Wind Erosion in Western Queensland Australia

Chapter 1 - Introductionsusceptibility of the rangelands to wind erosion is governed by complex relationshipsbetween soil types, vegetation cover and meteorological conditions, in particular rainfallquantities and timing (McTainsh et al., 1999). Subsequent studies sought to quantify changesin the erodibility of the claypan surface using remote sensing techniques (Chappell et al.,2003; Chappell et al., 2006; Chappell et al., 2007), and to quantify the effects of spatialvariations in dust source erodibility on emissions (Butler et al., 2005). Importantly, none ofthese studies sought to map spatial and temporal patterns in land susceptibility to winderosion at the landscape scale (10 3 km 2 ).Little research has been conducted in Australia to model the spatial distribution of winderosion. Lynch and Edwards (1980) used a pattern analysis approach for delineating winderosion zones in New South Wales. Their model defined nine zones within the state withvarying wind erosion hazards. The zones were aligned with the mean annual rainfall isohyets(increasing wind erosion risk with decreasing rainfall) and the pattern of dust-stormfrequencies reported by McTainsh et al. (1998). They could not, however, predict the preciselocation of areas with a wind erosion risk.Kalma et al. (1988) mapped potential wind erosion across Australia using an index of winderosivity (after Fryberger, 1978). They found that stream lines of airflow over Australiafollow an anti-cyclonic swirl about the centre of the continent. Variations in the flow occur inaccordance with seasonal changes in strength of the Zonal Westerlies and the Trade Windsover northern Australia. Maximum drift potential was found to occur in October, and reach aminimum in April. This result supported later studies which show these times to be roughlycoincident with periods of maximum and minimum wind erosion activity in central Australia(Eckström et al., 2004). The relative importance of seasonal variations in land erodibility indriving temporal changes in wind erosion activity remains yet to be considered in detail.Shao et al. (1994) and Shao et al. (1996) presented the first process-based model to assesswind erosion in the Murray-Darling Basin of south-eastern Australia. The model wassubsequently developed into an Integrated Wind Erosion Modelling System (IWEMS) forapplication on a national basis (Shao and Leslie, 1997; Lu and Shao, 2001). While the modelhas been used to simulate regional dust emissions, it has not been applied specifically toassess land susceptibility to wind erosion.10