Global hyper-resolution modelling of historical and future groundwater dynamics

Sustainable management of global groundwater resources is a key societal challenge and central to the Sustainable Development Goals. The localized impacts of groundwater abstraction and the subtle interaction with topography of groundwater dependent ecosystems call for high resolution groundwater information to support effective management. At the same time, groundwater observations are very limited and concentrated in a few countries, rendering large parts of the groundwater resources ungauged. To address limited observations and coarse global models, we use the global groundwater model GLOBGM to simulate past and project future groundwater heads and water table depth at 30 arc-seconds (~1 km) at a monthly time step. Using ISIMIP3a inputs, groundwater dynamics are simulated for a reference period (1960–2019) to support model evaluation and attribution of observed impacts to climate variability and change. Following ISIMIP3b, historical baselines (1960–2014) and three combined socioeconomic–climate scenarios (2015–2100; SSP1-RCP2.6, SSP3-RCP7.0, SSP5-RCP8.5) are simulated with five GCMs, supporting robust detection and impact assessment of future change. Regions of reduced reliability are mapped, and quality assurance flags are provided to guide appropriate use and interpretation of the results. The resulting dataset offers comprehensive, high-resolution information to assess groundwater dynamics for the past and future, supporting improved global water resource management and climate impact assessments.