Zhongling Guo¹, Ted M. Zobeck², John E. Stout², Keli Zhang¹

¹ Beijing Normal University, State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing, China;

² USDA-Agricultural Research Service, Wind Erosion and Water Conservation Research Unit, Lubbock, TX, USA.

Abstract: The Wind Erosion Prediction System (WEPS) and Revised Wind Erosion Equation (RWEQ) are widely used for estimating wind-induced soil erosion at a field scale. Wind is the principal erosion driver in the two models. 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 minute 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 one minute average wind speed data, all daily AWPD and Wf values calculated from 5, 10, 15, 30, and 60 minute averaged wind speeds tend to be significantly lower than values calculated from one minute values. In general, longer averaging times tend to produce smaller values of daily AWPD or Wf, which may lead to an under-estimation of wind erosion. Further studies are needed to extend and apply the findings obtained in this study to actual wind erosion predictions.

Keywords: wind speed; wind averaging time; wind erosivity; Wind Erosion Prediction System (WEPS); Revised Wind Erosion Equation (RWEQ).