Why does hydropower station affect ecology?

Humans have built dams and water conservancy projects for thousands of years. From Dujiangyan irrigation in China to urban water supply system in ancient Rome, successfully controlling floods and utilizing water resources by building canals and dams has become an important part of human civilization for thousands of years. After industrialization, especially after the invention of electricity, the use of hydropower to benefit mankind once became a symbol of human civilization and progress. By the beginning of the 20th century, the construction of large dams has become synonymous with economic development and social progress. Just because many important dams and hydropower stations built in the United States in the 1930s and 1940s were named after the President, it is not difficult to see the international community's admiration for dams and its pride in building hydropower stations at that time. Because dam construction is regarded as a symbol of modernization and human ability to control and utilize natural resources, dam construction is surging. By the time it reached its peak in 1970s, two or three new dams were put into use almost every day in the world. According to statistics of relevant institutions, by the end of the 20th century, 90% of the electricity in 24 countries in the world came from hydropower, of which one third accounted for more than half. 75 countries mainly rely on dams to control floods, and nearly 40% of farmland in the world is irrigated by dams. There is no doubt that dam construction and hydropower generation have become an important part of human social civilization today. Especially in modern society, the contradiction of water resources is very prominent, and dam construction is an important way to solve the water resources problem.

First, the significance of water resources to dam (hydropower) construction

The role of dam construction is not single. Besides flood control, irrigation, shipping, tourism and aquaculture, the most important thing is water supply and power generation. It is one of the important functions of modern dams to control floods and turn them into usable water resources by building dams and storing water. Taking China as an example, due to the monsoon climate, heavy rains are concentrated, and although floods often occur, fresh water resources are very scarce on the whole. With the development of economy and the increase of social water demand, one of the measures to solve the shortage of water resources in China is to build a number of large water storage reservoirs to increase the flood storage capacity of each basin in flood season, thus increasing the available amount of water resources. Throughout history, any developed country in the world, without the full guarantee of natural water resources formed by special environment, almost without exception, must rely on dam storage to solve its water supply problem.

In contrast, the dam construction in China is far behind. In theory, there are more than 80,000 dams in China, but in fact, most of them are irregular small earth dams, and there are not many dams that can really give full play to their functions. According to the statistics of China Dam Committee, by the end of 2003, there were only 4,694 dams over 30 meters in China (including 132 dams under construction), and the installed capacity of dams over 30 meters was 56300MW. The total storage capacity of reservoirs in China is only 584.3 billion m3 (including 654.38+040.5 billion m3 under construction). In 2004, the national hydropower generation was about 330 billion kWh. If we compare the per capita storage capacity of reservoirs, the gap between China and the United States is more than 100 times. Therefore, the social and ecological environment of China has been greatly affected by natural disasters. On the one hand, frequent floods, on the other hand, serious drought, serious shortage of water resources and serious water pollution. The fundamental solution to these problems can not be separated from building a certain number of dams and improving the ability to regulate and control natural water resources.

For developing countries, the contradiction between flood control and disaster reduction and water shortage is very prominent. Due to the limitation of national strength, the development and utilization of rivers in underdeveloped countries are far from in place, and the ability of flood control, irrigation, water supply and water transfer often cannot meet the needs of social development. For example, more than 400 cities in China are short of water, among which 100 cities are seriously short of water; There are still 300 million rural people in China who can't drink water that meets the hygienic standards. In fact, the shortage of water resources in many areas of our country will have a more fatal impact on the future development of our national economy than floods. With the development of modernization and the improvement of people's quality of life, the demand for water resources will increase greatly. One of the most powerful measures to solve the shortage of water resources is to build a number of large water storage reservoirs to increase the flood storage capacity of each basin in flood season, thus increasing the total available water resources. In this sense, dams and hydropower construction are not only for developing energy resources, but also for flood control and disaster reduction and water resources development.

Second, hydropower resources and their development and utilization

According to the statistics of International Hydroelectric Power Association in 2003, the theoretical reserves of global hydro-electric power generation are about 40 trillion kWh, the technical development is about10.5 trillion kWh, and the economic development is about 8.8 trillion kWh. The theoretical installed capacity of some hydropower stations in Chinese mainland is 694.4 million kilowatts (calculated according to 8760 operating hours), and the annual electricity consumption is 60829 trillion kilowatt hours, of which the technically exploitable capacity is 54/kloc-0.60 million kilowatts, the annual power generation is 2.474 trillion kilowatt hours, and the "economically exploitable capacity" (capacity is 448 million kilowatts, electricity consumption is/kloc-0.753 trillion kilowatt hours). It should be noted that the concept of installed capacity is rarely used to represent the hydropower resources of various countries in the world. Because the installed capacity is a value that is not easy to determine objectively. For example, pumped storage power stations play an extremely important role in the development of electric power industry, and many pumped storage power stations actually have only installed capacity and no power generation (even electricity consumption), so they cannot be used as developed hydropower resources. Secondly, according to the characteristics of hydropower resources in different countries, the installed capacity of each hydropower station may change greatly. 〖3〗

The problem of unclear degree of hydropower development has not attracted enough attention from some hydropower workers so far. Many people often compare the development of domestic installed capacity with that of foreign annual power generation. Therefore, the comparison results often exaggerate the degree of hydropower development in China. It is time to gradually popularize the annual output to express the degree of hydropower development, because this figure can not only objectively reflect the degree of hydropower development, but also be used to compare with the degree of hydropower development abroad. In addition, the development of hydropower resources has a degree called "economically exploitable". Some experts believe that because the scope of its economic development depends on many conditions, it will inevitably change with the development of the situation, the progress of science and technology and the rise of oil, natural gas and coal prices. Therefore, many countries suggest that this should not be taken as a measure.

Third, the sustainable development of the world calls for the development of hydropower.

3. 1 resources

Throughout the 20th century, mankind consumed 654.38+042 billion tons of oil and 265 billion tons of coal. At present, the world's proven remaining recoverable oil reserves are only1more than 40 billion tons, and the static guarantee period is only 40 years according to the current output; The remaining recoverable reserves of natural gas are 654.38+0.5 billion cubic meters, and the static guarantee period is only 60 years. Although there are more coal reserves in the world, if the current consumption rate is maintained, 100 years later will be exhausted. Therefore, in order to realize the sustainable development of human society, we must transform the world energy structure into renewable energy as soon as possible. There are essential differences between renewable energy and mineral resources. It is a time variable, and the longer it takes, the more resources it will have. On the contrary, it can't be saved. Whether you use it or not, it will disappear with time. Therefore, giving priority to the development and utilization of renewable energy is the biggest energy-saving and development resource. Although wind and solar power generation technologies have a broader development prospect, according to the existing technical level, other renewable energy generation technologies such as wind and solar power can not meet the large-scale social needs. At present, about 20% of the world's electricity comes from hydropower, while the proportion of other renewable energy sources is still small. Hydropower is the only renewable energy with mature technology that can be developed on a large scale.

3.2 The renewable energy function of hydropower is irreplaceable.

Renewable energy mainly includes wind energy, solar energy, water energy and biomass energy, in addition, there are some such as tidal and geothermal energy, but the proportion is very small. Biomass energy has a broad application prospect, but at present it is mainly simple direct combustion in China. Although there are relatively advanced application technologies of biomass energy abroad, its renewability is still greatly limited because the raw materials of biomass energy must also be produced by planting. Solar energy and wind energy resources are very rich and have broad application prospects, but I am afraid that only after solving the large-scale energy storage technology can they be applied as large as hydropower. At present, the main differences among solar energy, wind energy and water energy are random, scattered and inefficient. Solar energy is eternal, but it also changes with time and weather, and it can't generate electricity at night and in rainy days. Wind power is even more unpredictable and cannot be controlled artificially. In terms of power generation efficiency, some windmills in Europe and America are increasing rapidly, and the efficiency of some wind turbines is 10 times higher than that of the old ones, but their output is still not as good as that of a medium-sized hydropower station. Some developed countries envisage the formation of wind power generation network, but there are many problems, which have not been realized so far, and their functions are far from comparable to those of thermal power, hydropower and nuclear power. According to the experimental research of an internationally renowned solar energy research institution in Israel, the relatively mature large-scale solar power generation application only relies on solar energy to preheat the circulating water of thermal power plants to reduce the consumption of burning fuel. Due to the shortcomings of wind energy and solar energy, generally speaking, at present, solar energy and wind energy mainly play an auxiliary role in agricultural electricity consumption, or form a small independent power supply through storage batteries to provide domestic electricity for remote areas. The United Nations has been helping the third world countries to popularize wind power generation technology, but at present, most of them stay in solving the domestic power supply problem in remote and scattered areas, and it is difficult to form a strong power grid. 〖4〗

3.3 Environmental pressure

In terms of environment, with the acceleration of global industrialization, the scale of energy production and consumption has increased sharply, resulting in serious environmental pollution. At present, sulfur dioxide, dust and other harmful gases that cause acid rain due to coal burning can be controlled by technology. However, there is no effective solution because the combustion of fossil fuels and petroleum-derived energy sources produces a large number of greenhouse gases (GHG), such as carbon dioxide, methane and nitrous oxide. These gases absorb solar radiation and prevent it from spreading from the atmosphere to outer space. The long-term accumulation of energy leads to the continuous warming of global climate. The research shows that when the equivalent concentration of carbon dioxide reaches a certain value, climate change will lead to the intensification of the global water cycle, which will have a significant impact on regional water resources, and will also have serious consequences on local agricultural and forestry production, causing frequent natural disasters and directly threatening the living environment of human beings. Since the first World Climate Conference was held in Geneva from 65438 to 0979, the World Meteorological Organization and the United Nations Environment Programme have strengthened their scientific research on the GHG effect. 1992 At the United Nations Conference on Environment and Development held in Brazil in June, 166 countries, including China, signed the Framework Convention on Climate Change. The legally binding Kyoto Protocol was formed at the Kyoto Conference of the Parties held on June 5438+0997 65438+February 1. It stipulates that all developed countries should limit the emission of six greenhouse gases, and reduce the emission level of 1990 by at least 5% from 2008 to 20 12. In this case, the use of clean hydropower cannot but be regarded as a wise choice to reduce greenhouse gas emissions. There are about 8.8 trillion kWh/year economically exploitable water resources in the world. If more than 4 billion tons of raw coal can be used to replace combustion, it is equivalent to reducing carbon dioxide emissions by nearly 1000 billion tons every year.

Fourthly, environmental problems are plaguing dam construction and hydropower development.

Since the 1960s, the construction of Aswan Dam in Egypt has triggered a dispute between the United States and the Soviet Union over the dam. Out of the need of political struggle, in order to accuse the Aswan Dam, which was built with the help of the Soviet Union, there was a wave in the world, represented by denigrating the Aswan Dam and exaggerating its side effects infinitely. At one time, many scholars tried their best to find out the side effects of dams. Under the distortion of the political opposition, the image of the dam was artificially demonized. Some anti-dam organizations that are good at hype also take advantage of this to hype up. Before 1990s, there was a so-called world anti-dam alliance in the world. 17 when the international dam conference was held at 199 1 in the United Nations International Conference Center in Vienna, Austria, there were tents and demonstration slogans camped by demonstrators of the anti-dam alliance outside the conference hall. Protests and demonstrations against dam construction are almost accompanied by international dam conferences. At that time, the demonstrators only mechanically shouted slogans such as opposing dam construction and letting rivers flow freely, which did not have much appeal and did not attract enough attention.

As countries around the world pay attention to development and environmental issues, people will inevitably reflect on the role of dams. As a result, dam construction in some areas will inevitably face doubts and challenges from ecological and environmental protection. Undeniably, dam construction, like other human civilization activities, will inevitably produce side effects, such as resettlement, siltation, the impact of fish and biodiversity, the inundation of land cultural relics, the generation of greenhouse gases, changes in downstream hydrological and physical phenomena, and regional integration. These problems need to be carefully considered and handled by engineering decision makers and technicians. In fact, these environmental problems in the process of dam construction have always been one of the key points of dam construction. Many dams built around the world in the early 20th century have left fishways. Before the construction of Sanmenxia in China, the sediment problem was questioned by most water conservancy workers in the world. Because of this, so far, most of the dams built at home and abroad can be said to have more advantages than disadvantages, including the reconstructed Sanmenxia Reservoir, otherwise it would be unnecessary. Of course, because there is nothing without side effects in the world, dam construction will inevitably face a choice to weigh the pros and cons at any time.

Under the influence of anti-dam and deep reflection on dams,1In April, 1997, 39 people from different countries and classes and Greenpeace members proposed to establish the World Dam Committee for short after discussing a World Bank report on dam construction. 1May 1998, WCD began to investigate 125 dams in different countries in the world, and established the dam database. In June 2000, the report "Dams and Development-A New Decision-making Framework" was formally put forward. They are going to submit the report to the World Bank and the United Nations Commission on Environment and Development after consulting relevant international organizations, hoping to form an international standard for future dam construction decision-making. However, the report caused great repercussions in the discussions of relevant international organizations, especially the strong opposition from the representatives of developing countries. According to the statistics during the discussion in international commission on large dams, only three countries agreed to accept the decision-making framework proposed by WCD. In February, 20001,the heads of three international organizations in the world (international commission on large dams, the International Commission on Irrigation and Drainage and the International Hydropower Association) jointly wrote to the President of the World Bank, stressing that although the WCD Report can be used as useful information to trigger discussions on dam construction, it is extremely inadequate as a decision-making standard for dam construction. At the same time, he said that he could not accept the unfair judgment conclusion on the role of existing dams in the report.

Verb (abbreviation of verb) Argument and result about dam and hydropower.

5. 1 Different opinions on dams and hydropower

Although hydropower is the only renewable energy power generation method that can be applied on a large scale at present. However, with people's concern for nature and ecosystem and the rapid growth of global environmental awareness, dams and hydropower projects are experiencing unprecedented tests. This situation has led to dams and hydropower projects that have been built and are being planned becoming more and more sensitive topics. Some projects that have a huge negative impact on the environment and society have been strongly resisted by the public and finally forced to stop. With the establishment of the World Commission on Dams and the report Dams and Development, the debate on the advantages and disadvantages of dams reached its climax in the 1990s. The report of the World Commission on Dams is the product of people's deep reflection on dam construction. For the first time, the World Bank and other international organizations made full use of the initiative of anti-dam organizations and entrusted the World Dam Committee to systematically summarize and summarize various problems that may arise from dams from the perspective of environment and society. The report systematically summarizes the possible negative impacts of some completed dams through detailed investigation. 〖5〗

5.2 Conclusions of the World Summit on Sustainable Development

With the deepening of people's understanding of sustainable development, the demand for hydropower resources in developing countries is increasingly acute. In many developing China countries, water resources are the main way to provide sustainable energy in reality. On the African continent, there is a shortage of fossil fuels and abundant water resources. However, the controversy over environmental problems caused by dam construction has hindered the construction of hydropower projects and social progress. In order to solve these problems, at the World Summit on Sustainable Development in 1996, the status of clean and renewable energy without dams was established for the first time, and countries were encouraged to develop small hydropower. Since then, after further debates on dams and hydropower, especially on the basis of the survey report of Dams and Development of the World Dam Committee, some misconceptions such as "the greenhouse gas emission of hydropower is equivalent to thermal power" have been clarified. At the World Summit on Sustainable Development held in Johannesburg, South Africa in 2002, 192 countries unanimously recognized that the development of hydropower is beneficial to the sustainable development of resources and environment compared with burning mineral resources to obtain electricity. After discussion, the meeting held that it is necessary for large-scale hydropower to be recognized as renewable clean energy under the circumstances that all countries in the world are encouraging the development of various renewable energy sources to slow down global warming. The World Summit on Sustainable Development finally made a resolution and adopted the Johannesburg Plan of Implementation, calling for diversification of global energy supply and increasing the share of renewable energy, including large-scale hydropower. The summit also promised to increase international cooperation activities in the field of renewable energy, including hydropower. It is also suggested that a forum on hydropower and sustainable development be held in China in 2004 to discuss a series of topics through a high-level forum in the field of hydropower in the world, so as to further fulfill the task of the Johannesburg Summit on Sustainable Development and promote the sustainable development of the world.

5.3 Beijing United Nations Hydropower and Sustainable Development Forum and Beijing Declaration

According to the planning requirements of the World Summit on Sustainable Development, the United Nations Department of Economic and Social Affairs and the National Reform and Development Commission of China jointly held a seminar on hydropower and sustainable development in Beijing on June 27th, 2004. More than 500 government officials, experts, scholars and representatives of non-governmental organizations from more than 40 countries and regions gathered together to discuss issues of hydropower engineering concern, such as hydropower and sustainable development, environment-friendly hydropower development technology, existing hydropower station management, scientific decision-making of hydropower development, and the role and influence of hydropower development on economic and social development, and reached broad consensus.

The introduction and speech of the United Nations Forum on Hydropower and Sustainable Development in Beijing and the final Beijing Declaration on Hydropower and Sustainable Development promote the accessibility of hydropower development.

5.4 China's public opinion gap

It is understood that there are not many positive reports on this meeting convened by the United Nations in China news media, and there are more than one or two media with different opinions who distort the reports. In addition, many anti-dam NGOs in China have a negative attitude towards this meeting. In fact, this meeting was not organized by the hydropower system, as some news media distorted reports, but by the United Nations. The principles and spirit of the meeting, including the attendance and specific speech arrangements, are decided by the relevant UN agencies. This meeting was held according to the plan of the 2002 United Nations Summit on Sustainable Development, which is part of the United Nations Millennium Plan. Some anti-dam organizations and some anti-dam public opinion not only oppose this meeting to promote hydropower development, but also hold a negative attitude towards the conclusion of the 2002 World Summit on Sustainable Development. In fact, nearly 100 members of anti-dam NGOs in China (most of them journalists) attended the World Summit on Sustainable Development held in Johannesburg in 2002, and they knew the resolution made by the summit to support the development of hydropower. However, at that time, almost no domestic media reported it positively. On the contrary, since 2003, there has been a wave of anti-dam climax in China. Many propaganda against dams that unilaterally emphasize that hydropower destroys the ecological environment is still very popular in China.

In fact, any human activity will have an impact on the ecological environment, and the ecological impact of dams is also beneficial and harmful. For example, the social and ecological benefits of large hydropower stations such as Fengman, Xin 'anjiang and Ertan in China are very significant, and the positive ecological and environmental benefits far exceed the negative effects. It should be said that many arguments of some popular anti-dam propaganda in China are untenable, and many of these issues we are debating now have been debated internationally for a long time. At the World Summit on Sustainable Development, people fought fiercely on these issues many times. Until the summit in 2002, 192 heads of state reached a consensus, established the clean and renewable energy status of large-scale hydropower, and decided to encourage and promote hydropower development on a global scale. I believe that politicians all over the world will not know the actual situation like some tabloid reporters, fake experts and radical environmentalists, nor will they fail to pay attention to the ecological balance and sustainable development of the world. It must be reasonable for them to finally come to the conclusion that they support the development of hydropower. The crux of the problem is that some people in our country have not realized or are unwilling to admit it.

Conclusion of intransitive verbs

It should be admitted that up to now, many domestic public opinion propaganda, some views on hydropower are still not correct enough. It should be said that this is the cognitive gap between China's mainstream consciousness and the world. At present, many public media in China lack scientific knowledge and are influenced by anti-dam thoughts. The so-called "noble" and "romantic" they preach are often based on the extreme reverence for nature at the expense of preventing people in underdeveloped areas from developing. Today, some media are still promoting some unscientific anti-dam views that are contrary to the requirements of the World Summit on Sustainable Development. However, although the task of publicizing hydropower science is still arduous, we believe that with the in-depth discussion of hydropower understanding, truth will surely overcome fallacies. Faced with the problem of meeting people's development needs and the pressure of environmental resources, our people will certainly know hydropower more and more comprehensively like most people in the world. In order to truly realize the sustainable development of the country and the world, we must advocate the scientific spirit of seeking truth from facts, expose all pseudo-scientific and pseudo-environmental propaganda under the banner of respecting nature and protecting the original ecology, and vigorously develop clean and renewable hydropower resources in accordance with the requirements of the World Summit on Sustainable Development. Use Scientific Outlook on Development to guide national construction, build a harmonious society and realize the goal of a well-off society and social sustainable development.