Wind Erosion in Western Queensland Australia

Chapter 2 – Land Erodibility Controlssoil texture (particle size distribution), mineral content, organic/biological content, climate,and land management.Land Erodibility:The susceptibility of a land area to erosion by wind. Land erodibility is spatially variable andtemporally dynamic. The land area may vary in size from a field or paddock (10 2 to 10 3 m 2 )to regional scales (> 10 4 km 2 ). Land erodibility is a function of soil erodibility with the addedeffects of non-erodible surface roughness elements (rocks, vegetation, landforms) thatinfluence wind erosivity. Factors controlling land erodibility include those affecting soilerodibility, land type characteristics (vegetation and geomorphology), climate andmanagement. Where non-erodible roughness elements are absent, land erodibility iscontrolled by soil erodibility.2.2 Controls on Soil and Land ErodibilityThe following sections present a systems analysis, describing the process of wind erosion andthe effects of key environmental controls.2.2.1 Physics of Wind Erosion and Modes of Sediment TransportAirflow over natural landscapes is generally turbulent. Wind velocity measurements thatdescribe airflow represent time-averaged conditions (Lancaster, 1995). If wind velocity ismeasured at various heights above a surface a logarithmic profile results, with wind velocityincreasing with height away from the surface. Turbulence caused by surface heating andairflow over topographic obstacles may disrupt this profile (Livingstone and Warren, 1996;Sturman and Tapper, 2001). Frictional effects, enhanced by roughness elements on the landsurface, reduce the wind velocity close to the surface.For bare soil surfaces, a number of forces can be described that act on individual soilparticles. These forces determine whether or not particle mobilisation and entrainment canoccur:• Drag, lift and the particle moment;• Gravitational acceleration;32