With the progress of human society and economic development, industry, agriculture and cities are expanding day by day, especially the world population is increasing rapidly. In addition, human activities are out of control, leading to environmental degradation, water pollution and serious waste, forcing the world's water resources to become increasingly scarce. According to statistics, the global water consumption was 500 billion m3/y at the beginning of the 20th century, and it has increased to 500 billion m3/y by the end of this century (an increase of 10 times). The water consumption in the American continent increased by 1954-1994, and that in the African continent increased by more than 300%. The groundwater exploitation amount is 550 billion m3/y (1980s-1990s), of which more than 65.438 billion m3/y has been discovered in more than 654.38+00 countries, accounting for 8.5% of the total exploitation amount. At the Ministerial Meeting of the Second World Water Forum held in The Hague in March, 20001,the World Water Committee of the 20th century reported that at present, there are11billion people in the world who do not use clean water, and 2 1 billion people do not have good sanitation facilities. The report also emphasizes that only 2.5% of the water on the earth is fresh water, and two thirds of it exists in ice sheets and glaciers and cannot be directly used. About 20% of the remaining water resources are in inaccessible areas, and the remaining 80% of the water falls to the wrong place at the wrong time through monsoon, storm and flood. The water resources directly used by human beings are indeed limited, only 65438. According to the report, by 2025, the global population will increase by 3 billion, the required water supply will be short by 20%, and the waste and pollution will reach more than 50%. According to the estimation of "balance and population correlation", the water shortage population will reach 6543.8+0.5-2 billion in 20-30 years. According to the statistics of UNESCO, the per capita water consumption is about 8000- 10000 tons according to the world population of 5-6 billion. 1997 The First World Water Forum reported that the per capita fresh water consumption has dropped to 4,800 m3 (17300m3 in 995) because the world water consumption has soared by six times, far exceeding 4000km3. Due to the uneven distribution of only fresh water, more than 60%-65% of fresh water is concentrated in 9- 10 countries, such as Russia, the United States, Canada, Indonesia, Colombia and so on. Among them, Austria has 84 billion tons of water every year to meet the water demand of 370 million people in the European Union, and the water supply income reaches 654.38 billion euros. However, more than 80 countries, which account for 40% of the world's population, are short of water resources, among which nearly 30 countries are seriously short of water. Africa 19, such as Qatar 9 1m3, Kuwait 95m3, Libya 1 1 m3 and Malta 82m3, ranks fourth in the world. However, in several countries rich in water resources, the consumption of water resources has risen sharply. For example, the per capita daily water consumption in new york is 600-800 liters, that in Osaka is 575 liters, that in Paris is 443 liters, and that in Rome is 435 liters. The crisis situation of water resources in China shows that the total water resources in China is about 2.810.24 trillion cubic meters, accounting for 6% of the total runoff resources in the world; It is also the country with the largest water consumption. 193, the national water intake (fresh water) was 525.5 billion cubic meters, accounting for 12% of the world's annual water intake, which was higher than195, when the fresh water intake in the United States was 470 billion cubic meters. Due to the large population, China's per capita water resources are currently 2500 cubic meters, which is about 1/4 of the world's per capita water resources. After ranking 100, China is listed as one of the countries with poor water resources per capita in the world. In addition, our country belongs to monsoon climate, and the distribution of water resources is uneven in time and space, and the natural environment between north and south is quite different. Among them, the per capita water resources in the nine northern provinces are less than 500 cubic meters, which is a water-deficient area; Especially in recent years, the rapid increase of urban population, the deterioration of ecological environment, the backwardness of industrial and agricultural water technology, waste and serious water pollution have made the already poor water "worse" and become the bottleneck of national economic construction and development. According to recent media reports, 364 cities at or above the county level are short of water, with a daily water shortage of/kloc-0.3 million cubic meters and an annual water shortage of 5.8 billion cubic meters. Cities with severe water shortage involve 654.38+07 provinces and autonomous regions, including developed coastal cities. At the same time, there are still 36.2 billion tons of sewage discharged (80% of which are untreated). It is reported that 850 rivers in China 1200 are polluted, which is enough to show the grim situation of water pollution. In August this year, Xinhua News Agency reported that the vicious over-exploitation of groundwater has caused more than 80,000 square kilometers of underground funnels in China, leading to geological disasters of land subsidence. At present, there are 30 cities with different degrees of land subsidence. Funnel formation in North China has long been reported. Recently, the land subsidence in Xi has attracted people's attention. It has been found that 9- 1 1 cracks run through the city 155 square kilometers, and 2,600 buildings are threatened. In addition, there are more than 1200 square kilometers of seawater intrusion around Bohai Sea and Miaodong Peninsula. The strategic position of water in social economy With the gradual shortage of water resources, the economic and social functions of water are becoming more and more obvious, and the status of water in economic society is getting higher and higher. Many countries in the world, especially water-deficient countries, regard water conservancy construction as the basic industry of national economy, and invest huge sums of money to build various types of reservoirs, dikes and water storage, water storage and water diversion projects to ensure the supply and demand of water resources. According to the announcement of the World Water Commission, the global water investment must be increased from $75 billion per year to $654.38+08 billion. Another example is the recent data showing that the South-to-North Water Diversion Project in China has started. In the next 10 year, only the east diversion project (East Canal and Central Canal) will cost 25 billion US dollars, which is even more amazing. In addition, countries' investment in new technologies of water pollution prevention, water recycling and domestic water treatment is becoming more and more urgent and increasing rapidly. Water-deficient countries in the Middle East, such as Israel, Kuwait, Jordan, Libya, Oman, Qatar, Saudi Arabia, United Arab Emirates, Yemen and Gaza, mainly drink reclaimed water. Among them, rich oil-producing countries, such as Saudi Arabia, have invested 5 billion dollars in seawater desalination projects before 1997 in an attempt to solve or alleviate the water supply crisis; Israel has invested heavily in seawater desalination, both in investment and technical equipment. Israel alone imports 65.438+0.5 billion cubic meters of fresh water from Turkey every year, which is expensive. Malaysia exports 39 million tons of fresh water to Gulf countries every year. In order to transport fresh water, it changed the previous oil tanker into a water tanker. In order to develop groundwater and replenish new water sources, countries have also invested huge sums of money to carry out basic research on hydrogeology and conduct comprehensive exploration and drilling. With the aggravation of the world water crisis, the status of water resources is not only reflected in the economy and society, but also in the conflicts between military and countries. At the meeting of the World Water Forum held in Marrakech, an ancient city in central Morocco, the document "Preface" prepared for the forum said that it was predicted that there would be a major crisis in the world water resources before 2050 ... that "water may become a rare thing and a rare resource by 2 1 century" and called for "avoiding international conflicts caused by the lack of water resources". At the United Nations Conference on Human Settlements held in Istanbul, Secretary-General Wally N 'Dow warned: "According to my guess, in the next 50 years, we will see that the fuse of violent conflicts between countries and people will no longer be oil, but water." At the 84-country ministerial meeting on water resources held in Paris, France, Abu Zaid, chairman of the World Water Committee, proposed that "the lack of water resources is the root cause of tension between Middle East and African countries". The key to the peace talks between Israel and Syria is the Golan Heights occupied by Israel, and its strategic significance is also the water resource problem called water tower in the Middle East. For more than 30 years, despite many negotiations, it is difficult to reach an understanding, which involves the control of water supply sources and is still one of the main obstacles. Ismail Saradjedine, vice president of the World Bank, predicted that "if many wars in the last century were for oil, there will be wars for water in the next century". In the Mekong River basin, 50 million people in river areas are threatened by water because of the construction of reservoirs and dams in Laos and Thailand. Cambodia and Vietnam have warned that this will lead to conflict. The concept of water resources and its scientific connotation Water resources are the material basis of all production and life in human society. Without water and water resources, there would be no human beings. However, water and water resources are different in the concept of natural substances, and resources are not equal to water. Water resources account for only three thousandths of the earth's system water, about 4.7 trillion tons. As water resources, they are very limited and irreplaceable. The definition of water resources by UNESCO and the World Meteorological Organization is: "As a resource, water should be available or possibly available, with sufficient quantity and quality, suitable for a certain water demand and long-term supply". There is no unified concept definition in China, so some people say: "the water on the surface of the earth can be used by human beings"; Others think that "natural water in various forms (gas, liquid or solid) in nature" and so on. Water resources essentially refers to the sum of surface runoff and underground runoff. Water resources are generally divided into two categories: surface water resources and groundwater resources. Due to the influence of global climate change, surface water resources are unevenly distributed in time and space, so it is difficult to play its water supply function according to its natural laws. Groundwater resources deteriorated due to ecological pollution, especially over-exploitation, have issued a "yellow card" warning. As early as 1977, the message that "water resources will soon become a profound social crisis" was sent out. In recent 20 years, the water resources problems in the Jordan River basin, the Tigris River basin, the Euphrates River basin and the Nile River basin have become the fuse of differences (conflicts) between countries. Disputes over international rivers and waters in South Asia are one after another; North America, South America, North Africa and other places also have cracks due to international rivers and development (utilization) problems. Especially with the rapid increase of population, the environment is deteriorating, and the contradiction between water shortage and demand is becoming increasingly acute. The global water resources problem has become a hot issue that governments all over the world pay attention to and urgently need to solve. In this situation, governments all over the world and relevant international organizations have invested a lot of money in water resources research. After 50-60 years' practical development, water resources science has formed a multidisciplinary comprehensive discipline system, which mainly studies the formation and evolution of water resources on the earth and the laws of scientific utilization to meet the needs of sustainable development of human production, life, industry, agriculture and social economy. Water resources science includes water resources development and management, water resources system analysis, water resources engineering and environmental improvement, and has been extended to water resources sociology. On the basis of mutual blending, infiltration and absorption of basic disciplines such as natural science, water conservancy science and hydrology, sub-disciplines have been established, including: water resources ecology, water resources environment, water resources informatics, water resources engineering, water resources management, water resources system analysis, water resources economics, water resources law, water resources ethics and so on. , and is developing outward, including the atmosphere, glaciers, oceans, polar regions and so on. With the implementation of "2 1 century agenda", the characteristics and advantages of the discipline itself will continue to play, and the connotation of the discipline will continue to be improved and enriched, and a multidisciplinary and comprehensive water resources science system will be established.