What will happen to the terrain in the process of soil erosion?

The purpose of classifying soil erosion types is to reflect and reveal the characteristics of different erosion types and their regional differentiation laws, so as to take corresponding measures to prevent or reduce erosion hazards. The classification of soil erosion types is based on the nature of external forces, which are usually divided into hydraulic erosion, gravity erosion, freeze-thaw erosion and wind erosion, among which hydraulic erosion is the most important form and is customarily called soil erosion. Hydraulic erosion is divided into surface erosion and gully erosion, gravity erosion is characterized by landslide, collapse and mountain spalling, and wind erosion is divided into suspended wind erosion and moving wind erosion.

Water erosion

Hydraulic erosion or running water erosion refers to soil erosion caused by rainfall and runoff, referred to as water erosion. It includes surface erosion, potential erosion, gully erosion and erosion. 1. Surface erosion or sheet erosion: Surface erosion is a relatively uniform erosion of the surface by sheet water or raindrops, which mainly occurs on sloping farmland or barren slopes without vegetation or reliable soil and water conservation measures. It is the most basic erosion form in hydraulic erosion. Surface erosion can be divided into layered, structural, gritty and scaly surface erosion according to its external manifestations. The surface change caused by surface erosion is gradual, which is not easy to be noticed by people, but the speed of soil fertility decline is amazing, and the land area involved is often large. Soil erosion

2. Subsurface erosion: it is the mechanical erosion and dissolution of surface runoff concentrated in the soil layer, which causes peculiar karst landform. In addition, it is also quite common in loess areas where vertical joints are developed. 3. Gully erosion: Gully erosion is a form of soil erosion. Concentrated linear water erodes the surface and cuts into the ground to form an erosion ditch. According to its development stage and morphological characteristics, it can be subdivided into rill, shallow gully and gully erosion. Erosion gully is developed from sheet erosion, but it is obviously different from sheet erosion, because once it is formed, the land will be completely destroyed. Due to the continuous expansion of erosion gully, the cultivated land area on the slope is reduced, which makes the once large land cut into pieces.

gravity erosion

Gravity erosion refers to the unstable movement of weathered debris or unstable rock mass on steep slope under the action of gravity, which can be generally divided into three types: diarrhea, collapse, landslide and debris flow, among which debris flow is a serious form of soil erosion. Gravity erosion mostly occurs on high and steep slopes with deep valleys.

freeze thaw erosion

Mainly distributed in the cold areas of western China. On the slope composed of loose deposits, the soil will freeze in winter when the soil water content is high or groundwater seeps out. In spring, the surface layer melts first, while the lower part is still frozen, forming a water-resisting layer. The soil soaked by water flows down the slope, creeps or collapses, forming a debris flow slope or debris flow ditch. Therefore, this form mainly occurs in some areas with more soil water content, especially on shady slopes, such as late spring and early summer.

wind erosion

In the case of drought and sparse vegetation, when the wind force is greater than the anti-erosion ability of soil, soil particles are suspended in the airflow and lost. This phenomenon of soil erosion caused by wind is wind erosion, which is called wind erosion for short. Wind erosion occurs in a wide range, except in some places with good vegetation, plains, plateaus, mountains and hills can all occur, but to varying degrees.

There are some differences. Wind erosion intensity is closely related to wind power, soil properties, vegetation coverage and topographic characteristics. In addition, it is also affected by temperature, precipitation, evaporation and human activities. In particular, soil moisture is a very important factor affecting the intensity of wind erosion. The higher the soil water content, the stronger the adhesion between soil particles, and the better the general vegetation and the stronger the wind erosion resistance.

man-made erosion

Man-made erosion means that people do not pay attention to soil and water conservation and move a lot of soil in the process of transforming and utilizing nature and developing economy, which directly or indirectly intensifies erosion and increases the sediment transport capacity of rivers. At present, it is mainly manifested in the destruction of cultivated land and the disorderly accumulation of waste in the process of mining, building various buildings, highways, railways, water conservancy and other projects, some of which are directly poured into the river bed and some are piled up into hillsides. Erosion will occur under the action of other forces. The harm caused by man-made erosion in the Loess Plateau can not be ignored, especially the exploitation of a large number of open-pit coal mines, which has obviously aggravated soil erosion in some areas in recent years. The quantitative index to measure soil erosion mainly adopts soil erosion modulus, that is, the amount of soil loss per square kilometer per year. According to soil erosion modulus, the intensity of soil loss is divided into different regions.

Edit this paragraph factor

The factors affecting soil erosion are divided into natural factors and human factors. Soil erosion

Natural factors are the prerequisite for the occurrence and development of soil erosion, or potential factors, while human factors are the main reasons for aggravating soil erosion.

natural cause

1. Climate: Climate factors, especially monsoon climate, are closely related to soil erosion. Monsoon climate is characterized by heavy and concentrated rainfall, and heavy rain has aggravated soil erosion. The most important and direct climatic factor is precipitation, especially the most prominent climatic factor causing soil erosion. The so-called rainstorm refers to the heavy precipitation in a short time. When the daily precipitation exceeds 50 mm or 1 hour, it is called rainstorm. Generally speaking, the greater the intensity of rainstorm, the more soil erosion. 2. Topography: Topography is an important factor affecting soil erosion. The size, length and shape of slope have an impact on soil erosion, among which slope has the greatest impact. Because the slope is the main factor that determines the runoff erosion capacity, the planting of sloping farmland causes soil erosion by running water, which is the driving factor of soil erosion. Generally speaking, the steeper the slope, the greater the surface runoff speed and the more serious the soil erosion. 3. Soil: Soil is the main object of erosion, so the characteristics of soil itself such as water permeability, erosion resistance and erosion resistance will also have a great impact on soil erosion. The permeability of soil is related to texture, structure and porosity. Generally speaking, soil with sandy texture and loose structure is prone to erosion. Soil erosion resistance refers to the ability of soil to resist dispersion and suspension caused by runoff. If the combination between soil particles is strong, the structure is not easy to disperse, and the soil erosion resistance is also strong. Soil erosion resistance refers to the ability of soil to resist mechanical damage such as running water and wind erosion. According to the research, the greater the expansion coefficient of soil, the faster the disintegration and the weaker the anti-erosion ability. If there is root entanglement, soil erosion resistance will be. The erosion resistance can be enhanced. 4. Vegetation: The destruction of vegetation makes the soil lose its natural protective barrier and becomes the leading factor to accelerate soil erosion. According to the experimental results of South China Institute of Botany, China Academy of Sciences, the annual sediment discharge of bare board is 26,902 kg/hm2, that of eucalyptus forest land is 62 10kg/hm2, and that of broad-leaved mixed forest land is only 3kg/hm2. Therefore, protecting vegetation and increasing the coverage of surface plants,

human factor

Man-made activities are the main causes of soil erosion, which are manifested as vegetation destruction (such as indiscriminate cultivation and grazing) and sloping farmland reclamation (such as steep slope reclamation, slope farming and overgrazing), or failure to take necessary preventive measures due to mining and road construction, which will aggravate soil erosion.

The influence of editing this paragraph

China is one of the countries with the most serious soil erosion in the world, which mainly occurs in the Loess Plateau in the middle and upper reaches of the Yellow River, the hilly areas in the middle and upper reaches of the Yangtze River and the Northeast Plain. The main hazards include the following aspects:

Destroy soil resources

Due to soil erosion, a large number of soil resources have been eroded and destroyed, gullies have become more and more serious, soil layers have become thinner and soil erosion has occurred.

With the development of soil erosion year after year, the fertile soil layer on which human beings depend will be completely eroded. According to statistics, the total area of soil erosion in China is 654.38+500,000 km2 (excluding wind erosion area), accounting for almost 654.38+0/6 of the total land area. The total area of the Loess Plateau is 530,000 square kilometers, and the area of soil erosion is 430,000 square kilometers. 8 1% of the total area. According to the data, in Shanxi, Shaanxi, Gansu and other provinces, there are more than 50 branches and ditches per square kilometer, the length of which can reach more than 5- 10km, and the valley area can account for 50-60% of the basin area.

Decline of soil fertility and quality

Soil erosion leads to a large number of fertile topsoil loss, and soil fertility and plant yield decline rapidly. For example, in the black soil area of Jilin Province, the thickness of topsoil lost every year reaches 0.5-3cm, and the fertile black soil layer is becoming thinner, and even some places are completely eroded, so that all loess or rocks are exposed on the surface. In the rocky hilly area in the middle of Sichuan Basin, the slope is 150-200, and the annual erosion of topsoil reaches 2.5cm, and the loess plateau is strongly eroded. The average annual erosion is more than 6,000 tons/square kilometer, and the highest erosion can reach more than 20,000 tons. Taking Xingguo County in Jiangxi Province as an example, the average annual erosion amount is 50008000t/km2, and the highest is 13500t/km2. The surface temperature of bare granite weathering crust slope is 70℃ in summer. Known as the "red desert" in the south, the Pearl River Delta is advancing to the sea at a speed of 50- 100 meters per year. The annual soil loss in China is more than 500,000 tons, accounting for 20% of the total loss in the world, which is equivalent to peeling off the fertile soil surface with a thickness of 10mm, and the lost soil nutrients such as nitrogen, phosphorus and potassium are equivalent to more than 50 million tons of chemical fertilizers. The soil that has suffered from soil erosion is generally a fertile soil surface layer, which produces a lot of soil organic matter.

Deterioration of ecological environment

Due to serious soil erosion, serious destruction of surface vegetation, the imbalance of natural ecological environment has deteriorated, and natural disasters such as floods, droughts and hail have come one after another, especially the threat of drought has become more and more serious. According to the data, the Loess Plateau has 5-7 years of drought every 10 year. Frequent droughts seriously threaten the development of agriculture and forestry production. Due to the harm of wind erosion, a large area of soil is sandy, in the northwest of China.

Destroy water conservancy and traffic engineering facilities

A large amount of sediment carried away by soil erosion is sent to reservoirs, rivers and natural lakes, which leads to the siltation of riverbeds and the flooding of rivers, which is the main reason for the catastrophic floods in plain areas. According to the statistics of 20 key reservoirs in the past 20 years, the siltation has reached 7.7 billion m3, accounting for nearly 20% of the total storage capacity. The service life of water conservancy facilities is greatly shortened. At the same time, a large amount of sediment deposition will also cause secondary salinization of large areas of soil. In some areas, the collapse, landslide or debris flow caused by gravity erosion often leads to traffic interruption, road and bridge damage and river blockage, resulting in huge economic losses. It can be seen that the harm caused by soil erosion is very serious, and we must attach great importance to it and take effective measures to prevent it.

Edit this paragraph for prevention and control.

Preventing soil erosion, protecting and rationally utilizing water and soil resources are the fundamental measures to change the appearance of mountainous areas, hills and sandstorms, control rivers, reduce floods, droughts and sandstorms, establish a good ecological environment, and take the road of sustainable development of agriculture and forestry production. Soil and water conservation is the lifeline of ecological construction in mountainous areas, and effective comprehensive control measures must be taken. Through a large number of production practices and scientific research at home and abroad, water conservancy projects, agricultural and forestry production and sustainable development are summarized.

Water conservancy engineering measures

1. Slope treatment project can be divided into terrace project, slope water storage project and river closure and corrosion prevention project according to functions. Terrace is an effective measure for slope treatment project, which can intercept more than 90% of soil erosion. There are various forms of terraces, such as horizontal terraces, anti-slope terraces with high inside terraces and low outside terraces, and sloping terraces separated by a slope between two adjacent horizontal terraces. Terraces with a certain slope are sloping terraces. Slope water storage project is mainly used to store slope surface runoff and solve the problems of human and animal water and irrigation water. Generally, there are dry wells and waterlogging pools. Interception and erosion prevention project mainly refers to the intercepting ditch on the hillside, which is a passage built across the slope from top to bottom at regular intervals and can store and transport surface runoff. Its function is to change the slope length, store the rainstorm and discharge it into the water storage project. Play a role in intercepting, slowing down and storing runoff. 2. The gully control project mainly includes gully head protection project, gully workshop, gully water storage project and warping dam. The gully head protection project is a water conservancy project to prevent the gully head from advancing, undercutting and bank expansion caused by runoff erosion, and to protect the slope from erosion. First, strengthen the slope control of the ditch head to ensure that water does not fall into the ditch. Secondly, tamp the ditch head and slope. Build fish scale pits, horizontal ditches and horizontal steps on both sides of the ditch slope, plant trees and grass to prevent erosion and reduce surface runoff flowing down to the bottom of the ditch. According to different conditions, valley repair, warping dam, small reservoir, pond dam and other projects are adopted at the bottom of the ditch to stop flood and sand and prevent the harm of mountain torrents. 3. Small water conservancy projects are mainly to intercept surface runoff and sediment during heavy rain.

Bioengineering measures

Biological engineering measures refer to soil and water conservation measures such as planting trees and grass, greening barren hills and comprehensive management of agriculture, forestry and animal husbandry, in order to prevent soil erosion, improve soil, improve land productivity, develop production and prosper economy. Forest and grass measures can not only conserve water and soil, but also improve soil fertility and provide fuel, feed, fertilizer and wood. Promoting the comprehensive development of agriculture, forestry, animal husbandry and sideline, improving and regulating the ecological environment have remarkable economic, social and ecological benefits. Biological protection measures can be divided into two categories: one is the biological protection management type for protection, such as farmland protection forest, hill slope protection forest, gully head anti-erosion forest, gully slope protection forest, gully bottom anti-erosion forest, river bank protection forest, mountain water source forest, sand fixation forest and so on.

Agricultural practice

Agricultural technical measures of soil and water conservation, mainly soil and water conservation tillage, are the basic measures of soil and water conservation. They cover a wide range and can be divided into three categories according to their functions: 1. Agricultural technical measures of soil and water conservation are mainly to change the tiny topography of the ground, increase the roughness of the ground, intercept surface water and reduce soil erosion, which mainly include cross-slope tillage, furrow planting, horizontal tillage, ridge building and other high-yield planting ditches. 2. Agricultural technical measures of soil and water conservation, which mainly focus on increasing ground coverage: its function is to protect the ground, slow down runoff and enhance soil erosion resistance. There are mainly measures such as intercropping and interplanting, grass-field rotation, strip intercropping in grass-field, wide row and close planting, biological covering of straw weeds, no-tillage or less tillage. 3. Agricultural technical measures focusing on increasing soil infiltration: loosening soil, improving soil physical and chemical properties, and increasing soil anti-corrosion, infiltration and water storage capacity, mainly including increasing application of organic fertilizer, deep ploughing and soil improvement, rainwater harvesting and water storage, and cooperation with harrowing. To control and prevent soil erosion, necessary concrete measures must be taken according to the movement laws and conditions of soil erosion. However, it is difficult to achieve the ideal effect by taking any single preventive measures. According to the use and characteristics of different measures, the following comprehensive management principles must be followed: combining mountain management with water control, ditch management with slope management, combining engineering measures with biological measures, and combining field engineering with water storage and soil conservation tillage measures. The combination of management and utilization, the combination of current interests and long-term interests. Only by implementing the centralized and comprehensive management policy of taking small watersheds as a unit, simultaneously developing slopes and ditches, and combining engineering measures, biological measures and agricultural measures can we achieve lasting and stable results.