erosioon

Erosion, known in Norwegian as erosjon, is the process by which soil, rock, and other surface materials are worn away and moved by natural forces. Erosion involves three main stages: detachment of material from the source, transport of the particles by a transporting medium, and deposition where the material comes to rest. It is distinct from weathering, which is the breakdown of rocks in place without significant removal.

Agents of erosion include water, wind, ice, and gravity. Water erosion occurs on slopes and in rivers and seas, producing features such as rills, gullies, and alluvial fans. Wind erosion can lift and abrade loose material, forming dunes or deflation surfaces. Glacial erosion involves plucking and abrasion that carve valleys. Coastal erosion results from wave action and tidal currents. Factors that influence erosion rate include rainfall intensity, vegetation cover, soil type, slope angle, land use, and human activities such as deforestation and construction.

Impacts of erosion are widespread. In agriculture, soil loss reduces productivity and can degrade water quality through turbidity and sedimentation. Erosion shapes landscapes and creates landforms, deposits sediment downstream, and can threaten infrastructure and habitats. Bed, banks, and channels may become unstable, increasing the risk of bank collapse and sedimentation in waterways.

Mitigation includes soil conservation and land-management practices such as maintaining ground cover, mulching, agroforestry, contour plowing, terracing, and windbreaks; reducing tillage; reforestation; and engineering approaches like sediment-control structures. Effective erosion control relies on monitoring, appropriate land-use planning, and policy measures to limit disturbance of vulnerable soils.