邢国鑫
[个人文集]
加入时间: 2004/02/20
文章: 7501
经验值: 206975
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作者：邢国鑫 在 罕见奇谈 发贴, 来自 http://www.hjclub.org
SOIL EROSION IN CHINA
China is one of the countries that have the most serious problems of water loss and soil erosion in the world. The area of soil erosion in China at present is 3.67 million km2, accounting for 38.2% of the country's total territory. Of the total, the water erosion area is 1.79 million km2 and the wind erosion area 1.88 million km2. The soil erosion is widely distributed throughout China. It not only occurs in mountainous areas, hills, sandstorm areas and plains but also occurs in rural and city areas. The areas in the middle and upper reaches of the Yangtze River, Yellow River, Haihe River, Huaihe River, Pearl River, Songhua River, Liaohe River and Taihu Lake all have comparatively serious soil erosion, especially in the middle and upper reaches of the Yellow River and Yangtze River. But the areas of inland river basins have serious wind erosion and the desertification in such areas is increasing.
Effects of Soil Erosion in China
Soil erosion in China is characteristed by wide distribution, diversified types and serious damage. Soil erosion can destroy land resources, and aggravate natural disasters caused by flood, drought and sandstorm. It also can deeply restrict the sustainable development of the national economy. Serious soil erosion can result in poverty and the ecological environment dislocation. Soil erosion has become a chief environmental problem in China
Water erosion zones
Northwest Loess Plateau Zone Northeast Black Soil Hillock Zone South Red Soil Hilly Zone North Earth-rocky Mountainous Zone South Rocky Mountainous Zone
Northwest Loess Plateau Zone: This zone stretches from the Longyang Gorge in the Upper Yellow River to the Taohuayu of Henan Province and has a total area of about 640,000 km2, of which water erosion area is 350,000 km2 and wind erosion area is 70,000 km2. In this zone, the soil is loose and soft and the vegetation is short, with steep slopes and deep gullies. Therefore the soil erosion in this zone is very serious, especially in the region from Hekou Town of Inner Mongolia to Shaanxi Province and Longmen of Shanxi Province, with an area of 78,600 km2. The soil erosion modulus is 5,000~10,000 t/a. km2 and can reach up to 20,000~30,000 t/a. km2. Its sediment flowing into the Yellow River accounts for about 50% of the River's total annual sediment load. The soil erosion in the Loess Plateau is characterized by surface erosion and gully erosion. Surface erosion mainly occurs on sloping farmland. Those farmlands with a slope of 15~25 degrees have an average annual soil loss of 75~150 tons per ha. The gully area accounts for 30~40% of the total area in this zone. The gully erosion is extremely active. The top of the gully moves ahead while the sides are expanding and the bottom is declining, accompanied by serious gravity erosion such as collapse, landslide, chasm, sloughing, etc. Soil erosion in this zone is the main source of sediment flowing into the Yellow River. The serious soil erosion not only washes away a large amount of soil but also causes the sediment deposits in reservoirs and river beds and brings great threat to lifes and properties of more than 100 million people in the downstream area of 250,000 km2.
Destroying the land resources and endangering
the existence and development of the society
Soil erosion in China, on the one hand, causes annual soil losses of more than 5 billion tons on the average and the land is cut into the pieces, leading to the reduction of farmland. On the other hand, it loses the fertile soil in the surface layer of farmland and rushes away a large amount of organic matter, nitrogen, phosphorous and potassium, leading to the reduction of soil fertility and to an ever thinner soil layer. Thus the land loses its value. Soil erosion in the Loess Plateau causes the increasing development of gullies. The tops of gullies generally advance about one to three meters per year, which causes an annual land loss of more than 330 ha. In the limestone region in the southwest of China, its features are high in mountain and steep in slope, big rain and thin soil layer, more people and less farmland. Thus the land is over-cultivated and unsuitable land is reclaimed. Soil erosion results in the occurrence of serious petrifaction. In many regions, there is no land to cultivate, threatening the base of the existence of the society. In the South and North Panjiang River Basins of Yunnan and Guizhou Provinces, there are 4462 km2 of land to have been petrified. In the Bijie Prefecture of Guizhou Province, the petrifaction of land has caused serious results that no land could be planted so that the people are forced to relocate to other places. The wind erosion still nibbles away land and wastes farmland. For example, more than 37% of the Xinjiang's total land area are eroded by wind. The land is the base of the existence of mankind but serious erosion has caused the degradation of land productivity, directly threatening the existence and development of the society.
Sediment deposit raises river beds and aggravates flood disasters
There is serious sediment deposit in the large rivers such as the Yellow River and Yangtze River so that flood disasters occur frequently, which is closely related with the serious soil erosion in their middle and upper reaches. Due to the serious soil erosion in the Loess Plateau, the Yellow River carries a mean annual sediment load of 1.6 billion tons. About 0.4 billion tons per year are deposited in its downstream riverbed, raising the river bed by about 8~10 cm annually so that the famous "suspended river" is formed. This "suspended river" greatly threatens the safety of lifes and properties of more than 100 million people in the Huang-Huai-Hai Plain with an area of 250,000 km2. In 1998, an extraordinary flood occurred in the whole basin of the Yangtze River, which brought huge losses to the national economy and the life and properties of the people on both banks. The key cause of the occurrence of such flood is the serious soil erosion in its middle and upper areas and the worsening ecological environment. The annual soil erosion amount in the upstream area of the Yangtze River is up to 1.56 billion tons. About one third of the total sediment flow into the main stream and two third, mostly coarse sand and gravel, deposit in reservoirs the branch rivers and silt up in the middle and small rivers, which greatly reduces the flood discharging capacity of the rivers.
Impacts on the comprehensive development and effective utilization of water resources
Due to soil erosion causing losses of water, soil and fertility of the slope farmland, the land is getting poorer and the soil moisture retention capacity declines, leading to severe droughts. In the northwest region, due to drought and less rainfall, water resources is in shortage. The land area of the northwest region accounts for one third of the country's total but its water resources only about one eighth of the country's total. Because of the shortage of water resources, the proportions of the farmland and forestland in the northwest region are much lower than the country's total average values. Soil erosion greatly affects the utilization of limited water resources and worsens the ecological environment of rivers. In 1997, the Yellow River had no water flow for more than 200 days, affecting directly the comprehensive development and effective utilization of limited water resources. Especially with the fast development of the society and economy, the contradiction of the demand and supply of water resources will be further aggravated. The shortage of water resources has become a major ecological environment problem in the northwest region.
The desertification area of land is increasingly extending
The main deserts, i. e. Gobi and "Sanhua" grassland (meaning degradation, salinization and desertification of grassland), in China are mostly distributed in the western region. These areas are the main sources of sandstorms. Due to climate influence, vegetation destruction and soil erosion, the desertification area in the western region is expanding increasingly, leading to the frequent occurrence of sand-raising or sandstorm and also bringing the sandstorm threat to the eastern part of our country.
Serious disasters such as landslide and mud-rocky flow
frequently take place
The serious disasters of landslide and mud-rocky flow frequently take place in the southern part of Gansu Province, the upstream area of the Yangtze River, and in the downstream area of the Jinsha River. According to the survey and statistics in 1990, there are more than 1500 possible landslide places and more than 3000 mud-rock flow ditches in the upstream of the Yangtze River, all of them having high degree of damage. The annual soil erosion amount is about 1.2 billion tons. Recently, landslides and mud-rock flows have been intensifying. On September 23 of 1991, a large landslide of 20 million cubic meters occurred in the Touzhaigou Village of Zhaotong City of Yunnan Province. It resulted in the death of 216 people and a direct economic loss of about 10 million Yuan. On April 30 of 1994, a rock collapse of 4 million cubic meters occurred in the Jiguanling Mountain in Wulong County of Sichuan Province, leading to the blockage of navigation channel in the Wujiang River and a direct economic loss of over 100 million Yuan.
Actions of soil and water conservation in China and its achievements
China not only is one of the countries that have the most serious problems of water loss and soil erosion in the world but also is a country that has a long history and rich experience in developing the work of water and soil conservation. In the Shang Dynasty (c. 16th-11th century B.C.), the zoned field method occurred to prevent the slope farmland from water loss and soil erosion, which is similar to the "dig-farming" and "puddle-field" methods adopted in the dry area at present. The terrace fields in mountainous regions appeared in an embryonic form as early as the Western Han Dynasty (206 B.C.-A.D. 24). In the Wanli period (1573-1620) of the Ming Dynasty, Mr. Xu Zhenming, a famous water expert, put forward a theory of " first control its origin in taming river". In summary, the soil and water conservation in China occurred in ancient times as a production practice but was studied as a science in past 70 years only. The process of the soil and water conservationfor the past over 70 years can be roughly divided into five major stages in chronological order as follows.
Experience and Practices of Soil and
Water Conservation in China
Through 50 years of practice, especially since the reform and opening to outside world 20 years ago, the work of soil and water conservation and ecological environment rehabilitation in China has followed natural and economic principles and gradually was realized five changes as follows. Firstly, it has changed from laying undue emphasis on short-term benefits and plundering natural resources into restoring and optimizing the ecological environment and constructing ecological agriculture. Secondly, stressing the treatment of the downstream area has changed into simultaneously controlling the upstream and downstream areas. Thirdly, paying attention to the single treatment measure has changed into tackling comprehensively the problems concerning mountains, rivers, farmland, forests and roads with small watersheds as units. Fourthly, the simple prevention control has changed into combining the prevention with development to control soil erosion. Fifthly, the treatment work organized by simple administrative orders has changed into the treatment in accordance with administrative, economic and legal provisions. Therefore the work of soil and water conservationin China has opened up a new road of comprehensive control of soil erosion with Chinese characteristics.
With small watershed as a unit, the control of soil erosion is planned scientifically while concentrating key control projects and seizing demonstration project well to spread gradually. We consistently adhere to and pay great attention to the formulation of scientific soil and water conservationplanning. With a county as an agency and small watershed as a unit and according to the local conditions, the problems concerning mountains, rivers, farmland, forests and roads are tackled in a comprehensive way. The engineering measures, biological and agricultural practices are arranged in a scientific way. The prevention measure is taken according to possible disasters. The detailed planning is formulated and is strictly followed in the implementation. The key control projects are carried out in the area with serious soil erosion in different stages and batches. We firstly control the area where large rivers originate and take the measure of treating soil erosion in a region and then stabilizing and benefiting that region. Meanwhile demonstration projects are stressed in order to draw experience from selected units to promote overall control work gradually.
Control and development are combined to realize the unification of economic, social and ecological benefits. In the control of soil erosion, it is stressed that the control of soil erosion shall be closely combined with the development and utilization of water and soil resources, and the economic benefits shall be highlighted in order to enable the masses to gain outstanding economic benefits in the control of soil erosion and the protection of ecological environment and then encourage their initiative. Through the comprehensive control, the agricultural production conditions and ecological environment have been greatly improved.
Deepening the reform and relying on policies to control soil erosion by social circles. On the basis of household-responsibility contract system for small watershed control, the reform of soil and water conservation has been deepened continuously. The diversified control ways such as lease, contract, stock cooperation, and the auction of use right of "four wastelands" etc. are adopted to control soil erosion. Meanwhile the enthusiasm of the social circles is mobilized by relying on policies to control soil erosion. A new input system for soil and water conservation in multi-unit, multi-channel and multi-tier manners has been set up for forming a new situation where the whole society takes part in controlling soil erosion.
Stressing on prevention first and controlling soil erosion in accordance with laws. The system of laws and regulations on soil and water conservation and the construction of supervision and enforcement organizations is being increasingly perfected in order to make the work of soil and water conservation take the legalization road gradually. The supervision and enforcement are strengthened. The awareness and legal sense of soil and water conservation in the whole country have been enhanced and the artificial soil erosion has been controlled.
Strengthening leadership and doing well the work of organization and coordination. The soil and water conservation is a mass participation work with strong comprehensiveness of transcending disciplines, trades and sectors. Therefore, the government actions should be strengthened and the organization and coordination should be done well. The competent departments of water administration should give good advice to the government, draw up the plans, provide good technical services, and, with the support of departments concerned, actively develop the work of water and soil conservation. Thus the situation of "the soil and water conservation as arena, the government as director and the departments as performers" is realized and soil erosion is controlled commonly by all people.
Relying on science and technology to enhance the control level and benefits of soil erosion. In the control of soil erosion, the role of science and technology has been paid great attention to. Suitable techniques have been studied and popularized according to the local conditions. The transformation of scientific results has been strengthened to quicken the change of scientific results into productive forces. Diversified popular science education for the masses in the river basin has been stressed in order to enhance the awareness of scientific control and increase the control quality and benefits. Use of technologies such as ecological agricultural construction, hydraulic fill dam construction, runoff-intercepting and water-saving irrigation, use of seabuckthorn to control arsenic sand stone, etc. has been greatly extended. In the sandstorm area, the fence of grassland for grass growing, and the water-absorbent seed used for sowing by aircraft have been adopted. All these technologies has enhanced the control quality, quickened the control speed and lowered the control cost.
Funds for soil and water conservation and ecological environment rehabilitation have been continuously increased. The sources of such funds have been extended. We not only use domestic funds but also foreign capital such as loans from the World Bank and the Asian Development Bank and assistance from specialized agencies of the United Nations and from bilateral agencies. Therefore, the soil and water conservation and ecological environment rehabilitation have made great progress.
The development strategy in the 21st century
General concept
The Agenda adopted by the UN Congress on Environment and Social Development in 1992 and the UN Treaty of Desertification Control from 1994 shall be carried out. A sustainable development strategy shall be stressed. In view of the coordinated development of population, resources and environment, the work of soil and water conservation shall be taken as the basic measures of harnessing rivers, a principal body of ecological environment rehabilitation, the essence and the key point of the China's Great Western Development. The position of soil and water conservation as basic national policy shall be further strengthened and the comprehensive control of soil erosion and water loss shall be speeded up, in order to realize the magnificent goal of green mountains and clear rivers in the whole country.
In accordance with the requirements of national economic construction and ecological environment rehabilitation, the general concept of soil and water conservation in China in the future is as follows. The strategic deployment of water and soil conservation, ecological environment rehabilitation, and Great Western Development decided by the Chinese Central Government shall be fully carried out. The principles of "prevention first and protection priority" shall be adopted to save, protect, comprehensively control, rationally develop and effectively utilize the water and land resources in order to promote sustainable development of economy and society. The re-conversion of farmland into forest and grassland shall be stressed to resume and rehabilitate good ecological environment. The steep farmland with a slope of over 25 degrees shall be reconverted into forest land and grassland step by step in a planned way in accordance with the laws and regulations. With the seven large river basins as the frame, a county as an agency and small-watershed management as the basis, the arrangement of the measures for soil and water conservation shall be adjusted and the small-sized water conservancy and soil conservation projects and the vegetation of forest and grass shall be enhanced. Thus the farmland should be reconverted into forestland and grassland and the agricultural production structures should be adjusted in order to improve the ecological environment, to promote local economic development, to reduce the sediment content in rivers and to serve the harnessing of rivers.
In the concrete implementation, comprehensive control strategy shall be pursued. The areas with forest and grass coverage and slight soil erosion will be designated as key prevention and protection areas. The areas with comparatively concentrated activities of resources development and infrastructure construction and with degraded original land features and serious damages caused by soil erosion will be designated as key supervision areas. Areas with that have more serious soil erosion and serious local and downstream damages will be designated as key control area. Therefore different control countermeasures will be adopted in different areas.
Short-term goals and tasks
The short-term goals of soil and water conservation and ecological environment rehabilitation from 2000~2010 are as follows. An area of soil erosion of 50,000 km2 will be comprehensively treated annually. Up to the year of 2010, more than 550,000 km2 of soil erosion area and 22.0 million ha of desertified land area will be treated newly. The forest area of 39.0 million ha will be increased and the slope farmland area will be transformed. 50.0 million ha of grassland will be improved and the "Sanhua" (degradation, salinization and desertification) grassland of 33.0 million ha will be treated. The key control projects in the serious soil erosion regions in the upper and middle reaches of the seven major rivers especially the Yangtze River and Yellow River will begin to produce effectiveness and the worsening trend of ecological environment will be basically kept within limits. The sediment content in the large rivers and lakes will be reduced by 10% in southern rivers and 20% in northern rivers. The prevention and supervision system of soil and water conservation and the monitoring network of soil erosion and water loss will be basically set up in the soil erosion regions nationwide. The laws and regulations of soil and water conservation will be further perfected. The induced soil erosion will be controlled firmly to improve ecological environment and promote local economic development.
Middle-term goals
From 2010 to 2030, more than 60% of soil erosion regions suitable for treatment will be treated to varying extents. The desertified land area of 40.0 million ha will be treated and the forest area of 46.0 million ha will be increased. The area of various natural protection regions will account for 12% of the country's total territory. The grassland area of 80.0 million ha will be improved. The ecological environment in key control areas will begin to realize the sound cycle of activities
Long-term goals
From 2031 to 2050, almost all the soil erosion regions suitable for treatment will be treated and the land suitable for forest will be completely greened. The slope farmland will be basically transformed into terraced farmland. The "Sanhua" grassland will be completely rehabilitated. The ecological environment nationwide will be greatly improved. Most of the country's territory will basically reach the goal of green mountains and clear rivers.
作者：邢国鑫 在 罕见奇谈 发贴, 来自 http://www.hjclub.org |
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中国要出二位真龙天子。
