Wind Erosion in Western Queensland Australia

Chapter 4 –Modelling Soil Erodibility DynamicsChapter 4A Framework for Modelling Temporal Variations in SoilErodibilityThis chapter addresses Objective 3 by presenting a framework for modelling temporalvariations in soil erodibility. The framework draws on the systems analysis presented inChapter 2 to characterise the temporal response of soils subject to variable precipitation anddisturbance by livestock trampling, which are dominant controls on soil erodibility inrangeland environments.4.1 IntroductionGlobal interest in climate change, desertification and land degradation has drawn increasedattention to monitoring and modelling wind erosion processes in rangelands and cultivatedenvironments (e.g. Hagen, 1991; Lu and Shao, 2001; Gregory and Darwish, 2001). Central tothe development of functional wind erosion modelling systems is an understanding of howthe mechanisms driving wind erosion interact and change through space and time in responseto climate variability and land management. A recurring limitation to the development ofwind erosion models is the absence of robust schemes to simulate temporal changes in soilsurface conditions driving soil erodibility (Shao, 2000). This stems from the fact that themechanisms driving changes in soil erodibility to wind are complex and are yet to bequantified in many environments (Bresson, 1995). Developing our understanding ofprocesses forcing temporal changes in soil erodibility is therefore essential for advancing ourunderstanding of wind erosion dynamics (Merrill et al., 1999).Soil erodibility is defined as the susceptibility of a soil to mobilisation by wind. Soilerodibility is spatially variable and temporally dynamic and therefore exists within acontinuum (Geeves et al., 2000). The erodibility of a soil is controlled by the aggregate sizedistribution (ASD) of soil grains, and in particular the availability of loose erodible grains (