Wind Erosion in Western Queensland Australia

Chapter 2 – Land Erodibility ControlsFigure 2.2 Modes of particle transport by wind, including: creep; reptation; saltation; and suspension(after Pye, 1987).Creep describes the movements of mostly larger grains close to the surface. In particular,creep refers to the rolling motion of particles, and may be induced by impacts from finersaltating grains (Livingstone and Warren, 1996). Reptation is the splashing or low hopping ofgrains close to the surface. Particles pass between this mode and saltation depending onfriction velocity characteristics. Saltation describes the hopping action of grains. Saltation isinitiated by particle impacts that eject grains into the airstream. These particles are thencarried by the wind before descending back to the surface. Saltation is responsible formobilising static particles on the surface, and the ejection of fine particles into the air throughrupturing and abrasion. Clouds of saltating particles influence surface roughness and the windfriction velocity in a positive feedback called the Owen effect (Gillette et al., 1998). Particlesemitted from a surface that are carried by the wind by turbulent motion do so in thesuspension mode. In general, grain size decreases with height away from the surface andthrough these modes of transport.2.2.2 Climatic Controls on Soil and Land ErodibilityThe dominant, regional scale, control on wind erosion is climate. In addition to windiness,sites require a significant moisture deficiency in order to become susceptible to wind erosion.Land areas susceptible to wind erosion are therefore typically located within the world’s36