First, the present situation of soil erosion in China
China is one of the countries with the most serious soil erosion in the world. Soil erosion is widely distributed, large in area, with many types of erosion, serious in harm and difficult to control. According to the results of the second national remote sensing survey published by the Ministry of Water Resources in 2002, the area of soil erosion in China at the end of 1990s was 3.56 million km2, accounting for 37. 1% of the national territory. According to statistics, the total amount of soil lost in China reaches 5 billion tons every year. The total annual soil loss in the Yangtze River basin is 2.4 billion t, including 65.438+56 billion t in the middle and upper reaches. The annual amount of sediment entering the Yellow River in the Loess Plateau of the Yellow River Basin is as high as 65.438+0.6 billion tons.
Serious soil erosion leads to the decrease of cultivated land, land desertification and frequent sandstorms. Soil erosion is the root of poverty. At present, more than 90% of the rural poor in China live in areas with serious soil erosion, and the harsh ecological environment has brought many harms to China's economic and social development and people's production and life.
Second, the importance of soil and water conservation monitoring
At present, China has made many achievements in soil and water conservation. However, as the basic work of soil and water conservation, monitoring and forecasting is not mature enough in monitoring network construction, monitoring facilities and equipment, monitoring means and application of monitoring results in practice. For example, on the basis of long-term and a large number of experimental observations, the United States has summarized the general model of soil erosion. Spatial databases and information systems established in some European countries can locate and quantitatively reflect the area, distribution, degree and dynamic changes of soil erosion, effectively improving the scientific, targeted and preventive effects of soil and water conservation measures. Therefore, it is an arduous task for us to comprehensively improve the modernization level of soil and water conservation management and monitoring and forecasting. Therefore, we must start from the foundation and start from now, so that the monitoring and forecasting of soil and water conservation can better serve economic construction, ecological construction and protection, and further improve the social influence of soil and water conservation industry.
China is one of the countries with the most serious soil erosion in the world. The causes of soil erosion are complex, extensive and serious, which have a great impact on economic and social development, national ecological security and people's production and life. It is of great significance to timely, comprehensively and accurately understand and master the degree of soil erosion and ecological environment in China and scientifically evaluate the effectiveness of ecological construction of soil and water conservation. How to accurately grasp the regional distribution of soil erosion and its harm and serious consequences is a major event related to the survival and development of the nation. These can only be mastered through scientific monitoring, and correct judgments and decisions can be made. Therefore, it is extremely important to do a good job in monitoring and forecasting soil and water conservation.
Iii. Causes and characteristics of soil erosion in China.
(A) the causes of soil erosion
Soil erosion is a natural phenomenon, which includes both natural factors and human factors. Today, what we have to solve is mainly man-made soil erosion.
(1) Natural factors. There are mainly four aspects: topography, rainfall, soil (ground material composition) and vegetation.
(1) terrain. The steeper the slope of the ground, the faster the surface runoff speed and the stronger the erosivity to the soil. The greater the slope, the more surface runoff collected and the stronger the scouring force. In the loess hilly region, the ground slope is mostly above 15o, and some of them reach 30o. The slope length is generally 100-200m or even longer. The annual loss per mu is 5- 15 tons, even exceeding 15 tons.
② Rainfall. The rainfall that causes soil erosion is usually rainstorm. Only when the rainfall intensity exceeds the soil infiltration intensity will surface runoff be generated and the surface will be eroded.
(3) The composition of ground materials. Soils with soft texture, easy corrosion when meeting water and low corrosion resistance, such as loess and silty loam, are the objects of soil erosion.
④ Vegetation. Forest and grass vegetation with a certain canopy density can protect the soil from erosion. The higher the canopy density, the stronger the soil and water conservation capacity.
The loess plateau in the middle reaches of the Yellow River has less vegetation, loose soil, more rain, broken terrain and strong soil erosion.
(2) Human factors. The unreasonable use of land by human beings has destroyed the vegetation and stable terrain on the ground and caused serious soil erosion. There are two main aspects.
(1) Deforestation, steep slope reclamation, destruction of ground vegetation.
(2) Inadvertent soil and water conservation in infrastructure construction such as mining and road construction destroyed the ground vegetation and stable terrain, and at the same time dumped waste earth and stone into the river ditch at will, resulting in a lot of new soil and water loss.
(2) Soil erosion characteristics
China has a vast hilly area, uneven distribution of precipitation in time and space, and a long history of grazing and reclamation. In recent years, urbanization and the expansion of development and construction projects have further aggravated soil erosion, making soil erosion the number one environmental problem in China. The main features are as follows:
① Wide distribution and large area. According to the second national remote sensing survey, the total area of soil erosion in China is 3.56 million square kilometers, including water erosion area of 6.5438+0.65 million square kilometers and wind erosion area of 6.5438+0.96 million square kilometers. Soil erosion mainly occurs in mountainous areas, hilly areas and sandstorm areas, and also exists locally in plain areas and coastal areas.
② The forms and types of erosion are diverse and complicated, and it is difficult to control them. Water erosion, wind erosion, freeze-thaw erosion and gravity erosion such as landslide and debris flow are intertwined, and the causes are complex. The loess plateau in northwest China, black soil hilly area in northeast China, red soil hilly area in south China, rocky mountain area in north China and rocky mountain area in south China are dominated by water erosion, and some areas are accompanied by gravity erosion such as landslides and mudslides. The Qinghai-Tibet Plateau is dominated by freeze-thaw erosion. Wind erosion is dominant in the northwest sandstorm area and grassland area; The semi-arid farming-pastoral ecotone in northwest China is a joint action area of wind erosion and water erosion, with wind erosion in winter and spring and water erosion in summer and autumn. Serious soil erosion. According to statistics, the total amount of soil lost in China reaches 5 billion tons every year. The total annual soil loss in the Yangtze River basin is 2.4 billion tons, including 65.438+56 billion tons in the middle and upper reaches. The Yellow River Basin Loess Plateau imports 654.38+0.6 billion tons of Yellow River sediment every year, especially in the range of more than 70,000 square kilometers from Hekou Town to Longmen, Inner Mongolia. The annual average soil erosion modulus is 6.5438+100,000 tons/square kilometer, as high as 30,000-50,000 tons/square kilometer. The sediment transported into the Yellow River in this area accounts for more than half of the sediment transported by the Yellow River.
Four, how to do a good job of soil and water conservation
(1) Soil and water conservation should fully respect the laws of nature, give full play to the natural restoration ability of ecosystems, and adhere to the principle of adapting to local conditions. China has a vast territory, different natural conditions and various types of soil erosion. Soil and water conservation should adhere to the principles of suitable trees, irrigation, planting grass and drought resistance. It is not appropriate for all localities to put forward unrealistic slogans of ecological construction without reference to natural conditions such as precipitation, water and soil resources, and it is also not appropriate to promote soil and water conservation technology "across the board" without reference to local conditions. We should pay attention to summing up the local experience for many years and the creation of the masses.
(2) Strengthen basic research. Pay attention to the long-term impact of soil and water conservation on the whole basin ecosystem, water resources allocation and basin-scale social and economic development. For example, the regional environmental effect evaluation of soil and water conservation ecological environment construction; Impact on water, soil, gas, health and economy in this area and its adjacent areas; Study on regional soil and water conservation and global change: the influence of water and sediment accumulation and migration on the migration and transformation of main biological factors of terrestrial ecosystem and offshore water quality; Effects of global or regional precipitation, temperature and monsoon circulation on regional soil erosion; Treat soil erosion scientifically, and achieve moderate control and reasonable protection; Carry out sociological research on soil and water conservation.
(3) Strengthen special technology research. Actively carry out soil and water conservation monitoring and forecasting, apply "3S" and other high and new technologies, and establish a national soil and water conservation monitoring network and information system; Develop economical and applicable ecological restoration technologies; Find the economic benefit method to control soil erosion; Strengthen training and do a good job in popularizing soil and water conservation science and technology.
(4) Implement the "China Science and Technology Action Plan for Soil and Water Conservation", organize and carry out the national scientific survey on soil and water conservation, investigate and study the major soil erosion areas in China, grasp the real situation, clarify key issues, formulate strategic plans and put forward corresponding countermeasures.
Verb (abbreviation of verb) benefits of soil and water conservation and its evaluation
The benefit and evaluation of soil and water conservation is a comprehensive and complicated system engineering, and it is really not easy to test, analyze and evaluate its benefit comprehensively. Generally, the benefits of soil and water conservation are divided into three parts: economy, society and ecology, which adds a mud retaining benefit to the northern rivers with less water and more sand. The individual benefits of different soil and water conservation measures and different topographic and geological conditions provide the basis for soil and water conservation evaluation; The change of water and sediment from soil erosion to entering the main stream and its influence on the surrounding economy, society, ecology and humanities in each reach, so as to understand the possible negative benefits or adverse effects in the transportation process, such as the service life of large and small reservoirs, pits and waterlogged ponds, the erosion and destruction of river banks, and the reduction of crop sand pressure. Benefit calculation: comparison of time and space after taking measures or increasing or decreasing measures. In order to meet the requirements of scientific management and national decision-making, we must objectively and quantitatively understand and evaluate the comprehensive and individual problems of soil and water conservation, and reveal the basic situation and dynamic changes, achievements and progress, potential and prospects of soil and water conservation. Total benefit is the synthesis of various benefits, and the study of classified benefit and its relationship should be the main content. Ecological environment is not only a part of total benefit, but also an important factor to promote social and economic development. It is of practical significance to analyze and study the social and economic benefits of adapting to different ecological environments. Economy is not only the material basis of various measures, but also the necessary condition for developing the national economy and building a well-off society.
Conclusion and suggestion of intransitive verbs
Conclusions and Suggestions Soil and water conservation includes many measures, how to combine them and how to allocate them. In the past, it was generally based on local experience, the intention of superiors and the requirements of the masses. Whether it conforms to the objective situation, realizes relative optimization and achieves good results is rarely considered, and it is difficult to adapt to the laws and principles of socialist construction. The dispute between gully control and slope control, which comes first, engineering and biological measures, has been vacillating for a long time. The relationship between economic development and ecological environment has always been that the former overwhelms the latter. When emphasizing agricultural production, we can destroy forests and land, destroy grazing and land reclamation, and occupy rivers and lakes at will. In the pursuit of economic development, blindly attracting investment and enclosing fertile land have caused losses to land improvement and soil and water conservation, which has a far-reaching impact.
Follow the principle of Scientific Outlook on Development, coordinate with the sustainable development of national economy and the construction of harmonious society, and the principle of reasonable combination and optimal allocation should be put on the agenda of soil and water conservation planning and implementation, strive for initiative and avoid blindness. Terrace dam should have different primary and secondary proportions under different landform conditions, and soil and water conservation and utilization, benefit improvement and pest control should be determined according to different time and space conditions. Exploring the theory and practice of system science and environmental science is the basis of overall planning. The ultimate goal of optimization, in terms of economic requirements, is to strive for the minimum cost after the task is determined and pray for the maximum benefit after the input is clear. From the requirements of soil and water conservation, the best ecological environment and the best water-sediment ratio can be automatically selected. Generally speaking, the reasonable combination and optimal allocation of soil and water conservation is complex and difficult. At present, it seems that we should seriously investigate and test the management of various small watersheds, find a good model, sum up experience and lessons, cross the river by feeling the stones and gradually promote it to a large scale.
Soil and water conservation monitoring plays an important role in soil and water conservation. Only by scientific monitoring and providing accurate data for soil and water conservation departments can they formulate reasonable and effective measures to do a good job in soil and water conservation.
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