Mapping the Concentration and Pathway of Leachate Plumes of Major Dumpsites in Makurdi Metropolis, North Central Nigeria using an Integrated Approach.

Abstract

This study presents an integrated hydro-geophysical and hydro-chemical investigation of leachate plume migration beneath major municipal dumpsites in Makurdi. Twenty four Vertical Electrical Sounding (VES) surveys using the Schlumberger configuration were combined with groundwater quality analysis to delineate contamination extent, depth, and migration pathways. Apparent resistivity values ranged from 1.2 to 58,000 Ω·m, reflecting strong lithological and contamination contrasts. Zones with resistivity <20 Ω·m were interpreted as highly conductive leachate saturated layers, with plume penetration depths reaching up to 180 m in some locations. Hydro-chemical analysis revealed elevated concentrations of Fe (9.38–12.07 mg/L), Mn (3.78–4.89 mg/L), Pb, and Cd exceeding World Health Organization permissible limits, confirming geophysical interpretations. Spatial analysis shows dominant southwest–northeast plume migration consistent with regional groundwater flow. The study demonstrates that unlined dumpsites constitute major sources of deep aquifer contamination. The integration of resistivity imaging, hydrochemistry, and GIS provides a robust framework for environmental monitoring and groundwater protection.