MJSTEM

Abstract

Groundwater represents the primary accessible freshwater reservoir, necessitating rigorous management due to the disparity between anthropogenic extraction rates and natural recharge kinetics. This study evaluated the hydrogeological framework of Minna, Nigeria, a region underlain by Precambrian Basement Complex lithologies, specifically granite and schist, to model flow dynamics and vulnerability. Geological mapping at a 1:12,500 scale identified surface fracture networks, while a systematic grid-based inventory of 117 hand-dug wells facilitated the characterization of the aquifer system. The primary storage media consist of the regolith (weathered basement) and underlying fractured horizons. The static water level in the area ranges from 0.9 to 10.3 m, the water column from 0 to 4.8 m, and the well depth from 1.6 to 10.6 m. The static water elevation values were utilized to generate equipotential surface maps. The hydraulic gradient indicates a dominant NE-SW flow vector, with a secondary N-S component. High-head areas (recharge) were localized around Tundun Fulani and Maitunbi, while low-head sinks (discharge) occur near Kpakungu. A critical finding is the negligible overburden thickness (0.5–1.0 m). This thin vadose zone significantly compromises the aquifer’s natural attenuation capacity, facilitating rapid vertical transport of anthropogenic contaminants. The lack of a robust lithological filter renders the groundwater highly susceptible to surficial pollution, highlighting a requirement for immediate integration of hydrogeological constraints into urban planning to ensure resource sustainability.

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