Wu: What did the Three Gorges Dam leave for the Chinese nation?

China, like many developing countries, China's modernization process is accompanied by obvious ecological and environmental deterioration. In recent years, although the government has begun to attach importance to environmental protection, people are increasingly feeling the threat of environmental pollution to their living environment, but on the whole, the Chinese nation today pays far less attention to ecology and environment. In today's China, perhaps most people can intuitively detect air pollution or water quality deterioration, but it is often difficult for people to intuitively feel how economic and social activities threaten the ecological environment system that sustains human survival; Especially when the consequences of these activities have not been fully revealed, their potential negative effects are more easily overlooked. Perhaps, on the one hand, this is because the experience and lessons of developed countries in protecting ecology and environment have not aroused enough vigilance of the Chinese nation; On the other hand, it is because there is still a tendency that economic development overrides ecological and environmental protection in China. However, if we neglect the protection of ecology and environment for the sake of economic development, we will not only be punished by nature, but also leave endless hidden dangers for the future society. Ecology and environment are not only closely related to the current human existence, but also maintain the well-being of future generations. In the last decade or two, experts from all over the world have a deep understanding of the diversity of nature and its relationship with ecological environmental protection, and realized the urgency of promoting ecological environmental protection. So people say that 2 1 century will be an "environmental century". However, to really protect the ecology and environment, we need both scientific knowledge and political foresight, both of which are indispensable. When China is about to enter the 2 1 century, are there many cross-century projects in China that may pose a major threat to the ecology and environment due to the lack of necessary scientific knowledge and political foresight? The Three Gorges Dam Project may be an obvious example. If it is wise to protect the environment and stick to it, and things that may aggravate the environmental deterioration can never be started easily, then the Three Gorges Project is the last thing to do. Why? Looking at the ecological and environmental impacts of other dam constructions in the world, and comparing and analyzing the natural conditions and aftereffects of the Three Gorges Project, it is natural to draw the above conclusions. 1. When the investment in resettlement and historic site relocation is too large to build the Three Gorges Project, do you have enough economic ability to complete the arduous task of resettlement and historic site relocation? This is the first worrying thing. The first step of dam construction is resettlement, and the second step is the relocation of historic sites. Like China, Egypt is an ancient civilization with historic sites all over the country. When the famous Aswan Dam was built in Egypt, there were about100000 immigrants in the reservoir area, which was only one tenth of the immigrants from the Three Gorges Project in China. Even so, the investment in resettlement and historic site relocation of Aswan Reservoir exceeds the investment of the hydropower station itself, accounting for more than one third of its total investment of 400 million Egyptian pounds, that is,10.50 billion Egyptian pounds, which is equivalent to spending 50,000 yuan per immigrant at present value. It is estimated that the Three Gorges Project in China needs about one million people to emigrate. According to the resettlement standard of Aswan Dam, the Three Gorges Project needs a huge investment of 50 billion RMB. Has such a huge resettlement expenditure been implemented in the budget of the Three Gorges Project? Will the loss of immigrants be passed on to the immigrants in the reservoir area because of the shortage of funds? Moreover, subsidizing the immigrants in the reservoir area with a large amount of funds may appease the people's hearts; However, money cannot make up for the loss of a large number of precious cultural relics in the Three Gorges reservoir area. World famous historical sites such as Du Feng Ghost Town, Fengjie Bai Di City, Zhangfei Temple, Quyuan Temple, Zhaojun's hometown, etc. It will be completely submerged and gone, and the beauty of the Three Gorges, as a wonder of the world, will be greatly inferior. How will these irreparable losses be estimated? Will our descendants forgive? Second, the ecology and environment around the reservoir area may deteriorate after immigration. Even if millions of immigrants are resettled nearby according to the resettlement plan of the Three Gorges Project, it does not mean that the problem has been solved. On the contrary, it will cause more serious ecological and environmental problems. After millions of new immigrants moved into the vicinity of the reservoir area, the population density on the land around the reservoir area inevitably increased rapidly. So many immigrants want to survive, can the local cultivated land conditions meet their needs for agriculture? In fact, both sides of the reservoir area are high-altitude mountains with steep slopes, poor soil and extremely limited arable land. In such a mountainous area, once the population density suddenly increases excessively, the limited cultivated land will inevitably be unbearable, which will force new immigrants to open up wasteland all over the mountain. In this way, the destruction of natural vegetation will be intensified, the area of forests and grasslands will be rapidly reduced, and soil erosion will be more serious, followed by the acceleration of reservoir siltation. Once the forest vegetation in the reservoir area is destroyed, the habitat of biological population will also shrink, and the ecological environment in the Three Gorges area will inevitably fall into a vicious circle. 3. Reservoir siltation poses a serious threat. If a huge investment is spent, many famous historical sites are submerged, resulting in serious deterioration of the ecological environment, and only a short-lived reservoir is exchanged, then such a project is tantamount to wasting people and money. The life of a reservoir mainly depends on the speed of reservoir siltation, which is also a key hidden danger for any dam project manager in the world. In Aswan Dam in Egypt, about1.300 million tons of sediment is deposited in the reservoir every year. Such a large amount of sediment has obviously reduced the effective storage capacity of the reservoir and greatly reduced the benefits of water conservancy projects. Once the Three Gorges Reservoir in China is completed, it is estimated that the total annual sediment volume will be 520 million tons, which is four times that of Aswan Dam, but the dead storage capacity of the Three Gorges Reservoir is only one eighth of that of Aswan Dam. Obviously, siltation is more threatening to the Three Gorges Reservoir than the Aswan Dam. Domestic experts have long noticed that hillside collapse is one of the frequent natural phenomena in the Three Gorges area, and there are more than 200 potential landslides on both sides of the reservoir area. Moreover, an earthquake of magnitude 5. 1 occurred in the Three Gorges area. In this way, earthquakes and landslides may also cause serious siltation of reservoirs. Faced with the problem of preventing reservoir siltation and prolonging reservoir life, the designers of Three Gorges Project put forward the idea of "lowering the water level in front of the dam to near the dead water level before flood season, releasing water with large flow during flood season, similar to the situation of natural rivers, and storing fresh water in the reservoir after flood season". How feasible is this idea in logic and reality? In fact, the idea of washing sand with water in the Three Gorges Project is questionable. Because only the suspended sediment can be washed away by flood discharge, but the coarse sand moving at the bottom of the reservoir is difficult to be discharged. The sediment carried by the Nile in Egypt is mainly silt, which leads to serious siltation in Aswan Reservoir. The sediment in the Three Gorges of the Yangtze River mainly comes from coarse sand and fine gravel in Sichuan Basin. They are not suspended in the river, but move at the bottom of the river. Even if the designer of the Three Gorges Project promised to wash sand with "large flow" in flood season, how can the reservoir water in front of the dam wash away the coarse sand and fine gravel deposited at the bottom of the reservoir with a large area? What's more, the reservoir siltation caused by earthquakes and landslides is distributed in the upper reaches of the reservoir area, and it is mainly composed of rock blocks and gravel residues, which cannot be eliminated by flood discharge. 4. Silting prevention and flood control can't have it both ways. Can the Three Gorges Reservoir ensure the smooth realization of flood control, navigation and siltation prevention? An important reason for building the Three Gorges Project is to prevent floods. As we all know, when the flood season comes, large reservoirs can store and delay flood discharge, so they can play a role in flood control; If, as mentioned above, the reservoir opens the spillway in the flood season and lets the flood surge down, then the downstream flood will be the same as when there is no reservoir. How will the Three Gorges Project balance siltation prevention and flood control? When people question the reservoir siltation, the defenders of the Three Gorges Reservoir use flood discharge in flood season to explain it. When people suspect that the reservoir dam is too high and there are various risks, the designer defends the need of flood storage and flood control. However, the flaw of "the spear of the child is the shield of attack" is exposed. Because the Three Gorges Reservoir relies on flood discharge to prevent sediment deposition in flood season, it is practically impossible to store water for flood control in flood season. If the Three Gorges Reservoir wants to store flood in flood season, it must reduce the amount of underwater discharge, so that a large amount of sediment brought by river water can not be discharged from the reservoir in flood season, and serious siltation of the reservoir can not be avoided. In a word, it is impossible for the Three Gorges Reservoir to achieve the best of both worlds between flood control and siltation prevention. If flood control is to be carried out, the reservoir will be silted, and if siltation is to be prevented, the downstream will be threatened by flood. In fact, because the downstream flood disaster is more obvious than reservoir siltation, in order to avoid public criticism, reservoir managers generally tend to pay more attention to flood control than to prevent siltation. Therefore, the sediment in the reservoir is increasingly silted and difficult to remove. Coupled with the rubble accumulation caused by landslides, the silted sand is finally distributed more and more widely and reaches Chongqing along the river. In that case, the life of the Three Gorges Reservoir will be shortened rapidly, and the improvement of shipping will become a bubble; What's more, not only the ability of the Three Gorges Reservoir to defend the downstream flood is greatly reduced, but also the reservoir may cause new flood hazards to the upstream. After the impoundment of the Three Gorges Reservoir, the tail of the reservoir will crush Chongqing. According to the designer's estimation, "the total storage capacity of the Three Gorges Reservoir is 20 billion cubic meters, accounting for only 4% of the annual runoff at the dam site." If the upper reaches of the Yangtze River are flooded and the Three Gorges Reservoir is seriously silted, the cities along the Yangtze River, such as Chongqing, will be flooded, which constitutes a flood disaster that has never happened in these areas. 5. The reservoir itself causes ecological and environmental deterioration. People often think that hydropower projects will not cause pollution, but from the history of dam construction in the world for nearly 30 years, this view is incorrect, because hydropower itself may not directly cause pollution, but reservoirs built for hydropower may cause serious environmental pollution. For example, the Brazilian government spent $750 million to build the Balbina Dam on the Amazon River, which flooded 2,360 square kilometers of forest. When submerged trees rot, the reservoir water is seriously acidified and anoxic, releasing a lot of toxic hydrogen sulfide and methane gas. In this way, the polluted reservoir water not only corrodes and destroys the turbine of hydropower station, but also causes a large number of aquatic organisms and fish to die, making the water quality of the reservoir worse and more smelly. Building dams and using hydropower will not only create new pollution sources, but also turn some valuable and reusable resources into endangered resources or make them extinct. In the United States, dams built in the past 50 years have affected rivers, estuaries, bays and deltas to varying degrees. For example, in the Columbia River basin, fishing has decreased due to dam construction. According to the American Fish Society, nearly half of the fish have disappeared, and nearly a quarter are almost extinct. At present, there are 73 pollution sources in the Three Gorges reservoir area of China, and the total amount of wastewater discharged each year reaches 975 million tons. After the completion of the dam, the flow velocity of reservoir water will decrease, which will cause the accumulation and precipitation of toxic pollutants such as heavy metals in the reservoir and aggravate the deterioration of reservoir water quality. The river flows eastward. This endless river flowing into the sea has benefited mankind for generations, and mankind often regards it as a gift from nature. The Yangtze River, the third largest river in the world, pours into rivers, lakes and swamps, feeding people on both sides of the Yangtze River with its huge and natural energy. Many natural life processes such as deltas, estuaries and beaches in the Yangtze River Basin depend on it, and the Yangtze River is the source of all these natural things. Once this source is polluted and destroyed, it will inevitably endanger the living environment of the Chinese nation and delay the disaster of future generations. 6. Large hydropower projects may not be a panacea for "economic take-off". Using hydropower and energy to promote economic development is an expectation of human beings, but people often overestimate the economic benefits of reservoirs. In 1930s and 1960s, the United States invested by the government to build reservoirs and dams in Tennessee Valley and develop water resources in an attempt to obtain various benefits such as power generation, irrigation, shipping, flood control and tourism, thus promoting the economic and social development of the whole valley. In this basin of 1 1 10,000 square kilometers, dozens of hydropower stations were built in 30 years, and then thermal power plants and nuclear power plants were expanded in the 1970s, forming a comprehensive network centered on electricity in the basin. However, such superior conditions may not guarantee the accelerated development of the local economy. In fact, with abundant electricity, the economy of Tennessee Valley has not "taken off", but has lagged behind neighboring regions. 1975, although the annual per capita income of Tennessee Valley increased by 75% compared with 1933, it was still only 77% of the national average. 1933, the per capita income of neighboring areas is equivalent to that of the river basin, but the per capita income ratio of 1975 1933 has increased by 90%, which is obviously faster than that of Tennessee valley. Because the actual economic benefits of large-scale hydropower projects may be far lower than expected, the huge investment spent in that year will not be recovered for a long time. In 1930s, a large amount of investment was used to improve the shipping conditions in Tennessee Valley. However, because we failed to correctly estimate the changes in the future cargo transportation structure at that time, we mistakenly thought that the revenue of water transportation would increase rapidly after the improvement of water transportation conditions; As a result, it backfired, and spending these investments did not bring corresponding benefits. Due to the fierce competition between highway and pipeline transportation, the revenue of water transportation has grown slowly. As a result, it took a long 40 years and a lot of investment to improve the shipping conditions in this basin, and it was not until 1975 that it was restored. Similarly, the flood control investment in the whole basin was 208 million US dollars, and it took 40 years to reach the balance of payments. The American government and people had expected the Tennessee Valley to be a model for the popularization of other basins, but this idea turned out to be just a "utopia". 7. Entering the 2 1 century: Learn to be in harmony with nature * * * Human society's understanding of nature has gone through a long process, and every time it passes, people find that their understanding of nature needs to be revised. Just as people finally realized that forest wildfires can regenerate forests, recently people began to realize that rapids and floods are natural forces to renew countless biological species in river basins. However, due to the limitations of past understanding, human beings have taken many improper actions, which have caused serious damage to ecology and environment. Now, on the one hand, human beings are paying a heavy price for this, on the other hand, they are spending huge investments to correct the consequences of past misconduct in order to restore ecological balance and reduce environmental pollution. Therefore, human beings have paid a huge price for their understanding of nature. Today, it is regarded as a successful experience and great feat to conquer and transform nature, but tomorrow, they will pay a higher price for it to correct the environmental consequences caused by these "great projects". Recently, the test conducted by the United States at Glenkanyan Dam is an example. Built in the 1960s, this dam is one of many dams on the Colorado River. It cut off the Colorado River, which is violently leaking into the Grand Canyon, and "the mountain comes out of the lake", thus changing the flow rate of the river and the environment of the flood plain. However, the change of the river course has harmed the fish in the river, making many local endemic species such as bow-backed carp endangered. In April this year, the US Department of the Interior decided to spend $4 million to implement a project on the dam and open three drainage pipes to simulate the course of the Colorado River before the dam was completed. This part gives up the function of the dam, but it is of great value to save endangered wildlife species and restore the flood plain ecosystem and the natural landscape of the Grand Canyon. Similar experiments will be carried out in other dams in the United States. The Kishimi River project currently under way in the United States represents another experiment to correct the bad results of past water conservancy projects. Kismi River is located in central Florida, USA. It connects Kismi Lake in the north and Okeechobee in the south. The original river twists and turns, with a total length of 166 km. In order to meet the needs of flood control, from 1962 to 197 1 year, American engineers spent ten years and 30 million dollars to straighten the river into a 96-kilometer-long channel (artificial canal). However, after the completion of this project, 14000 mu of wetland disappeared, which completely changed the hydrology of the basin and the ecosystem of the flood plain, and caused serious damage to vegetation, fish, birds and other biological communities. In the next twenty-five years, experts repeatedly studied the lessons of this project, and finally made the American public, the federal government and the state government determined to restore the natural water system of the Kismi River. From 1996, it lasted 15 years and invested 4.1500 million dollars to change the straight river channel back to the original winding river channel, so as to restore the floodplain ecosystem and save endangered species. These lessons are worth learning from the designers and managers of the Three Gorges Project in China. The Yangtze River in China is fast-flowing, and the unique rapids environment breeds nearly 100 species of endemic fish. Once this special current habitat disappears due to dam construction, it will bring a disastrous threat to the survival of these fish. Are we trying our best to rescue and protect the world-famous endangered species baiji and Chinese sturgeon in the Yangtze River, while at the same time, we are wantonly artificially increasing endangered species and destroying fish resources? The gradual understanding of nature by human beings has paid a huge price, and the lessons of others should be our good lessons. If you subjectively "conquer and transform nature" for immediate interests, you will eventually be punished by nature. Man should learn to protect the nature on which he lives and live in harmony with it. Chinese civilization has a long history, and the Yangtze River is the main artery of the Chinese nation. The Three Gorges Project is equivalent to cutting a knife in this artery, which is definitely something that must be cautious. Nature will reveal to future generations how expensive the Three Gorges Project is and how painful its consequences will be. A few years later, will our descendants berate our ancestors for their short-sightedness and ignorance today, and at the same time spend more money angrily to remedy the consequences caused by the Three Gorges Project today? [The author is a Ph.D. in plant ecology at the University of Wyoming, USA, and is now a senior researcher in environmental science at the South Florida Water Resources Administration] Source: Contemporary China Studies (No.58) Thank the author for authorizing the reprinting of Three Gorges Exploration.