Validation of WEPS for soil and PM10 loss from agricultural fields within the Columbia Plateau of the United States

Wind erosion from agricultural fields contributes to poor air quality within the Columbia Plateau of the United States. Erosion from fields managed in a conventional winter wheat– summer fallow rotation was monitored during the fallow period near Washtucna, WA, in 2003 and 2004. Loss of soil and PM10 (particulates ≤10 μm in diameter) was measured during six high wind events (sustained wind speed at 3 m height >6·4 m s). Soil loss associated with suspension, saltation and creep as well as PM10 emission was used to validate the Wind Erosion Prediction System (WEPS) erosion submodel. Input parameters for WEPS simulations were measured before each high wind event. The erosion submodel produced no erosion for half of the observed events and over-predicted total soil loss by 200–700 kg ha− for the remaining events. The model appears to over-predict total soil loss as a result of overestimating creep, saltation and suspension. The model both over-predicted and underpredicted PM10 loss. High values for the index of agreement (d > 0·5) suggest that the performance of the model is acceptable for the conditions of this study. While the performance of the model is acceptable, improvements can be made in modeling efficiency by better specifying the static threshold friction velocity or coefficients that govern emissions, abrasion and breakage of silt loams on the Columbia Plateau. Copyright © 2006 John Wiley & Sons, Ltd.