Author
 |
Hagen, Lawrence |
|
Submitted to: Journal of Environmental Modeling and Software
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/6/2004 Publication Date: 8/8/2004 Citation: Hagen, L.J. 2004. Evaluation of the wind erosion prediction system (weps) erosion submodel on cropland fields. Journal of Environmental Modeling and Software, 2:171-176. Interpretive Summary: Wind erosion models are widely used to design control practices and to estimate both on-site and off-site erosion impacts. But most have not had extensive validation. This study was part of a project by scientists participating in the Global Change and Terrestrial Ecosystems Soil Erosion Network to validate a number of wind erosion models. In this part of the project, we compared measured soil loss with simulated soil loss for individual storms using the erosion submodel of the Wind Erosion Prediction System (WEPS). The measured data included 46 storms at seven locations in six different states. The WEPS model generally predicted less erosion than was measured for rare, large storms with more than 2 kg/m^2 (9 tons per acre) loss. However, on dates with large storms the soil conditions were likely more erodible than the average condition input to the model. For other storms WEPS provided good agreement with measured values. Thus, WEPS should be a useful tool for those who design conservation practices and estimate erosion impacts. Technical Abstract: 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 form small (2.5 hectare), 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 from large storms, and the probable reasons are discussed. |
