About 56% of the annual average precipitation in China is consumed by land evaporation and plant transpiration, that is, the utilization rate of water resources converted from rainfall resources to surface runoff (secondary water resources) is only 44%.
At present, only 30% of the urban water sources in China meet the hygienic standards, more than half of the seven major water systems in China are polluted, and about 93% of the 44 rivers flowing through 42 large and medium-sized cities are polluted. Of the 669 cities in China, 400 are short of water, and 1 10 is seriously short of water. Most of these cities are in semi-arid and arid areas in the north and northwest of China, and the shortage of water resources in North China has become an important obstacle to the development of national economy.
Of the 32 megacities with a population of more than one million, 30 have been plagued by water shortage for a long time; 14 coastal open cities, 9 are seriously short of water. Among them, cities with severe water shortage account for 16.5%, and more than 300 million people have unsafe drinking water. Moreover, according to the data, the final utilization rate of water resources in China is only 7.5% of that of primary water resources, 18% of that of secondary water resources and 56.25% of that of tertiary water resources.
The spatial and temporal distribution of water resources in China is obviously uneven, and the distribution between north and south is obviously uneven. 8 1% of China's water resources are concentrated in the Yangtze River and its south area, while the Huaihe River and its north area only account for 19% of China's water resources. Generally speaking, the distribution of water resources is more in the south and less in the north, and less in the east and west.
Extended data:
Code of conduct for citizens to protect water resources
1, concept: save water with pride.
Strengthen the legal construction and publicity work of protecting water resources and saving water, enhance the awareness of saving water of the whole people, make people consciously realize that water is a valuable resource, abandon the outdated concept of "inexhaustible", and a good social fashion of cherishing, saving and protecting water resources has taken shape.
2, a water multi-purpose
It can reuse water resources, improve the utilization rate and help to save water.
3. Use detergent carefully
Detergents are mostly chemical products, and a large amount of wastewater with high detergent content will be discharged into rivers, which will worsen the water quality.
Improper use of detergents for a long time will damage people's central system, hinder people's intellectual development, reduce their thinking and analytical abilities, and even cause mental disorders. Detergent residue on clothes will irritate the skin and cause allergic dermatitis. If the detergent with high concentration is used for a long time, carcinogens in the detergent will enter the human body from the skin and mouth, which is harmful to health.
Most washing powders produced in China contain phosphorus. The annual output of washing powder in China is 2 million tons. According to the average phosphorus content 15%, more than 70 thousand tons of phosphorus are discharged into surface water every year, which brings great harm to rivers and lakes. According to the investigation, the total phosphorus levels in Dianchi Lake, Erhai Lake and Xuanwu Lake are quite high, and the phosphorus brought by washing powder in Kunming domestic sewage exceeds 50% of the total phosphorus load.
After a large amount of phosphorus-containing sewage enters the water source, it will cause algae to grow wildly in the water, make the water eutrophication, reduce the oxygen content in the water, and make the creatures in the water die due to lack of oxygen. Water will also become stagnant water, smelly water.
Step 4 cherish paper
The soaring demand for paper is one of the reasons for the increase in wood consumption. The annual consumption of wood for papermaking in China is100000 cubic meters, including 65438+300000 tons of imported wood pulp and 4 million tons of imported paper. The large consumption of paper not only causes the destruction of forests, but also seriously pollutes rivers and lakes because of the sewage discharged from pulp production (the pollution caused by paper industry accounts for more than 30% of the total water pollution).
5. Develop and popularize water-saving appliances.
According to incomplete statistics, there are nearly 40 million sets of toilet water tanks and a large number of other sanitary appliances in China, and the water lost every year due to the leakage of toilet water tanks reaches hundreds of millions of cubic meters.
Changsha Hydrological Bureau-Water Resources Status in China
Baidu Encyclopedia-Protecting Water Resources