Causes of soil erosion
1. Natural cause
The transitional nature of geographical location and fragile ecological environment. For example, the Loess Plateau is in a special geographical position, that is, it is in the transition from plain to mountainous plateau, from coastal to inland, from humid to arid, from forest to grassland, and from agriculture to animal husbandry. Various natural elements interlace with each other, and the ecological environment is relatively fragile.
The loess soil is loose, with many pores and vertical joints, and it is easy to be eroded by running water. The characteristics of loess determine that its soil is loose, with large porosity and high dispersion rate. Soil particles are easily dispersed and suspended in water, and soil blocks disintegrate quickly after encountering water.
The topography restricts the land use and the degree of soil and water loss. The Loess Plateau has the characteristics of precipitation concentration, heavy intensity and heavy rain, so the Loess Plateau has been eroded and cut by running water for a long time. Runoff caused by heavy rainfall is the main driving force for the continuous development of soil and water loss in the Loess Plateau.
2. Human cause
Destruction of vegetation. Due to the unreasonable use of land resources for a long time in history, mainly due to several changes in the mode of farming and animal husbandry, large areas of forests and grasslands gradually disappeared, becoming today's barren mountains and balding mountains. A large number of forest and grass vegetation is destroyed, so that rainwater and runoff, as well as wind directly erode the loess ground, will inevitably cause serious soil and water loss.
Unreasonable farming system. Soil and water loss in the Loess Plateau is closely related to the prevailing crop rotation tillage system since ancient times. Farmers do not choose the land suitable for cultivating similar documents to reclaim, and do not rely on intensive cultivation to increase grain production, but adopt the way of crop rotation.
Mining coal. The construction of open-pit coal mines has dug up a large area of the native ground, destroyed vegetation, and doubled the erosion resistance of the soil in the mining area, forming a new source and trigger mechanism of soil and water loss. The mining of river channels and beaches makes a large amount of sediment directly enter the river, increasing river sediment.
The effects of soil erosion
1. Restricting the development of social economy. Serious soil and water loss makes the soil layer thin, soil nutrients loss, the quality of cultivated land decline, resulting in the decrease of crop yield per unit area, which seriously restricts the development of social economy.
2. Silt rivers, lakes and reservoirs. Soil erosion causes a large amount of sediment to flow into the Yellow River, and the sediment content of the Yellow River increases sharply. Silt accumulates in the lower river bed, threatening the safety of flood control of the Yellow River. Sediment flows into a lake or reservoir, resulting in siltation of the lake or reservoir, reducing flood storage standards and water supply efficiency.
3. It causes the deterioration of the local ecological environment and directly or indirectly induces and intensifies the occurrence of natural disasters. Soil and water loss destroys the original vegetation, worsens the ecological environment, intensifies the drought degree of land and microclimate and other natural disasters.
The measures to control soil erosion
1. Biological measure
Forest grassland has the functions of water storage, soil conservation, ditch fixing, slope protection and source protection, and forest and grassland measures are the fundamental measures to control soil and water loss. In areas with serious soil erosion, vigorously plant trees and grass to prevent heavy rains from washing the top soil. Building farmland protection forest, water conservation forest and soil and water conservation forest can effectively promote the soil and water conservation work on the Loess Plateau.
2. Engineering measure
The engineering measures mainly include the construction of silting DAMS, small reservoirs, the construction of horizontal terraces, the leveling of land, the repair of basic farmland and the pumping of water for irrigation. The construction of horizontal terraces on some gentle slopes with small slopes can smooth the land, reduce soil and water loss, and is conducive to water, soil and fertilizer preservation and cultivation.
3. Agricultural technical measure
Agricultural technical measures mainly include deep tillage and soil modification, mulch, crop rotation and interplanting, scientific fertilization, selection and breeding of good varieties and advanced irrigation technology. These methods can effectively avoid the loss of deep soil water and improve the ability of soil water storage and resistance to rain erosion. It not only enhances the soil's absorption rate and storage capacity of precipitation, avoids surface runoff, but also promotes the growth and development of crop roots.