摘要:隧道工程导致地下水系统被破坏，但由此可能带来的土壤侵蚀却很少被涉猎。在重庆观音峡背斜隧道密集影响区和非隧道影响区的两个相邻小流域建立径流小区，基于高分辨率水文数据结合δD-H₂O、δ¹⁸O-H₂O同位素，对比两径流小区坡面、壤中产流规律和地表侵蚀产沙特征。结果表明，观测年内隧道影响区坡面产流对降雨响应更快，地表径流系数0.027，侵蚀模数16.68 t km^-2 a^-1；非隧道影响区地表径流系数0.013，侵蚀模数7.73 t km^-2 a^-1。相反，隧道影响区产生的壤中流产流系数仅为非隧道影响区的31%。对一场强降雨监测发现，两径流小区坡面流中δD-H₂O、δ¹⁸O-H₂O相似，但壤中流中却差异较大。用氢氧同位素混合模型分析得出隧道影响区坡面流、壤中流中降雨贡献率均大于非隧道影响区，侵蚀能力更强。这与土壤含水率减小和土壤结构的差异有关：隧道影响区土壤中粘粒的含量高于非隧道影响区，且出现上粘下松的异常土壤结构，使土壤下渗能力降低，地表径流增加。较小的土壤含水率与土壤粒径也有利于土壤搬运。研究为隧道工程导致的喀斯特区水土流失研究提供了基础数据，为喀斯特区水土流失防治和石漠化治理研究提供了新视角。



Abstract:Karst groundwater systems have been destroyed because of the excavation of tunnels. However, the effects of the tunnel excavation on soil erosion in karst areas remain largely unknown. This study aims at investigating disciplines and processes of slope runoff, interflow and surface soil erosion in two runoff plots where are or are not affected by tunnel excavation, respectively, in a karst trough valley, SW, China based on high-resolution hydrological data and isotopic values (δD-H₂O and δ¹⁸O-H₂O). The results show that the annual coefficient of slope runoff is 0.027 and soil erosion modulus is 16.68 km^-2 a^-1 in the tunnel-influenced plot where the slope runoff responds faster to precipitation, while the corresponding values in the tunnel-free plot were 0.013 and 7.73 km^-2 a^-1, respectively. In contrast, the interflow in the tunnel-influenced plot is only 31% of that in the tunnel-free plot. The monitoring values of δD-H₂O and δ¹⁸O-H₂O were similar in slope runoff but different in interflow during a storm event. The contributions of rainwater to both the slope runoff and interflow increased in the tunnel-influenced plot based on the stable isotope mixing model. These discrepancies could be due to a decrease in the soil moisture and differences in the soil structures, as the soil clay content is higher and the original loose and sticky layers in the soil profile are damaged in the tunnel-influenced plot, leading to the decrease in the infiltration capability but an increase in the slope runoff. In general, the tunnel excavation increased the slope runoff and soil erosion and decreased the interflow in the karst trough valley. Our study can provide fundamental data on soil erosion and water loss resulting from tunnel construction in karst areas and shed light on the protection and management of karst environments.





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