Zhang Jun, Fu Zhi-Yong, Chen Hong-Song, Lian Jin-Jiao, Qin Chang
Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Huangjiang Observation and Research Station of Karst Ecosystem, Chinese Academy of Sciences, Huangjiang 547100, Guangxi, China.
Ying Yong Sheng Tai Xue Bao. 2021 Jun;32(6):2107-2118. doi: 10.13287/j.1001-9332.202106.013.
Epikarst is the core area of karst critical zone, with important hydrologic regulation and storage function. However, the effects of karst development degree on hydrologic characteristics of epikasrt is still unclear. We used geophysical exploration and hydrogeological techniques, combined with the dynamic monitoring of moisture and water levels, to quantify the karst development degrees and their hydrologic characteristics on slope lands. We analyzed the responses of soil-epikarst systems to rainfall. Results showed that geophysical exploration technology could be well applied to the detection of surface-subsurface structures in the karst areas. The average thickness of soil and surface karst zone on the slope was less than 0.63 m and 2.60 m, respectively. The slopes of strong-karstification characterized by high apparent resistivity, well-developed joint fractures, and strong permeability (0.73 m·d). Such a result indicated that epikarst could regulate precipitation. The responses of soil moisture had a larger rainfall threshold (>20.50 mm·d) and the water level was determined by rainfall amount. In contrast, the slope with weak-karstification had low apparent resistivity and weak permeability (0.07 m·d). Moisture and water level were sensitive to rainfall. Karst channels were developed locally at 240-300 cm with a permeability coefficient of up to 432 mm·d. Obvious preferential flow was observed in extreme rainfall events on this slope, which could induce flood disaster in the adjacent depression. Our results would provide scientific basis for further research on water resources regulation, management, and eco-hydrology in karst areas of southwest China.
表层岩溶带是岩溶关键带的核心区域，具有重要的水文调节与存储功能。然而，岩溶发育程度对表层岩溶带水文特征的影响仍不明确。我们运用地球物理勘探和水文地质技术，结合对土壤湿度和水位的动态监测，来量化坡地的岩溶发育程度及其水文特征。我们分析了土壤 - 表层岩溶系统对降雨的响应。结果表明，地球物理勘探技术能够很好地应用于岩溶地区地表 - 地下结构的探测。坡地上土壤和表层岩溶带的平均厚度分别小于0.63米和2.60米。强岩溶化的坡面具有高视电阻率、发育良好的节理裂隙和强渗透性（0.73米·天）。这一结果表明表层岩溶带能够调节降水。土壤湿度的响应具有较大的降雨阈值（>20.50毫米·天），水位由降雨量决定。相比之下，弱岩溶化的坡面视电阻率低且渗透性弱（0.07米·天）。湿度和水位对降雨敏感。在240 - 300厘米处局部发育岩溶通道，渗透系数高达432毫米·天。在该坡地的极端降雨事件中观察到明显的优先流，这可能会在相邻的洼地引发洪水灾害。我们的研究结果将为中国西南岩溶地区水资源调控、管理及生态水文的进一步研究提供科学依据。
