Water flow velocity is an important hydraulic variable in hydrological and soil erosion models, and is greatly affected by freezing and thawing of the surface soil layer in cold high‐altitude regions. The accurate measurement of rill flow velocity when impacted by the thawing process is critical to simulate runoff and sediment transport processes. In this study, an electrolyte tracer modelling method was used to measure rill flow velocity along a meadow soil slope at different thaw depths under simulated rainfall. Rill flow velocity was measured using four thawed soil depths (0, 1, 2 and 10 cm), four slope gradients (5°, 10°, 15° and 20°) and four rainfall intensities (30, 60, 90 and 120 mm·h⁻¹). The results showed that the increase in thawed soil depth caused a decrease in rill flow velocity, whereby the rate of this decrease was also diminishing. Whilst the rill flow velocity was positively correlated with slope gradient and rainfall intensity, the response of rill flow velocity to these influencing factors varied with thawed soil depth. The mechanism by which thawed soil depth influenced rill flow velocity was attributed to the consumption of runoff energy, slope surface roughness, and the headcut effect. Rill flow velocity was modelled by thawed soil depth, slope gradient and rainfall intensity using an empirical function. This function predicted values that were in good agreement with the measured data. These results provide the foundation for a better understanding of the effect of thawed soil depth on slope hydrology, erosion and the parameterization scheme for hydrological and soil erosion models.

中文翻译：

---

融化土壤深度对小溪流速影响的实验研究

在水文和土壤侵蚀模型中，水流速是重要的水力变量，在寒冷的高海拔地区，表层土壤层的冻结和解冻会极大地影响其流速。受解冻过程影响时，准确测量小溪流速对模拟径流和沉积物输送过程至关重要。在这项研究中，使用电解质示踪剂建模方法来测量模拟降雨条件下沿不同解冻深度的草甸土质边坡的钻探流速。使用四个解冻的土壤深度（0、1、2和10 cm），四个坡度梯度（5°，10°，15°和20°）和四个降雨强度（30、60、90和120 mm）测量小河流速·h ^-1）。结果表明，融化土壤深度的增加导致钻探流速的降低，从而降低的速度也在减小。虽然小溪流速与坡度和降雨强度呈正相关，但小溪流速对这些影响因素的响应随土壤融化深度的变化而变化。融化土壤深度影响钻探流速的机理归因于径流能量的消耗，斜坡表面粗糙度和截割效应。使用经验函数，通过融化的土壤深度，坡度梯度和降雨强度对小河的流速进行建模。该功能预测的值与测量数据非常吻合。这些结果为更好地了解解冻土壤深度对边坡水文学的影响提供了基础，