Geoelectric Layers Research Articles

A geophysical assessment for engineering performance of subgrade soils: a case study of the Ago-Iwoye/Ilishan road, South-Western Nigeria

Geophysical application of electrical resistivity method has been employed to differentiate subsurface target of interest from the encompassing strata along the Ago-Iwoye/Ilishan road in South-western Nigeria. However, a geological model which links variation in lithological characteristics of subgrade soils to the engineering performance of the road is yet to be a research subject. This research is a special geotechnical application of geophysics for revealing the subsurface disposition and predicting the stability state of subgrade materials. Field assessment of rock types, and their relationship was followed by electrical resistivity measurement along the road. Schlumberger and dipole – dipole arrays were adopted for fifty-eight (58) Vertical Electrical Sounding (VES) and 2-D resistivity imaging involving Dipole-Dipole profiling technique was adopted in the sedimentary segment. Field data were inverted to 2-D resistivity structures inferentially delineated contour colorations using ‘DIPRO for Windows’ software. Geo-electric layers revealed Sedimentary Basin (SB) between Ilishan and Irolu, between Irolu and Ijesha-Ijebu, Transitional Zone (TR) with abrupt contrast along the plane of an unconformity and crystalline Basement Complex (BC) towards Ago-Iwoye. The 2-D resistivity structures across the different geological terrains revealed with 50Ωm - 3289Ωm at SB,233Ωm - 8028Ωm at TZ and 8Ωm - 3009Ωm at BC. From geotechnical view, subgrade materials underlying the SB and TZ segments can be adjudged competent to sand and clayey sand units with minor occurrences of incompetent clay and sandy clay lenses. The occurrence of subsurface discontinuities at the BC end of TZof the road would adversely affect the pavement stability.

Geology and Hydrogeophysical Investigation of Gurum and Environs, Lere Sheet 147SE, Bassa-Plateau, North-Central Nigeria

Geology and hydrogeophysical investigation of Gurum and its environs was undertaken within Lere Sheet 147 SE. The geological studies revealed the presence of Precambrian rocks (undifferentiated migmatites and Older Granites) and Jurassic rocks (Younger Granite) of different varieties belonging to the Buji Complex. The Buji Complex is composed of two (2) super imposed ring complexes, the earlier volcanic and high- level hyperbyssal intrusion dominated by granitic rocks. Hydrogeophysical results showed depth to various geo-electric layers and the range of apparent resistivity values with lithological units and their water yielding potentials. The studies clearly show the aquifer thickness is sufficient and the resistivity value falls within the range of good water yield. Additionally, it can also be said that the aquifers in the study area including both weathered overburden and fractured crystalline rocks are capable of yielding significant amount of water to wells. The aquifer thickness appears to increase towards the north eastern part of Gurum.

PRELIMINARY ASSESSEMENT OF AKEREBIATA CLAY DEPOSIT, ILORIN SOUTH WESTERN NIGERIA

The study focused on the preliminary assessment of Akerebiata clay deposit Ilorin south western Nigeria. The mineralogical and elemental compositions of the clay sample were determined using X ray diffraction (XRD) and X ray refractory fluorescence (XRF) techniques respectively while the probable reserve of the deposit was estimated using vertical electrical sounding (VES) and horizontalelectrical profiling (HEP)(dipole-diploe). Interpretation of results from XRD and XRF revealed that Kaolinite is the dominant clay mineral in the deposit while quartz is the dominant silicate mineral and this indicates that the deposit could be of residual origin. Chemical analysis revealed the predominance of SiO2, Al2O3 with values 61.73 % and 27.01 % respectively, and low CaO, MgO, K2O and Na2Oindicates that the clay is probably non expansive and with low feldspar content. Results of the VES shows three geo-electric layers which include: topsoil, clay and basement rocks. The average thickness of the clay layer is inferred to be 6.87m while the area of the deposit is calculated to 42,416.873 m2. With a specific gravity of 2.70, the inferred reserve of the deposit is 781,048 tons. These results will be of utmost importance to stakeholders and explorationists in the solid mineral sector.

Geophysical and Geotechnical Investigations of the Subsurface for Construction Purposes at Federal College of Education Osiele, Abeokuta, Southwestern Nigeria

Knowledge of the surface and subsurface structures are vital for construction procedures. Integrated geophysical and geotechnical methods were applied to image the subsurface for evaluation of the stratigraphy and the competency of each geoelectric layer for construction purposes at the Federal College of Education Osiele, Abeokuta South-western Nigeria. Nine Vertical Electrical Sounding (VES) using Schlumberger electrode configurations were conducted over a current electrode spacing of 200 m. Multi-channel Analysis Surface Wave (MASW) was the seismic technique used for the geotechnical analysis of the study area and laboratory analysis was performed to investigate, Atterberg limit, particle size distribution, compaction test, specific gravity, and California bearing ratio. Results from the geophysical investigation revealed four to five geoelectric layers: topsoil, clayey sand, sandy clay, laterite, and fresh basement. The MASW results have s-wave velocities range of 40–500 m/s and analysis showed four layers. The laboratory analysis revealed that all the ten traverses have specific gravity, which is out of limit except sample 8 which is 2.80, plastic index and Atterberg limits of liquid were within permissible values of 12% and 35% respectively except samples 9 and 10, and California Bearing Ratio within specified limits. Geophysical and geotechnical investigation of the subsurface carried out in the study area for construction purposes revealed that the foundation of a heavy structure should be targeted at around 20 m into the subsurface.

Groundwater Potential Evaluation and Aquifer Characterization using Direct Current Resistivity Method in Wasinmi South-West Nigeria

The effectiveness in near-surface characterization makes geoelectrical resistivity techniques viable for groundwater exploration, geotechnical studies and environmental investigations. Geo-electric soundings were carried out in 25 different locations in Wasinmi, South-West Nigeria to acquire aquifer properties required for groundwater production of the study area using Direct Current Resistivity (DCRE) of Vertical Electrical Sounding (VES) utilizing AGI Super-sting Earth Resistivity meter with schlumberger configuration; current electrode spacing (AB) ranging from 1 to maximum of 100 m and the potential electrodes (MN) were consequently changed from 0.25 m to 5 m respectively. The simulated results of the 25 VES points reveal the presence of 3 to 4 geo-electric layers. The top layer comprises clay, sand, siltstone intercalations. Layers underneath the top soil are the Lithified Laterite, Clayey Sand, Clay/Shale, Sandy Clay and Limestone/Sandstone, Saturated, Sandstone Aquifer. The area is also characterized with relatively high depth to sandstone aquifer which varies from 20 m to 69.1 m. This can be attributed to the thick water saturated Shale/Clay and Clayey Sand in the area. However, at the extreme of North-Western part of the study area, depths to aquifer are far lower, with VES location VESWAS15 having a thickness of about 14.4 m. Aquifer thickness in the study area varied from 14.4m to 63.5m. VESWAS19 has the highest aquifer resistivity value (2473 Ωm) in the study area, with depth to aquifer of 69.1 m. The transmissivity varies between 0.17695×/s in VESWAS4 to 8.97654×/s in VESWAS13. This study further shows that aquifer resistivity values vary from 284 Ωm to 2473 Ωm with a range of 2189 with the resistivity values suggesting lithology in the suite of Sandy Clay, Sandstone and Karst Limestone found to be widespread in the study area with mean aquifer thickness value of 32.25 m and a variance of 124.63 m...

Delineation of seawater intrusion in the Yanbu industrial area, northwest Saudi Arabia, using geoelectric resistivity sounding survey

Eleven Schlumberger array vertical electrical soundings were done at specified places in the Yanbu industrial sector, northwest Saudi Arabia, to identify possible seawater intrusion that may influence the shallow groundwater aquifer along the city's coastline zone. The variations of the resistivity values indicate the subdivision of the study area into two zones. These zones are characterized by different VES curve types; the Q-type and the H-type which dominate in the western and the eastern zones, respectively. VES data show three geoelectric resistivity layers. The first layer is an inhomogeneous layer with a wide range of resistivities correlated to Quaternary sediments (ranges from gravel, and sand to silt and clay) of variable lithology and water content. The resistivity of the second layer indicates abundant clay with a local change in the lithology to become gravel and coarse sand. The third layer shows a sudden and sharp variation of the resistivities; indicating a possible fault affected the coastal plain. This faulting system uplifts the basement, which may operate as an impermeable or sealing wall to prevent seawater from entering the shallow groundwater aquifer in the west. Most seawater intrusion in the studied area is regulated by faulting and lateral lithologic changes.

Application of Geophysical Methods for Investigation of Groundwater Potential in Layunrun Village, Ogun State, Southwestern Nigeria

An investigation of the groundwater potential of the area for tube well construction has been conducted in Layunrun village in a typical basement complex of Ogun State using electromagnetic and electrical resistivity techniques in geophysical exploration. Six (6) electromagnetic profiles were used, and twenty-eight (28) Vertical Electrical Soundings (VES) were performed along some of the profiles' potential regions. The typical partial curve matching utilized to create the VES curves was examined, and the results were used to create themed maps of the region. Within the study area, between four and six geoelectric layers were found. These layers are Topsoil, weathered layer (clay), weathered layer, fractured basement, and fresh basement. According to the findings, a bigger percentage of the land has an overburden thickness ranging from 9 to 17 m, with a maximum overburden of about 23 m. It also showed how well fractured the research area is, with thicknesses of the fractures varying from about 12 m to more than 30 m. The study area has a good chance of accumulating groundwater and, consequently, developing groundwater through digging boreholes. The outcomes also suggested that a community with similar geological settings may use the electromagnetic method in addition to the electrical resistivity method to identify places with high groundwater potentials.

Near surface assessment of New capital city using geophysical techniques

ABSTRACT The Egyptian government announced the creation of a brand new capital city to address Cairo’s rapid population expansion and improve the quality of life for citizens, which is thought to have a strong demand for housing. In this study, we focused on the application of geophysical techniques, specifically Electrical Resistivity Tomography (ERT) and Very Low Frequency Electromagnetic Method (VLF-EM), to investigate the shallow subsurface in the New Capital city in Egypt. The study area is located in the eastern part of Cairo and is characterised by Oligocene and Miocene rocks. The ERT profiles reveal four geoelectrical layers based on resistivity values, with the first layer (Resistivity >300 Ω.m) interpreted as sand and conglomerate on the surface or basalt below. The second layer (100–300 Ω.m) is identified as sandstone, while the third layer (15–100 Ω.m) is interpreted as humid sandstone. The fourth layer (1–15 Ω.m) is characterised as shale. The abrupt changes in resistivity values horizontally indicate the probability of subsurface structures, including faults. The VLF-EM method is used to identify faults and cracks in the earth’s crust. The results provide information on the size, shape, and depth of both shallow and deep subterranean conductors. Anomalies of high conductivity suggest fault or fracture zones influencing underlying strata.

Interpretation of vertical electrical soundings by means of ISM, PHT and C-N, case of a ditch in Al-Sharquieh phosphate mine in Syria

The main objective of this paper is basically to calibrate and compare the different geoelectrical results obtained by the three interpretative techniques of the inverse slope method (ISM), Pichgin and Habibuleav (PHT) and concentration-number (C-N) fractal modeling with the well lithology of an existing known ditch in the Al-Sharquieh phosphate mine in Syria. Those interpretative techniques are applied herein to interpret the vertical electrical soundings (VES) points measured along a parallel profile to the ditch. ISM reveals the presence of four to five geoelectrical layers in the study region. The PHT allows the determination of the tectonic subsurface features of the study region, by analyzing the non homogeneity points and their distributions along a given geoelectrical profile. The fractal C-N modeling provides the different apparent resistivity ranges dominating in the study region. Good agreements are obtained between the direct observed field lithological descriptions of both wall sides of this ditch, and the results obtained by those three interpretative geoelectrical techniques. The high radioactive readings exceeding four hundred count per second (cps) are due to the presence of secondary uranium accompanied with fractures, cracks and joints. The secondary uranium occurrences accompanied by phosphate deposits are found in the study area in the fractured zones, as determined by the geoelectrical PHT technique. The three mentioned geoelectrical methodologies are therefore used as indirect techniques for delineating the radioactive zones related to uranium prospecting. It is a successful application of the joint use of those three techniques, that could be applied in mining to delimit the subsurface geological structure. The reliability and efficacy of (ISM), (PHT), and (C-N) fractal modeling techniques are consequently well confirmed, and it is therefore recommended to use and apply them for characterizing and describing similar lithological phosphatic sequences, and for several shallow mining, environmental and civil engineering applications.

PRELIMINARY ASSESSMENT OF GROUNDWATER POTENTIAL ZONES IN AYEDE-EKITI, EKITI STATE, SOUTHWESTERN NIGERIA USING ELECTRICAL METHODS

An electrical resistivity survey was conducted at different locations within Ayede Ekiti, Ekiti State, Southwestern Nigeria. This is aimed at evaluating groundwater potential zones and aquifer properties within the study area. Data were acquired at four (4) different locations using the vertical electrical sounding method by employing the Schlumberger array configuration. This study utilizes resistivity data processed with IPI2win software to analyze the subsurface geology of a basement complex region. The result of the study showed that qualitatively, three major curve types (A, HA, and H) were observed. Varying curve types, predominantly A curves, were observed across the research area, with notable groundwater potential indicated by H and HA curve types at select points. Through curve matching techniques, three to four distinct geo-electric layers were identified, while the quantitative interpretation resulted in deducing layers with different resistivity and thickness values for each VES(s) of the study area. It was deduced that the VES 2 and 3 zones are connected to a high output of groundwater. However, VES 1 and 4 are characterized by low groundwater potential. This research contributes valuable insights for geological mapping and groundwater resource assessment in complex basement terrains of the study area.

Geophysical techniques and geomatics-based mapping for groundwater exploration and sustainable development at Sidi Barrani Area, Egypt

The exploration of groundwater on the northwestern coast of Egypt holds significant importance for urbanization and sustainable development. This is due to a deficiency in water resources, particularly in the arid regions, and the increasing reliance on groundwater as an alternative water source in response to the declining rainfall in the region. Therefore, this study adopts a comprehensive approach that combines the Geographic Information System (GIS) and remote sensing techniques with a geophysical survey. The Time Domain Electromagnetic (TDEM) and Vertical Electrical Sounding (VES) methods are used in the survey to investigate and characterize the fractured limestone aquifer that dominates the study area. A pedological investigation, including both in-situ and laboratory testing, is conducted on the soil. The findings reveal multiple layers—such as the top fill layer, sandstone layer, upper limestone layer, clayey layer, middle gypsiferous limestone layer, and lower limestone layer—within the soil profile. The fill layer is typically composed of fine- to medium-grained sand. A total of 47.7 acres were lost and 28.6 acres were gained according to the results of the shoreline change over several spatial and temporal scales. Sea level rise-related shoreline changes result in saltwater intrusion, which has a substantial effect on the groundwater quality in coastal aquifers. The integration of geophysical tools indicates the presence of two geoelectrical layers in the subsurface succession. The second layer corresponds to the Marmarica limestone of the Middle Miocene, which represents a shallow water-bearing formation in the study area. This layer exhibits moderate and low resistivity, with depths ranging from 1.58 to 52.8 m and a thickness from 23.6 to 139.12 m.

Application of Electrical Resistivity Method to Decipher Groundwater Occurrence Status at Isikuku, Southern Nigeria

Electrical resistivity method is a type of geophysical survey employed for groundwater investigation, conducted in Isikuku Community in Benin City, Edo state with the aim of delineating groundwater occurrence. Schlumberger electrode array configuration was employed in this study. Six (6) VES points were surveyed with linearised inversion technique used for the interpretation of sounding taken at various locations in the area. The data collected were interpreted by curved matching and computer iteration using Interpex Ix1D v 2 software. From the geoelectric section, VES 1 possess the AK curve with four layers ρ1˂ρ2˂ρ3˃ρ4, VES 2 possess the KQ curve with four layers ρ1˂ρ2˃ρ3˃ρ4, VES 3 possess the A curve with three layers ρ1˂ρ2˂ρ3, VES 4 possess the AK curve with four layers ρ1˂ρ2˂ρ3˃ρ4, VES 5 possess the A curve with three layers ρ1˂ρ2˂ρ3, VES 6 possess the K curve with three layers ρ1˂ρ2˃ρ3. Geo-electrical layers identified in the study area included topsoil, sandy clay, clay basement and sandstone. The VES study revealed the layer which constitute the productive water-bearing zones referred to as good groundwater potential aquifers. The analysis of the interpretation of the field data showed that the area under investigation delineated four layers earth in each of the vertical electrical sounding point. Generally, the geoelectric survey conducted in the study area revealed the subsurface lithologies: Clay, Clayey Sandstone, Sand stone, Coarse Sand, Lateritic soil and Top soil. Thus, vertical electrical sounding techniques employed in this study has proved useful and successful in delineating subsurface lithology in the study area.

Multi-Criteria Evaluation (MCE) of Groundwater Prospect and Vulnerability Index Mapping from Second-Order Geo-Electric Indices: A Case Study of Coastal Environments

Exploration, management, and conservation of groundwater resources are critical stages toward potable water supply, driven by an expanding populace and the threat of a new norm posed by the distinctive coronavirus (COVID-19) pandemic. An in-depth assessment of the potential of groundwater reserves and susceptibility, using a multi-criteria evaluation, is required to aid in the planning of exploration programs for groundwater well location. Thirty (30) vertical electrical soundings (VES) were collected in Okerenkoko, Warri-Southwest, Delta State, to assess groundwater potential and vulnerability indicators. The VES data were used to obtain the first-order geoelectric variables, which were further exploited to calculate the geo-hydraulic parameters (hydraulic conductivity and transmissivity) and the vulnerability indices of the aquifer. For aquifer vulnerability appraisal, the AVI (aquifer vulnerability index), GOD (groundwater occurrence, overlying lithology, and depth to the aquifer), and GLSI (geoelectric layer susceptibility index) models were used. The groundwater characteristics in the area were evaluated using the aquifer resistivity, thickness, transmissivity and coefficient of anisotropy values of the aquifer layers defined from VES 1-30. The results show that aquifer layers with low resistivity favor more saturation due to immense porosity and therefore have greater groundwater potential than aquifers with high resistivity. The geoelectric structures defined by VES 1, 2 and 4 were consistent in their groundwater potential and yield judging from the multi-criteria assessments. The estimation of AVI, GOD, and GLSI models for aquifer threat assessment was facilitated by the multi-criteria evaluation of vulnerability indices utilizing hydro-geophysical parameters and index-based approaches. The models depend on the symbiotic effects of geologic array and thickness as the basis for the magnitude of conservation imparted to any particular aquifer involved. The AVI model map depicts that most of the VES locations were rated high (C between 1 and 2) to extremely high (C < 1), indicating that the aquifers at these locations are vulnerable to pollution. However, the extent of vulnerability observed in the GOD model is less than in the AVI model, as GOD accords much more inclination to the inherent properties of geologic entities. The GOD model map categorized the vulnerability index ratings in the area as negligible (0.0-0.1), low (0.1-0.3) and moderate (0.3-0.5), with most VES locations ranked low to moderate, which indicates that these locations are susceptible to vulnerability. In the GLSI model, individual overlying layer thicknesses were prioritized. The GLSI model map shows that the vulnerability index ratings in the area are ranked as moderate (2.00-2.99), high (3.00-3.99) and extremely high (≥ 4.00) with most of the VES locations ranked moderate to high with the exception of VES 27, which ranked extremely high in both AVI and GLSI indices. By correlating the results of vulnerability index valuation for the AVI, GOD and GLSI models, more correlation was observed between the AVI and GLSI models. These findings validate the adoption of a multi-criteria evaluation methodology for groundwater potential and aquifer vulnerability studies and are strongly recommended as practical criteria for locating subsurface aquifers and their protective measures for groundwater prospect development planning and management.

Mapping Leachate Pathways in Aging Mining Tailings Pond Using Electrical Resistivity Tomography

Mining activities often leave behind a legacy of environmental challenges, with aging tailings ponds representing a significant concern due to their potential for leachate formation and subsequent contaminant release. Thus, this study employs Electrical Resistivity Tomography (ERT) to investigate the intricate pathways of leachate within an aging mining tailings pond, addressing the pressing environmental and human health concerns associated with potential contaminant release. Ten 2D ERT profiles were acquired at the El Mochito mine waste site, covering an area of approximately half a square kilometer. These profiles, ranging in length from 104 to 363 m, provided insights into subsurface conditions down to a maximum depth of 60 m. The subsurface mapping of the ERT data showed three different geoelectric layers. The uppermost layer, with a thickness of approximately 2.5 m and resistivity values ranging from 60 to 100 Ohm.m, was identified as a dry tailing/soil zone. Beneath it, the second layer exhibited moderately resistive values (30–60 Ohm.m) with varying thicknesses of 10–20 m, signifying a percolation/leaching zone (semi-saturated zone). The third layer, characterized by substantially low resistivity (1–30 Ohm.m), indicated saturation and the presence of conductive materials, strongly suggesting active leaching. Based on these findings, this study recommends further investigation through geochemical analysis of subsurface samples and more advanced geophysical imaging techniques to validate the distribution of anomalous zones and delineate remediation pathways. This study lays the foundation for future comprehensive research that will integrate geophysical surveys with geochemical analysis and establish 4D modeling techniques to monitor pollutant penetration over time, with a particular focus on mine waste tailings mapping. Plus, this study contributes valuable insights into the characterization of leachate pathways within mining tailings ponds, offering a foundation for informed environmental management and remediation strategies.

Electrical Resistivity Investigation of Dumpsites in Gusau Metropolis, Zamfara State, Nigeria

Electric resistivity survey was carried out in three selected dumpsites in Gusau metropolis for groundwater contamination. The dumpsites were investigated by conducting Vertical Electrical Soundings (VES) using Schlumberger array with maximum current electrode separations of 180 m. Five VES were conducted on each dumpsite making a total of fifteen VES along three profiles. The field data obtained from VES were analyzed using WinGlink softwar. The VES results revealed three subsurface layers. The topsoil had resistivity ranging from 1.45 Ωm to 48.2 Ωm while the thicknesses varied from 0.47 m to 3.37m across the profiles. The second layer's resistivities varied from 5.4 Ωm to 144.35 Ωm and their thicknesses' ranges from 1.36 m to 16.93 m. The third geoelectric layer had resistivity from 70.0 Ωm to 6003.0 Ωm. The results indicated that the top soils in all the dumpsites were characterized by very low resistivity depicting possible pollution and contamination. Findings from this study indicated that there may be possible contamination of shallow groundwater system in the nearest future if proper mitigation measures are not taken into consideration at the dumpsites.

Evaluation of Groundwater Potentiality and Subsurface Structural Setting by Using Geophysical Data in Wadi Hubuna, Southwest Najran, Saudi Arabia

A geophysical study was conducted to explore the shallow groundwater aquifer and to identify the subsurface structure on the basis of resistivity and geomagnetic surveys. The study area is situated in the southwestern portion of Saudi Arabia, southwest of the Najran region. The total intensity magnetic map is reduced to the northern magnetic pole. The estimated mean depths of the regional and residual magnetic sources are 3 km and 1.4 km respectively. Eighty vertical electrical soundings were measured using the Schlumberger configuration with AB/2 spacing of up to 700 m. Four geoelectrical layers were identified, and could be described from ground surface to deeper layers as the following: The first layer encompasses wadi deposits with true resistivity values ranging from 452 Ω.m to 1353 Ω.m and thicknesses of 2-4 m. The second layer is comprised of dry fine to medium grain-sized deposits with true resistivity values ranging from 104 Ω.m to 451 Ω.m, and thickness varying between 2 and 16 m. The third layer consists of water-bearing friable deposits beside the topmost part of the underlying weathered (fractured) basement. The true resistivity of this layer ranges from 22 Ω.m to 188 Ω.m, whereas the thickness of this layer is highly variable and ranges from 5 to 35 m. Generally, the resistivity values and the thickness of these three layers exhibit an increasing trend toward the main wadi stream. A fourth layer was also detected and is represented by a thin clay layer directly overlying the hard rocks of the basement complex. The dominant tectonic trends controlling the shallower parts are N-S and NNW-SSE. Meanwhile, the structural trend controlling the deeper parts is NE-SW, E-W, and. NNE-SSW. The ideal areas for drilling wells, according to the interpreted cross-sections, are along the main stream of Wadi hubuna and other small wadis, as well as the lower portions of the wadi in the extreme east direction.

Evaluation of geophysical parameters for groundwater productivity in the Commune of Jesse, Delta State Nigeria


 Aquifer geohydraulic properties in Jesse were studied by the application of vertical electrical sounding (VES) and pumping test. The VES data was collected using ABEM SAS 1000 Terrameter and results processed using manual matching of curves and computer iteration, and interpreted in the forms of geologic models and geoelectric layers. The aquiferous unit was found at a depth of 5.30 m to 30.30 m with a range of resistivity from 87.30 Ω-m to 1945.40 Ω-m. Dar-Zarrouk parameters estimation and results of borehole pumping test produced the aquifer hydraulic parameters. The hydraulic conductivity values range from8.171 - 8.279 m/day, transmissivity from 43.8770 - 517.7480 m2/day, and formation factor from 0.369 - 8.501. These results are indications of a prolific and high yielding aquifer capable of withstanding long duration of pumping. Results of groundwater electrical conductivity and total dissolved solids ranged from 11.65 - 198.80 μs/cm, and 29.40 - 35.40 mg/dm3 respectively, signifying very moderate mineralization of the groundwater. The average electrical conductivity of 68.04 μS /cm and total dissolved solids of 32.58 mg/L were lesser than the acceptable limits of the Nigerian Standard for Drinking Water Quality (NSDWQ) of 1000 μS/cm and 500 mg/L respectively. This study affirmed that the aquifer in Jesse is suitable for groundwater exploitation for local and regional purposes.

Evaluation of Aquifer Hydraulic Properties and Vulnerability Indices in Mosogar using Geoelectrical Approach

Geophysical investigation employing vertical electrical sounding (VES), pumping test and in situ groundwater conductivity measurement were carried out in Mosogar, Delta State in order to determine the aquifer properties and vulnerability indices. The Schlumberger electrode configuration was used for the vertical electrical sounding (VES) survey to acquire electrical resistivity data which were interpreted using the WinResist software, version 1.0 (2004). The results revealed that the lithology is composed mainly of sand with various grades with four to five delineated geoelectric layers. Results of hydraulic conductivity, transmissivity and formation factor of the aquifer were found to vary from 7.9233 to 9.2799 m/day, 45.670 – 235.323 m2 /day and 0.545 – 23.664 respectively. Aquifer vulnerability indices within the study location indicate moderate to extremely high vulnerability as classified by aquifer protective capacity (APC), aquifer vulnerability index (AVI), Geo-electric layer susceptibility index (GLSI) and groundwater confinement, overlying strata and groundwater depth index (GOD) models employed, with values ranging from 0.00766 - 0.038728, -0.5631- 0.3025, 2.25 - 3.00 and 0.4 -0.8 respectively. The results revealed that the groundwater is prone to contamination because of weak protection provided by overlying geologic units. Using the Golden surfer 10 software, maps of geo-hydraulic parameters and vulnerability indices were constructed which characterises the aquifer parameters in the area. This study provides an important tool for sustainable groundwater exploration and management in Mosogar

Exploration of Ground Water Potential of Federal University of Technology, Owerri and Its Environs Using Resistivity Survey

The research focused on evaluating the groundwater potential in the vicinity of Federal University of Technology Owerri (FUTO) using a resistivity survey method. The investigation involved the utilization of eleven Schlumberger vertical electrical soundings (VES). The data collection was conducted using an ABEM Terrameter SAS4000 and then processed with IPI2Win Software, which relies on the conventional theory of curve matching. This process aimed to determine the depth, quality, and subsurface formations of the groundwater. The VES interpretation results revealed the presence of 3-5 geoelectric layers above the aquiferous layers. Various curve types were identified in the study area, including monotonically ascending (AA), bowed-ascending (HA), bowl-bell (HK), and ascending-bell (AK) curves. The majority of the field curves were found to be of the A-shaped type, signifying specific aquifer characteristics. The study indicated that the depth to the water table is relatively shallow in the Ihiagwa area, with an average depth of 7.26 meters. In contrast, the aquifer's depth is deeper around Avu, Nekede, and Eziobodo areas, with a mean depth of 32.33 meters. Obinze had very deep aquifers, with an average depth of 57.75 meters. Furthermore, the study established a relationship between aquifer characteristics and geoelectric parameters, allowing for the estimation of hydraulic conductivity and transmissivity values at all the sounding locations, even in areas lacking boreholes. These hydraulic characteristics showed that the aquifer had protective capacities ranging from 0.036 to 0.509 mhos, transmissivity values ranging from 11856.32 to 28661.28 m2/day, and hydraulic conductivity ranging from 13.47 to 1009.2 m/day. These values suggested that the aquifer materials are highly permeable, facilitating fluid movement within the aquifer. This research demonstrated the effectiveness of surface geophysics in estimating aquifer hydraulic characteristics, particularly in situations where pumping test data are unavailable. It also highlighted the vulnerability of the aquifer to surface contaminants. The findings are expected to be valuable for the long-term planning of groundwater exploitation projects in the study area.

Subsurface mapping of petroleum product (diesel) spillage in Apapa, Lagos, Nigeria from geophysical, lithological, and hydrogeological studies

A multi-disciplinary method has been applied for the subsurface mapping of a diesel (refined petroleum product) spillage in the Apapa area of Lagos, Nigeria. The methods include geological, geophysical, hydrogeological, and geoinformatics approaches. Apapa is located within the eastern sector of the Dahomey Basin, Nigeria. Twelve profiles were probed, adopting a 2D Wenner configuration. Three 3D resistivity images were produced from the 2D profiles using ZONDRES 3D and SURFER 16. Additionally, six boreholes were drilled for lithological information and the determination of groundwater flow directions of the area. The study area is characterized by loose, fine to coarse grained sand underlain by peat. The sands were observed to be partly contaminated by diesel (spilled diesel). The 3D resistivity images revealed that the area is composed of 3 geoelectric layers; an organic debris layer (<15 Ωm), overlain by a clean sandy layer (15–54 Ωm), as well as a contaminated sand layer (>55 Ωm). The results showed that higher resistivity values were obtained at shallow depths ≤3 m which depicts the diesel contaminated sand. The 3D model also showed that the magnitude of contamination decreases from the southern part (close to the source of contamination) towards the north of the area. These results are in tandem with the principal flow direction of water which is from south to north, confirming that the pollution source is from the southern part of the area. The combination of the resistivity, groundwater flow direction, and lithological information, therefore, unraveled the source, direction, and extent of contamination in the study area for a successful remediation plan.