ARS | Publication request: Effect of wind averaging time on wind erosivity estimation

Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 2012
Publication Date: June 15, 2012
Citation: Guo, Z., Zobeck, T.M., Stout, J.E., Keli, Z. 2012. Effect of wind averaging time on wind erosivity estimation. Earth Surface Processes and Landforms. 37(7):797-802.

Interpretive Summary: The USDA-ARS has developed two wind erosion models, the Revised Wind Erosion Equation (RWEQ) and the Wind Erosion Prediction System (WEPS) that use wind data to predict soil loss due to wind erosion. However, wind data is collected in a wide variety of locations using different wind speed averaging times. For example, one site might present wind speed averages for one minute while another might present one hour averages. These differences can produce differences in estimates of the power of the wind to generate wind erosion (erosivity). In this study, we determine the effect of using 1, 5, 10, 15, 30, and 60 min average wind speed data. The results show that averaging wind speed data can produce important differences in wind erosivity. In general, the longer averaging times tend to produce smaller values of wind erosivity and when used in RWEQ and WEPS, tend to under-estimate wind erosion.

Technical Abstract: The Wind Erosion Prediction System (WEPS) and Revised Wind Erosion Equation (RWEQ) are widely used for estimating the wind-induced soil erosion at a field scale. Wind is the principal erosion driver in the two models. The wind erosivity, which describes the capacity of wind to cause soil erosion is defined as erosive wind power density (WPD) in WEPS, and wind value (W) in RWEQ. In this study, the daily average WPD (AWPD) and the daily average W (Wf) were chosen to investigate the effect of averaging time on wind erosivity estimation based on observed wind data. We compare the daily AWPD and Wf calculated from 1, 5, 10, 15, 30, and 60 min average wind speed data. The results of comparisons indicate that averaging wind speed can significantly influence estimates of wind erosivity. Compared with the daily AWPD and Wf calculated from 1 min average wind speed data, all daily AWPD and Wf values calculated from 5, 10, 15, 30, and 60 min averaged wind speeds tend to be significantly lower than values calculated from 1 min values. In general, longer averaging times tend to produce smaller values of daily AWPD or Wf, which leads to an under-estimation of wind erosion.