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Wind Erosion:
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Saltating Sand Erodes Metastable Loess: Events in the Impact Zone

Ian F. Jefferson and Ian J. Smalley


In the classic forms of wind erosion energy is transferred from the wind to the ground via a saltating sand grain. The sand grain impact causes a disruptive tensile failure in a discrete failure zone and soil particles are injected into the air stream. A whole set of variables (which we need to understand and perhaps manipulate) operate in the impact zone and these control the wind erosion process. A simple functional equation defines the parameters. Two major erosion resisting factors operate in the failure zone, a cohesion force and a particle weight force, and the interaction of the forces causes the most effectively eroded particles to be in the coarse silt size range; hence the large loss in loess soil regions.

The wind erosion equation can be generalised to cover all impact erosion processes and hence most erosion processes. In the metastable system there is a trade-of; high metastability is good in agricultural production terms, but involves a vulnerability to erosion. Preventing soil erosion may involve finding ways to preserve the metastability factor in soils at risk.