Techniques for Wind-Erosion Measurements

Much of our understanding of wind erosion is derived from wind-tunnel experiments, in which the phenomenon is observed under controlled conditions. Laboratory wind tunnels have been used for the investigation of saltation (e.g. Bagnold, 1941), the determination of threshold friction velocity (e.g. Iversen et al. 1987), the process of drag partitioning (Marshall, 1971; McKenna Neuman and Nickling, 1995), the equilibration of saltation (Shao and Raupach, 1992), the process of dust emission (Shao et al. 1993b; Rice et al. 1996a, 1996b), as well as the formation and evolution of sand dunes (Tsoar et al. 1985). Portable wind tunnels, which can be set up in the field, have been used to study wind erosion on natural soil surfaces by Gillette et al. (1980, 1982), Nickling and Gillies (1989) and Leys and Raupach (1991), among others (Fig. 11.1). A particularly useful application of portable wind tunnels is to study how environmental factors influence the threshold of wind erosion, by applying wind-tunnel tests over the natural surface and then over that same surface with modifications.