ABSTRACT

Considering three sites under different climate conditions (arid, semi-arid, and subhumid), this study aims to use the vadose-zone water stable isotope profiles to estimate the groundwater recharge rate. High-resolution vertical subsurface soil sampling along the vadose zone of the investigated sites was conducted. The collected samples were analysed to determine their stable isotope ratios (δ²H and δ¹⁸O) that were used along with the piston displacement method to estimate recharge. Annual recharge rates of 0.2% (± 0.1%), 2.5%, and 18% of the total annual precipitation were obtained for the arid, semi-arid, and subhumid sites, respectively. Recharge rates at the semi-arid and subhumid sites are comparable to those previously estimated using water balance-based methods. The recharge rate at the arid site is lower than that previously estimated for that site using the water budget-based method, revealing difficulties in applying the piston displacement method under an arid regime.

摘要

考虑到三个不同气候条件下的站点（干旱、半干旱和半湿润），本研究旨在使用包气带水稳定同位素剖面来估计地下水补给率。沿调查地点的包气带进行了高分辨率垂直地下土壤采样。分析收集的样品以确定它们的稳定同位素比率（δ ² H 和δ ¹⁸O) 与活塞位移法一起用于估算补给量。干旱、半干旱和半湿润地区的年补给率分别为年总降水量的 0.2%（±0.1%）、2.5% 和 18%。半干旱和半湿润地区的补给率与之前使用基于水平衡的方法估计的补给率相当。干旱地区的补给率低于先前使用基于水预算的方法对该地区估计的补给率，这表明在干旱地区应用活塞置换法存在困难。