to protect communities around its immediate downstream against a "once in a century flood," its efficacy has frequently been questioned. Those doubts recently resurfaced, as the Yangtze basin saw its heaviest average rainfall in nearly 60 years since June, causing the river and its many tributaries to overflow. More than people have died or gone missing, 3.
Despite the havoc, Chinese authorities claim the Three Gorges Dam has succeeded in playing a " crucial role " in intercepting floodwaters. The dam's operator, China Three Gorges Corporation, told China's state news agency Xinhua that the dam has intercepted A water resources ministry official told state-run newspaper China Youth Daily that the dam "effectively reduced the speed and extent of water level rises" on the middle and lower reaches of the Yangtze.
But with multiple gauging stations monitoring river flows in the Yangtze basin seeing record-high water levels this summer, some geologists say the limited role of the Three Gorges Dam in flood control has been laid bare. The Three Gorges Dam is an awe-inspiring structure.
Firstly, it is one of the few man-made structures on Earth that's visible to the naked eye from space, according to NASA. Completed in , the body of the dam is immense.
It is meters feet tall and spans 2, meters 1. Then there's its accompanying hydropower plant, which was completed in and has a generating capacity of 22, megawatts, or more than three times the capacity of the Grand Coulee Dam, the largest in the United States.
But according to the Chinese government's proposal , the top reason for building the dam wasn't power generation, but to prevent flooding. Workers hold up a layout plan of the Three Gorges Dam project by the Yangtze river in Hubei province in September Scroll through the gallery for images of the Three Gorges Dam, through the years. Here's how it works: the enormous dam is situated on an upstream section of the Yangtze and helps prevent flooding downstream by trapping rainwater in a huge reservoir, and then controlling the release of that water through its sluice gates.
The kilometer mile reservoir winds upstream through the narrow valleys of the Three Gorges -- a series of steep canyons known for their imposing beauty and once treacherous currents -- to Chongqing, a sprawling municipality of During the dry season, October to May, the reservoir's water level is kept at a maximum of meters feet to optimize electricity generation at the adjoining hydropower plant.
Before the summer rains arrive in June, it's gradually lowered to meters feet to make room for the incoming floodwaters. The lowering of water levels creates 22 billion cubic meters of storage space -- enough to contain nearly 9 million Olympic-size swimming pools of water.
But that's nothing compared with the sheer volume of floodwater that can flow into the dam during bad years, said Fan Xiao, a Chinese geologist and long-time critic of the dam.
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