Wind Erosion in Western Queensland Australia

Chapter 5 – Land Erodibility Model Developmentsurfaces has been observed by the authors, these areas which occur along the river systemsdissecting the study area were not included in the mask.5.4 Model Input DataSoil texture data (clay content in topsoil) at a 1 x 1 km spatial resolution was acquired fromthe Australian Natural Resources Atlas (ANRA), as used by Shao et al. (1994). Foliageprojective cover (FPC – a vertical projection of tree canopy cover) data for 2003 were used asa representative measure of tree cover. FPC data at a 30 x 30 m spatial resolution weresourced from the Statewide Landcover and Trees Study (SLATS), and were derived fromLandsat ETM+ satellite imagery by the methods of Danaher et al. (2004). Aerial photographassessments (1:250 000 scale) of the extent of stony pavements within the study area wereused to derive the stone cover mask and were sourced from the Western Arid Regions LandUse Study (WARLUS; QDPI, 1974). Daily spatial data of grass cover (%) and soil water(mm per top 10 cm of profile) were obtained from the Australian pasture growth modelAussieGRASS (Carter et al., 1996a,b; Littleboy and McKeon, 1997). AussieGRASS is run ata 5 x 5 km spatial resolution on a daily time-step and can be used to hind-cast pastureconditions from 1890 to present. All data except FPC were rescaled to a 5 x 5 km resolutionfor modelling with AUSLEM. The FPC data were used at the 30 x 30 m resolution asrescaling resulted in a significant loss of tree cover detail (due to sub-grid scale averaging ofthe sparse tree cover in the study region), and poor model performance in regions where treecover is a significant control on wind erosion.Calibration and validation of AussieGRASS was carried out in Queensland pasturecommunities, so the model can be expected to perform best in the current study area.However, model performance may vary between pasture communities due to plantphysiological and growth characteristics. AussieGRASS output is most accurate over areas25 to 50 times the resolution of its 5 x 5 km inputs (Carter et al., 1996b). This hasimplications for AUSLEM output validation and interpretation, which must also beconducted at these scales.142