Lacustrine Groundwater Discharge Studies in China:History, Current State & Future Vision

This review is motivated by deep concern over the current, relatively fragmented state of lake and groundwater research. For example, Chinese mega lake basins such as Lake Taihu, Dongting, Poyang, Hongze, and Chaohu are not only major cropland areas but also habitats for over 120 million residents. These lakes have faced serious issues for decades, such as the rapid shrinking of water areas and volume in Poyang, and severe eutrophication and algal blooms in Taihu and Chaohu. Despite significant efforts by environmental and limnology scientists to prevent these eco-environmental problems and restore ecosystem services, these uninvited guests continue to harass the lake systems. This underscores the need for optimal management, protection, and restoration of lake eco-environments, which should encompass both visible surface water and invisible groundwater.
Lakes are always the outcrops of the regional groundwater system. To gain a comprehensive understanding of hydrological and biogeochemical functions, and to pave the way for better lake eco-environmental protections and restoration, we must carefully consider the role of groundwater inflow, specifically lacustrine groundwater discharge (LGD), and the associated biogeochemical fluxes. In this review, we first provide a historical and comprehensive overview of groundwater-lake water interaction studies in China. Our main finding shows that over 22% of lakes, among the 673 lakes with areas exceeding 10 km², were identified as groundwater discharge lakes prior to the 2000s. Subsequently, the increased study of groundwater-lake water interaction study is discussed in main study areas, e.g. Badain Jaran Desert, Qinghai-Tibetan Plateau (QTP), the middle-lower Yangtze plains, Volcanic and Maar lakes etc. The current state of study is encapsulated by examining the study methods and techniques employed, with a particular emphasis on the study of lacustrine groundwater discharge (LGD). Finally, we discuss the major challenges and problems remaining in LGD studies, including driving mechanisms, scale differentiations, and temporal evolutions. This review also aims to advocate for close collaboration between multidisciplinary scientific communities and stakeholders to protect lake environments from a hydrogeological perspective.