Wind Erosion in Western Queensland Australia

Chapter 5 – Land Erodibility Model DevelopmentThe development of models provides a means for assessing and extending our understandingof wind erosion processes across multiple spatial and temporal scales. There are fewaccessible methods for modelling or mapping spatio-temporal patterns of wind erosionhazard in Australia at moderate to high spatio-temporal resolutions (< 10 3 km 2 ; daily –monthly). The development of the Integrated Wind Erosion Modelling System (IWEMS) hasprovided a resource for addressing this deficiency, but the model is currently only applicableat a moderate (5 x 5 km) spatial resolution within south-eastern Australia (Lu and Shao,2001). Webb et al. (2006) presented a spatially explicit Australian Land Erodibility Model(AUSLEM) for predicting land susceptibility to wind erosion. The model was applied at a 5 x5 km spatial resolution on a monthly time-step across Australia. Qualitative comparisons ofmodel output with an index of wind erosion activity indicated that the model could hind-casterosion hazard with a reasonable level of success. However, the model used a thresholdbasedrule-set which tended to bias output predictions toward areas situated in a small rangeof soil textures.This chapter addresses the limitations of the AUSLEM rule-based modelling system byderiving a new scheme to predict land erodibility. The chapter presents a description of therevised land erodibility model and evaluates model performance through a comparison ofoutput and observational records of wind erosion activity. The focus of this research was todevelop AUSLEM to predict land susceptibility to wind erosion in western Queensland,Australia.5.2 Study AreaAnalyses of long term dust-event frequencies in Australia indicate that the eastern half of thecontinent is the most active wind erosion region (McTainsh et al. 1990). Model developmentand validation were carried out for the northern part of this region, in western Queensland.Figure 5.1 provides a map of the study area, as described in Chapter 1, Section 1.6. The mapshows the extent of the four bioregions covering the western Queensland rangelands and thelocation of meteorological stations from which observational records of dust events, used inthis chapter, were acquired. Wind erosion is infrequently observed to the east of the studyarea due to higher annual rainfall and vegetation cover, so that area is not considered here.131