Study on the Response Relationship of Near-Surface Soil Wind Erosion to Different Underlying Surface Factors

The wind–water erosion crisscross region in the middle reaches of the Yellow River is a typical ecologically fragile area in China, which seriously restricts the sustainable development of the regional ecological environment. For the soil wind erosion issue in typical wind–water compound erosion zones, this study selected three representative watersheds from different sub-regions, namely Liudaogou, Zhifanggou, and Hailesitaigou, as the research objects. Indoor wind tunnel experiments were conducted to investigate the driving mechanisms of wind speed, soil moisture content, and vegetation coverage on wind erosion processes under different underlying surface conditions, and to compare near-surface soil wind erosion responses among three typical watersheds with different soil backgrounds. The results indicated that when soil moisture content increased from 0.01 to 0.05 g/g, the threshold wind velocities for sand entrainment in Liudaogou, Zhifanggou and Hailesitaigou increased by 5%, 10%, and 5%, respectively. Regression analysis was adopted to establish the empirical formulas of critical sand-blowing wind speed for each watershed, and soil moisture content exerted the most significant influence on the critical wind speed in the Zhifanggou watershed. At a constant wind speed, the increases in soil moisture content and vegetation coverage could markedly reduce wind erosion yield. Under the wind speed of 12–18 m/s, wind erosion yield was strongly dominated by wind speed and weakly affected by soil moisture content. The improvement of vegetation coverage could substantially mitigate wind erosion intensity. Additionally, soil moisture content and vegetation coverage presented more prominent inhibitory effects on near-surface sediment transport. The three watersheds exhibited different wind erosion response patterns and sensitivity characteristics, indicating that soil type and underlying surface conditions should be fully considered when conducting wind erosion risk assessment and vegetation restoration planning in the wind–water erosion crisscross region.