Comprehensive influence of gravel cover and soil particle characteristics on wind erosion rate: A wind tunnel investigation

• Factors affecting erosion rate on bare soil are wind velocity, mean diameter, density, sorting, and particle sphericity. • Factors affecting erosion rate on gravel-covered soil are wind velocity, gravel lateral coverage, and particle sphericity, sorting, diameter, density. • An unusual phenomenon is the intensification of wind erosion rate under high wind velocity and low lateral coverage. • A new wind erosion rate equation including gravel coverage and soil particle characteristic parameters has been established. Gravel-covered surfaces are common in arid regions, where both natural and artificial gravels play a key role in suppressing soil wind erosion. Previous studies have often focused on specific regions or soil types, leaving the combined effect of gravel cover and soil particle characteristics on the wind erosion rate ( q ) underexplored. The main objective of this study was to clarify the combined effects of gravel cover and soil particle characteristics on q and to develop a predictive equation through wind tunnel experiments using four soil samples with different particle characteristics under five incoming friction wind velocity ( u *∞ ) for bare soil and 25 gravel-covered beds. Results showed that greater lateral coverage ( λ ) significantly suppressed q , but at high friction wind velocity ( u * ) and low λ , q intensified. Soil particle characteristics affect bare and gravel-covered beds differently, indicating that traditional adjustment methods based on bare soil erosion were unsuitable. Random Forest (RF) algorithm was applied as an auxiliary tool to rank variables affecting wind erosion: for bare soil beds, u * , mean particle diameter ( d ), density ( ρ p ), sorting coefficient ( σ ), and sphericity ( S p ); for gravel-covered beds, u * , λ , S p , σ , d , and ρ p . The RF model achieved RMSE Test of 0.010 kg·m −2 ·s −1 for bare soil and 0.001 kg·m −2 ·s −1 for gravel-covered beds. Based on these insights, we proposed an extended wind-blown soil flux equation incorporating λ and S p . This new equation achieved an RMSE of 0.004 kg·m −2 ·s −1 . This equation effectively captures the combined effects of gravel cover and soil particle characteristics.