Study of groundwater recharge using combined unsaturated‐and saturated‐zone chloride mass balance methods
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Date
2023-06-19
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Wiley
Abstract
Understanding groundwater recharge mechanisms is essential for reliable groundwater recharge estimation for sustainable groundwater resource assessment and management, especially in arid and semiarid areas. In this study, chloride, together with stable isotopes (18O and2H), in 1‐year rainfall, soil water from representative profiles, and groundwater samples, collected in the Ordos Plateau, northern China were analysed. Groundwater recharge was estimated using unsaturated‐ and saturated‐zone chloride mass balance (CMB). An equation that describes the relationship between chloride concentrations in saturated zone water (Csz) and soil water residence time (τ) was derived. With the help of the relationship, chloride concentrations in unsaturated zone water (Cuz) and in groundwater (Csz) can be used to uncover water flow and chloride transport in the unsaturated zone. The relationship betweenCszandCuzindicates that, the groundwater was recharged mainly by intense rainfall events. Small rainfall events did not lead to groundwater recharge but contributed to the flux of chloride to soil surface. Stable isotopic compositions of18O and2H provided corroborative evidence of the recharge processes. The relationship betweenCszandτindicates further that there is no source of chloride in the groundwater other than that from precipitation. Thus,Cszcan give more reliable recharge estimates.Cuzwas influenced by heavy rainfall‐induced runoff, run‐on and bypass flow events and cannot give reliable recharge estimates. However, if used jointly withCsz,Cuzcan help to gain insights into recharge processes and yield groundwater recharge estimates with higher certainty. The outcomes of this study can assist for groundwater recharge investigation and assessment in regions where the assumptions and boundary conditions necessary for the correct application of the CMB method may not be met. © 1999-2024 John Wiley & Sons
Description
This work was supported by the National Natural Science Foundation of China [40973001, 41877487], the International Partnership Program of Chinese Academy of Sciences [131432KYSB20200029], and the Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences [WSGS2020001]. The authors would like to thank the three anonymous reviewers for taking time and efforts to review the manuscript. The authors sincerely appreciate all valuable comments and suggestions, which helped us to improve the quality of the manuscrip.
Keywords
Ground water, Chlorine, Groundwater recharge, Stable isotopes, China, Rain, Runoff
Citation
Jiang, S., Rao, W., Han, L., & Meredith, K. T. (2023). Study of groundwater recharge using combined unsaturated-and saturated-zone chloride mass balance methods. Hydrological Processes, 37(6), e14927. doi:10.1002/hyp.14927