Near-Surface Geophysical Methods for Assessing Waste Disposal Impacts in Niger Delta Communities: A Narrative Review

Abstract

Improper waste disposal can affect soil, shallow groundwater and the physical integrity of near-surface materials in the Niger Delta. Near-surface geophysical methods offer non-invasive means of investigating subsurface contrasts that may be associated with buried waste, leachate migration and changes in sediment properties. This paper presents a narrative review of the use and limitations of electrical resistivity methods, ground-penetrating radar (GPR), magnetometry, electromagnetic (EM) profiling and seismic methods for environmental waste assessment, with emphasis on their relevance to Niger Delta conditions. The review draws on published Nigerian case studies, methodological literature on landfill investigations and authoritative technical guidance. Studies were identified through targeted searches of scholarly and technical sources using combinations of terms relating to geophysics, landfill, dumpsite, leachate, groundwater contamination and Nigeria/Niger Delta. Eligible sources were compared according to method, target, geological setting, reported interpretation and validation evidence. The reviewed literature indicates that low-resistivity or high-conductivity zones can help delineate conductive subsurface features, but these responses are not unique to leachate and may also arise from clay-rich sediments or saline groundwater. GPR can resolve shallow interfaces and buried objects where electrical conductivity is sufficiently low, while its penetration is commonly restricted in conductive clayey and saline materials. Magnetometry is useful for locating ferrous objects but does not measure leachate or contaminant concentration. The evidence therefore supports the use of geophysics as a screening and site-characterisation tool rather than a stand-alone test of contamination. Integrated interpretation with borehole information and hydrochemical analyses is necessary before contamination is confirmed or remediation decisions are made. The review is limited by its narrative, non-systematic selection of sources and the scarcity of directly comparable Niger Delta waste-site geophysical studies.