Wind Erosion in Western Queensland Australia

Chapter 2 – Land Erodibility ControlsRice et al. (1996) and Rice et al. (1997) explored relationships between crusting and particlebinding strength and erosion due to particle impacts (by saltation bombardment). Theypresented a conceptual model to define erosion rates based on probability distributions ofparticle impact energy and surface strength (Figure 2.6). This work was followed by studiesseeking to quantify the effects of abrasion on crusted surfaces and resulting dust emissionrates (McKenna-Neuman and Maxwell, 1999; Houser and Nickling, 2001a, 2001b).Figure 2.6 Illustration of probability distributions of the energy delivered to a soil surface by saltatinggrains, P[Ei], and the local energy required to break surface crusting, P[Es] (after Rice et al., 1999).Eldridge and Leys (2003) demonstrated that there is a strong relationship between crust coverand dry aggregate size distribution, for which there is an established functional relationshipwith wind erosion rates (Equation 2.11). Their results suggest that aggregation is a betterpredictor of erodibility than crust cover alone. Fryrear et al. (1998) developed a model topredict crust cover based on soil clay, CaCO 3 and organic matter contents. The empiricalnature of the model, and the complex relationship between climate, soil properties and crustformation mean that the model has limited application outside the limits of the data fromwhich it was derived. Accounting for the effects of soil surface crusting and aggregation inwind erosion models has, and continues to be, a global problem. The implications of thespatial variability in crust properties, and with time, dictate that further research is required,particularly in monitoring the temporal evolution in surface crusting and its effects onerodibility. This issue is described in detail in Chapter 4.53