Journal of Geographical Sciences ›› 2020, Vol. 30 ›› Issue (6): 935-948.doi: 10.1007/s11442-020-1763-2

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Using water isotopes and hydrogeochemical evidences to characterize groundwater age and recharge rate in the Zhangjiakou area, North China

ZHANG Qinghua1, LUO Zhuanxi1,*(), LU Wen3, HARALD Zepp4, ZHAO Yufeng1,2, TANG Jialiang3   


  1. 1. Key Laboratory of Urban Environment and Health, Institute of Urban Environment, CAS, Xiamen 361021, Fujian, China

    2. College of Geographical Science, Shanxi Normal University, Linfen 041000, Shanxi, China

    3. Institute of Mountain Hazards and Environment, CAS, Chengdu 610041, China

    4. Geographical Institute, Ruhr-University Bochum, Bochum D-44780, Germany
  • Received:2019-09-20 Accepted:2020-03-05 Online:2020-06-25 Published:2020-08-25
  • Contact: LUO Zhuanxi E-mail:zxluo@iue.ac.cn;zxluoire@163.com
  • About author:Zhang Qinghua (1990–), MS Candidate, specialized in environmental geochemistry. E-mail: tsinghua_cags@163.com
  • Supported by:
    The National Major Science and Technology Program for Water Pollution Control and Treatment(No. 2017ZX07101001-02)

Abstract:

Despite the increasing depletion of the groundwater at the Zhangjiakou aquifer system in the northwest of Beijing-Tianjin-Hebei region, little information is available on the hydrological process of groundwater in this region. In this study, we utilized water isotopes composition (δ18O, δD and3H) of groundwater, river and precipitation to identify the characteristics of hydrochemistry, groundwater age and recharge rates in different watersheds of the Zhangjiakou area. Results showed that the river water and groundwater could be characterized as HCO3-Mg·Na, HCO3·Cl-Na and HCO3-Mg·Na, HCO3·Cl-Na, HCO3·Cl-Na·Mg types, respectively. The δD and δ18O values in precipitation were linearly correlated, which is similar to the Global Meteorological Water Line (GMWL). Furthermore, the decreasing values of the δD and δ18O from precipitation to surface water and groundwater indicate that groundwater is mainly recharged by atmospheric precipitation. In addition, the variation of3H concentration with depth suggests that groundwater shallower than around 100 m is generally modern water. In contrast, groundwater deeper around 100 m is a mixture of modern and old waters, which has longer residence times. Groundwater showed a relatively low tritium concentration in the confined aquifers, indicating the groundwater recharged might be relatively old groundwater of over 60 years. The flow velocity of the groundwater in the study area varied from 1.10 to 2.26 m/a, and the recharge rates ranged from 0.034 to 0.203 m/a. The obtained findings provide important insights into understanding the groundwater recharge sources and hydrochemistry in the Zhangjiakou area, in turn developing a sustainable groundwater management plan.

Key words: hydrogen and oxygen isotopes, tritium isotope, water cycle, groundwater, Zhangjiakou