Selective erosion is a specialized form of erosion which affects specific materials, usually of an agricultural or geological nature. This type of erosion typically does not affect all parts of the landscape, as some areas may remain largely unaffected. It also does not cause significant sediment transport or significant runoff.
Selective erosion is caused by natural forces such as wind, rain, freezing and thawing, as well as human-caused events such as overgrazing, construction and deforestation. Selective erosion occurs when the material is weak and the local geology, land use and climate create an environment that favors the erosion of that particular material. For example, soils can be weakened by plowing, leading to erosion along field boundaries. Similarly, deforestation and overgrazing can weaken vegetation, which can then act as a transporter of specific material in the form of fallen leaves and soil.
Erosion affects the land in a variety of ways. In the short term, it can lead to deposition of materials carried by runoff. In addition, the shape of the land can be altered by the formation of gullies and canyons. Over a longer term, it can lead to an overall reduction in soil fertility and reduce the utility of the land for agricultural or geological purposes.
The potential for selective erosion to cause damage depends on a variety of factors, including the type and degree of vegetation in a given area, the soil texture and soil moisture content, the frequency and intensity of weather conditions that cause erosion, and even human activities such as construction.
Prevention of selective erosion is the best way to limit its effect on the environment. Conservation land use practices are essential, such as proper management of grazing and maintaining a crop rotation system. In areas that are particularly vulnerable to erosion, terracing, strip cropping and windbreaks can be used to reduce its impact. In addition, proper drainage and leaching of soils can help prevent the erosion of specific materials. In severe cases, artificial structures such as dams or bunds can be used to control water flow and protect against erosion.
National wetlands and conservation programs can help protect areas that are especially prone to selective erosion. In addition, correctly managing construction activities such as roadbuilding, mining and flood control, along with proper maintenance of existing structures, can help reduce the effect of human activities on the environment.
Ultimately, understanding the mechanism of selective erosion, and implementing appropriate strategies to reduce its effect, can help protect the stability of the land and the environment it contains.