南洞地下河水文地球化学特征及径流量识别

Research on Hydro-geochemical Characteristics and Identification Runoff of Nandong Underground River

南洞地下河由南支洞、北支洞两个独立地下河系统组成,并在复杂的洞穴系统内混合后通过多个出水点出漏地表。特殊的洞道结构和极差的洞内空气环境,给各子系统径流量的测量、区分、监测和演化等研究工作带来困难。本研究以端-源法为指导思想,利用枯季对洞穴探测研究,并在两地下河和洞外三处采水样进行分析。分析了南洞地下河水化学特征和该时期泥沙含量、氢氧同位等特征;根据溶液稀释规律对水化学离子、同位素和河流泥沙含量等指标进行筛选,运用质量守恒原理来研究两子系统径流量的比例关系。分析结果表明:1南洞地下河属于碳酸盐硬度超过50%的HCO3-Ca·Mg型水,主要受到岩石风化作用的控制;2南、北支洞的径流量比为4.372 2∶1,即南支径流量占南洞地下河总流量的81.48%。这为南洞地下河水资源的评价、合理开发与调配提供了参考,同时该研究方法为岩溶地下河系统径流量识别研究具有一定的借鉴意义。

Nandong Underground River is composed of two independent underground river systems of South Branch Cave and North Branch Cave,which flows out of the ground surface through many outlets after being mixed in the complex cave system.Special cave structures and extremely poor air environments in the cave lead to difficulties in measuring,dividing,measuring,evolving and studying subsystem runoff volume.End-source method is adopted as guiding ideology in the study.Caves are explored and studied in dry seasons.Water is sampled from two underground river locations and outside the cave for an analysis.Nandong Underground River water chemical features,mud content,hydrogen and oxygen isotopic feature and other characteristics are analyzed.Hydro-chemistry ion,isotope,river sand content and other indexes are filtered according to the laws of the dilute solution.Principle of mass conservation is utilized for studying proportion relations between the runoffs of two subsystems.Analytic results show that firstly Nandong Underground River belongs to HCO3-Ca·Mg water with carbonate hardness more than 50%,which is mainly controlled by rock weathering effect.Secondly,runoff ratio of south and north branches is 4.372 2∶1,namely south branch runoff accounts for81.48% of the total runoff in Nandong Underground River.It provided a reference for evaluation,rational development and allocation of water resources in Nandong Underground River.Meanwhile,the research method has a certain reference significance for studying system runoff identification.