Evaluation of the Wind Erosion Prediction System (WEPS) erosion submodel on cropland fields

This study represents part of a project by the Global Change and Terrestrial Ecosystem Soil Erosion Network to validate wind erosion models. Soil loss measurements from 46 storm events from eroding fields in six states were compared to predictions from the Wind Erosion Prediction System (WEPS) erosion submodel. The field data were collected from small (2.5 ha), circular, cropland fields with nonerodible boundaries. Samplers were arranged in vertical clusters to sample horizontal soil discharge passing a point. Weather data, including wind speed, wind direction, solar radiation, relative humidity, air temperature, and rainfall, were collected on-site. Temporal field site characteristics were measured periodically and included surface roughness, plant/residue cover, and dry aggregate size distribution. The WEPS erosion submodel was used to calculate the threshold erosion friction velocity based on surface conditions and then simulate soil loss during daily periods when the speed exceeded that threshold. Measured and simulated erosion values were in reasonable agreement (R2 = 0.71). On average, the erosion model underpredicted soil loss, and the probable reasons are discussed.