Response of soil detachment capacity to freeze‒thaw process for five loess soils from the Loess Plateau of China

Abstract

The combined effects of freeze-thaw and water erosion significantly increase the risk of soil erosion in seasonally freeze-thaw regions. Although soil detachment capacity (SDC) is a critical parameter for evaluating soil erosion degree, the effect of freeze-thaw cycles (FTC) on SDC is not comprehensively understood. Therefore, experiments were conducted in a scouring flume under six freeze-thaw cycles (i.e., 0, 1, 5, 10, 15, and 20 FTC), five flow discharges (2−18 L min⁻¹), and five soil types. The results showed that FTC caused varying degrees of degradation in soil properties, leading to variations in SDC. Under different initial moisture contents, SDC exhibited an increasing trend during the initial stages of FTC and stabilized after 10 FTC. Compared with unfrozen soil, under different freeze-thaw levels (1−20 FTC), the mean SDC of Wuzhong soil, Shenmu soil, Ansai soil, Dingxi soil, and Changwu soil increased by 27, 30, 25, 38, and 57 %, respectively. Apart from porosity, SDC showed notable inverse correlations with other soil properties, including cohesion, shear strength, internal friction angle, organic matter, and bulk density (p < 0.05). Stream power was identified as the ideal hydrodynamic parameter for characterizing SDC (R² = 0.85). An SDC prediction model was established according to these key factors. The model effectively predicted the SDC under the synergistic action of flow and freeze-thaw (R² = 0.90, RE = −9.02 %). Additional verification is necessary when applying the predictive model outside the conditions under which it was developed. The findings contribute novel understanding into the operational mechanism of soil detachment in freeze-thaw affected regions.