Integrated Geophysical and Hydrochemical Assessment of Groundwater Quality Near Urban Dumpsites in Port Harcourt, Nigeria

Open dumpsites may affect groundwater quality where permeable overburden permits surface derived solutes to enter aquifer materials. This study integrated vertical electrical sounding (VES), electrical resistivity tomography (ERT), and borehole hydrochemical analysis at Eliozu, Rumuolumeni, and Iwofe in Port Harcourt, Nigeria. Seventeen VES stations and thirteen ERT profiles characterised subsurface resistivity structure and geoelectric protective capacity, while six borehole samples were analysed for physicochemical, microbial, heavy-metal, groundwater quality-index (GQI), and hydrochemical-facies indicators. Conductive anomalies occurred at shallow to intermediate depths, including intervals extending to 33.40 m at Iwofe. Longitudinal conductance ranged from 0.001877 to 0.023766 S, placing all VES points in the poor class of the adopted protective-capacity rating. Reported GQI values were 126.72, 163.71, and 198.88 for the near-dumpsite boreholes and 35.94, 36.18, and 36.35 for the control boreholes. Higher reported phosphate, nitrate, iron, lead, and cadmium concentrations at near-dumpsite locations, together with an alkali–chloride facies tendency, are consistent with poorer measured groundwater quality. The results from the integrated geophysical and hydrochemical investigation of shallow aquifers around Eliozu, Rumuolumeni and Iwofe, demonstrate that groundwater within the dumpsite impacted zones has been affected by leachate infiltration.