Water is the source of all things. 70% of the earth's surface is covered with water, but 97% of it is seawater that humans can't drink or use directly. Of the remaining 3% non-salt water, only 1/3 can be used for human development. Even so little fresh water is extremely uneven in distribution. At present, 232 million residents in 26 countries around the world are often short of water, and 400 million residents have already faced a "water crisis". Water shortage has sounded the alarm for human survival and development; The shortage of water resources has become a "bottleneck" restricting regional economic development. The modern water crisis is another serious problem for human survival. With the development of social economy, it is difficult to meet the water demand of economically developed areas only by transferring water within the basin, and it is urgent to transfer water across the basin. Inter-basin water transfer is an engineering measure to solve the uneven distribution or shortage of water resources in time and space. With the growth of population and economic development, the problem of water resources has become a bottleneck factor restricting human survival and sustainable development in the 2/kloc-0 century. The uneven distribution of water resources and the objective existence of water demand balance in human society make water transfer inevitable. Since 1950s, many water transfer schemes have been put forward abroad. According to incomplete statistics, at present, there are more than 160 large-scale inter-basin water transfer projects built, under construction or planned in 24 countries in the world, covering all regions of the world. For more than half a century, experts and scholars at home and abroad have put forward many decision-making models and methods for planning, management and operation of inter-basin water transfer projects, which can be summarized into two categories: first, after simplifying the complex inter-basin water transfer system through various methods, a single mathematical planning model or simulation model is used to study the planning, management and operation decision-making of inter-basin water transfer projects; Secondly, the decision-making model and method of large-scale system optimization are directly adopted. Through the establishment of hierarchical structure models of various large-scale systems and the combination of various mathematical planning or simulation technologies (including self-optimizing simulation technology), the planning and management decision-making research of such projects is carried out. In recent years, with the continuous development and perfection of new theories and methods such as fuzzy mathematics, decision support system and expert system, and neural network, people began to explore the possibility of applying these new theories and methods to the planning and management decision-making research of inter-basin water transfer projects. For example, Jamieson et al. established the mixed decision-making model structure of inter-basin water transfer planning based on the planning, design and management decision-making process of general inter-basin water transfer system, and suggested using mixed integer programming model to optimize the system structure, the scale of engineering facilities included in the simulation model design, and dynamic programming method to conduct real-time decision-making research of the system.

1 project example

1. 1 Israel's South-to-North Water Transfer Project is extremely short of water, and there are more water resources in the south than in the north. The trunk line of the South-to-North Water Diversion Project is about 300 kilometers long, with a diameter of 2.2 ~ 2.8 meters. It passes through several pressurized pumping stations. The total length of branch pipelines exceeds 65.438+million kilometers, and the annual water supply is 654.38+04 billion cubic meters. The project not only promoted the economic development in the south, but also turned a large desert into an oasis, expanding the living space of Israel.

1.2 Australia Snow Mountain Project Australia has a dry climate and a relative shortage of water resources, so the Snow Mountain Project was built. It builds a reservoir on the eastern slope of the snow-capped mountain to store water, and leads the excess snow water to the western slope to generate electricity along the water transfer route by using the drop. Snow Mountain Project is one of the most complicated large-scale hydropower projects in the world, including 7 hydropower stations, 80km diversion pipeline, 11*145 km pressure tunnel, 16 dam,1pumping station, 5 10km high-voltage power grid, etc. The annual water supply is 23.6. With its help, the water quality in the west has also been greatly improved and the ecological environment has become more pleasant.

1.3 California South-to-North Water Diversion Project The western United States is dry and short of water. For this reason, more than a dozen water transfer projects have been built, the most representative of which is the famous California North-South Water Transfer Project. Northern California is full of rain, and the Sacramento River often overflows. The southern sky is dry and the earth is cracked and smoking, but there are two-thirds of the population in the whole state, and the distribution of water resources is extremely uneven. As early as 19 19, geologists put forward the idea of transferring water from south to north. After World War II, the economic development and water shortage in California became more and more serious, and the water transfer project was put on the agenda. To this end, the debate between the north and the south of California is endless, and the media is also adding fuel to the fire, publicly calling on voters to oppose the state government's water transfer plan. 1960, California held a referendum on this issue, and the result was 5 1% in favor and 49% against, with only 170000 votes in favor. It has been noticed that in the northern water supply area where most counties voted against it, 1 county also voted for more than 50%, because the residents of this county realized that the project was really beneficial to flood control and disaster reduction. The project was completed on 1973, and 1990 reached the designed water conveyance capacity. The project is still being expanded and improved. In 2002, the project generated 8.57 billion kWh of electricity, benefiting a vast area with a population of 23 million centered in Los Angeles. At present, California ranks first in the United States in population, economic strength, irrigated area and grain output, and Los Angeles has developed into the second largest city in the United States. At that time, many residents who voted against it had to admit that the contribution of the South-to-North Water Transfer Project to California's economic take-off was indeed indispensable.

1.4 Moscow Canal Project in Russia 1930. After Moscow's water resources were exhausted, the former Soviet Union began to build the Volga Canal in Moscow (renamed Moscow Canal after 1947), which not only provided a stable water source for the capital Moscow, but also significantly improved the water quality and urban landscape of moscow river.

1.5 west-to-east gas transmission project in Egypt. 96% of Egypt's territory is desert. In order to develop the Sinai Peninsula, the West-to-East Gas Transmission Project was built. The trunk line is 262 kilometers long, with 7 pumping stations and an annual water supply of over 4 billion cubic meters. It provides valuable water resources for the Sinai Peninsula and promotes the all-round development of the Sinai Peninsula. It has also made great contributions to the overall economic development of Egypt.

2 influence

2. 1 Reduce the flood disaster in the water transfer area. For the water area, the serious flood disaster can be said to be the biggest ecological and environmental disaster. The water conveyance project has obvious flood control benefits in the outlet area, and its flood control function is essentially to reduce the occurrence of ecological and environmental disasters.

2.2 Improving the climate, environment, groundwater and water quality in the water conveyance area is conducive to improving the climate and environment on both sides of the strait, especially to the recharge of groundwater along the line. However, the greater impact of water conveyance channels on the natural ecological environment lies in the impact on the terrestrial ecosystem. Many wasteland, desert and coastal areas have been irrigated into fertile fields, vegetable fields, forest farms and orchards, and the groundwater level on both sides has generally risen, which is a useful supplement to groundwater overexploitation.

2.3 Alleviating the ecological crisis in water transfer areas Water transfer can increase the water area in water-deficient areas, leading to the strengthening of vertical water-gas exchange between hydrosphere and atmosphere, biosphere and lithosphere, which is beneficial to water circulation, improving meteorological conditions in water receiving areas and alleviating the problem of ecological water shortage. In addition, water transfer can also increase the surface water supply and soil water content in the water receiving area, form local wetlands, which is beneficial to purify sewage and air, collect and store water, compensate and adjust the amount of rivers and lakes, and protect endangered wildlife.

2.4 Disadvantageously affecting the water transfer project will also lead to the reduction of the flow of the water transfer river, resulting in the backflow of salt water in the estuary and the destruction of the estuary ecosystem; Causing insufficient water for ecological environment in the water transfer area; The river appears "water bloom" flooding, algae reproduction, odor and discoloration; River flow conditions deteriorate; The industrial and agricultural water sources in the downstream of the water transfer area and the estuary area are exhausted, and the water quality is deteriorating.

3 Conclusion

3. 1 There are many problems in China's water resources, such as resource-based water shortage, time-space water shortage, pollution water shortage, wastewater water shortage, regional water shortage and serious shortage of per capita water resources, which seriously affect and restrict the sustainable development of social economy. In a certain period and region, it is necessary to adopt inter-basin water transfer project, which is a strategic measure for sustainable development.

3.2 Inter-basin water transfer is a measure to transform nature, involving geography, environment, society, economy, culture, history, legal rights and sustainable development, and it is the object of comprehensive research in many disciplines, departments and regions. Only after extensive and in-depth research and demonstration can we seek advantages and avoid disadvantages. Only by attaching importance to the study of water resources and water environmental carrying capacity can we promote the sustainable utilization of water resources.

3.3 The planning and design of water transfer project should pay attention to the ecological environment, do a good job in the environmental impact assessment of the project, and weigh the advantages and disadvantages; Before and after the implementation of the project, as well as the whole process of project completion and operation, strict management should be carried out from beginning to end to reduce pollution damage; Different water transfer projects have their own uniqueness, and their adverse effects on the environment may be different, and their effects are also different. Therefore, there are many specific evaluation methods of environmental impact, and we should pay attention to the comprehensiveness, flexibility and purpose of the methods when choosing them, so as to accurately find out the real impact, master the key impact, evaluate the actual impact and identify the overall impact.

3.4 Inter-basin water transfer has its advantages, but the long construction period and high cost are its weaknesses, and it is not the only way to solve the water shortage. Throttling is as important as scientific management of sustainable utilization of water resources. Solving the uneven distribution of water resources in time and space is a major prerequisite for the implementation of water transfer projects. As far as water quantity is concerned, to determine whether a region needs water transfer, it is necessary to analyze the nature of water shortage in the water transfer area. In areas with scarce resources, it is easy to determine the necessity of water transfer. The necessity of water transfer should be fully demonstrated in the water-deficient areas with incomplete resources; It is not a resource-based water shortage area at all, and there is no need to transfer water at all. Therefore, we must judge the nature of regional water shortage, carefully analyze the balance between supply and demand of regional water resources according to the short-term and long-term needs of the economy and society, and determine the reasonable scale of water transfer. At the same time, inter-basin water transfer is an important source of income in water transfer areas, and the source of income must be carried out on the premise of throttling. In most cases, water transfer should be a supplement to local water sources. Only by realizing regional throttling and fully tapping the potential of regional water resources can water transfer be the most economical and reasonable. The countermeasures of tapping the potential and throttling simultaneously can not only alleviate the water shortage pressure before the implementation of the water transfer project, but also reduce the scale of the water transfer project, thus reducing the loss of interests in the water transfer area and the negative environmental benefits of the whole project.

3.5 Water saving and pollution control are two major problems to solve the rational allocation and sustainable utilization of water resources. The sustainable development of social economy is restricted by the carrying capacity of regional water resources and water environment, and throttling is the most direct and main method to improve the carrying capacity of water resources and water environment. Pollution prevention is the eternal theme of water resources protection and management, and sewage treatment is a problem that must be solved. Especially in areas with water shortage and serious pollution, there is no way out without pollution control. The construction of water transfer project must follow the principle of "three first and three later", that is, the principle of "saving water first and then transferring water, pollution control first and then passing water, environmental protection first and then using water".

3.6 Water regulation should be reasonable. ① Both local water and foreign water are valuable water resources, which should be considered in a unified way and allocated rationally. In principle, diversion should be considered on the basis of full and reasonable utilization of local water resources, otherwise, the more diversion, the more waste and pollution. (2) The ecological water must be met. In the calculation of water consumption, the water demand for vegetation, afforestation and greening must be included, and the over-exploited groundwater must be replenished. The exploitation and utilization of groundwater must be balanced in a long series, replenished in wet years and temporarily overexploited in dry years. Each river channel should maintain a certain flow rate in a certain season, so as not to make the river channel cut off, shrink and deposit for a long time, which will worsen the situation in the estuary area. (3) Follow the principle of demand determined by supply, change water supply management into water demand management, and adjust the industrial structure through water demand management, so as not to let a large number of water-consuming industries develop indefinitely. (4) In the process of determining the adjustable water quantity, the conflict of water interests between the water diversion output area and the water diversion input area is inevitable. In principle, it will not affect the current situation and future water demand of the export area, or reduce the impact on the transfer area through compensation to ensure the interests of the transfer area.

3.7 The ownership of water resources belongs to the state, which requires the government and its water administrative department to play a macro-control role in the development, utilization, protection and management of water resources, guide and adjust the sustainable development plan of river basin economy, control water according to law, prevent pollution, reduce expenditure, and realize the optimal allocation and sustainable utilization of water resources. This includes: formulating relevant water conservancy policies, formulating and establishing corresponding legal guarantee system, establishing management institutions and industry access, etc.

3.8 Inter-basin water transfer should be based on water rights. At present, water has become more and more important as a resource. As a resource, water is regional. Transferring water from one area to another is at the expense of the former's water rights and interests. According to the law of market economy, the beneficiary areas should pay equal benefits. Under the premise of not infringing the interests of the original water rights holders, the allocation of water resources can be improved through water rights trading, thus achieving a "win-win". The paid use of water resources requires realizing the paid transaction of water resources and water rights, forming a water trading market, establishing a water resources management system based on water rights and water market theory, giving full play to the role of market mechanism, and making economic means play an important role in water resources allocation.