SPATIAL and temporal dynamics of groundwater vulnerability to contaminants under climate and land use changes in the Pra and Ankobra basins

Abstract

Groundwater resources in Ghana’s Pra and Ankobra Basins face growing contamination risks due to the combined effects of climate change and land use/land cover (LULC) modifications, with existing studies often examining these drivers in isolation. This investigation addresses this gap by examining how groundwater recharge variability, influenced by these environmental changes, affects aquifer vulnerability to contaminants. An integrated GIS-based DRASTIC model approach incorporating well logs, precipitation records, geological maps, and land use data assessed and mapped climate-LULC interactions on vulnerability zones across the basins. Results demonstrate significant spatiotemporal variability, with 32 % of the area classified as moderately vulnerable, while high (23 %) and very high (17 %) vulnerability zones concentrate predominantly in the Ankobra Basin, particularly near mining towns like Prestea, Tarkwa, and Bibiani. Model validation confirmed high reliability (85 % accuracy, Kappa = 0.65), with projections indicating a transition toward lower vulnerability under future scenarios. Very low vulnerability areas may expand across all periods (near, mid, and far future), while high and very high zones could decline by 9.58 % and 11.93 % respectively by the far future. The findings highlight the need for targeted strategies in mining-affected areas, including stricter environmental regulations, groundwater protection zones, and sustainable land management. Integrating continuous monitoring with adaptive approaches, such as artificial recharge systems and climate-informed land use planning, can enhance groundwater resilience. This study provides policymakers and water managers with actionable insights to develop robust protection measures, offering a transferable framework for vulnerable basins facing similar climatic and anthropogenic stresses. Science-based monitoring and multi-stakeholder collaboration emerge as critical components for safeguarding groundwater resources under changing environmental conditions.