Groundwater-based water services as complex socio-hydrogeological systems: insights from Vietnam’s Mekong Delta

Groundwater systems are critical to global water security, yet the complex interactions between household coping strategies, resource sustainability, and climate change remain difficult to govern. This study applies qualitative systems mapping to characterise socio-hydrogeological dynamics in Vietnam’s Mekong Delta, a region currently facing intensifying saline intrusion and rapid land-use change. Drawing on a household survey (n = 404) and in-depth interviews (n = 25) in Sóc Trăng and Trà Vinh provinces, three critical system interactions were identified: (1) climate variability and household adaptation intensify groundwater system pressures, (2) policy-practice gaps undermine effective management of a multisource water system, and (3) social vulnerability and water stress constrain resilience. Together, these interactions illustrate how household behaviours, institutional arrangements, and resource conditions are interconnected in ways that shape system behaviour. These findings advance socio-hydrogeological frameworks by using systems mapping to make visible the relationships and interactions that influence groundwater-based water services. The research offers evidence for policymakers, suggesting that inclusive, climate-resilient service delivery depends on integrating actual household water behaviours into planning and groundwater governance, moving beyond a singular focus on piped supply.