自然降雨条件下砒砂岩坡面细沟微形态及其侵蚀特征

目的] 研究自然降雨条件下砒砂岩坡面细沟微形态及其侵蚀特征，为区域土壤侵蚀机制研究提供理论参考。方法] 选择裸露砒砂岩坡面为研究对象，采用野外径流小区原位监测与三维激光扫描技术结合的方法，分析砒砂岩坡区13次降雨过程中坡面细沟数量、形态以及几何特征的动态变化特征，揭示细沟微形态变化过程对坡面产流产沙的影响机制。结果] 观测期研究区总降雨量为267.40 mm，总降雨历时为5 893 min，总径流量为294.05 L，总泥沙量为111.34 kg。降雨对径流和泥沙的贡献率表现为：中雨（10.0～24.9 mm）>大雨（25.0～49.9 mm）>小雨（<10.0 mm）。中雨对坡面侵蚀影响程度最高。水力侵蚀导致坡面细沟形态上趋于复杂化，其总长达为40.52 m，平均宽度为4.31 cm，平均深度为1.22 cm。次降雨坡面细沟的发育过程表现为：溅蚀—片蚀—宽浅型细沟—连续细沟网—沟壁坍塌—沟道稳定；细沟趋于向窄深型发育。结论] 细沟各形态指标均呈现明显的二次多项式相关关系，细沟宽深比与沟壑密度对坡面产沙量存在显著影响。

Micromorphology and Erosion Characteristics of Rills on Feldspathic Sandstone Slopes Under Natural Rainfall Conditions

Objective] The micromorphology and erosion characteristics of the feldspathic sandstone under natural rainfall conditions were studied, in order to provide theoretical reference for understanding the mechanism of soil erosion in this region.Methods] The exposed feldspathic sandstone slope was selected as the research object, and the field monitoring and 3D laser scanning technology were combined to analyze the dynamic changes of the number, shape and geometric characteristics of the rills during 13 rainfall events. The influence of rill micro-morphological change processes on slope runoff and sediment yield was analyzed.Results] The total rainfall in the study area during the observation period was 267.40 mm, the total rainfall duration was 5 893 min, the total runoff was 294.05 L, and the total sediment was 111.34 kg. The contribution of rainfall to runoff and sediment followed the order of moderate rain>heavy rain>light rain. Moderate rain had the highest impact on slope erosion. After the erosion stopped, the overall morphology of the rill became more complicated, with a total length of 40.52 m, an average width of 4.31 cm, and an average depth of 1.22 cm. The development process of the rills on the slope surface during a single rainfall was as follows:splash erosion-sheet erosion-wide and shallow rills-continuous rill network-ditch wall collapse-channel stability, the rills tend to be narrow and deep.Conclusion] The morphological indicators of the rills all present an obvious quadratic polynomial correlation, the ratio of rill width to depth and gully density have significant effects on sediment yield.