Evaluation of the SWEEP model during high winds on the Columbia Plateau

Abstract

A standalone version of the Wind Erosion Prediction System (WEPS) erosion submodel, the Single-event Wind Erosion Evaluation Program (SWEEP), was released in 2007. A limited number of studies exist that have evaluated SWEEP in simulating soil loss subject to different tillage systems under high winds. The objective of this study was to test SWEEP under contrasting tillage systems employed during the summer fallow phase of a winter wheat-summer fallow rotation within eastern Washington. Soil and PM10 (particulate matter ≤10 μm in diameter) loss and soil and crop residue characteristics were measured in adjacent fields managed using conventional and undercutter tillage during summer fallow in 2005 and 2006. While differences in soil surface conditions resulted in measured differences in soil and PM10 loss between the tillage treatments, SWEEP failed to simulate any difference in soil or PM10 loss between conventional and undercutter tillage. In fact, the model simulated zero erosion for all high wind events observed over the two years. The reason for the lack of simulated erosion is complex owing to the number of parameters and interaction of these parameters on erosion processes. A possible reason might be overestimation of the threshold friction velocity in SWEEP since friction velocity must exceed the threshold to initiate erosion. Although many input parameters are involved in the estimation of threshold velocity, internal empirical coefficients and equations may affect the simulation. Calibration methods might be useful in adjusting the internal coefficients and empirical equations. Additionally, the lack of uncertainty analysis is an important gap in providing reliable output from this model. Published in

Soil Carbon Loss by Wind Erosion of Summer Fallow Fields in Washington's Dryland Wheat Region

“…Similarly, soil loss during the 17 and 23 Oct. 2003 erosion event (44 kg ha -1 ) may have been lower than the 9 Sept. 2005 event because of differences in aggregate geometric mean diameter. Although the data of Sharratt et al (2015) indicated that differences in random roughness (10 versus 9 mm) and residue cover (3 versus 11%) could not account for differences in soil loss between the 17 and 23 Oct. 2003 and 9 Sept. 2005 erosion events, the geometric mean diameter was 1.4 mm for the 17 and 23 Oct. 2003 event (Feng and Sharratt, 2007) and 0.4 mm for the 9 Sept. 2005 event (Feng and Sharratt, 2009). In contrast to observed soil loss across erosion events, Schillinger and Papendick (2008) estimated a loss approaching 180 Mg ha -1 during a single erosion event in the region.…”

Evaluation of a new model of aeolian transport in the presence of vegetation

“…It is critical in these comparisons to note that all of the studies referenced above were from agricultural fields, many of them were bare, and on which soil parameters could be measured in detail. All of the studies cited above except Feng and Sharratt [] were also for individual storms. Bare soil or homogenous crop plantings and single events with on‐site meteorological measurements are arguably much simpler systems for modeling aeolian transport than the structurally and spatially heterogeneous rangelands used in this study.…”

“…All of the studies cited above except Feng and Sharratt [2009] were also for individual storms. Bare soil or homogenous crop plantings and single events with on-site meteorological measurements are arguably much simpler systems for modeling aeolian transport than the structurally and spatially heterogeneous rangelands used in this study.…”

Application of the WEPS and SWEEP models to non-agricultural disturbed lands

“…SWEEP requires input of 38 parameters (as described in Feng and Sharratt, 2009) that define crop and residue characteristics (e.g., growing and dead crop leaf area index and residue flat cover), soil properties (e.g., geometric mean diameter of aggregate size and surface water content), and weather characteristics (e.g., wind direction and wind speed). The SWEEP model simulates soil loss (in terms of total, creep + saltation, suspension, and PM-10 emission) for site-specific, planned surface conditions and control practices for a given day of the year.…”

“…Total amounts crossing each cell boundary are also provided. Similar to WEPS, the SWEEP model has been extensively validated in both the United States and internationally (e.g., Feng and Sharratt, 2009; Liu et al, 2014; Pi et al, 2014a; Pi et al, 2014b; Pi et al, 2016) and has been shown to perform well across a wide range of soils and cropping systems.…”