The threshold friction velocities and soil flux rates of selected soils in south-west New South Wales, Australia
A portable wind erosion tunnel has been used to measure the wind erodibility of nine soil types with a range of surface textures under two treatments (bare uncultivated and bare cultivated) in western New South Wales. The erodibility has been characterised by the soil flux function Q(u *), whereQis the streamwise soil flux (measured with a modified Bagnold soil trap) and u * the friction velocity (obtained by fitting the logarithmic wind profile law to a wind profile measured in the tunnel). Threshold friction velocities u *t were also observed for the range of surfaces. These data represent the only Australian tests published to date and supplement the American measurements of semi-arid soils by Gillette , , .
Averaging over 10 replicate plots for each surface type was necessary to smooth the large scatter in Q and smaller scatter in u *. The Q values spanned three decades of magnitude. Soils with a sandy loam surface texture were the boundary between the highly erodible sand and the basically noner-odible clay. Cultivation increased the erodibility of the majority of soils by about a factor of 10, but decreased the erodibility of the clay. The function Q(u * is well described by the Owen [4J soil flux equation. Threshold friction velocity decreased as soil texture became sandier. In comparison with work of Gillette , Australian soils have lower u *t values, which is most likely due to higher sand and lower silt contents.
KeywordsWind Velocity Sandy Loam Surface Texture Friction Velocity Wind Erosion
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