Assessment of wind erosivity based on wind speed conversion over different averaging times

Purpose Wind speeds over different averaging times significantly influence the assessment of wind erosivity, which describes the capacity of wind to cause soil erosion. This study aims to quantify this time interval effect on wind erosivity assessment. Methods This study took the wind erosion region of northern China as the study area and compared the changes in wind erosivity indexes (including wind-generated near-surface shear stress and drift potential (DP)) over different averaging times based on wind speed conversion. Results Both DP and the effective shear stress (generated by sand-driving wind) decreased as the averaging time increased. On the contrary, total shear stress (generated by all the wind) exhibited an opposite trend and is much higher than effective shear stress. Compared to DP, near-surface shear stress can better reflect the erosion capacity of wind on the land surface. This is because the calculation of near-surface shear stress considered the differences in land surface aerodynamic properties. Land surface properties play an important role in the assessment of wind erosivity. Conclusion Wind erosivity will be underestimated when wind speed with a larger averaging time is used. Wind speed below the threshold that drives sand transport should be eliminated to improve the accuracy of wind erosivity assessment. Surface properties are important factors influencing wind erosivity evaluation. Results from this study will provide a basis for the establishment of wind erosion force conversion models over different averaging times, and provide accurate data support for sand control engineering.