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Using hydrochemical, stable isotope, and river water recharge data to identify groundwater flow paths in a deeply buried karst system
Author(s) -
Qin Dajun,
Zhao Zhanfeng,
Guo Yi,
Liu Wencai,
Haji Muhammed,
Wang Xiaohong,
Xin Baodong,
Li Yu,
Yang Yong
Publication year - 2017
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.11356
Subject(s) - groundwater recharge , groundwater , aquifer , karst , hydrology (agriculture) , surface water , geology , groundwater flow , depression focused recharge , spring (device) , water table , environmental science , environmental engineering , paleontology , geotechnical engineering , mechanical engineering , engineering
The deeply buried river‐connected Xishan karst aquifer (XKA) in western Beijing, China, has been suffering from diminishing recharge for several decades, which in turn leads to the disappearing of spring water outflows and continuously lowering of groundwater level in the area. Thus, it is important to correctly recognize the groundwater recharge and flow paths for the sustainable development of the XKA. To investigate these issues, the hydrochemical and isotopic compositions are analysed for both surface water and groundwater samples collected over an area of about 280 km 2 . Results show that (a) the river water is characterized by high Na contents; (b) the δ 2 H and δ 18 O values in the river water are distinctively higher than those of groundwater samples, after experiencing the long‐time evaporative enrichment in the upstream reservoir; (c) the Sr concentrations and 87 Sr/ 86 Sr ratios of groundwater clearly indicated the interaction between water and carbonate minerals but excluded the water–silicate interaction; and (d) the groundwater samples in the direct recharge area of the XKA have the lowest Na concentrations and the δ 2 H and δ 18 O values. Based on the large differences in the Na contents and 18 O values of groundwater and surface water, a simple two‐component mixing model is developed for the study area and the fractions of the river water are estimated for groundwater samples. We find that the distribution pattern of the river water fractions in the XKA clearly shows a change of directions in the preferential flow path of the groundwater from its source zone to the discharge area. Overall, our results suggest that the recharged surface water can be a useful evidence for delineating the groundwater flow path in river‐connected karst aquifer. This study improves our understanding of the heterogeneity in karst groundwater systems.