THE MEMORY, WEATHERING, AND CONNECTIVITY NATURE OF NATIONWIDE GROUNDWATER SYSTEM
Groundwater is an integral component of the global water cycle, actively responding to and modulating Earth system dynamics. Despite its importance, groundwater is often neglected in continental-and global-scale hydrological and biogeochemical studies. This thesis addresses two critical gaps: (1) understanding continental groundwater system memory and resilience, and (2) quantifying the groundwater-river chemical connection under both natural and human-disturbed conditions. By compiling and curating catchment-scale, nationwide, and global datasets, we developed and applied novel frequency-domain metrics, machine-learning predictions, and geochemical indicators to evaluate groundwater resilience and trace groundwater signatures in river chemistry. Collectively, our studies demonstrate that groundwater systems are not only hydrologically dynamic but also chemically reactive and ecologically consequential. By bridging the conceptual gap between groundwater quantity and quality, this work shows how changes in storage under natural and anthropogenic stressors propagate to river chemistry and ecosystem function. The integration of frequency-domain metrics, global geochemical budgets, and diversion impact analyses provides a comprehensive framework for understanding and managing groundwater under increasing climatic and human pressures.
These insights underscore the urgency of safeguarding groundwater as a critical component of
Earth system boundary for planetary habitability.
Additional information: Mr. Jintao SU, sudosu@connect.hku.hk