Groundwater Governance, Hydrogeological Uncertainty, and Sustainable Aquifer Management in the Basement Complex Aquifers of North Central Nigeria

Crystalline basement complex aquifers across Nigeria's Middle Belt zone are characterised by extreme spatial heterogeneity in hydraulic properties, creating profound challenges for groundwater governance systems designed to manage abstraction, protect quality, and ensure long-term sustainability. This doctoral research examines the intersection of hydrogeological uncertainty, governance system design, and sustainable aquifer management outcomes in basement complex aquifer systems serving communities in Niger, Kwara, and Kogi states. An innovative methodological design combines airborne electromagnetic geophysical surveys generating high-resolution subsurface structure data, network of 96 piezometers instrumented for continuous automated water level monitoring, isotopic analysis of groundwater residence times and recharge origins, and institutional analysis of groundwater governance arrangements at national, state, and community levels. Groundwater resource models incorporating hydrogeological uncertainty quantification are developed for three representative aquifer sub-systems and used to assess sustainability of current abstraction regimes under population growth and climate change scenarios. Governance analysis identifies critical mismatches between the scale and heterogeneity of basement aquifer systems and the administrative boundaries and monitoring capacity of responsible institutions. The study makes original contributions to hydrogeological science through application of airborne geophysics in characterising Nigerian basement aquifer geometry, to governance science through an aquifer governance typology applicable to fractured rock settings in sub-Saharan Africa, and to management practice through co-developed sustainable yield guidance for Kwara and Niger state water resource authorities. Recommendations address governance boundary reform, community monitoring participation, and minimum monitoring network standards. Keywords: groundwater governance, basement aquifer, hydrogeological uncertainty, sustainable yield, North Central Nigeria.