第一章 我国水资源的特点及分布状况（Chapter one characteristics and distribution of water resources in China）

1、第一章 我国水资源的特点及分布状况（Chapter one characteristics and distribution of water resources in China）Chapter one: characteristics and distribution of water resources in ChinaIntroduction of water resources in the worldWater is an indispensable natural resource for human development. It is the material base fo

2、r human beings and all living things. In today's world, the shortage of water resources and the water crisis caused by pollution have become a major problem faced by any country in policy, economy and technology, as well as the major constraints on social and economic development. In January 199

3、2, the United Nations held an International Conference on water and environment in Iceland, calling for new ways to evaluate, develop and manage freshwater resources. In 1993, the world bank raised a new topic on water resources. FAO recently established an international project on water and sustain

4、able agricultural development (LAP-WASAD), which shows that the issue of water resources has attracted worldwide attention.The exploitation of water resources is divided into two categories: one is required to take the water from the water resources, meet the needs of people's life and industria

5、l and agricultural production, the number of consumption, quality change, in another place return water. The other is to take water (hydro), the development of water transport, fisheries and water recreation, maintaining ecological balance, the use does not need from the water away from the water, r

6、ivers, lakes, estuaries but need to maintain a certain water level, flow and water quality. The utilization of water resources discussed in this section is mainly the first form of water use.In order to make good use and protection of water resources, it is necessary to understand the water resource

7、s and their important functions, the utilization of water resources in the world, the characteristics of water resources in China, the utilization and protection measures of water resources.(1) water resources and their important functions1. Water resourcesThe total water supply of the earth is abou

8、t 1 billion 390 million KM3, about 97% of which is sea salt water and can not be used directly for human beings. Two of the total amount of fresh water is only 36 million KM3, and the total lack of water 3% of the earth's fresh water, 77.2% of the glaciers and ice caps in polar regions and the h

9、igh mountains, which is also hard for direct human use; 22.4% for groundwater and soil water, which 2/3 groundwater buried deep in the deep underground water of rivers, the total; the lake is only about 230 thousand KM3, accounting for 0.36% of the total freshwater. Therefore, only about 20% of the

10、fresh water is easily available to humans, while the fresh water and fresh water only account for 0.3% of the total amount of fresh water. It can be seen that the fresh water available for human use is very limited.2, water cycleThe interaction of the earth's surface water in the solar radiation

11、 energy and gravity, continuous evaporation and Evapotranspiration to the atmosphere, and the clouds in the sky, spread to different regions in the atmospheric circulation under the effect of surface by rain or snow and other forms to return to the ocean or land. These precipitation, part into the g

12、round, become the soil water or groundwater; forming a part of the surface runoff into the river, the sea, and then by evaporation into the atmosphere; there is a part of direct evaporation or absorption and transpiration by plants into the atmosphere. The process repeats itself without end.Through

13、the recycling of water resources have been constantly updated. In a long time, the global precipitation evaporation in a basic balance, but in a certain time and space range, the number is very limited, and not as people imagine to be inexhaustible. Circulating rate of different forms of water, biol

14、ogical removal of water, atmospheric water and river water cycle period is the shortest, update the utilization rate is high, is the most active and the most important, but also to human and biological growth most closely related to water resources.3, the important role of water resources1) regulati

15、ng the climate. Water is an important component of the atmosphere. Although the atmosphere contains only one millionth of global water, however, the cyclic interactions between the atmosphere and water determine the earth's water cycle and form a climate that supports biology. Water in the atmos

16、phere helps to regulate the global energy balance, and water circulation plays a role in the transport of energy in different regions.2 of the earth's surface morphology) shaping mill. The flowing water creates and pushes the formation of land geomorphology, rearrangement of the landscape and fo

17、rmation of deltas. Water is a key factor in the formation of soil,It also plays an important role in physical weathering of rocks.3) water has the function of material transportation. Water can transport a wide variety of materials and nutrients. There are two forms of water transport: dissolved min

18、erals and whole matter. Various particulate matter in the atmosphere can be settled into water bodies and then transported by water. From this perspective we can see that water can transport environmental pollutants to further and wider areas.4) water is essential to all living things. The formation

19、 of life can not be separated from water. Water is the main body of biology, and the water contained in organism contains 6080%, or even more than 90%. Water is part of the protoplasm of life, involved in cellular metabolism, as well as biochemical agents in and outside organisms. Therefore, all lif

20、e can not be separated from water. Water interacts with living organisms in various ways. Within a regional scale, water is a key factor in determining vegetation communities and productivity, as well as determining the type of animal communities and animal behavior.5) water is the most basic materi

21、al base for human survival and production. The relationship between water and human is very close, whether it is life or production activities are inseparable from the boiling water of the precious natural resources, an important component of water is the body, and the body of the medium water conte

22、nt The new supersedes the old., human body weight 2/3, maintain the normal physiological metabolism in humans, at least 23L of water per person per day. Industrial production, irrigation and urban life need to consume a lot of water. However, with the increase of population and economic activities,

23、the global water cycle has greatly deviated from its natural state, and the flow of water has changed dramatically. Rapid population growth, accelerate the consumption of water resources, the development of agriculture and industry in serious pollution of the water, forest destruction has changed th

24、e direction of evaporation and runoff, these human activities caused serious damage to water resources, the world faces a water crisis. Return(two) characteristics and distribution of water resources in China1, general situation:There are many rivers in our country. There are more than 50 thousand r

25、ivers with more than 100km2 of the basin area, and there are about more than 1500 1000km2. However, due to the influence of climate and topography, rivers are unevenly distributed. Most of the rivers are located in the humid and rainy monsoon areas of the eastern part of China. The inland climate in

26、 the northwest is dry and little rain, and the rivers are very few.China has more than 2300 lakes over 1 km2, with a total area of 7187 km2, accounting for about 0.8% of the land area. The total water reserves of the lake are about 708 billion 800 million m3, including 32% of fresh water.There are a

27、bundant glacier resources in China. There are more than 43000 glaciers, which are concentrated in the western region. The total area is 58700km2, accounting for more than half of the total glaciers in Asia, and the total reserves are about 52000 billion m3.The average annual precipitation in China i

28、s 61889 million m3, the average precipitation is 648.4mm deep, and the average annual runoff is 27115 m3, and the runoff is 284.1mm deep. River runoff is mainly supplied by precipitation, and only about 50 billion m3 is supplied by glaciers. The average annual groundwater resources in China are 828

29、billion 760 million m3.According to the analysis and calculation, the amount of surface water and groundwater in China is 27115 and 828 billion 800 million m3, respectively. After deducting two of the 727 billion 900 million repetitions, the average annual water resources in China is 28124 m3 m3.2.

30、Characteristics of water resources in ChinaThe temporal and spatial distribution characteristics of water resources in China can be reflected by the distribution of water balance elements such as precipitation, evaporation and runoff:1) the total amount of water resources is abundant, and the per ca

31、pita and land ownership is smallChina's average annual water resources amount to 28124 m3 billion, the runoff accounted for about 94%, lower than that in Brazil, the former Soviet Union, Canada, the United States and Indonesia, accounting for 5.8% of the global total runoff, ranking sixth in the

32、 world. The average runoff depth is 284mm, which is 90% of the world average, ranking seventh in the world. Visible, China's water resources are still relatively abundant. However, our country has a large population, according to the 1 billion 200 million population, the average annual per capit

33、a possession of streamflow in 2260m3, less than the world average of 1/4, which is the per capita 1/6, the 1/8 of the former Soviet Union, Brazil's 1/19 and Canada 1/58.China's vast territory, the average per hectare of arable land runoff accounted for about 28320m3, 80% of the world average

34、. Therefore, the contradiction between our country's water resources and the need for adaptation is very prominent. It accounts for 7 of the world's cultivated land and 6% of the fresh water resources, making up 22% of the world's population.2) the temporal and spatial distribution of wa

35、ter resources is unevenPrecipitation is the main recharge source of river runoff in China, 44% of the national precipitation is converted into runoff, and the average runoff is 284.8mm deep. The precipitation in China is affected by the sea land distribution and topography, and the distribution of t

36、he precipitation is very uneven in the region. The annual precipitation and runoff depth decrease from the southeast coast to the Northwest inland. The runoff depth in the southeast coast is 1200mm, while the northwest arid area is less than 50mm, or even zero. The distribution of water resources an

37、d the geographical distribution of population and arable land is unsuitable for the cultivated land area, the South accounted for only 35.9% of the country, but the water has accounted for 81% of the total, per capita water resources is about 1.6 times the national average, per mu of water is 2.3 ti

38、mes the national average. North of the Yellow River, Huaihe, Haihe River and Liaohe River Valley four piece of arable land, population density, the amount of fresh water resources is only 19% of the country, the national average per capita water only about 18% per mu of water is only the national av

39、erage of 15%. In arid and semi-arid areas of China, because of the scarcity of precipitation, the evaporation is vigorous and the capacity of evaporation is much higher than that of precipitation.In the west, inland, desert and grassland areas, the evaporation capacity is 1600 - 2000mm, which is the

40、 most powerful area of evaporation in china. In the northeast, Xingan, Changbai Mountain, Qianshan hills and Sanjiang plain, the temperature is low and the humidity is large. Therefore, the annual evaporation is small, only 600 - 1000mm.The distribution of surface runoff in China is very uneven with

41、 time. The seasonal distribution of runoff has the characteristics of abundant summer water, low winter drought and spring autumn transition, and the interannual change is greater in the north than in the south.The Northeast China Plain, the Yellow River, Huaihe, Haihe Plain and the middle and lower

42、 reaches of the Yangtze River are mainly supplied by rainfall, while in the northwest inland basin the river runoff is the main supply. A large amount of groundwater recharge in southern mountainous areas, generally 20 - 250 thousand m3/ (km2 - a); and Western Inner Mongolia, northeast and northwest

43、 inland river hilly area is generally less than 50 thousand m3/ (km2 - a).(three) the main problems existing in water resources in China1) of China's water resources per capita and per mu of water lessThe total amount of water resources in China is 28124 million m3, of which the river runoff is

44、27115 billion m3, ranking sixth in the world. However, China's per capita water resources is only 2710 m3, about 1/4 of the world's per capita water resources, ranking eighty-eighth in the world. Average amount of water resources is only 1770m3, equivalent to the world average of about 2/3.

45、Therefore, although the total amount of water resources in China and many, but the per capita and per mu of water is not rich.2) the temporal and spatial distribution of water resources is uneven, and the combination of water and soil resources is unbalancedThe temporal and spatial distribution of w

46、ater resources in China is very uneven, which is not suitable for the distribution of cultivated land and population. The cultivated land area in southern China only accounted for 35.9%, accounting for 54.7% of the country's population, but the total amount of water resources accounted for 81% o

47、f the total amount of water resources per capita; and four regions of North China accounted for only 14.4% of the national total, arable land area is accounted for 58.3% of the country. Due to the strong impact of monsoon climate, precipitation in China and the annual runoff distribution is very une

48、ven, interannual variability, and much less water in water years, frequent drought and flood, on average about once every three years the serious flood and drought disasters.3) soil erosion is serious, and many rivers are rich in sedimentDue to the restrictions of natural conditions and long-term hu

49、man activities, China's forest coverage rate is only 12%, ranking 120th in the world, serious soil erosion, the national water erosion area of about 1 million 500 thousand Km2, accounting for about 1/6 of the land area. As a result, the sediment concentration of many rivers, such as the annual a

50、verage sediment concentration of 37.7kg/m3 in the Yellow River and the annual total sediment output of 1 billion 600 million T, is the highest in the world.4) the development and utilization of water resources in China are very unbalancedIn the southern multi water area, the utilization rate of wate

51、r is low, such as the Yangtze River is only 16%, the Pearl River 15%, Zhejiang and Fujian provinces less than 4% of rivers,And optimize the amount of fertilizer. Our latest research shows that mulch irrigation is more efficient for water use, and it is a new irrigation technology suitable for arid a

52、nd semi-arid areas.3) recycling urban sewage and opening up second water sourcesRecycling and reuse of wastewater to make it available is another way to increase water use efficiency. In Tokyo, the municipal water reclamation center uses three stage water treatment plants to recover waste water by s

53、low sand filtration. After chlorination, it is used to flush toilets in high-rise buildings. A similar "middle channel" system has been built in Beijing.2, regulate the flow of water sources, increase reliable water supplyThe first reason for the water shortage is the influence of natural

54、conditions, such as climate, geographical location, and uneven distribution of fresh water. People try to solve the problem by regulating the flow of water sources and developing new water sources.1) build a reservoir: build a reservoir to adjust the flow rate. It can store excess water in the sprin

55、g period in the storehouse and supplement the insufficient flow during the dry season. Not only can improve the water supply capacity, but also for flood control, power generation, the development of aquatic products and other services. At present, a total of 1350 reservoirs with more than 100 milli

56、on m3 of capacity built on rivers in various countries, with a total storage capacity of 4100km3.However, in many developed countries, the cost of new water storage facilities is increasing rapidly and the speed of reservoir development is slowing down with the increasing difficulty of choosing the

57、address of the database. Reservoir construction in developing countries is still in its prime. When building the database, we must also study the impact on the ecological system around the basin and reservoir, otherwise it will lead to adverse consequences.2) trans basin water transfer: trans basin

58、water transfer is an expensive water supply project, which is regulated from the rich water basin to the water shortage basin. Because of its high cost and serious environmental damage, many countries no longer carry out large-scale inter basin water transfer. Pakistan West Water Transfer Project an

59、d Australia snow river water diversion project in China in recent years and the completion of the Luanhe diversion, and the water diversion project is a large project of water supply from water to water river basin, China water diversion project has commenced.3) underground water storage: at present, more than 20 countries have been actively planning artificial recharge of groundwater. In the United States, the local water conservancy in California stores about 2 billion