Aeolian sediment transport over the Gobi with high gravel coverage under extremely strong winds in the Hundred Miles windy area along the Lanzhou-Xinjiang High-Speed Railway

Abstract Aeolian transport driven by extremely strong winds over Gobi areas with high gravel coverage remains poorly understood. In this study, field observations of aeolian transport over a Gobi surface with 70–94% gravel coverage were performed in the Hundred Miles windy area along the Lanzhou-Xinjiang High-Speed Railway. The results reveal that during a typical transport event, approximately continuous saltation can occur in the most intense transport period under such high gravel coverage, and the average saltation layer height (0.58 ± 0.12 m) is approximately 6 times larger than that over sand surfaces. The annual sediment transport rate reached 46.31 kg m−1·a−1 under an annual sand drift potential of 705.14 vector units (VU), indicating that wind-blown sand activities are still strong over Gobi surfaces with high gravel coverage in extremely strong windy areas. Furthermore, the grain size distribution indicates that the saltation height of sand particles can reach 2 m, and the cumulative frequency of the sediment flux density indicates that 99% of sand is transported within 0–3 m of the surface. Our findings suggest that the height of sand fences should be raised from the present 2 m–3 m, which can trap more transported sand particles.