Natural forces like water, wind, and ice erode away bits of rock and soil before depositing them elsewhere – this process is known as erosion.
Living things can also contribute to erosion. Plant roots, for instance, can wedge their way between cracks in rocks to cause further eroding effects. Glaciers also play a part in shaping mountains by slowly moving around carving valleys out.
Water
Water erosion is most frequently caused by running rivers, ocean waves and glaciers, with brown-tinged riverwater often carrying dirt and rock from elsewhere in its path. Erosion differs from weathering which simply breaks up rocks without moving them physically; both involve movements.
Waves and winds both contribute to erosion. Waves pounding against coastlines wear away pebbles and sand, leaving behind sea stacks as they form. Meanwhile, winds carry sand from place to place, changing their shape over time into dunes that form over time; in some instances it blows soil off farmland, known as wind erosion.
Human activities that contribute to erosion include intensive farming, deforestation and road building. Planting trees and growing grasses may help combat erosion as they help hold soil together. Wildfires and climate change may also exacerbate erosion by decreasing topsoil amounts while making it easier for water to flow across the ground carrying particles with it.
Waves
Waves crash against coastlines with force, leading to erosion. Wave erosion involves several processes such as Hydraulic Action – whereby water’sandpapers’ the rocks – and Abrasion, in which rocks and sand particles carried by waves knock into each other and rub against one another, both occurring simultaneously.
Wave erosion can create various coastal landforms, including beaches, spits and barrier beaches. In addition, seaside cliffs may be damaged, creating caves and archways while leaving isolated towers of rock known as sea stacks behind.
Research has demonstrated that the rate of erosion on any coast depends on its wave energy exposure and geological composition, for instance a coastline composed of soft materials like clay and sand can erode faster than hard materials like granite. Furthermore, position can play an important role; areas with rougher waves – like headlands – erode more rapidly than bays due to more energy from their waves passing over quiet waters than through channels and being refracted through quiet channels can concentrate or disperse their power more effectively than more serene locations like bays or calm waters.
Wind
Wind can transport dust and sand particles that wear away at rock surfaces (abrasion). Furthermore, wind helps disperse these particles over large areas to spread plant seeds or nonliving materials – this process is known as dispersal.
Wind erosion is a key concern in deserts and other regions with limited rainfall, particularly when soil surfaces remain unprotected, such as during periods of drought when agricultural activities leave land bare and vulnerable.
Wind speed and direction play an essential role in erosion. Winds blowing in one direction carry away material eroded from one area while winds from opposite directions deposit it elsewhere. Climate is another major influencer; variations in rainfall can alter water balance between surface water and groundwater sources while extreme temperature fluctuations cause rocks and soil to break down more rapidly than usual – leading to sudden downhill movement known as mass wasting.
Soil
Wind erosion of dry areas by picking up dust particles is an enormous problem in semi-arid regions and contributes to desertification.
As more top fertile layers of soil are washed away by rainfall or runoff, food production declines and food security becomes an issue. Furthermore, loss of soil carries with it insecticides, fertilizers and other chemicals into rivers and lakes polluting aquatic environments further.
Erosion alters river courses, leading to flooding. Erosion also contributes to landslides.
Climate change exacerbates erosion processes. Increased rainstorms and temperature swings cause more soil to be washed away, which speeds up its movement towards water bodies like rivers and oceans. Deforestation, intensive agriculture and clearing grasslands all make soil more vulnerable to erosion by water and wind–human activities known as land degradation–making erosion even more likely. Sustainable land management practices that reduce risk can be cost-effective ways of mitigating this erosion risk.