ARS | Publication request: VALIDATION OF WEPS FOR SOIL AND PM10 LOSS FROM AGRICULTURAL FIELDS ON THE COLUMBIA PLATEAU

Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2006
Publication Date: December 10, 2006
Repository URL: http://hdl.handle.net/10113/44270
Citation: Feng, G., Sharratt, B.S. 2007 Validation of WEPS for soil and PM10 loss from agricultural fields on the Columbia Plateau of the United States. Earth Surface Processes and Landforms 32:743-753.

Interpretive Summary: The Wind Erosion Prediction System (WEPS) is new technology developed by the USDA-ARS for predicting wind erosion. WEPS will be used in the near future by the USDA-NRCS for conservation planning and creating natural resource inventories, but WEPS has not been widely tested across the United States. The performance of WEPS appears to be marginal in predicting erosion and emission of PM10 (particulate matter '10 µm in aerodynamic diameter that is regulated as an air pollutant by the US EPA) from agricultural lands in eastern Washington. Better specification of the threshold wind velocity to initiate erosion or of processes that govern abrasion and breakage of very fragile soils are needed to improve the performance of WEPS. Thus, laboratory and field studies should be undertaken by soil scientists and agricultural engineers to better delineate threshold velocities or breakage processes of the fragile soils in eastern Washington prior to using WEPS in US agency programs .

Technical Abstract: Wind erosion from agricultural fields contributes to poor air quality within the Columbia Plateau of eastern Washington. Erosion from fields near Washtucna, Washington managed in a conventional winter wheat – summer fallow rotation was monitored during the fallow period in 2003 and 2004. Loss of soil and PM10 (particulates '10 µm in diameter) was measured during six high wind events over the two years. Soil loss associated with suspension, saltation, and creep as well as PM10 emission were used to validate the Wind Erosion Prediction System (WEPS) erosion submodel. The erosion submodel produced no erosion for half of the observed events. For the remaining high wind events, the model over predicted soil loss by 200 to 700 kg ha-1 and either over predicted or under predicted PM10 loss. The model appears to over predict soil loss as a result of overestimating creep and saltation. 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. However, low values for the modeling efficiency (EF<0.5) indicate that the model does not adequately simulate loss of soil and PM10 from agricultural soils in the Columbia Plateau. While the performance of WEPS appears marginal, improvements in modeling efficiency may require better specification of the static threshold friction velocity or additional parameterization of various coefficients that govern emissions, abrasion, and breakage of silt loams on the Columbia Plateau.