Large Dams and Sustainable Development in China

andrewwangzhen

In China, we define water as a strategic economic resource. Water is also a dominating element that maintains the sustainability of our ecology and environment. Large dams are playing very important role in water resources management, for flood mitigation and clean energy supply, thereby promoting the sustainable development of society and economy. In recent years, there are lots of debates about large dams. At this ICOLD Symposium, I would like to take this opportunity to share with you the Chinese practice in large dam construction and sustainable development. I Large dam construction and social-economic development The history of Chinese long civilization is also a history of managing water to mitigate water disasters and develop water utilization. China is one of the earliest countries that had built ancient dams in the world. Since the founding of New China in 1949, China has completed more than 80,000 reservoirs, in which over 4,860 are created by large dams higher than 30 meters. All these dam projects have played a huge role in assisting the Chinese people mitigate poverty and promote socio-economic development. In this 21st century, large dams still have their strategic importance in the progress of sustainable development. 1. Large dams and flood control In China there are numerous rivers, including the seven major large rivers, like the Yangtze, the Yellow, etc. Affected by the Pacific monsoon and by the continental climate, China has long been a country frequently suffering from flood and drought calamities. In the last century, the whole country was hit by more than 60 large flood disasters, averagely once in less than two years. For example, in 1933 the large flood in the Yellow River caused the dike breaches at more then 50 locations and drowned 20,000 people. In 1931 the Yangtze River flood breached the main dikes at more than 300 sections, and took away the life of 145 thousand people. In 1954 another large flood in the Yangtze River breached the main dikes at 52 places, drowning 33 thousand people. The floods in China are mainly caused by over concentrating rainfalls. Moreover, the areas along the middle and lower river reaches are densely populated, having higher level of urbanization and industrialization. Once a flood disaster occurs, the loss is often very serious. After the founding of New China, many large-scale flood control projects and dam projects are completed, greatly reducing the loss of lives caused by floods. However, the economic loss is still on the increase with the increase of overall economic dimension. According to the statistical data, the average annual losses due to flood disasters have been around RMB110 billion (US$13.75 billion). Since the safety flood discharging capacity of many rivers are limited, the mitigation of flood disasters to protect life and property must rely on an integrated flood control system, consisting of reservoirs, dikes and flood detention basins, especially huge reservoirs with large regulating capacity. For example, the Three Gorges Project can raise the flood control standard from resisting a 10-year flood to resisting a 100-year flood for the economically well-developed flood plain regions in the middle Yangtze River. Even if a 1,000-year flood occurs, the peak flow in the Yangtze River can be reduced from 110,000 m3/s to 71,700 m3/s, ensuring no catastrophic disasters occurring in the middle and lower reaches of the Yangtze River. Another example is Xiaolangdi dam project on the Yellow River, which can decrease a 1,000-year flood discharge at Huayuankou section from 42,100 m3/s to 22,600 m3/s and a 100-year flood discharge from 29,200 m3/s to 15,700 m3/s, greatly enhancing the flood prevention capacity. Xiaolangdi project has thus become a key multiple purpose dam project in safeguarding the economically developed regions lying in the lower Yellow River basin from flood hazards.

andrewwangzhen

One primary feature of water resources in China is the uneven distribution of water resources both in time and in space. Almost 70% of the annual rainfall occurs in June through October. The total quantity of water resources in China is about 2,840 billion m3, but the quantity of water emptying into the ocean and flowing out off the border amounts to 2,300 m3. The climatic and geographical characteristics have determined that the rivers in China cannot naturally regulate themselves for effective water supply nationwide. China is a country with a population of 1.3 billion people. The grain supply is basically relying on irrigation agriculture. In China, the irrigation farmland is about 55 million hectares, while the non-irrigation farmland is another 55 million hectares. Each year, the farmland stricken by droughts is about 20 million hectares due to scarcity of water supply for irrigation. At present, China is accelerating its urbanization and industrialization. There are more than 400 cities suffering from water shortage to varying degree. It is predicted that by 2030 when the population reaches its peak of 1.5 billion people, the conflict between water demand and supply will be further gravened. Hence, dam construction for increasing the water supply from the rivers will provide important guarantee to safeguard the security of both the drinking water supply and grain supply so as to satisfy the development of urban and rural economy and society. 3. Large dams and energy supply Hydropower provides one important support to guarantee the energy security of China in the 21st century. Fossil oil is in shortage in the country, and coal provides the main source of energy. However, the excessive use of coal will certainly cause the problem of excessive emission of carbon dioxide. Consequently, China has to develop various types of renewable energy, including hydro energy, wind energy, solar energy, biomass energy, etc. The total quantity of hydropower in China ranks the first in the world. The theoretical hydropower potential amounts to nearly 700,000 MW and the technically exploitable quantity is 600,000 MW. Presently, the exploited quantity is less than 120,000 MW, indicating that the proportion of exploitation is still very low as compared with the developed countries. The development of hydropower will conserve the resources of coal, oil, and natural gas and also will reduce the air pollution from the emission of carbon dioxide and sulfur dioxide. By 2020, the total installed capacity of hydropower in China will increase to 300,000 MW and the electricity from hydropower will be equivalent to a reduction of the use of 326 million tons of coal, that is, a decrease in 820 million tons of carbon dioxide emission and a decrease in 570,000 tons of sulfur dioxide emission. This will play very important role in sustainable development of energy and in environment protection.

andrewwangzhen

The last 50 years have witnessed the rapid development of large dam construction in China. Abundant engineering practice with scientific and technological innovation has enabled China to make outstanding advancements in large dam construction. 1. The Yangtze Three Gorges Project, the world largest multiple-purpose hydro project, to be completed ahead of schedule The Yangtze Three Gorges Project is a world famous hydro project. The Project will acquire the world topmost important function of flood control, directly protecting the downstream prosperous Yangtze-Han Plain and the big cities like Wuhan Municipality. It will be the largest hydroelectric station with an installed capacity of 18,200 MW, directly supplying huge amount of electric power to Central China, East China, South China and Chongqing Municipality. It has the world largest navigation lock with a capacity of annual shipment volume of 50 million tons and it also greatly improves the Yangtze golden waterway. The Three Gorges Project needs to resettle 1.2 million people, the largest resettlement in the world history of hydro development. The reservoir ecology also receives the most concern worldwide. Starting from 2003, the navigation lock has been in operation and several turbine-generator units have generated electricity. In last May, the concrete placement of the whole gravity dam was completed to the design elevation of 185 m. In this June the dam has retained water throughout the whole length, marking that the Three Gorges Project has commenced to display its overall huge benefits of flood control, power generation and navigation. The construction of the Three Gorges Project totally follows the international practice of contracting mechanism. The concrete placement of the gravity dam has created new world record. The project is of good quality and Phase 3 dam concrete does not have a single crack found in quality checking and testing. The resettlement of over one million people is going on smoothly and the project budget is under good control. It is expected that the whole project will be completed one year ahead of schedule. 2. Overall progress in the technology of various types of high dams By the end of 2005, there are 4,860 dams higher than 30 m completed or under construction. Many of them are topmost in the world. For arch dams, the existing one is the 240-m high Ertan arch dam; several ones now under construction are Jinping I arch dam (305 m), the highest one under construction in the world), Xiaowan arch dam (292 m) and Xiluodu arch dam (278 m). For concrete face rockfill dams (CFRD), the completed one is Tianshengqiao I CFRD (178 m); those under construction are Shuibuya CFRD (233 m), the highest of its type in the world), Sanbanxi CFRD (186 m high) and Hongjiadu CFRD (180 m). For roller compacted concrete (RCC) dams, China has achieved great progress; there were 90 RCC dams completed or under construction, of which the highest one under construction is Longtan RCC dam (216 m), which is the highest RCC dam in the world. In addition, other types of dams/projects like the asphaltic concrete face rockfill dams and pumped-storage power plants also achieve rapid development. 3. Breakthrough in key technology of dam construction The successful completion of the Three Gorges concrete gravity dam, Ertan concrete arch dam, Xiaolangdi sloping core rockfill dam and the ongoing construction of a number of high dam (300 m) is marking the breakthrough progress in the key technology of high dam construction. First, the simulation analysis of mass concrete structure, the mix proportion, construction technology, etc have achieved breakthrough, with the successful placement of 28 million m3 mass concrete in the Three Gorges gravity dam. Secondly, the comparative studies of dam types have achieved a broad range of results, enabling dam construction to attain more reliable safety, greater economy and higher speed in construction. Thirdly, we have gained more developed techniques in dam construction through completion of a great number of high dams under various complicated conditions. For instance, some high arch dams like Xiaowan and Xiluodu dam projects are all constructed on highly seismic areas, while Kezier earth-rock dam is founded on active fault. Fourthly, fruitful results of researches have been obtained in a variety of areas such as geological exploration techniques, river diversion and closure techniques, construction techniques of large scale underground works, dam construction materials and river sedimentation, etc. 4. Further enhancement in dam safety The Chinese government attaches significant importance to dam safety and safety management. The authorities have issued a series of relevant administrative laws, regulations and technical specifications, e.g., Management Regulations on the Safety of Reservoirs and Dams, Provisional Regulations on the Assessment of Safety Impoundment of Hydro Projects, and many others. These are for reforming the management mechanism of water resources projects, for extending the application of new technique on safety monitoring automation network, for realizing the responsibility system of reservoir safety management and for enhancing the safety supervision and inspection of reservoir and dam operation, so as to guarantee the safety operation of dams. Especially, in light of the situation that defects and hazards are found in the existing reservoirs and dams, the governments had put in large investment totaling RMB 40.8 billion (US$5.1 billion), including RMB21.9 billion (US$2.74 billion) from the central government from 1998 to 2005. There are 1,803 such defective and hazardous dams and reservoirs, which have been strengthened up to the safety standards through eliminating all the hidden defects and so the basic functions of these dams and reservoirs have been recovered.

andrewwangzhen

The development of dam construction in China has gone through four stages, characterized by four different restraining factors, namely, technical restraint, investment restraint, market restraint and ecological restraint. With the continual improvement in dam construction technology, continual enhancement in overall economic strength of the country and continual improvement in market mechanism, the first three restraints have been no longer a big factor effecting dam construction. However, the social and environmental elements of ecology and resettlement are exerting more and more impacts on dam construction. Through the fundamental examination on the dam construction over the past decades and through the scientific overview of the past, China is now placing greater emphasis on the issues of ecology for attaining harmonious and sustainable development in carrying out dam construction in this 21st century. 1. Implementation of the concept of harmony between humankind and water in dam construction At the start of this century, China has set a grand target of building an all-round well-off society. For realizing this strategic target, the Chinese Government has advocated the people-oriented principle in all-round coordinated and sustainable development, conforming to the scientific concept of development. The important aspects are to build a resource–efficient and environmental-friendly society. Under the guideline of the scientific concept of development, dam construction in China will proceed in attaching greater importance to the various impacts of dam construction on ecology, in giving equal weight to both engineering construction and ecological protection, in realizing the win-win situation for dam construction and ecological protection, as well as in achieving the target of harmony in humankind and nature. In fact, in China trial effort has been made in carrying out dam construction in the past years to realize harmonious coexistence of humankind and nature. By the end of the last century China put forward the necessity to change the concept from project-oriented way in managing water to resource–oriented way in managing water, The core is to restrain the behavior of humankind itself in order to realize harmony between humankind and water through conservation and protection of water resources and through scientific management. Subsequently, the concept of healthy rivers is proposed and also put into practice in dam construction and operation. Take the example of the Yellow River, in the eighties and nineties of the last century, owing to the unfavorable conditions of water inflow and sediment inflow and also owing to the excessive utilization and development of the water resources, the lower Yellow River suffered from continual desiccation; the longest duration of desiccation was 226 days in 1997, extending 600 km long in the downstream river. This had resulted in continual rise of the river bed and in the decline of the river channel, causing a series of ecological disasters. After the completion of Xiaolangdi Hydro Project on the Yellow River, an important target of the reservoir operation is to rehabilitate the ecology of the lower Yellow river reaches. The special mode of reservoir operation has guaranteed the basic river flow needed for ecology, thereby realizing no river desiccation for seven consecutive years and also recovering the ecology of the downstream reaches and the estuary. For solving the serious sedimentation in the lower Yellow river channel and restoring the flood discharging capacity of the river channel, starting from the end of 1999, the rational operation of Xiaolangdi Reservoir has created a “man-made flood” that enables continual erosion in the downstream river reaches and continual enlargement of the main-flow section area. The flood plain overflow discharge has increased from 2,000 m3/s to 3,500 m3/s due to the operation. As such, the flood discharge capacity of the river channel has been gradually recovered and the river bed has been successfully checked from further rising caused by sedimentation. 2. Proper handling of resettlement in dam construction China is a developing country. From now on up to a certain period, it is still necessary for the country to build a number of dam projects for flood mitigation, water supply and hydropower generation. Consequently, there will be a reasonable amount of reservoir resettlement of people. The Chinese government has been highly concerned about the issues of reservoir resettlement and has laid down the people-oriented principle, adhering to that the resettled people can share the fruitful benefits of reform together with the rest of the whole nation, and persisting in attaching equal importance to project construction, resettlement and ecological protection. The resettlement should follow consistently the development-oriented way to ensure improvement of the livelihood of the resettled people. Recently, China has issued new regulations for reservoir resettlement and new policies for supporting the resettled people throughout the later stage. This is a combination of raising the compensation standard in the initial stage of resettlement with giving greater support in the later stage, a combination of ensuring adequate food and clothing for the resettled people with solving the long-term development problem, and also a combination of giving support from the governments with relying on the self-efforts of the resettled people. The objective is to promote the initiative capability of the resettled people to increase their income. All these are aiming at realizing sustainable development of society and economy both in the reservoir areas and in the new resettlement areas. In this way, it will be possible that the construction of one hydropower station can bring about the economic development and environmental improvement of one area and also the prosperity of the resettled people. The Three Gorges Project in handling resettlement of nearly 1.2 million people provides an evidence of a successful case study. 3. Dam construction and river sedimentation When a dam is built on a river, it blocks the natural river channel and changes the river flow pattern, especially for a sediment-laden river, it will also alter the sediment transport pattern. This is one important ecological issue arisen from the construction of a dam. The design standards of reservoir construction in China has stipulated that in designing and constructing a new reservoir studies must be conducted on the natural characteristics of sediment movement in the river, on the sediment sluicing measures, on the possible impacts of the dam on the river bed and river regime, as well as on the necessary preventive measures. For the existing dams that have already caused adverse impacts on the river sedimentation, necessary renovation of the dams and changes of the reservoir operation modes should be executed to alleviate such adverse effects. One example is the Sanmenxia Hydro Project, which had changed the flow pattern of the Yellow river channel and the sediment transport pattern, leading to serious sedimentation in the upstream river channel. For alleviating these adverse impacts of reservoir sedimentation, the operation of Sanmenxia Reservoir is performed in such a way that during flood season the river inflow will all be discharged fully off the reservoir, whereas in non-flood season the reservoir water level will be put under operation control, realizing the effective control of sedimentation in the reservoir and the upstream. Another example is Guanting Reservoir, which suffered serious reservoir sedimentation after its completion in 1955. For controlling the sedimentation immediately upstream of the dam, the density current that can easily occur in the reservoir on the sediment-laden river is fully made use of to flush away the deposited sediment by basing on the characteristics of the density current with respect to its formation, development and transportation. This has decreased the reservoir sedimentation, prolonged the service life of the reservoir, and maintained the comprehensive benefits of the reservoir. 4. Dam construction and biodiversity Dam construction will change the hydrological regimes of the river, alter the environments of the living beings, and affect the biodiversity. The Chinese government has been adhering to the principle of protecting the ecology and the biodiversity of the river. We have issued relevant policies, laws and regulations, which necessitate that the protection of river ecology must be fully considered in all aspects of the planning, design, construction, operation and management of the dam construction. This is to realize the rive development requirement that “the protection will be within the development, while the development will be within the protection”. Various measures should be taken to reduce the impacts of dam construction on the survival of fishes in the rivers. These may include building fish passage facilities during dam construction, or breeding fishes to supplement the quantity of living beings in the river. Moreover, some other measures can also be adopted, such as regulating the discharge flow from the reservoir to minimize the impact of low temperature on the living beings, and changing the reservoir operation mode to improve the river regime and thus compensate the environmental demand of living beings in the characteristic river flow. In the progress of sustainable development in this 21st century, China in its dam construction will continue to persist in the new concept of harmony of humankind and water and persist in building a resource-efficient and environmental-friendly society, and will follow the road of orderly, healthy and rational development. In ending my speech, I would like to express on behalf of the Ministry of Water Resources our sincere gratitude to all the members of International Congress on Large Dams for their long support and assistance to China. I wish great success on this Symposium and the Twenty Second ICOLD Congress. Thank you all for your attention.