Evaluation of the RWEQ and SWEEP in simulating soil and PM10 loss from a portable wind tunnel

Abstract

Wind erosion threatens sustainable agriculture and environmental quality in the US Pacific Northwest. Wind erosion models such as the Revised Wind Erosion Equation (RWEQ) and Wind Erosion Prediction System (WEPS) have been developed as tools for identifying practices that control windblown soil loss. Models, however, must be tested under a range of crop, soil, and weather conditions. The objective of this study was to test the performance of the RWEQ and WEPS erosion submodel (Single-event Wind Erosion Evaluation Program or SWEEP) in simulating soil and/or PM10 (particulate matter ≤10μm in diameter) loss from a portable wind tunnel. A wind tunnel, which allows simulations to be conducted under known conditions, was used to assess wind erosion from four tillage treatments imposed during the fallow phase of a winter wheat – summer fallow rotation near Lind, WA. There was good agreement between the measured and simulated soil loss using the SWEEP for conventional and reduced tillage. However, the SWEEP inadequately simulated soil loss for minimum and no tillage and PM10 loss from all tillage treatments. The performance of the SWEEP improved when the SWEEP threshold friction velocity algorithm was replaced with the Lu and Shao algorithm. The RWEQ adequately simulated soil loss, but only for minimum tillage. Model performance can be improved to a certain extent by modifying parameters or perhaps by calibration, but poorly simulating wind erosion under the known surface conditions in this study suggests the models inadequately define the complexity of erosion processes in the field.