Erosion is the process of loosening, removing and transporting weathered or unweathered solid material by water, wind, waves, glaciers or gravity.
Erosion plays an essential part in shaping Earth’s landscape. River erosion carries pieces of rock and soil downstream to form beaches, estuaries, sand bars, spits and deltas.
Water
Erosion occurs naturally in wet environments due to rainwater and swift running streams wearing away rock and soil, or due to glaciers gradually eating away at bedrock along their travel route, or by landslides.
Wind can erode rock and soil in dry regions through aeolian erosion. Dust, sand and ash transported by this form of erosion is transported from place to place as it weathers rocks and cliffs into smooth surfaces that form weathering features on them. Furthermore, wind creates towering dunes, giving some deserts their distinctive appearance.
Moving water is the primary culprit of erosion. It creates canyons in steep terrain and enriches floodplains in flatlands, transports sediment from one place to the next as it travels downstream, depositing it as it goes, leaving behind deposits like sandbars, river deltas, or other landforms in its wake. Water erosion is further amplified by factors like abrasion that wears away surface materials as well as flow velocity that increases gravity’s force on them; human activities like intensive agriculture or deforestation can further accelerate erosion rates as it goes down river.
Wind
Wind erosion occurs more slowly than water erosion and involves the transport of dust or sand particles from one area to another, which may travel a few millimetres or many kilometres – sometimes creating dunes at beaches, changing rock forms in deserts or blanketing crops with dust storms such as those seen across North America in the 1930s – known as “The Dust Bowl.”
Erosion rates depend on many variables, such as rock or soil type, rainfall amounts and winds speed; vegetation can help mitigate erosion through its roots attaching themselves to soil and rocks thereby slowing their movement; human activities like intensive agriculture, deforestation or road building may increase erosion rates further.
Waves
Waves can erode landforms in multiple ways. Sediments carried by waves act like sandpaper, wearing away at rocks that lie in their path. Furthermore, when waves crash against sea cliffs they can erode away at them, creating features such as rock arches or sea stacks in their wake.
Wave refraction can contribute to erosion. When waves approach shore they slow as they enter shallower waters, and as soon as their front edge hits shallow water the part closest to shore bends or refrescts.
Researchers from MIT and elsewhere have discovered an indirect correlation between wave power and how quickly rocky coasts erode, suggesting that nonstormy waves provide a good indicator of how fast coastlines will erode. If beaches experience larger than usual waves, their coastlines tend to erode more quickly while those experiencing smaller-than-usual waves will experience slower erosion because less powerful or frequent waves carry less sediment with them.
Soil
Resistance to erosion depends on several factors: texture, organic matter and permeability of soils. Sand, loam and clay-textured soils tend to be less erodible than silty and very fine sands; also, ridged and sloped surfaces help reduce wind speed to reduce erosion.
Water erosion can have devastating results, as witnessed in Jakarta earlier this year with flooding caused by sediment accumulation clogging rivers and canals that led to their overflow.
Agriculture, mining, deforestation and road construction activities all increase erosion. These activities disrupt the structure of soils by dismantling their ability to retain moisture and nutrients – decreasing crop emergence, growth and yield while making some cultivation-unsuitable soils irremediably unusable for farming altogether. Erosion also has other repercussions, including decreasing biodiversity above and below ground and degrading ecosystems; increasing pollutants entering lakes streams oceans polluting coral reefs while diminishing drinking water quality; ultimately erosion can diminish quality while decreasing drinking water quality as a consequence of its effect.