The lake and groundwater interaction based on water balance in Dongting Lake, China

Abstract

Study region: Dongting Lake (DTL), the second largest freshwater lake in China, plays a crucial role in regulating and storing water within the Yangtze River Basin.Study focus: The study utilized the water balance method to extensively investigate the exchange volume of groundwater and DTL from 2003 to 2020. Furthermore, we analyzed the impact of climate change and human activities on the interaction between groundwater and DTL.New hydrological insights for the region: Unlike previous studies, our study further included the ungauged runoff, providing a more comprehensive assessment of the water balance of DTL. From May to July, groundwater recharge from DTL, with an average monthly recharge of 0.71 km³. Conversely, groundwater discharges into DTL from August to April of the following year, with an average monthly discharge of 1.12 km³. The net groundwater discharge into the lake from 2003 to 2020 amounts to 7.98 km³/yr. Intriguingly, precipitation over the lake contributes a mere 0.6% to the total inflow, while lake evapotranspiration constitutes only 0.4% of the total outflow. Inflow runoff and outflow runoff play a leading role in the water balance of DTL, significantly influencing the exchange capacity between the lake and groundwater. Groundwater discharge into the lake serves as compensation for diminished runoff stemming from extreme climate occurrences, like droughts, and anthropogenic actions such as dam construction.