Wind Erosion in Western Queensland Australia

Chapter 3 – Modelling Land Erodibility Review10 to 31 vertical layers, and a horizontal resolution ranging from 5 x 5 km to 75 x 75 km. Theatmospheric model provides forcing for both the dust emission and transport models (Lu andShao, 2001).In addition to the spatial expansion of model application, and input upgrades, the modelestimation of u *t was also revised. The revisions built upon the model presented by Shao et al.(1996) and Shao and Leslie (1997), with the inclusion of factors to account for multiple nonerodibleroughness element layers, and the erodible fraction of the exposed surface (Lu andShao, 2001). In a development from the drag partitioning scheme used in WEAM, IWEMSuses a double drag partitioning approach that allows for the independent (and combined)effects of large roughness elements (e.g. trees) and also small roughness elements to bemodelled (Shao, 2000).Lu and Shao (1999) developed a soil classification map to account for spatial differences insoil erodibility. In using this the model groups soil inputs into erodible and non-erodibleclasses, with the erodible soils being assigned particle size distributions based on fieldsamples from the soil type classes (Lu and Shao, 1999). This is similar to the methodologyemployed by Marticorena and Bergametti (1995) to account for spatial variability in desertdust source areas (Section 3.4.1). Due to a lack of quantitative research on the temporalevolution of surface crusts in Australia, the surface crust/mobility factor remained set to aconstant (1) for all soils. The model therefore still lacks a dynamic component to define soilerodibility (Lu and Shao, 2001). This means that temporal changes in u *t in IWEMS aredriven by variations in surface roughness and soil moisture conditions.3.4 Continental to Global Scale ModelsThis section describes the prediction of land erodibility in continental and global scale dustemission and transport models. The section includes reviews of the Dust Production Model(DPM) and Dust Entrainment and Deposition Model (DEAD), and notes characteristics of theCommunity Aerosol and Radiation Model (CARMA), and the Global Ozone ChemistryAerosol Radiation and Transport (GOCART) model. In general these models use erosionschemes developed for smaller scale models, with adaptations to suit their applicationenvironments.86