(China Geo University (Beijing))
"Water and City" is a very complicated subject, which is of great significance in the current social and economic development of China and the world. For a long time, in the economic construction of China, the problem of water resources has troubled, troubled and debated the whole society, and it is also a major problem to be solved urgently. Around this theme, this paper holds that it is of the most basic and critical significance to understand the water resources situation in China and its restrictive effect on urban development. At the same time, it is also the most reliable problem in earth science research and analysis. This paper only takes Beijing as an example to discuss this point, and puts forward a plan to solve the water shortage in North China.
The earth is the only known planet with liquid water in the universe. Water breeds life on the earth and nourishes human civilization. Water is an extremely important basic material condition for human survival and social and economic development. Nature has endowed mankind with the most precious water resources, but the available water resources are unevenly distributed in time and space because the water on the earth circulates according to its own inherent laws. Some inland and arid countries lack water, and there is too much rain in coastal areas, which sometimes causes disasters. China has a vast territory and a long coastline. Due to the particularity of climate, regional geology and topography, there are many unfavorable factors in the allocation of water resources: the water-rich area in the southeast coastal area is not large enough, while the inland water-deficient area exceeds half of the land area, so it is a country with insufficient water resources as a whole. However, China is not an absolute water-deficient country, and the main contradiction is that the temporal and spatial distribution of precipitation is extremely uneven. Therefore, at present, with the rapid development of China's social economy and urbanization, the rigid demand for water resources is increasing, and there are also factors such as the global climate drought background and the lack of water resources management, which have led to the embarrassing situation of "more water but less water, muddy water, dirty water and uneven water" for a long time. It has seriously affected and restricted the development of building a well-off society in an all-round way. At present, whether we can fully tap the potential of water resources, scientifically allocate and manage water conservancy, and achieve the goal of ensuring water supply to the maximum extent is a test of the wisdom of contemporary China people, especially the scientific and technological team. Our ancestors once gave excellent answers. In the history of our country, we have made achievements in flood control, drought resistance, irrigation and water transportation that deserve our pride. Many developed countries have also created advanced water resources development and utilization and efficient flood control projects according to their own national conditions. The effective development and scientific management of water resources in China can only rely on the wisdom and innovation of China people.
1. Strong constraints of water resources on urban development-A case study of Beijing
(A) the history of Beijing's water resources development
Beijing is located in the piedmont plateau formed by the intersection of Xishan Mountain and Dujun Mountain, and on the alluvial plain formed by the deposition of four major river systems, which is high in the northwest, low in the southeast and open to the sea. In ancient Beijing, there were many rivers and springs, dense lakes and wetlands, complete types of surface water and groundwater resources, and abundant reserves, which had the superior conditions for building a densely populated city. Beijing has a history of 3000 years, and it has been nearly 800 years since the Yuan Dynasty was designated as the capital of the Yuan Dynasty. With the growth of population and economic aggregate, the capital of each stage is accompanied by the development and utilization of water resources with different properties and occurrences to ensure the demand of the city. See table 1 for a brief history of water resources development in Beijing.
Table 1 History of Beijing's Urban and Population Development and Water Resources Development
sequential
As can be seen from the table 1, with the expansion of urban scale and the increase of population, Beijing must continuously develop various types of water resources: from surface water to groundwater until the development of ultra-deep groundwater, and from the suburbs near the city to neighboring provinces to supply water, so as to attract distant rivers, such as Sanggan River in the upper reaches of Yongding River in Lvliang Mountain area; And the long-distance regulation of the Yangtze River water. From 2007 to 2009, the population of Beijing increased dramatically. Except for over-exploitation of deep groundwater, almost all methods such as developing reclaimed water and increasing artificial rainfall have been adopted. At present, the development of water resources in Beijing has reached its limit, and the per capita water resources in Beijing are declining.
(B) Beijing water resources status and bottom line
According to the report in 2007, the annual water consumption in Beijing is 3.4 billion-3.6 billion cubic meters, and the current annual water supply is 2.6 billion cubic meters, with a gap of 654.38+0 billion cubic meters. At present, there are five ways to ensure water use in Beijing: ① Overexploitation of groundwater. From 2000 to 2007, the city has over-exploited 5.6 billion cubic meters of groundwater. As a result, the groundwater level in this area drops, as shown in figure 1. ② Expand circulating water, develop reclaimed water and improve utilization rate. ③ Save water. (4) Foreign aid, such as water supply, has predicted that the Yangtze River will be transferred to Beijing in 20 10 to partially alleviate the water shortage in Beijing (Beijing TV Station February 2007 15). ⑤ Transfer water from Hebei and Shanxi to protect Beijing. 20 10, the South-to-North Water Transfer Project failed to reach Beijing, and it will take another five years. Therefore, the present situation of water resources in Beijing is extremely unsatisfactory. According to statistics in 2006, the average annual rainfall in Beijing is 585 mm, equivalent to 9.828 billion cubic meters of precipitation, resulting in surface runoff of 65.438+77.2 million cubic meters and underground water storage of 2.559 billion cubic meters. The local self-produced water resources totaled 3.739 billion cubic meters. However, in recent 10 years, the annual rainfall in Beijing has decreased by 10% ~ 20%, and it is unlikely to increase rainfall. According to the population of Beijing in 2005, the per capita water resource is 248 cubic meters, which is 1/8 of the national per capita water resource and 1/20 of the global per capita water resource. Ranked behind 100 in the world 120 capitals. According to the population in 2009, the per capita water resources are less than 200 cubic meters.
Figure 1 Schematic diagram of groundwater level decline in Beijing suburbs for many years.
(3) Planning, reality, controversy and way out.
20 1 1 1 The newspaper reported that the permanent population of Beijing at the end of 2009 was19.72 million; According to the 11th Five-Year Plan, the population of Beijing in 2008 was16.25 million, more than 3 million. It is planned that the population of Beijing will reach180,000 in 2020, 654.38+00 years ahead of schedule. "Eleventh Five-Year" population planning has made progress; In fact, during the 11th Five-Year Plan period, the average population increased by 543,000, which was 200,000 more than that during the 10th Five-Year Plan period. At present, we must face the test of breaking through the 20 million population mark. At present, Beijing is facing a crisis situation of population explosion and water resources depletion. Where is the bottom line of Beijing's water resources? According to the research results of Beijing Geological Exploration Bureau, the total groundwater reserves in Beijing150m depth range are 60 billion cubic meters. From 200/kloc-0 to 2008, the average annual water supply gap in Beijing was 65.438+0.27 billion cubic meters, with a cumulative deficit of 65.438+0.02 billion cubic meters. In 1960s, the depth of water wells was less than 100 m, but at present, all the deep wells in plain areas 100 m have been abandoned, and the newly drilled water wells are as deep as 150 m.. If 25 million people are supplied with water, the groundwater in Beijing will be completely exhausted in about 20 years. This is the bottom line of Beijing's water resources.
Investigating the causes of population explosion in Beijing in recent years is related to the specious understanding that has appeared for some time. Some economists and media people hold a negative attitude towards the formulation of "the limit of urban population carrying capacity". Practice has proved that urban development and population size are strictly restricted by natural basic conditions, and water resources are the first restrictive factor in northern China. 20 1 1Mar 17 Professor Wu Yongping of Tsinghua University School of Management, a member of Beijing Municipal Political Consultative Conference, suggested "decentralizing some capital functions to surrounding areas" and pointed out that this problem should be solved by the central government. The author agrees with Wu's suggestion. Beijing's urban functional orientation and population size should be planned in strict accordance with Scientific Outlook on Development's concept.
However, even if the population is strictly reduced according to Beijing's original plan, it is still necessary to open up a new water source with low price, large flow and stable water supply for Beijing from the standard requirements of building a "world city". This paper suggests to solve the problem of water shortage in North China, find water sources from all over the country, and put forward a solution to divert water from the Yangtze River to Beijing.
Second, the present situation of water resources in China and its deep development potential
(A) the overall situation of water resources in China.
China is a vast country with complex climate and topography. Due to the influence of monsoon, the precipitation distribution in the whole country is extremely uneven. In the geological structure background, due to the continuous uplift of the Qinghai-Tibet Plateau since Permian, the terrain in the southwest is steep and high, and it drops sharply to the low and broad plains in the east, forming a stepped steep slope terrain, which leads to the rapid flow of rivers, carrying a lot of sediment, and the thin soil layer, which is not conducive to storing groundwater and buffering the flow rate of rivers. This is the geological background of frequent floods and droughts. According to the annual report of the Ministry of Water Resources, the national average precipitation in 2004 was 600.6 mm, equivalent to the total precipitation of 5,687.64 billion cubic meters. In that year, the total amount of water resources occupied in China was 2,465.438+0.296 billion cubic meters, which was less than the average of 2,865.438+0.244 billion cubic meters in recent 40 years 12.9%, ranking sixth in the world. China's per capita water resources are 2,300 cubic meters, accounting for 1/4 of the world's per capita water resources, ranking 2 1 in the world, and being listed as one of the world's 13 water-poor countries by the United Nations. The cultivated land in China occupies water resources per mu 1770 cubic meters, which is 3/4 of the world average. The population of China accounts for 22% of the world's total population, but the renewable fresh water accounts for 8% of the world. On the whole, China's water resources are not rich enough, the per capita and per mu water consumption is low, and the distribution of water resources is uneven among regions, years and years, which are unfavorable factors in natural conditions. The frequent floods and droughts in China's history, coupled with global warming in recent years, have increased the area of water-deficient areas. At present, nearly 400 of the 655 cities in China are short of water, of which about 200 are seriously short of water.
In recent years, the shortage of water resources in China has obviously increased, which is manifested in the following aspects: the rainfall in North China has decreased, and there has been a continuous drought in winter and spring of 2010-2010, and Shandong and Henan have suffered a severe drought once in 60 years, which has intensified; The vast northwest region is still dry and short of water; In the spring and summer of 20 10, there was a drought in Yunnan-Guizhou Plateau and drought in Chongqing for years. In recent years, due to the weakening of the typhoon, the rainfall in Guangdong, Guangxi, Fujian and other places is insufficient, and the drought in the south has attracted attention. In recent years, the frequent occurrence and expansion of floods and droughts are not only due to irresistible factors, but also related to some vacancies in national water resources management.
(b) The water resources potential of China needs to be reassessed.
At present, there are different opinions on whether there is still development potential of water resources in China. One view is that China's water resources have no development potential, and the only way to solve the water problem is to save water and prevent pollution. Vigorously advocating water conservation, such as improving agricultural irrigation efficiency, adjusting water price and controlling water pollution, are all necessary and effective water control measures. However, from the aspect of deep development of water resources, the experience of some grass-roots water conservancy departments deserves attention and promotion. For example, the Water Resources Department of Shandong Province summed up the idea of "flood recycling" and a set of water management and engineering measures to solve the problem of flood storage and drought prevention according to the years of water management practice in the province, which ensured the growing demand for water resources for social development and economic construction in the province.
Judging from the overall precipitation, China is not an absolutely water-deficient country: the national average annual rainfall is 600.6 mm, and the per capita water resource is 2,300 cubic meters. The problem is that a lot of water resources flow into the sea or are evaporated. It is an effective and feasible way to overcome China's water crisis to find out the invalid water resources through investigation and certain engineering measures, that is, to manage water conservancy by adopting the principle of "increasing revenue and reducing expenditure". The countermeasures of combining flood control and resource utilization put forward by Shandong Province are in line with the contemporary water resources development and protection concepts of "integrated management of water resources and river basins" and "sustainable water management" put forward by the Fifth World Water Congress held in Beijing in September 2006.
(3) Five suggestions on the deep development of water resources in China.
(1) Evaluate the development and utilization rate of water resources in major rivers and lakes in China. Some data in Table 2 are quoted from water resources planning and design, numbered 1, 20 10, and supplemented.
Table 2 Development and utilization rate of water resources in major river basins and lakes in China.
As can be seen from Table 2, in addition to the high utilization rate of Haihe River and Taihu Lake, there are a considerable number of rivers and lakes in China, especially in the south. In order to solve the problem of frequent droughts in the south, we should fully plan, carry out engineering experiments and further develop and utilize them. Due to the severe drought in northern China, some water areas are over-exploited, such as the Yellow River cut off and groundwater over-exploitation in Beijing and Hebei, and so on, and countermeasures should be studied as soon as possible. However, in view of China's national conditions, the international understanding that the development and utilization of river basin water resources should not exceed 40% needs to be reconsidered. In a word, it is urgent to investigate and evaluate the water resources and pollution status of major rivers and lakes in China, as well as the potential for deep development.
(2) Using the engineering measures of "preserving salt and storing light" to store fresh water from rivers into the sea. According to the China Water Resources Bulletin of the Ministry of Water Resources, the total precipitation in the Yangtze River basin in 2004 was 65.438+085.468 billion cubic meters, but the regional available water resources were only 875.46 billion cubic meters, which were 568.764 billion cubic meters and 246.5438+0.296 billion cubic meters in China respectively. That is, about 42.4% ~ 47.2% of precipitation is lost, mainly by evaporation or flowing into the sea. In 2004, the amount of water flowing into the sea of the Yangtze River estuary was 797.4 billion cubic meters, which was 1292 1 100 million cubic meters nationwide. Through certain engineering control, a part of fresh water can be stored and transported to the arid areas in the north. After years of water supply, the water resources in the north will be greatly increased and the drought will be alleviated. This idea of water control existed in ancient China, and it is called "saving salt and storing light". It is an effective way to utilize flood resources and make up for the apology with abundance.
(3) Rational development of snowmelt water in Qinghai-Tibet Plateau. With an area of 2.3 million square kilometers and an average elevation of 4,500 meters, the Qinghai-Tibet Plateau is known as the "roof of the world" and the "roof of the world of the earth". The Permian began to uplift 240 million years ago, forming a plateau ice sheet with an area of 59,406 square kilometers and a total volume of 5,590 cubic kilometers, with an average runoff of 359 billion cubic meters, which constitutes a unique "solid reservoir" in the world, and its snowmelt water is the source of seven major rivers in Asia. Due to global warming, the plateau ice sheet began to melt in the 1960s, and the source of the Yangtze River retreated 50 meters every year. The Qinghai-Tibet Plateau is a unique treasure in China, and the roof of the world ice is a solid reservoir with sovereignty in China. However, for many years, our research and development of snowmelt water in Qinghai-Tibet Plateau is not enough. The total number of glaciers is 46,298, and only a few hundred have been observed. Glacier melting is a very complicated phenomenon. On the one hand, the ice and snow are melting, some places are still growing, and the plateau is still rising, so there is a balance of payments. Recently, it has been reported that the area of plateau lakes is expanding, and the water source comes from the melting of ice and snow; As a water resource, a large amount of snowmelt water should be developed and utilized. Without research and development, it is impossible to stop the melting of ice and snow, and most of the melted water will be evaporated and lost. The premise of the development and utilization of snow melting in plateau is in-depth investigation and study.
(4) Utilization of rainstorm resources. China is a country with frequent rainstorms, and the occurrence of rainstorms is mainly related to strong airflow activities and certain topographic factors, with a certain temporal and spatial distribution law. For example, Jiangxi, Hunan and other provinces in the middle and lower reaches of the Yangtze River have frequent rainstorms in the spring and summer rainy season, and Xingtai and other places in the eastern foot of Taihang Mountain in Hebei Province often have local heavy rainfall. Heavy rain is destructive and may cause disasters, but it is also a kind of water resource. Through certain engineering measures in rainstorm-prone areas, we can prevent the rainstorm from becoming a disaster and store it, so as to turn harm into benefit. The grass-roots water conservancy departments in China have accumulated many years of experience, which should be further studied and popularized. In this regard, the Dutch use the engineering measures of building a "water square" to store heavy rainfall, so as to achieve the purpose of scientific utilization, which is worth learning.
(5) Development and utilization of boundary river water resources. There are many great rivers crossing China, and water resources belong to both countries. Among them, the water resources originating in China and flowing out of the country should be paid special attention to and researched and developed. For example, in 2004, the total amount of water resources flowing out of China or into international rivers was 706.4 billion cubic meters, of which 585.5 billion cubic meters flowed out from southwest rivers. According to international law, we have the right to use and develop these water resources according to certain agreements with neighboring countries. In international relations, we should attach importance to the ownership, national sovereignty and national interests of river water resources.
The geographical and climatic conditions in China are complex and changeable. Through the national water resources system survey, more exploitable water sources can be found. The above aspects should also carry out special water regime investigation first, and put forward demonstration and engineering planning on the basis of certain engineering tests.
Third, the solution to the water crisis in the north: expanding the Beijing-Hangzhou Grand Canal and realizing the "South-to-North Water Diversion"
(a) The golden waterway that runs through the north and south of the prosperous economic zone in eastern China.
The Beijing-Hangzhou Grand Canal, which is as famous as the Great Wall of Wan Li, was built in the Spring and Autumn Period. The Yuan Dynasty opened to Beijing from 65438 to 0293, with a total length of 65438 to 0794 kilometers. It is the longest water conservancy project in the world and the earliest water conservancy project in human history. The Beijing-Hangzhou Grand Canal is a precious legacy left by our ancestors. After more than 2000 years of ups and downs, the ancient canal has played a significant and lasting role in promoting the social and economic development of China. It can be said that it is a golden waterway that runs through the prosperous economic zone in the east of China, and it also fully demonstrates the highly creative wisdom of the Chinese nation and the advanced level of water conservancy development and utilization in the history of China.
In today's historical period when science and technology are highly developed and the country is building a well-off society in an all-round way, many experts and leading departments have been thinking about what role the Beijing-Hangzhou Grand Canal can play, how to give full play to its geographical advantages, and how to expand and develop its functions of shipping, water conservancy and water transfer. For example, the East Route Water Diversion Project of South-to-North Water Diversion, as well as shipping, development, water diversion and irrigation, and restoration of canal monuments in the provinces along the Yangtze River. During the National "Two Sessions" in 2006, many CPPCC members put forward suggestions on restoring the cultural relics of the Grand Canal and applying for the World Cultural Heritage of the Grand Canal, and made an investigation. In 2007, the Shandong provincial government put forward the policy that the East Route Project of South-to-North Water Transfer should give consideration to river development and realize the comprehensive functional objectives of water transfer and shipping, and invested in the expansion of Dongping Lake to Jining 101.19 km high-standard navigable river course within10. The "canal fever" of the people of the whole country continues.
Today, facing the plight of water resources in northern China, the Beijing-Hangzhou Canal provides us with a ready-made water conveyance channel. Its southeast starting point is the coastal areas rich in water resources, and its destination is Beijing, Tianjin, Hebei, Shandong, Henan and Shanxi, which are the most water-deficient areas in northern China. The coastal plain of the province where the canal passes is not undulating, which is convenient for construction. Without expanding land acquisition, the original river course can be used to expand the river course. Therefore, the Beijing-Hangzhou Canal has been expanded and developed, making it the best channel to divert the flood in the flood season in the south and some fresh water into the sea to the arid areas in the north. The expansion of the canal focuses on self-flowing water delivery across the basin. On the basis of increasing runoff on a large scale, the canal can maintain sufficient water, and then play a role in the allocation and management of large-scale water resources such as flood storage and drought resistance.
(two) the expansion and development of the Beijing-Hangzhou Grand Canal and the feasibility of the project.
(1) water source. The basis for expanding the canal water volume is the annual rainfall of the Yangtze River and Qiantang River basin in southeast China 1600 ~ 2000mm, and the flood in spring flood season caused by the huge runoff of the Yangtze River. In 2004, the amount of water flowing into the East China Sea through the Yangtze River reached 797.4 billion cubic meters, accounting for 6 1.7 1% of the national inflow. Therefore, the Yangtze River Basin is the largest water resource area in China. Through the construction of certain engineering diversion and flood storage, the canal will be introduced to introduce gravity flow into North China. If1/20 ~110, that is, about10 ~ 200 billion cubic meters of water is introduced into the canal, the canal runoff can be increased by nearly 2 ~ 4 Yellow Rivers, and the canal water volume can be increased through reasonable engineering measures. The most basic project of the expansion is to widen and deepen the canal channel and develop some outlets to draw water from the Yangtze River.
(2) Realize self-mobility. Yangzhou-Tianjin section of the Beijing-Hangzhou Grand Canal is the first phase of the project, with a total length of about 1 150 km. The ground at both ends is low altitude. According to the Institute of Geography of China Academy of Sciences (1985), the bedrock surface of the Yangtze River in Yangzhou section of Zhenjiang is10 ~ 40m lower than that of the Yellow Sea, and the sediment bottom surface is 3 ~10m lower than that of the Yellow Sea. The annual average water level of the Yangtze River at Nanjing Station is 5.48 ~ 4.97m, with the highest water level10.22m in flood season and the lowest water level10.54m in dry season. If the estuary of Haihe River in Tianjin is set at 0 meters above sea level. According to this calculation, when the river bottom of the whole canal is dug to -2m (Yangzhou) to-15m (Tianjin) below the Yellow Sea base, the average water level drop is 15 ~ 20m, the water surface drops above 0. 13 in the off-season and 0. 10 in the dry season. In addition, the canal can also accommodate and digest the floods in the flood season of Huaihe River and Yellow River and store them in the canal water system. At the same time, the canal acts as a plain reservoir.
(3) related projects of the canal expansion project. Develop and construct the Grand Canal water system centered on the canal, including lakes, tributaries, reservoirs, wetlands and canals and ponds along the river, and carry out dredging, dredging and deep excavation. In addition, dams, sluices and reservoirs will be built at the junction of the canal and the five major rivers to regulate the direction and flow of the canal, and the ecological environment of the canal will be built and the ancient canal monuments will be restored, so that the ancient canal will glow with new vitality and vitality in the 2 1 century and bloom with the wisdom of Chinese descendants.
Four. conclusion
To sum up, Beijing's development needs to be planned in strict accordance with the concept of Scientific Outlook on Development and sustainable development. Beijing's urban functional orientation, economic aggregate and population size should be controlled according to the standards of local and foreign aid for sustainable and stable water supply. To solve the dilemma of water resources in Beijing and Tianjin, we should start with the overall drought problem in North China, and we can take water from the national water sources, but the best policy is gravity water delivery. The overall water resources in China still have potential to be tapped, so it is suggested to implement the water conservancy policy of combining open source with throttling. The expansion project of the Beijing-Hangzhou Grand Canal will make efficient use of the land occupied by existing canal rivers, lakes, canals and ponds, and will not expand land acquisition and immigration. After the completion of the project, the income is high, the risk is zero, and future generations will benefit for a long time. Make full use of modern science and technology, and build a set of grand projects suitable for China's national conditions, with complete functions, efficient operation and leading technology in the world in 2 1 century. The long-term operation of the water diversion function of the new canal and the scientific allocation and management of water resources in the large water system in the east will greatly change the situation of water shortage in northern China and effectively guarantee the rapid and sustainable development of China's national economy.
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