Rock surface flow, originating from outcrop surfaces during rainfall, represents a distinctive form of runoff influencing surface erosion and subsurface soil leakage in karst rocky desertification areas. Despite their significance, the processes governing runoff generation and erosion at the rock–soil interface (RSI) under the influence of rock surface flow remain poorly understood. This study aims to elucidate the generation and transformation of runoff at the RSI, along with their scouring erosion effects influenced by rock surface flow from concave-shaped outcrops. Artificial rainfall experiments were conducted on simulated rock–soil structural units featuring exposed rock surfaces and unexposed RSIs of outcrops with concave shapes. Two driving factors, namely rainfall intensity () and the inclination of the rock surface (), were manipulated to investigate the formation and output processes of runoffs and sediments from the surface, RSI, and non-RSI (a site away from the RSI). The presence of an exposed rock surface altered the distribution pattern of rainfall–infiltration–runoff. An increase in the led to a significant decrease in surface runoff ( < 0.05). When the was close to vertical, the rainfall-runoff was primarily in the form of surface runoff; however, for inclinations less than 90°, the primary contributors to rainfall-runoff were the RSI and non-RSI runoffs. Surface soil erosion emerged as the predominant form of soil loss, with runoff yield demonstrating a linear positive correlation with sediment production. Both the and were identified as significant factors affecting surface runoff and soil erosion. Notably, when the was less than 45°, the total soil loss reached its minimum. Therefore, runoff generation at the RSI led to a reduction in surface runoff and an increase in subsurface runoff, contributing to soil leakage at the RSI. Nevertheless, surface erosion remained the primary mechanism of soil loss.

中文翻译：

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石漠化地区凹面露头岩土界面产流及侵蚀过程

降雨期间源自露头表面的岩石表面流代表了影响喀斯特石漠化地区地表侵蚀和地下土壤渗漏的独特径流形式。尽管具有重要意义，但在岩石表面流影响下控制岩土界面（RSI）径流产生和侵蚀的过程仍然知之甚少。本研究旨在阐明 RSI 径流的产生和转化，以及凹形露头岩石表面流对冲刷侵蚀的影响。对模拟的岩土结构单元进行了人工降雨实验，该单元具有暴露的岩石表面和未暴露的凹形露头的 RSI。操纵降雨强度（）和岩石表面倾角（）两个驱动因子，研究地表径流和沉积物的形成和输出过程、RSI和非RSI（远离RSI的地点） 。裸露岩石表面的存在改变了降雨-入渗-径流的分布模式。增加导致地表径流显着减少（<0.05）。当接近垂直时，降雨径流主要以地表径流形式存在；然而，对于小于 90° 的倾角，降雨径流的主要贡献者是 RSI 和非 RSI 径流。地表土壤侵蚀成为土壤流失的主要形式，径流产量与沉积物产生呈线性正相关。和 均被确定为影响地表径流和土壤侵蚀的重要因素。值得注意的是，当角度小于45°时，土壤总流失量达到最小。因此，RSI 处的径流产生导致地表径流减少和地下径流增加，从而导致 RSI 处的土壤渗漏。尽管如此，地表侵蚀仍然是水土流失的主要机制。