Wind erosion alters landforms by removing and carrying particles of earth, silt, and sand, and wearing away surfaces. It primarily occurs in arid and semi-arid regions due to lack of moisture and sparse vegetation. Deflation causes subsidence and desert pavement, while abrasion creates wind-shaped rock formations. Wind erosion can make land uncultivable and expand deserts, worsened by human activities like deforestation and intensive agriculture. Dust from soil erosion poses hazards to air quality, machinery, and flooding. The “Dust Bowl” in the 1930s was a severe example of wind soil erosion.
Wind erosion is a natural process by which the landforms are altered by the action of the wind. This can happen in two main ways. Wind can remove and carry particles of earth, silt and sand, sometimes carrying them long distances and depositing them in other areas, and can wear away surfaces by the abrasive effect of small airborne mineral particles, resulting in a variety of characteristic formations. Wind-driven soil erosion is a serious problem in many parts of the world and can have a significant economic impact. The problem has been exacerbated by human activities in many areas.
It is in the arid and semi-arid regions of the world that wind erosion is primarily observed, due to the lack of moisture needed to hold soil particles together. Sparse vegetation also contributes to the effects of wind erosion, as plant roots help hold the soil together while stems and foliage tend to block wind. Wind transport of material can take the form of suspension, in which very small particles remain suspended in the air and can be carried long distances, and salting, in which larger particles bounce along the surface, sometimes displacing larger particles as they advance. This results in some areas depleting into small particles and other areas, where these particles settle, are transformed by a buildup of dust, silt or sand.
The process of removing small particles from a land surface by wind is known as deflation. It results in a subsidence of the land surface, forming deflationary cavities in some areas, and a surface composed mostly or entirely of larger particles that have been left behind, known as the desert pavement. The material is usually deposited by the wind where there is some type of obstruction, such as rocks, vegetation or man-made structures: the wind speed is reduced where it flows over the obstruction and the material falls to the ground. The deposited material can itself form an obstruction which causes the accumulation of further windblown material, as in the case of sand dunes, which can cover very large areas, such as the Great Eastern Erg and the Great Western Erg in the desert of Sahara of North Africa. The dust and silt deposited by the wind is known as loess and can also cover large areas.
The wearing of rock surfaces by wind-blown particles is known as abrasion, and the resulting rock shapes are known as winds. Among the most common wind patterns observed in desert areas are flat, smooth rock surfaces facing the prevailing wind direction and inclined 30-60 degrees from horizontal, often with distinctive furrows and pits. The presence of these rock forms in the sediments is an indication of an arid climate in the past. Long wind-sculpted ridges that taper downwind are known as yardangs and can be seen in many desert areas. Ventifacts have also been observed on the surface of Mars.
Wind erosion of soil can make large areas of land uncultivable and can lead to the expansion of deserts, as soil depleted of soil and smaller particles is less able to hold moisture. Although soil erosion occurs naturally, intensive agriculture and deforestation have made soil more vulnerable to wind erosion by exposing the surface, increasing evaporation, and removing protective cover. Windblown dust from soil erosion can also pose a hazard by reducing air quality and visibility, clogging machinery and accumulating in rivers, raising river beds and increasing the risk of flooding. One of the worst examples of wind soil erosion was the “Dust Bowl” during the 1930s on the southern and central Great Plains of America and it continues to be a problem in drier parts of the world.
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