Theoretical Model of Enhanced Soil Physical Crust Wind Erosion Characteristics by Freeze-Thaw Action

Physical soil crusts, acting as the "skin" of land surfaces, can effectively protect soils from wind erosion. However, seasonal freeze-thaw cycles, which are recognized as a unique climatic characteristic, exert significant influence on soil wind erodibility. Freeze-thaw processes alter the physical and mechanical properties of soil crusts, thereby markedly affecting soil erodibility. Current physically-based soil erosion models do not adequately account for both the presence of physical soil crusts and the effects of freeze-thaw cycles, lacking accurate and effective parameterization schemes. This limitation poses a major challenge for predicting wind erosion in mid- to high-latitude regions. To tackle this gap, this study integrates freeze-thaw impacts and crust mechanical properties into a wind erosion model using dimensional analysis and soil mechanics theory. Validated via multiple wind tunnel experiments, the model effectively predicts crust mechanical behavior changes and associated wind erosion rates under freeze-thaw conditions. Sensitivity analysis reveals the physical mechanism of crusted soil erosion under the coupled influence of soil moisture, crust mechanical properties, and freeze-thaw. Results show freeze-thaw’s impact on crusted soil erodibility is regulated by initial moisture, with competition between them. At low moisture, freeze-thaw is negligible, and moisture-induced interparticle cohesion dominates, reducing erosion rates with increasing moisture; at high moisture, freeze-thaw enhances erosion by decreasing crust hardness and shear strength. This study deepens understanding of cold-region soil erosion and provides a parameterization scheme for quantitative prediction, guiding soil conservation and desertification control in cold areas.