Érosion

Érosion refers to the process by which soil, rock, and other surface materials are worn away and transported by natural agents such as water, wind, ice, and gravity. Although erosion is a natural part of landscape evolution, its rate can be accelerated by climate variability and human activities, leading to environmental and economic consequences.

The main agents are water, wind, ice, and gravity. Water erosion includes rainfall impact, sheet flow, and the development of rills and gullies, with rivers and streams transporting sediment. Wind erosion dominates in arid and semi-arid regions, causing deflation, abrasion, and dune formation. Glacial erosion occurs as moving ice scours and plucks rock; coastal erosion results from waves, tides, and longshore drift eroding shorelines. Gravity-driven erosion encompasses mass wasting, such as landslides and rockfalls, which remove material downslope. Erosion is distinct from weathering, which breaks down material in place; erosion removes and relocates it. The processes shape landforms, including valleys, dunes, and coastlines, and contribute sediment to downstream systems, where deposition occurs when transport capacity decreases.

Impacts and management: Soil erosion reduces agricultural productivity and can degrade water quality through sedimentation. Coastal erosion threatens infrastructure and ecosystems. Management strategies include maintaining vegetation cover, contour farming, terracing, windbreaks, riparian buffers, reduced tillage, and prudent land-use planning. Reforestation and soil-conservation practices help reduce erosion rates. Monitoring with field measurements and remote sensing supports assessment and policy decisions, particularly as climate change increases rainfall intensity and sea-level rise can exacerbate erosion in many regions.