Soil resulting from weathering and crushing of rocks. Soil is a suitable environment for growing plants and a place for some living things to live. Soil is known as the most shallow layer of the earth and the bed of agricultural production, which is constantly exposed to physical, chemical, and biological changes.
What is soil erosion in geography
Soil erosion is a continuous process in which soil particles are separated from their main bed and transported to another location using transport agents. Human activities reduce or increase it, but they cannot stop it completely. The amount of soil erodibility is usually not constant at different times of the year.
Erosion occurs naturally and slowly or rapidly by factors such as running water, wind, glaciers, gravity, and groundwater, without human intervention.
Human activities such as agriculture, mining, road construction, and other construction activities intensify natural erosion. In addition to humans, other organisms also play a role in increasing these erosions.
What causes soil erosion
The natural causes of soil erosion are the same types of soil erosion: water, wind, gravity, glaciers, etc.
The most common type of soil erosion is water erosion because there is a lot of water on the ground and it also has a lot of power. Water erosion is also seen in deserts, resulting in the formation of fine sand. Wind erosion is also common in deserts, with strong winds moving soil from one surface to another.
Agriculture is the most important human factor that causes soil erosion. The area of cultivated lands and a large amount of soil exploitation due to high human demand cause the rate of erosion to increase.
Farmers plow to destroy natural vegetation to grow their crops. Continuous irrigation of agricultural products both washes the farm soil and drains groundwater.
Tractors create deep grooves in the soil that adversely affect the natural path of the water. Using the soil without resting it in spring and summer frails the soil, frail soil in winter is easily washed away by wind, rain, and snow, This causes the soil to lose its previous fertility.
Grazers live all over the earth. Grazers use vegetation such as grasses and shrubs and destroy the vegetation of the soil and expose it directly to erosion.
If the balance is break and the growth rate of plants exceeds the number of grazing animals, soil erosion will accelerate. Also, these animals with their toxins affect the roots of plants and cause them to be uprooted from the soil.
Overgrazed lands will become plant less and will experience severe soil erosion.
Trees in forests protect the soil from leaching, the roots of the trees compact the soil and place it close together, which causes soil erosion to occur at the slowest rate, even in torrential rains. Leaves, twigs, or in general plant debris that covers the forest floor also protect the soil.
The leaves of the trees prevent the raindrops from hitting the soil directly; the raindrops, which come down almost at a very high speed, hit the leaves and fall to the ground at a slower speed.
Human activities and needs have caused the extinction of trees and vegetation of forests on a large scale, which leads to many losses, that one of which is soil erosion. Soils that are displaced by erosion clog the natural passage of water.
Mining that damage topsoil for various purposes makes the soil vulnerable to soil erosion.
Construction is another human factor influencing soil erosion. For this purpose, vegetation is destroyed in various environments to build roads, bridges, and residential buildings. They also move a lot of soil to build tunnels.
Among the recreational activities that can accelerate soil erosion are mountaineering or off-roading.
Off-road vehicles crush and destroy soil vegetation. In soils with delicate plants, mountaineering activities can be harmful.
Soil erosion, like other erosions in nature, is a normal process that cannot be stopped completely, human activities increase its speed effectively, even in some areas to more than ten times of natural speed.
Types of soil erosion
Surface Runoff and Rainfall Erosion this type of erosion which happens whenever the weather is rainy. Erosion has four stages: splash, sheet, rill, and gully.
The first stage of erosion is splash erosion in which raindrops hit the soil surface, compacting soil particles and rising to about 60 cm, scattering around and moving the soil with them.
When it rains a lot or the intensity of the rain is high, sheet erosion occurs. The amount of water that falls on the ground in the rain washes the soil into a thin layer. This type of erosion, like splash erosion, is not a concern if done naturally.
Vegetation at this stage significantly prevents sheet erosion. Bare soil areas, overgrazed areas, or areas where vegetation has been lost for any reason are more at risk.
Due to the flow of water, cracks and strips are created on the surface of the soil, water flows in these gaps and makes them deeper, water collects there and begins the rill erosion. Small hills can be affected by rill erosion.
Like other types of erosion, the rate of rill erosion in lands without vegetation increases significantly. People should prevent this stage of soil erosion by having grassed waterways, contour drains and mulching. If these precautions are not taken, erosion will enter a higher stage.
Runners that flow widely and vigorously on the ground cause soil erosion to more than 30 cm, this is the worst type of erosion. These runoffs can even be strong enough to wash away large parts of the soil. This erosion causes gullies in severe cases.
More water flow causes the water pathway to becoming deeper, it happens because of water erosion. If these canals exist in the valleys, they will make the valley deeper.
At the beginning of the water pathway in valleys, valleys are V-shape, As the slope increases, water energy also increases, and as a result, the amount of water erosion increases. At the end of the valley route, it can be seen as U-shaped because it has affected the valley’s rocks and soil.
In the tunnel, erosion soil loss happens in the subsoil. Water enters the ground through cracks and leaves a small tunnel under the ground by washing the water around it. If the topsoil is washed away, the surface of the tunnel will gradually approach the topsoil and the topsoil will collapse in the tunnel, creating a gully.
This erosion occurs when the edges of rivers are destroyed by repeated water collisions. Floods greatly increase this erosion so that they can destroy river banks.
One of the biggest reasons for bank erosion is the lack of vegetation on the river banks, which can be due to the following:
- Human and vehicle traffic at river banks
- Changes in soil
- Acceleration of water flow
There are three types of glacial erosion: plucking, abrasion, and freeze-thaw
Plucking occurs when melted ice freezes around the fractures again and moves the pieces of soil and carries them along with them.
Abrasion occurs when the ice of natural glaciers is eroded or scratched by natural factors, in which case the substrate soil is also affected.
Freeze-thaw occurs when rain or melted water gets frozen in cracks of rocks or soil and again melt, this freezing and melting happen many times until complete erosion of rock or soil.
Glacial erosion can even affect large mountains, so if accelerated by various factors, it will have very adverse effects.
Flood with high speed and strong water flow can cause to occur vortices and kolks in bed soil, Water accumulates in these areas and erosion occurs. Many agricultural lands are destroyed due to this type of erosion and lose their fertility. Floodplain erosion can remove the topsoil and cause subsoil erosion starting. Flood velocity and a certain amount of covering vegetation can affect floodplain erosion.
Frequent beach waves or sea-level changes can cause this erosion. The waves hit the rocks with force and break them, or the rising water level causes the rocks to corrode.
Carbonic acid in seawater can also cause corrosion, especially on rocks that contain lime. Sea waves can also carry sediments and cause soil erosion.
So it’s too much important to create armor for beaches to prevent coastal erosion.
Wind erosion occurs mostly in arid and semi-arid regions. This erosion can increase evaporation, desertification, increase dust and destroy agricultural products.
Mass erosion is a type of soil erosion in large scale erosion and happens step by step.
This erosion occurs continuously in the foothills, sometimes at low speeds and sometimes suddenly, which carries dangers.
This erosion can be controlled by creating vegetation, checking dams, reduce water flow, and building barriers.
Chemical soil erosion occurs when soil salts and minerals are leached. The release of toxic waste into nature causes chemical erosion.
How soil erosion Effacts the environment
The most significant effect of soil erosion on the environment is the loss of agricultural land, but this is only one of its negative effects. Soil erosion pollutes and closes rivers, endangers aquatic life, and reduces their numbers, species that feed on these water sources and their organisms lose their food source, and the number of these species decreases, too.
Destroyed lands do not have much ability to hold water, causing widespread flooding that is dangerous to the inhabitants of an area and the remaining plants.
If the natural soil composition of an area changes due to erosion, there is a possibility of increasing soil acidity, in which case plant growth will be seriously affected.
The soil is the breeding ground for plants, soil erosion means the loss of plants, this can indirectly affect the climate because, with the loss of vegetation, the absorption of carbon dioxide also decreases.
If primary erosion occurs or the area has previous erosion, it will be more difficult to protect against erosion. This means that eroded areas are much harder to recover from than preventative measures.
How to prevent soil erosion
Although human activities have had negative effects on soil erosion, some damage can be compensated by observing and doing some work.
The old methods used in agriculture caused a large increase in soil erosion. New and regenerative agricultural techniques can preserve ecosystems and prevent soil erosion effectively.
Creating linear vegetation and restoring lost vegetation dramatically reduces wind erosion. Windbreaks decrease the speed of the wind and they can be helpful to prevent wind erosion.
Creating Stone Walls
Creating stone walls in areas that are suitable for these walls reduces soil erosion, in addition, the sediments that accumulate behind these stone walls over time create the fertile ground.
Reforestation creates vegetation, which prevents floods, soil leaching, sediment spills in the waterway, and climate balance in the area. All of this in turn increases the quality of food and life and preserves plant and animal species.
Conservation tillage techniques are widely used to prevent soil erosion. In this case, the strength of the soil to maintain the vegetation increases, and water and wind erosion decreases.