Soil Erosion: Significance, Multiscale Processes, and Mitigation Principles

par Christian Valentin (emeritus soil scientist, French Research Institute for Development (IRD), French Academy of Agriculture)

mercredi 28 févr. 2024, 14:00 → 16:00 Europe/Paris

Amphithéâtre Léon Motchane (IHES)

Soil undergoes numerous degradation processes, including compaction, sealing, salinization, acidification, impoverishment, contamination, and biodiversity loss. Among these, soil erosion stands out as the most critical in terms of both intensity and widespread impact. Although soil erosion is inherently a natural process, human activities, notably agriculture, deforestation, and urbanization, significantly accelerate it. With the continued growth of human populations, the strain on land resources intensifies, exacerbating soil erosion dynamics. This presentation aims to shed light on the nonlinear processes and mitigation strategies associated with soil erosion.

The processes involved encompass the detachment, transportation, and deposition of soil particles, leading to adverse environmental, agricultural, and socio-economic consequences. On-site impacts include the loss of organic matter and nutrients from the topsoil, resulting in soil impoverishment, diminished biodiversity, and reduced crop yields. Off-site effects involve sedimentation in rivers and reservoirs, adversely affecting water quality, aquatic ecosystems, and infrastructure.

Soil erosion is a dynamic phenomenon influenced by various factors such as rainfall, water flow, gravity, tillage, topography, vegetation cover, and land use. Three primary factors drive soil erosion: water, wind, and tillage. Water erosion further subdivides into sheet erosion, rill and gully erosion, and mass movements. Wind erosion entails the detachment and transportation of soil particles by the force of the wind. Tillage contributes to erosion through the force of gravity. Understanding these mechanisms is pivotal for devising effective soil conservation strategies.

The susceptibility of an area to soil erosion is influenced by diverse factors, including climate, soil type, topography, vegetation cover, and land use practices. Successful soil erosion control needs implementing sustainable land management practices. Conservation tillage, cover cropping, associated cropping, contour plowing, and agroforestry represent examples of sustainable agricultural practices that aid in erosion reduction. Terracing, check dams, and vegetative buffers are additional solutions employed to mitigate water erosion, while windbreaks and cover crops prove effective measures against wind erosion.

Addressing soil erosion necessitates a multidisciplinary approach that integrates community engagement, scientific knowledge, and policy development.

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