What Causes Soil Erosion?

Soil erosion, like rock erosion, is caused by the movement of water and wind, and glaciers. Since soil (whether loose of compact) is less resistant to these forces, soil erosion tends to occur more rapidly than rock erosion. This article will consider the causes of soil erosion that humans are more likely to perceive directly, namely water and wind erosion, since the influence of glaciers upon the soil tends to play out over decades and centuries.

Water acts on soil particularly through rainfall and surface runoff. When raindrops strike the soil’s surface, they break apart soil aggregates (that is, the clumps of dirt, sand, and other particles and components that make up the soil) making it easier for water to carry these particles away. This process in which a thin layer of soil is removed uniformly across a large area is known as sheet erosion. In other areas, water can carve small channels in the ground (rill erosion) or larger channels (gully erosion) which further accelerate soil loss. The impact of water-induced erosion is particularly pronounced in areas with steep slopes and heavy rainfall, where the force of water can quickly strip away the topsoil.

Wind erosion is another major cause of soil erosion, especially in dry and arid regions. It occurs when strong winds lift and transport loose soil particles over long distances. The process, known as saltation, involves smaller soil particles being lifted into the air and carried away by the wind, while larger particles are rolled along the ground. This type of erosion is exacerbated in areas with little vegetation cover, such as in environments characterized by sand dunes or other types of bare soil, since plants help to anchor the soil and reduce the wind’s ability to dislodge particles (see also Dust Bowl). Over time, wind erosion can lead to the formation of desert pavements, where only larger, more resistant particles remain on the surface.

Human activities may also contribute to soil erosion by altering the natural landscape and removing vegetation cover. Agricultural practices, such as plowing and tilling, disturb the soil structure and make it more susceptible to wind and water. Deforestation, which involves the removal of trees and vegetation, also increases the risk of soil erosion by eliminating the root systems that stabilize the soil (see also desertification). Additionally, construction and urban development can lead to increased water runoff and soil compaction (from the installation of hard, impermeable surfaces such as roofs, roads, paths, and other walkways). These activities often result in accelerated rates of erosion, which can reduce the amount of topsoil available for agriculture and habitat for plants and animals (see also habitat loss).