Abstract:

Aeolian disasters result from the interaction between wind dynamics and exposed sand sources. The Alxa Plateau is a major source region for sandstorms in China， and the Urad Rear Banner in Inner Mongolia functions as a critical transitional zone where sandstorms occur frequently， yet the mechanisms driving these events remain insufficiently understood. To address this gap， this study conducted a systematic investigation of surface sediments across seven different surface types， including dunes， gobi surfaces， and dry riverbeds. Combining grain size analysis with wind regime characterization， this study aims to reveal the spatial variability of sediment grain size characteristics and their implications for dust emission. The findings can support targeted mitigation strategies. The results reveal that： （1） Surface sediments in the Urad Rear Banner are dominated by fine sand （13.94%±4.86% to 53.04%±6.76%） and medium sand （17.62%±5.22% to 43.06%±7.51%）， providing the material foundation for dust storm formation. （2） Over the past decade， the region’s average wind speed was 4.18±0.13 m·s⁻¹， with an annual sand transport potential of 353.72±63.24 VU， indicating it as a medium wind energy environment with sufficient dynamic force to generate dust storms. （3） Among the various surface types， dry riverbeds were identified as the primary sources of aeolian dust. Additionally， when the protective gravel armor of Gobi surfaces is disrupted， the exposure of underlying fine sediments significantly increases the potential for dust emission. Based on the integration of topographic features， wind conditions， and sediment characteristics， dry riverbeds and other silt and clay rich surfaces should be prioritized for dust control， while greater efforts are needed to preserve the natural integrity of Gobi surfaces.

Key words: surface sediment, wind condition, grain size, Alxa Plateau, Urad Rear Banner