How Wind Erosion Processes Affect Selection and Performance of Erosion Control Systems

During the past decade, the physical processes governing erosion of soil by wind have been investigated by a number of researchers (Anderson et al., 1991; Armbrust and Bilbro, 1997; Gillette et al., 1997; Hagen et al.; 1992; Hagen et al.; 1999; Marticorena et al., 1997; and Mirzamostafa et al., 1998). The results of these investigations have improved our understanding of several wind erosion phenomenon. Among these are estimates of erosion threshold wind speeds, entrainment rates of loose soil, abrasion rates of crust/clods, breakage rates of saltation/creep, interception efficiencies of plants, and trapping rates of eroding soil. But to fully utilize our improved understanding of these processes, wind erosion models must incorporate them. However, even models that incorporate most of these processes still rely upon the model user to optimize the design of individual wind erosion control systems. Generally, the goal of optimization is to achieve acceptable erosion control at minimum cost for a given land management system. While implementing erosion controls may or may not provide short term positive economic returns for the land manager, failure to control erosion often generates large offsite costs ( Huszar and Piper, 1986 ). Effectively mitigating offsite impacts may include the need to consider other factors in addition to total soil loss. For example, emissions of PM-10 (i.e., particulate matter less than 10 microns in diameter) from farmlands and other disturbed areas near the rural-urban interface may prevent urban areas from meeting air quality standards. Other critical offsite impacts are caused both nutrient and sediment transport to water bodies, pesticide movement to non-target areas, and decreased visibilities that hinder transportation. For all these cases, erosion control specialists need to understand the influence of various processes on their design parameters. They also may need to use specialized designs that vary depending on the location of critical offsite targets. The objectives of this report are twofold. First, to present a brief overview of several of the wind erosion processes, and second, to suggest how these processes might influence selection and design of wind erosion controls.