Mapping Groundwater Contamination Plumes Around an Urban Solid Waste Dumpsite Using Two-Dimensional Electrical Resistivity Tomography: A Case Study of Tukur-Tukur, Zaria, Nigeria

Abstract

Uncontrolled open dumpsites in peri-urban environments generate leachate that poses a persistent threat to shallow groundwater in Basement Complex terrain. This study delineates subsurface leachate plume distribution and the extent of groundwater contamination at the Tukur-Tukur dumpsite, Zaria, Kaduna State, Nigeria, using two-dimensional electrical resistivity tomography (2D-ERT). Eight 200-metre survey profiles were acquired using the ABEM LUND Imaging System with Schlumberger electrode configuration. Apparent resistivity data were inverted using RES2DINV software and correlated with borehole lithological data. The resistivity models resolved a four-layer subsurface consistent with borehole lithology: reddish lateritic clay (0–3 m), brownish sandy granite (3–6 m), weathered/fractured basement (6–36 m), and fresh crystalline basement (>36 m). Low-resistivity anomalies (<100 Ωm) in the uppermost 0–7 m across all profiles indicate pervasive topsoil contamination. Critically, anomalies of 10–80 Ωm at 28–38 m depth in the eastern sector suggest deep aquifer impairment. Root mean square errors ranged from 4.3% to 25.9%. The result indicates that plumes have migrated beyond dumpsite boundaries in all directions and have reached the principal aquifer horizon. This finding highlights the need for dumpsite engineering upgrades, water quality monitoring, and community health protective measures.