Wind Erosion in Western Queensland Australia

Chapter 3 – Modelling Land Erodibility ReviewWEPS uses a series of empirical relationships to compute changes in soil erodibility withinthe soil sub-model. The soil sub-model accounts for surface crusting through a linearrelationship with cumulative precipitation. It then computes the amount of loose erodiblematerial on the crust as a function of soil textural properties, organic matter, carbonatecontent (after Zobeck and Popham, 1992). As for surface crusting, the loose erodible fractionof soil can be adjusted within the model by accommodating precipitation effects (Hagen,1991). Additional soil properties that affect soil erodibility such as dry aggregate sizedistribution and stability are also derived within the soil sub-model. Like RWEQ, WEPS hasa relatively small spatial application, with the model simulation region being confined to asingle field, or a few adjacent fields. The model accommodates land surface heterogeneity bydividing non-homogeneous regions into smaller homogeneous sub-regions, and runningsimulations for each (Hagen, 1991).WEPS has been applied to simulate field conditions (crop residue roughness effects) andwind erosion on cultivated fields in North America and Europe (Van Donk and Skidmore,2003; Funk et al., 2004; Hagen, 2004). Hagen (2004) compared WEPS predictions tomeasured data from 46 wind erosion events across North America. Across the sites, WEPStended to under-predict soil loss, but reproduced the field data reasonably well (r 2 = 0.71). Ina similar comparison, Funk et al. (2004) found a better match between WEPS predictions andfield measured erosion rates (r 2 = 0.91) for a series of erosion events in Germany. Coen et al.(2004) used WEPS to map wind erosion risk of soils in Alberta, Canada. However, the modelwas run at a coarse (field scale) resolution, and did not provide information on high spatialand temporal resolution changes in soil erodibility.3.2.4 Texas Erosion Analysis Model (TEAM)The Texas Erosion Analysis Model (TEAM) was developed to have a low dependence onfield-measured inputs and empirical relationships as used in WEQ, RWEQ and WEPS.TEAM simulates the detachment, maximum transport rate and emission of dust particles(Singh et al., 1999). Like WEPS, the model erosion scheme operates on the principle thatentrainment occurs when u * exceeds u *t . The schemes used to compute land surfaceconditions draw upon external studies of the effects of land surface processes on u *t . LikeWEPS, TEAM computes both a static threshold friction velocity required for the initiation ofentrainment, and a dynamic threshold for sustained sediment transport.77