Development of an Original Integrated Groundwater Management Model for the Basement Complex Aquifer System of Kogi State

The basement complex aquifer system of Kogi State, North Central Nigeria, is the primary groundwater resource for rural and peri-urban communities, but its complex fractured-rock hydrogeology and highly variable aquifer productivity present significant challenges for sustainable management. This study develops an original integrated groundwater management model for the Kogi State basement complex aquifer system. A multi-scale modelling framework is developed integrating: geophysical characterisation of aquifer structure using electrical resistivity tomography at 120 sites across the state; a stochastic hydrogeological database of aquifer productivity statistics derived from pumping test analysis for 340 boreholes; a regional groundwater flow model using MODFLOW-USG with unstructured grids suited to the heterogeneous basement complex geometry; and a multi-criteria optimisation module for sustainable yield allocation. The integrated model simulates groundwater availability under a range of abstraction management scenarios and climate projections. Original contributions include a Kogi State basement aquifer productivity prediction algorithm using remotely sensed lineament density and electrical resistivity indices as predictors (R2 = 0.71), a heterogeneous basement aquifer MODFLOW parameterisation protocol, and a groundwater allocation optimisation framework balancing demand satisfaction, minimum baseflow maintenance, and equitable geographic distribution. The model results indicate a sustainable yield for the state aquifer system of 180 to 220 million litres per day under current recharge conditions. The integrated management model is proposed for adoption by the Kogi State Water Corporation.

Keywords: groundwater management model, basement complex aquifer, Kogi State, MODFLOW, North Central Nigeria