Disparity in soil erosion processes between freeze-thaw and unfrozen slopes under artificial rainfall conditions in high-altitude and dry valleys of the Southeast Tibet region

The arid valley region in southeastern Tibet exemplifies an ecologically vulnerable area in southwestern China, where soil erosion has intensified in recent years as a consequence of socio-economic growth and infrastructure construction. This study aimed to elucidate the mechanism by which freeze-thaw cycles affect soil erosion processes on the bare slopes of this alpine arid valley region under artificial disturbances from engineering construction. Focusing on bare slopes with inclinations of 20° and 40°, we analyzed the impact of freeze-thaw cycles on flow and sand production through indoor artificial rainfall experiments. The findings indicated an approximately threefold increase in soil splattering following the freeze-thaw cycle compared to unfrozen slopes; cumulative flow production exhibited a declining trend, decreasing by 15.99 % and 37.42 % after the freeze-thaw cycle at slope angles of 20° and 40°, respectively; cumulative sand production increased by 2.29 % and 51.24 % after the freeze-thaw cycle at slope angles of 20° and 40°, respectively. On the freeze-thaw and unfrozen slopes, the sand production rates escalated swiftly following the initiation of flow production, reaching peaks of 1.34 g m⁻²·min⁻¹ and 1.52 g m⁻²·min⁻¹ in 10 min and 12 min, respectively. Post the freeze-thaw cycle, the rates stabilized, with the sand production rates on the freeze-thaw slopes exceeding those on the unfrozen slopes. These findings will serve as a significant reference for the management of bare ground surfaces and the conservation and restoration of biological environments following construction disturbances.