Spatiotemporal Variation of Groundwater Recharge in the Lower Reaches of the Poyang Lake Basin, China: Insights From Stable Hydrogen and Oxygen Isotopes

Abstract

Abstract Understanding of groundwater recharge and associated hydrological processes is important for sustainable management and utilization of water resources, especially in the monsoon regions. However, few systematic studies have been conducted on the spatiotemporal variation of groundwater recharge. In this study, stable isotopes of precipitation and groundwater were used to explore the spatiotemporal variation of groundwater recharge in the lower reaches of the Poyang Lake Basin of China, a region affected by the interplay of different monsoons. The results indicated that isotopic values (δ 2 H and δ 18 O) of precipitation exhibited obvious seasonal variations, higher in winter and lower in summer, controlled by different monsoons. The stable isotopes of groundwater also presented distinct seasonal variations, revealing the dominant influence of seasonal precipitation, but they had different characteristics in space. In the northern study area and Rao and Xin Basins, the isotopic signatures of groundwater showed the shift to lower values in summer and higher values in winter, consistent with those of precipitation, while in the Ganfu Plain, which is characterized by poorly permeable strata, isotopic signatures of groundwater presented opposite temporal variations than those of precipitation (lagged behind precipitation). The characteristics of groundwater isotopes might be linked with the spatial heterogeneity of groundwater recharge rate, which was affected by recharge mechanisms, lithology of aquifer materials, and interaction between groundwater and lake water. This study provides insights into the groundwater recharge of the Poyang Lake Basin and other similar areas.