The air current in motion is called “wind”. The wind is an important agent of erosion, transport and deposition. Its work is particularly seen in arid regions.
Wind Erosion
Although wind erosion is not restricted to arid and semiarid regions, it does its most effective work in these areas. Wind does erosion in three ways: (i) deflation, (ii) abrasion, (iii) attrition.
(1). Deflation: Lifting and removal of loose material by wind is called “deflation”. By this process, the land surface is gradually lowered. In many desert areas, deflation produces hollows or basins with their bottoms at the water table. Such basins containing some water called “oases”.
(2). Abrasion: During dust storms the wind carries minute grains of sand in suspension. They dash and collide against the exposed rock masses and cause erosion. This process in which sand grains are used as tools for eroding rocks, is called “abrasion”.
(3). Attrition: The particles that travel with wind, collide against one another. These mutual collisions lead to their further breakdown and the process is called “attrition”.
Erosional Features
The important features of wind erosion are the polishing of rock faces and the formation of ventifacts and pedestal rocks.
Ventifacts: Wind armed with sand abrades rock near the ground surface. This effect is called “sandblasting”. When pebbles and boulders are subjected to sandblasting they develop flat sides and sharp edges. If these stones contain coarse crystals of unequal hardness, they become pitted. Such stones, which are polished, pitted, and contain sharp edges are called “ventifacts”. These stones are faceted by erosion of their windward side.
Pedestal Rocks: Pedestal rocks are the undercut vertical columns of rocks, which have wider tops and narrower bases. When wind blows, the sand particles being heavy travel near the surface and cause undercutting of rock faces.
Wind Transport
Turbulent wind can easily sweep small dust particles and carry them to great distances in suspension. Sands, however, are transported in a series of jumps or these merely roll along the ground. The process by which sand particles travel in a series of jumps is called “saltation”. The greater part of the sand grains are transported very near the ground surface and they are seldom lifted more than a meter above the ground.
Wind Deposits
The wind deposits are commonly called the “eolian deposits. The rock particles in the eolian deposits are generally well-rounded and are sorted according to their size and weight. Wind deposits are of two types: (i) accumulations of sand, called “sand-dunes”, and (ii) deposits of silt, called “loess”.
Sand Dunes: The wind generally deposits sand in mounds. These mounds are called “sand dunes”. The sand traveling as a bed load in wind accumulates wherever it meets any obstruction, such as a boulder or a bush. As the accumulation of sand grows, it traps even more sand. In this manner, dunes are created. Sand dunes have a gentle slope (5° – 15°) on the windward side, and a steeper slope (20° – 30°) on the lee side. The height of a dune depends on the speed of wind and the size of sand grains. Dune heights of 30 meters are not uncommon. The sand dunes migrate slowly in the direction of wind movement. In some cases, they move as much as 20 meters per year. The migrating sand dunes may advance and cover farmland, railroads, highways, and other valuable properties. Their movement may be checked by planting vegetation. Read: Types of sand dunes
Loess: The suspended load transported by wind consists mainly of silt and dust particles. when it settles, it forms a blanket deposit of silt, known as “loess”. These deposits are typically non-stratified and have a grayish-yellowish color. Loess is composed of many minerals including quartz, felspar, hornblende, and calcite. These minerals are derived by wind from deserts or flood plains of rivers. Deposits of loess are very fertile. Loess deposits in some parts of China approach a thickness of 300 meters or more.
Loess deposits are often found in areas with a history of glaciation, where glaciers ground rocks into fine particles. These fine particles are then transported by the wind and deposited as a blanket of loosely compacted material. The particles in loess are usually well-sorted, with a predominance of silt-sized grains.
Loess deposits can be quite extensive and cover large areas. They are known for their fertility and are often agriculturally productive due to their high content of fine-grained minerals. Regions with significant loess deposits include parts of China, the United States, Europe, and other areas with a history of glaciation.
In addition to its agricultural importance, loess also plays a role in shaping landscapes and can be found in river valleys, contributing to the development of distinctive landforms. The term “loess” is derived from the German word “löss,” which means loose or crumbly.
Areas of Wind Erosion
Wind erosion is most common in desert areas and coastal sand dunes and beaches. It is because of the presence of large amounts of weathered sediments, and lack of herbs. Moreover, certain land conditions can cause wind erosion in agricultural areas. In these areas, wind drives the erosion, but it’s mainly the landscape and condition of the land that leads to the most damaging wind erosion. The main cause of wind erosion is not wind, but the amount of weathered particles and other landscape conditions. Wind erosion causes severe damage to the land surface and has a deep impact on living organisms. It can be protected by growing herbs and plants over erosion-prone areas. The stems and branches of the plants slow down the motion of the wind and develop obstacles in the way of moving particles.
Impact of Wind Erosion
Wind erosion causes damage to agricultural land and other properties like roads and rail-tracks. It is costly for the economy, human health, and the environment. It can lead to soil loss, high cleaning bills, absenteeism, transport delays, sand-blasted crops, and retail losses. Wind erosion can affect human life and its environment in following ways.
Human Health
Wind erosion can have several direct and indirect impacts on human health, primarily through its influence on air quality, environmental conditions, and respiratory health. Wind erosion can contribute to the release of particulate matter into the air. Fine particles, known as PM10 (particles with a diameter of 10 micrometers or smaller), can be suspended in the air for extended periods and transported over long distances by the wind. When inhaled, these particles can penetrate deep into the respiratory system, causing or exacerbating respiratory problems. Inhalation of airborne dust generated by wind erosion can lead to respiratory issues such as coughing, wheezing, and shortness of breath. Individuals with pre-existing respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD), may experience worsened symptoms.
Moreover, windborne dust may contain allergens, such as pollen and mold spores, which can trigger allergic reactions in susceptible individuals. This can lead to symptoms like sneezing, itching, and watery eyes.
Fine particulate matter generated by wind erosion has been associated with cardiovascular problems, including heart attacks and strokes. Prolonged exposure to air pollution can contribute to the development and progression of cardiovascular diseases.
Wind erosion can transport soil particles into water bodies, leading to sedimentation and degradation of water quality. Contaminants carried by the wind can end up in water sources, potentially affecting human health through contaminated drinking water or disrupted aquatic ecosystems.
Prolonged exposure to environmental degradation, including the effects of wind erosion on landscapes, can have indirect impacts on mental health. Changes in living conditions and landscape may contribute to stress, anxiety, and overall reduced well-being.
Please remember that the severity of these impacts depends on various factors, including the amount and type of erodible materials, local environmental conditions, and the vulnerability of the population. Efforts to mitigate wind erosion through land management practices, vegetation cover, and other conservation measures can help reduce these health risks. Additionally, monitoring air quality and issuing advisories during periods of high wind erosion can be important for protecting public health.
Agricultural Production
Apart from its impact on human health wind erosion can have severe impacts on agricultural production, leading to challenges for farmers and the environment. Wind erosion can lead to the removal of the fertile topsoil, which is crucial for plant growth. This top layer contains essential nutrients, organic matter, and microbial activity. As soil is lost, the productivity of the land decreases, and it becomes more challenging to support healthy crop growth.
Wind erosion can create a crusted surface on the soil, reducing its ability to absorb and retain water. This can result in poor water infiltration and increased runoff, leading to waterlogged areas and decreased overall water availability for crops.
Young and emerging crops are particularly vulnerable to wind erosion. Wind-blown particles can physically damage seedlings, reducing their chances of survival and establishment. This can lead to poor stand establishment and lower crop yields.
Wind erosion doesn’t just remove soil particles; it can also carry away nutrients essential for plant growth. This depletion of nutrients can result in nutrient-poor soils, negatively impacting the fertility and productivity of the land.
Impact on Environment
Wind erosion can have significant environmental impacts, affecting ecosystems, air quality, and overall environmental health. It negatively impacts plant and microbial communities by removing the topsoil and fertile layer of the land. This, in turn, can affect the habitat and food sources for various organisms, leading to a decline in biodiversity in affected areas. It also affects water quality, by the addition of wind-eroded soil particles into water bodies. This sedimentation can degrade water quality by introducing excess sediment, nutrients, and agrochemicals into rivers, lakes, and other aquatic ecosystems.
Another severe impact of wind erosion is the displacement of plant and animal species as their habitats become degraded or destroyed. This can lead to habitat fragmentation, making it difficult for species to find suitable environments for survival and reproduction. Moreover, it can release stored carbon into the atmosphere, contributing to greenhouse gas emissions. The disturbance of soil through erosion may accelerate the decomposition of organic matter, releasing carbon dioxide (CO2) into the atmosphere and contributing to climate change.
Other Economic Consequences
The environmental impacts of wind erosion can have economic consequences beyond agriculture. For example, wind erosion causes loss of soil, damage to crops and infrastructure, contamination of air, property loss, and water quality issues. The degraded air and water quality can lead to increased healthcare costs, and the loss of biodiversity can disrupt ecosystems and the services they provide.
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