China is a developing country and a big energy country. The primary task of the country is to develop the economy. After decades of hard work, China's economy has advanced by leaps and bounds, people's living standards have improved significantly, and a well-off society has been gradually realized. In these decades, while developing economy, we have also attached importance to ecological protection, strengthened the construction of ecological environment, and effectively protected and improved the ecological environment in some areas of China. Mainly manifested in: afforestation, soil and water conservation, grassland construction and land improvement and other key ecological projects have made progress; The key prevention and control projects of soil and water conservation in the middle and upper reaches of the Yangtze River and Yellow River have been fully implemented; The protection of natural forest resources in key areas and the project of returning farmland to forests and grasslands have been started; A number of different types of nature reserves, scenic spots and forest parks have been established; The pilot demonstration of ecological agriculture and the construction of ecological demonstration areas have developed steadily; The legal system of environmental protection has been gradually improved.

However, despite these shortcomings, the national ecological environment is still facing a grim situation, mainly in the following points:

1 Soil erosion is seriously distributed in the northeast black soil area of Heilongjiang, Jilin, Liaoning and Inner Mongolia, and it is one of the three largest black soil areas in the world. According to the measurement, the average annual loss of topsoil in the black soil area of Northeast China is 0.4 ~ 0.7 cm, and the thickness of black soil layer is generally about 80 cm in the initial stage of reclamation, and it is reduced to 50 ~ 60 cm after 40 years of reclamation. The black soil layer of cultivated land with serious soil erosion has completely disappeared, exposing the lower loess, which is called "broken skin yellow" locally. It is distributed in the western grassland areas of Inner Mongolia, Shaanxi, Gansu, Qinghai, Ningxia, Xinjiang and other provinces. Due to drought and lack of rain, overgrazing, over-reclamation, grassland degradation and serious desertification, the rivers in the upper reaches and southwest of the Yangtze River are distributed in Sichuan, Yunnan, Guizhou, Hubei, Chongqing, Shaanxi, Gansu and Tibet. Due to the prominent contradiction between man and land and the large proportion of sloping farmland, the problem of soil erosion is very serious in recent years. Soil erosion is not only the main form of land degradation and ecological deterioration, but also the concentrated reflection of the degree of land degradation and ecological deterioration. Its impact on economic and social development is multifaceted, overall and far-reaching, and even irreversible.

First, it leads to land degradation and cultivated land destruction, which makes people lose their survival foundation and threatens national food security. The per capita arable land area in China is far below the world average, and the contradiction between man and land is prominent, which is aggravated by serious soil erosion. The average cultivated land lost by soil erosion in China every year is about 6,543,800 mu. A considerable proportion of farmland in the rocky mountainous areas in the north, karst areas in the southwest and the upper reaches of the Yangtze River has lost topsoil and exposed parent rocks, completely losing agricultural production capacity. According to this scientific investigation, according to the current loss rate, the black soil layer of northeast black soil area/kloc-0.4 million mu of cultivated land will be lost in 50 years; After 35 years, the area of rocky desertification in southwest karst area will double.

Second, it leads to siltation of rivers, lakes and reservoirs, aggravates flood disasters, and poses a great threat to flood control safety in China. Soil erosion leads to a large amount of sediment entering rivers, lakes and reservoirs, which weakens the flood discharge capacity of rivers and the storage capacity of lakes and reservoirs. The crux of the Yellow River flood lies in the soil erosion in the Loess Plateau. 1950 ~ 1999, 9.2 billion tons of sediment was deposited in the lower reaches of the river, resulting in a general elevation of the river bed of 2 ~ 4m. The lower part of the main stream of Liaohe River has been 1 ~ 2m higher than the ground, and it has also become a suspended river on the ground. There are more than 80,000 reservoirs in China, with an average annual sedimentation of 654.38+624 million m3. The average annual siltation of Dongting Lake is 98 million m3. Sediment deposition is one of the main reasons for the decline of storage capacity.

At the same time, due to soil erosion, the upstream soil layer becomes thinner, the soil water storage capacity decreases, the frequency and peak flow of mountain torrents increase, and the probability of landslides and mudslides in some areas increases. Debris flow is an extreme form of soil erosion. Steep terrain, a large amount of loose solid matter and high-intensity rainfall are three necessary conditions for the formation of debris flow. In the process of production and construction, unreasonable activities such as vegetation destruction, land reclamation on steep slopes, and indiscriminate excavation and abandonment will all lead to an increase in runoff, an increase in the frequency of debris flow, an increase in the scale of debris flow, and an increase in the degree of harm.