Prevention of Soil Erosion : 9 Methods Explained
Prevention of soil erosion can be achieved through; barrier building, sustainable farming, soil conservation, geotextile covering, terracing, bunding, forestation, flow control facilities, optimal land use, and incentive management.
The above methods may also be referred to as the solutions to soil erosion.
This article discusses prevention of soil erosion, as follows;
1). Barrier Building (as a method for Prevention of Soil Erosion)
Barrier-building is a very effective method for prevention of soil erosion. It is also versatile and can be used under various geological and physicochemical conditions, with good results.
There are different types of barriers that can be built to control erosion. The choice of type depends on specific circumstances.
Some examples of the types of erosion barriers are; retaining walls, fiber logs, windbreaks, coastal groins, jetties, breakwaters, and silt fences.
Retaining walls are relatively common for erosion control, and are most suited to regions with undulating or sloping topography .
They generally occur in the form of a rigid wall that is built across the base or inclined portion of a slope. The key role of retaining walls is slope-stabilization.
When installed, these walls ‘retain’ and prevent the downslope movement of soil, rock debris and rapid runoff. As a result, erosion is mitigated.
It is important to note that methods of prevention of soil erosion are each best-suited to specific types of erosion. Retaining walls are best for preventing creep and slump erosion, or mass movement.
Fiber logs are also effective for sloping regions where erosion occurs predominantly through creep and slump mechanisms. Barriers in such regions help to prevent not only soil erosion, but also natural hazards like landslides.
As the name implies, fiber logs are wooden logs which can be lain across an erosion-prone slope to stall the downward movement of soil and water. They are a good option in areas occupied by forests, tundras or other ecosystems that can supply woody biomass.
The effectiveness of fiber logs depends on their weight, and mass in terms of length and width.
Windbreaks are useful for prevention of soil erosion in regions where wind is the primary erosive agent .
This includes areas prone to drought and desertification, as well as areas under the influence of wave power dynamics and ocean-driven air currents.
Windbreaks may be composed of any suitable material depending on specific requirements. However it is necessary for these barriers to be mechanically resilient and massive enough to obstruct incoming winds.
In vegetated areas, evergreen trees can be cultivated in dense rows to serve as windbreaks. Otherwise, manmade barriers can be used.
-Coastal Groins and Jetties
Groins and Jetties refer to barriers for prevention of erosion in coastal areas.
The role of groins is to control erosion caused by longshore drift along the coast. They are usually built as sturdy barriers obstructing the path of incoming water currents. These barriers reduce drift velocity and trap eroded sediments, thereby protecting the coastline from erosive degradation.
Jetties perform a similar role. They are usually built to support sediments and rocks surrounding the water-inflow points close to the coast. This prevents inflowing water currents from causing erosion.
The idea behind in-water barriers (or breakwaters) is to prevent erosion by reducing the velocity of water currents within the reservoir or basin.
In-water barriers are most needed where the energy and erosive impact of waves is high. They are usually installed at specific locations or at intervals such as allows them to break oncoming waves and reduce their velocity as these waves approach the coast.
Silt fences are temporary structures built from rock material, debris, or compost. They are suitable only where the force exerted by erosive agents is low. Silt fences may absorb runoff and trap eroded soil.
2). Sustainable Farming and Soil Conservation
Sustainable farming and soil conservation are related concepts, and are both useful for prevention of soil erosion .
Various practices of sustainable agriculture can help prevent erosion. They include organic mulching, composting, ‘trash-matting’, no tillage farming, sustainable irrigation, contour farming, crop rotation, cover cropping, and strip cropping.
Organic mulching is the use of organic materials like leaves and wood waste to cover the soil .
This organic layer (called ‘mulch’) provides mechanical protection from erosive agents. It also protects seedlings and less-resistant crops from the effects of erosion.
Composting is a sustainable farming practice whereby organic materials are used to replace chemical fertilizer for soil .
In composting, the process of biodegradation is exploited to covert organic waste to useful soil nutrients in such a manner that ensures environmental and economic sustainability. The organic matter is accumulated to form what is known as the ‘compost heap’ that is subsequently spread over, or mixed with topsoil.
Composting improves various soil properties like moisture-retention capacity, nutrient concentration, pH and particle adhesion; all of which make the soil more resistant to erosion.
Trash-matting is similar to mulching in terms of outcome.
However, the procedure of trash-matting is not the same as that of mulching.
Trash-matting is simply the disposal of waste from forest management or agricultural harvest, by spreading this residue over the soil, in the same land from which it was derived.
Plants that are most suitable for this practice are fibrous species like cane plants and palms.
Crop rotation is the sequential and alternate cultivation of multiple crop types on the same agricultural land .
It is a recommendable approach for prevention of soil erosion, provided the rotation sequence includes resistant crops as well as soil-enriching crops.
Also, crop rotation becomes more effective when seasonality of precipitation and wind currents are considered.
The idea behind cover cropping is to vegetate land with crops that are rapid-growing, competitive and resistant to erosion.
This approach is best for regions where land-use is yet to be decided. It is also suitable for agricultural lands and pastoral lands.
For pastoral lands that occur in hilly terrain, cover crops can protect soil on slopes from being removed by agents of erosion. The roots of these crops hold soil in place and stabilize the slope.
Cover cropping can be integrated into crop rotation , so that the sequence of rotation includes resilient cover crops.
Conservative grazing is simply the avoidance of overgrazing.
It involves the use of sustainable techniques such as rotational grazing to reduce the point-concentration of cattle within any pastoral land.
Excessive grazing in a small, specified location will ultimately cause vegetation loss, soil compaction, and loss of soil fertility . These effects can all lead to soil erosion, and therefore should be mitigated.
Aside rotational grazing, other ways to mitigate overgrazing include the use of supplementary feed materials for cattle.
-No Till Farming
Also called ‘conservative tillage’, the concept of no-till farming involves minimizing the rate at which soil is tilled or disturbed during farming.
This is important because excessive tillage can cause soil to lose its structural and compositional integrity, thereby increasing erosion risk .
Through no-till farming, soil properties can be conserved while the soil is used for crop cultivation. This makes the soil more resistant to erosion.
-Contour Farming and Strip Cropping
Contour farming and strip cropping are similar practices which are based on the principles of sustainable agriculture.
Contour farming refers to the cultivation of crops in well-defined rows that are aligned with the topographic levels or contour lines across the surface of a slope. This is a highly effective way to mitigate erosion for farmlands in hilly regions.
Strip cropping also refers to cultivation of crops in rows. The difference between contour farming and strip cropping lies in the use of contour lines in the former, and their exclusion in the latter.
The goal of contour farming and strip cropping is to provide a vegetative barrier which intercepts erosive agents and eroded materials along slopes.
Sustainable irrigation is a water conservation practice whereby irrigation water is carefully managed in terms of volume and composition.
The approach aims to protect soil from the effects of unsustainable irrigation, such as leaching and salinization. These effects are precursors to erosion.
3). Geotextile Covering (as a method for Prevention of Soil Erosion)
Geotextiles are polymeric materials made from components that are biochemically compatible with the ecosystem .
These components include biodegradable plastics and other biomass-derived materials.
Soil can be protected from erosion by overlaying with such geotextiles. The act of soil overlaying is called ‘matting’.
In addition to providing mechanical protection, geotextile soil covers can enable soil to develop and improve in fertility and structure.
Terracing is the act of creating a series of parallel barriers across a slope or hillside, to control and restrict the dynamics of erosive forces.
As the definition above implies, terracing is used in sloping regions.
The ‘terraces’ are step-like barriers whose function is to obstruct the downslope flow of erosive fluids like water and wind. The may be cut into the slope or constructed from sturdy materials.
Terracing prevents erosion by reducing the velocity and pressure of erosive forces, retaining water and loose soil, and increasing infiltration. With proper planning and execution, the method is very effective for prevention of soil erosion .
5). Bunding (as a method for Prevention of Soil Erosion)
Bunding is the act of building polygonal rigid barriers across a slope, and along the lines of equal contour or elevation, to intercept erosive agents.
The polygonal barriers are called ‘bunds’, and they may be viewed as an advanced type of contour terrace. Bunds provide an obstruction that prevents wind and water from flowing rapidly down a slope and causing degradation.
Small outlets can be integrated into the bunds to allow excess retained water seep through.
This method is applicable across a broad range of climatic conditions. It also requires a significant level of engineering expertise for the bunds to be installed efficiently.
Forestation is a term that can be used to define all acts and processes of vegetation growth.
However, with respect to the prevention of soil erosion, forestation refers to reforestation, afforestation, and revegetation.
The ideology behind forestation for preventing erosion is simple. Deforestation is one of the common causes of soil erosion, leading to exposure and vulnerability of land. The reverse of this effect can be achieved through forestation.
Although the concept indicates a link to forest ecosystems, forestation extends beyond the establishment of forests.
It is more accurate to view forestation as a type of environmental remediation; specifically bioremediation. The growth of vegetation plays multiple roles to improve soil. These include fertility enhancement, structural improvement and mechanical protection .
An advantage of forestation is its versatility. Various plant species are usable for forestation purposes, including woody perennials and shrubs.
Forestation is applicable across various topographic regions. Trees can be cultivated in hilly terrain to prevent erosion and landslides. In relatively flat terrains, forestation can also be used to protect and conserve soil.
In addition to the interception of erosive agents, vegetation stabilizes soil through the binding effect of root systems. They also infiltration and moisture retention, and may provide an organic layer of decaying plant matter that supplies nutrients to the soil.
7). Flow-control Facilities (as a method for Prevention of Soil Erosion)
Flow-control facilities include all infrastructure designed to channel floodwater in a preferred direction.
These include drainage canals for diverting stormwater toward a containment reservoir.
In slopes, pipes may be installed to drain water, and reduce the risk of slumping and landslide .
Water dams can help control flooding, which is a precursor to erosion. These dams are often integrated with power plants that generate hydroelectricity from renewable hydro energy.
8). Optimal Land Use
With regards to prevention of soil erosion, the concept of optimal land use is concerned with ensuring that land resources are not used beyond their suitability and capacity.
Factors that determine the capacity and best use of land resources include geographic, geologic, physicochemical and biological elements.
When land resources are used optimally, the risk of degradation through leaching, overgrazing, excessive tillage or pollution, decreases. Since these are all precursors to erosion, it can be said that optimal land-use reduces the risk of soil erosion.
9). Incentive Management
As part of efforts to achieve sustainable development, governments can use incentives to facilitate environmental protection programs .
In the case of erosion prevention, tax waivers; credits, and loans can be made accessible to farmers and other concerned entities for participating actively in soil conservation projects or practices
Incentive-driven programs can be implemented in the form of large-scale soil rehabilitation and erosion prevention schemes.
Prevention of soil erosion can be achieved through;
1. Barrier Building
2. Sustainable Farming and Soil Conservation
3. Geotextile Covering
7. Flow Control Facilities
8. Optimal Land Use
9. Incentive Management
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