Assessment of hydrogeophysical delineation of groundwater zones using vertical electrical sounding (VES) in Jeypore Block, Koraput District, Odisha

VES-based characterization of lithological heterogeneity for potential groundwater development in the quaternary floodplain of Jashore Sadar, Bangladesh

Subsurface geology in deltaic floodplains is highly heterogeneous, strongly influencing groundwater development. In response to growing groundwater stress and the need for potential management, this study investigates the capability of vertical electrical sounding (VES) to characterize lithological variability and infer hydrostratigraphic conditions within the active floodplain of the Quaternary deposits of Jashore, Bangladesh. A total of 18 VES surveys were conducted using the Schlumberger array with investigation depths of 90–150 m. One-dimensional inversion modeling using IX1D was validated against nearby borehole logs, showing strong agreement for layer depth and thickness (R² > 0.95) and approximately 75% agreement in lithological classification. The results show five geoelectric layers with resistivity values ranging from 6 to 60 Ωm, corresponding to topsoil, clay, silty clay, and sandy lithologies, indicating considerable lateral and vertical heterogeneity across the floodplain. Furthermore, geo-electric cross-sections indicate that shallow or thick sandy units are concentrated around VES-3–7, 9–11, and 14–17, whereas clay-rich deposits dominate VES-1, 12, 13, and 18. In particular, the sandy layers characterized by relatively high resistivity (36–60 Ωm) and substantial thickness (32.35–94 m) are interpreted as potential aquifer zones, while the overlying clay and silty clay units suggest as confining to semi-confining layers. Moreover, the absence of very low resistivity signatures suggests limited saline water intrusion within the investigated depth range. Although hydrochemical and pumping-test data are still required for confirmation, our study develops a conceptual framework of lithological heterogeneity using VES for potential groundwater management applicable for similar floodplain environments.

Characterization of subsurface lithology based on resistivity grain gradation data in Mon Ikeun, Village, Aceh Besar, Indonesia

To address the growing challenges of water resource management in coastal karst areas, this study investigated subsurface lithological characteristics and evaluated aquifer potential in Mon Ikeun Village, Aceh Besar. The research integrated Electrical Resistivity Tomography (ERT) and grain size gradation analysis to provide a scientific basis for sustainable groundwater exploration. Resistivity data were collected along three survey lines, each 420 m long, using the Wenner-Schlumberger configuration. The 2D inversion results identified conductive zones with resistivity values below 454 Ωm, interpreted as alluvium comprising sand, silt, and gravel. These high-porosity, permeable layers extend to depths of approximately 25 m, indicating significant aquifer potential. In contrast, resistive zones above 454 Ωm were interpreted as limestone bedrock, representing impermeable layers with very low porosity. Laboratory grain size analysis using the hydrometer method revealed sand-dominated samples with high porosity (25-50%) and moderate permeability (2.5-45 m/day), while gravel-sand mixtures displayed moderate porosity (25-40%) and high permeability (150-450 m/day). The strong correlation between resistivity data and grain size distribution confirms the consistency of the lithological interpretation. This integrated approach offers an effective framework for securing freshwater resources in regions with complex geological settings and high vulnerability to water scarcity.

Integrated Geophysical and Hydrogeochemical Assessment of Dumpsite-Induced Soil and Groundwater Contamination in a Fractured Shale Aquifer System of Abakaliki, Southeastern Nigeria

Rapid urbanization and indiscriminate waste disposal have intensified soil and groundwater contamination in many Nigerian cities. This study presents an integrated geophysical and hydrogeochemical assessment of subsurface contamination associated with major urban waste dumpsites within Abakaliki Metropolis, southeastern Nigeria, underlain predominantly by fractured and weathered shale of the Asu River Group. Vertical Electrical Sounding (VES) employing the Schlumberger electrode configuration and two-dimensional (2-D) electrical resistivity imaging using the dipole–dipole array were conducted at three major dumpsites: Rice Mill, Umuoghara, and Mechanic Village. The acquired resistivity data were processed using Advanced Geosciences Incorporated (AGI) inversion software and Res2Dinv software to delineate subsurface lithology, fracture systems, aquifer characteristics, and leachate-contaminated zones. The geophysical results revealed low resistivity values ranging from 7–19 Ωm within the topsoil and weathered shale units, indicating highly conductive zones associated with moisture accumulation and leachate infiltration. Moderately to highly resistive layers (118–24,201 Ωm), interpreted as sandstone lenses, silty sand, and siltstone units, were identified at intermediate depths, while deep conductive zones with very low resistivity values (0.18–3.04 Ωm) were interpreted as fractured and saturated shale aquifers vulnerable to contaminant migration. To validate the geophysical interpretation, physicochemical and heavy metal analyses were carried out on soil and surface water samples collected around the investigated dumpsites. Elevated concentrations of heavy metals, including Pb, Cd, Hg, Cr, and Ni, were detected in several samples, with some values exceeding World Health Organization (WHO) permissible limits. The integration of geophysical, physicochemical, and geochemical data confirms the occurrence of leachate-induced subsurface contamination and demonstrates the vulnerability of fracture-controlled aquifer systems within the study area. The study demonstrates the effectiveness of integrating electrical resistivity techniques with hydrogeochemical analyses for environmental assessment and groundwater vulnerability studies in shale-dominated terrains affected by uncontrolled waste disposal activities.

Hydrogeophysical investigation for groundwater development in the crystalline terrain of Ohagainyi area of Lokoja, North-Central, Nigeria

Integrated geophysical and lithological analysis of a semi-arid karst basin for sustainable water management: Wadi Zouzfana (South-Western Algeria)

Semi-arid regions are often characterized by strong spatial heterogeneity of geological formations, surface processes, and groundwater circulation, which critically control water availability and land use planning. This study investigates the subsurface structure of the Wadi Zouzfana basin (south-western Algeria) using an integrated approach combining vertical electrical sounding (VES) and lithological data from three core boreholes (21-30 m depth). Twenty-four VES measurements were conducted using the Schlumberger configuration (= 200 m) and calibrated against borehole logs to establish reliable resistivity-lithology relationships in a karstified carbonate environment. Five main geoelectrical units were identified, corresponding to recent alluvium, karstified limestone, transitional carbonates, weathered dolomite, and compact bedrock. Low resistivity values (100-600 Ω•m) dominate the wadi axis, reflecting water-saturated alluvial deposits and karstified limestone, while higher resistivities (>1200 Ω•m) characterize structurally uplifted carbonate formations along the basin margins. Spatial interpolation of resistivity data within a GIS frame-work reveals an asymmetric bedrock morphology controlled by NE-SW tectonic structures, with a central depression guiding surface runoff concentration and groundwater storage. The results highlight the strong geomorphological and structural control on groundwater distribution and infiltration potential in this semi-arid karst basin. The integrated geophysical-lithological methodology provides a cost-effective framework for site-scale subsurface characterization applicable to similar semi-arid karst environments and supports sustainable water resource management and land planning in data-scarce arid environments.

DELINEATION OF QUATERNARY AQUIFER USING VERTICAL ELECTRICAL SOUNDING (VES) IN OGBIA AREA, BAYELSA STATE, NIGERIA

Electrical resistivity method using the schlumberger configuration were employed to delineate the quaternary aquifer in Ogbia area of Bayelsa State, Nigeria. The aim of this research is to determine the viability of the aquifer for borehole drilling. 10 VES points were carried out in Ogbia Area. They were interpreted by the use of IP12Win software. The interpreted VES data revealed 4-5 delineated layers of silty-clay, clay, clayey sand, sandy-clay, fine to coarse sand. Five sounding curve types were identified in the study area and they are of the KA, HA, QH, AK, and HKH types. The 4-layer geo-electric section were dominant compare to the 5-layer. The first aquifers were delineated at average depth of 24m and 34m with thicknesses ranging from 9.2m to 26.5m and resistivity ranging from310 to 8254Ωm while the 2nd aquifer were delineated at average depth of 37m to 43m with thicknesses ranging from 19.2m to 27m and resistivity values ranging from 740 to 9086Ωm. The second aquifer in the area are more reliable as sources of groundwater because they are less vulnerable to infiltration of surface contaminants and as well as possess better indices for higher groundwater yield due to their texture and greater thickness when compare to the first aquifer.