Global Groundwater Risk : Integrating Physical Fluxes and Societal Vulnerability in a Coupled Human– Environment System

Global groundwater is a critical yet often overlooked component of the Earth system, supporting human well-being, ecosystems, and economic development. However, increasing groundwater withdrawal and climate-driven changes in recharge are intensifying groundwater stress worldwide. While this imbalance is well recognized, its translation into societal risk remains poorly understood. This dissertation addresses this gap by integrating physical groundwater processes with societal vulnerability in a global risk framework. It combines newly developed models of global groundwater recharge and withdrawal (2001–2020) to quantify groundwater stress and its trends. The analysis identifies climatic and anthropogenic hotspots where groundwater sustainability is under pressure, affecting billions of people. Building on this, the study introduces the first global groundwater risk framework, incorporating hazard (groundwater stress), exposure, and societal vulnerability. The findings reveal that nearly 2 billion people live in highly vulnerable regions, and that a large share of the global population and groundwater-dependent agriculture is located in risk hotspots. The results highlight that while groundwater stress is the main driver of risk, societal vulnerability strongly shapes its impacts. Overall, this work advances global groundwater assessment by linking physical and societal dimensions, providing new insights, datasets, and tools to support vulnerability-aware water management and adaptation planning.