Submitted to: International Conference on Aeolian Research
Publication Type: Abstract Only
Publication Acceptance Date: 7/28/2006
Publication Date: 7/28/2006
Citation: Sharratt, B.S., Feng, G. 2006. Evidence of Direct Suspension of Soil Particulates on the Columbia Plateau. International Conference on Aeolian Research.
Technical Abstract: High wind events during spring and autumn contribute to erosion of agricultural lands on the Columbia Plateau of the Pacific Northwest United States. Wind erosion occurs as a result of creep, saltation, and suspension; in many regions of the world, creep and saltation are the dominant processes governing wind erosion. Direct suspension is thought to be an important process affecting erosion of loessial soils within the Columbia Plateau due to the lack of extensive depositional features. The purpose of this study was to determine the contribution of direct suspension to wind erosion by examining wind velocity profiles and the size distribution of eroded soil from an agricultural field. The 9-ha field, located near Washtucna, Washington, was maintained in fallow and dominated by Ritzville silt loam. Profiles of wind velocity, PM10 (particulates 10'µm in diameter) concentration, and the size distribution of particulates captured by airborne soil collectors were measured above the soil surface during high wind events. There was little modification of the wind velocity profile due to saltation loads and elevated PM10 concentrations corresponded closely with their threshold velocity. Of the total mass of eroded soil captured by the BSNE collectors, less than 10% was saltation-sized particles (100-500µm in diameter) while more than 90% was suspension-sized particles (<100µm in diameter). The largest fraction of soil eroded was in the size range of 30-45µm. These results indicate that direct suspension of fine soil particles is a dominate process whereby soil is eroded from agricultural fields on the Columbia Plateau.