Vertical Electrical Sounding Survey Research Articles

Assessment of Aquifer Resistivity, Depth, and Thickness using Vertical Electrical Sounding (VES) in Parts of Bori Metropolis for Groundwater Exploration

Groundwater exploration is vital to guaranteeing a reliable water supply in both urban and rural locations. In Bori Metropolis, the growing demand for potable water necessitates a thorough examination of the aquifer system. Therefore, the purpose of this study is to determine the groundwater potential in Bori Metropolis by assessing aquifer resistivity, depth, and thickness using Vertical Electrical Sounding (VES). A total of 13 VES surveys were completed in the study region using the Schlumberger array. The apparent resistivity measurements were analyzed using 1D inversion techniques to determine aquifer depth and thickness. The results showed that aquifer resistivity values ranged from to at depths ranging from to . Aquifer thicknesses ranged from to , indicating a high groundwater potential in the area. The results indicate that the Bori Metropolis area comprises a well-defined aquifer system with a high potential for groundwater extraction. These findings give important information for future water resource management in the region.

Geospatial and geo-electrical assessment of groundwater vulnerability and potential in parts of Cross River, Southern Nigeria

Assessing groundwater vulnerability and potential is essential for sustainable management. This study evaluates these factors in southern Cross River, Nigeria, using geospatial and geo-electrical methods, including Vertical Electrical Sounding (VES), Geographic Information Systems (GIS), and Remote Sensing (RS). Twenty VES surveys were performed, revealing aquifer resistivity from 5.12 to 506.00 Ω/m, thickness from 6.60 to 34.30 m, and depth from 18.60 to 68.00 m. Rainfall was the most significant factor (38 %) affecting groundwater potential, followed by geology (24 %), slope (13 %), drainage density (8 %), land use/cover (6 %), lineament density (5 %), and soil type (3 %). With a Consistency Ratio (CR) of 0.043884, data consistency was high. Groundwater potential zoning (GWPZ) maps categorized the area into low, moderate, good, and excellent zones, highlighting high potential in western areas with high lineament density and moderate slopes. This research demonstrates the effectiveness of integrating geospatial and geo-electrical techniques for groundwater assessment.

Delineation and validation of GIS-based groundwater potential zones under arid to semi-arid environment using multi-influence-factors approach

ABSTRACT Groundwater is an indispensable source for domestic-use, agriculture, industry and sustainable development. Groundwater scarcity is Pakistan’s emerging issue, especially in the arid and semi-arid regions of southern Khyber Pakhtunkhwa. This study intends to demarcate the groundwater potential zones (GWPZ) in these regions using Multi-Influence-Factors (MIF), validated with Vertical Electrical Sounding (VES) and well data. The study region was classified into four GWPZ: very high (340 km2), high (4997.11 km2), moderate (17615.14 km2) and poor (16355.46 km2). These interpretations were supported by the VES survey, and water bearing layers have been recognized at 32 m, 137 m, 87 m, 10 m at VES points 1, 2, 3, and 4, respectively in Karak, and at 152 m, 194 m, and 93 m at VES points 1, 2, and 3, respectively in Lakki Marwat, while at 125 m, 119 m and 80 m at VES points 1, 2 and 3, respectively in D. I. Khan. The southern region is predominantly poor, the northern and northeastern parts are high to very high, while the southwest part has moderate potential. Water depth is <40 m at very high potential, 40 to 70 meters at high potential, and 150 to 180 meters in poor zones. This study will help to enhance the applicability of integrated methodologies for groundwater investigations under arid conditions.

Hydrogeological assessment and aquifer potential of a coastal area, South Nigeria: insights from VES surveys and spatial analysis

ABSTRACT This study provides a comprehensive analysis of aquifer properties using vertical electrical sounding (VES) surveys conducted in Eket, Nigeria, to address the challenges of groundwater management in coastal areas. The VES method was employed for hydrogeo-electrical analysis and to investigate the hydrogeological dynamics of the region. The results reveal varying subsurface layers with distinct resistivity values. Spatial distribution analysis indicates densely settled areas exhibit lower resistivities, while sparsely settled regions show higher resistivities. The spatial location labeled EK2 features the largest aquifer, measuring 246.70 m, predominantly located in the central research area. Aquifer depths range from 87.10 to 250.20 m, with variations in thickness highlighting geographical heterogeneity and its impact on groundwater transport. These spatial differences in groundwater characteristics are crucial for understanding groundwater movement, storage, and extraction potential. The study underscores significant variability in porosity, reflecting differences in the aquifers’ water storage capacity and susceptibility to contamination. These findings have important implications for groundwater flow rates and extraction feasibility. The research provides essential data for hydrogeological investigations and groundwater resource management, emphasizing the intricate relationship among geological formations, aquifer properties, human activities, and the potential risks of contamination in variable porosity zones.

Geophysical Investigation of Bulding Distress in Gashua, Nigeria

Gashua is the Headquarter of Bade local government in Yobe State, it has a population of about 125, 000 according to the 2006 population census. It is a densely populated town located in a flood plain within the Chad Basin. In an attempt to proffer solutions to the prevailing building distress in Gashua and its environs, this study was carried out to accurately characterize the subsurface geology of the area, thereby reducing the incidence of building failure in the area to minimum. In this study, electrical resistivity method was used to determine the causes of building distress and failure in Gashua and its environs. Vertical Electrical Sounding (VES) using Schlumberger array and Electrical Resistivity Tomography (ERT) were adopted for the study. The results of the VES survey showed that the area is composed of five geologic layers which are; the topsoil, clay, sand, sandy-clay, and sand. The ERT results showed that most of the building foundations in the study area were laid within the second layer which is a clay formation. The findings of this study showed that the building distress and failure which are common in the study area were caused by the volumetric changes of the clay formation due to hydrological dynamics. The clay formation absorbs water during the raining season and swells up, and during the dry season it shrinks, this changes in the volume of the clay formation underlying the building foundation in the study area induces a significant mechanical stress on the buildings leading to the formation of cracks, voids, fissures and fracturing of the buildings, which eventually culminate into collapse. In this study, electrical resistivity method of geophysical investigation has demonstrated to be a veritable tool for geotechnical soil evaluation. Based on the findings of this study, geophysical investigation of a proposed site...

Use of remote sensing, spatial and geophysical modeling, and real recharging capabilities to identify suitable areas for groundwater exploitation in dry coastal areas

Accurate identification of groundwater potential areas in arid regions is an important task for groundwater management and sustainability. As a result, this study used the innovative integration of remote sensing (RS), geographic information system (GIS), watershed modeling system (WMS), geophysical survey, and water mass balance equation to identify potential groundwater areas in the W. Dara, Eastern Desert, Egypt. A weighted spatial probability model (WSPM) of groundwater potential based on eight regulatory factors was implemented within ArcGIS software. Drainage density (DD), precipitation (P), net groundwater recharge (NGR), terrain slope (TS), lineament density (LD), lithologic group (LG), water quality (TDS), and depth to groundwater level (DGW) are the aspects considered. The Analytical hierarchy process (AHP) method was used to assign weights to these parameters, and their accuracy was estimated using the consistency ratio (CR). The resulting groundwater potential map classified W. Dara study area into five categories, ranging from very low to very high potential. A geophysical survey, in the form of Vertical Electrical Sounding (VES) and Transient Electromagnetic (TEM), was conducted along W. Dara to validate the results of the WSPM, which identified areas of high groundwater potential. The 1D inversion of VES/TEM shows that the central and western parts of W. Dara are considered the most promising areas for groundwater occurrence, and are located in areas of high and very high potential classes derived from WSPM. Moreover, the results of VES and TEM surveys showed that the proposed aquifers (Nubian Sandstone, Miocene, and Quaternary) in the study area are horizontally and vertically connected through a set of normal faults traversing NW-SE. Ten sites have been proposed for drilling additional exploitative wells in W. Dara area based on the WSPM and geophysical survey with the aim of sustainable development. Thus, the integrated techniques applied in this study proved effective in accurately determining the development strategy for arid and semi-arid coastal areas, especially those that suffer from scarcity of rainfall and increased agricultural reclamation requirements in remote areas.

Predicting soil parameters in Maroua 1st, Cameroon, using correlations of geophysical and geotechnical data

This study aims to predict specific soil parameters based on quantitative and qualitative correlations between electrical and geotechnical data. A total of 21 geotechnical boreholes followed by sampling, 21 light dynamic penetrometer tests, and 76 vertical electrical sounding surveys were carried out in Maroua 1st. The electrical resistivity data of the soil layers were obtained through 1D and 2D inversions of the ERT surveys. The geotechnical data were obtained from field tests and laboratory experiments. The statistical analysis of the entire dataset indicates that most of the samples are clay formations, as demonstrated by the means of variables and low variance coefficients, enabling qualitative identification. The distribution analysis of the parameters confirms the complexity of the physical characteristics of soils and the measurement procedures for each parameter. The Spearman's rank correlation matrix indicates that these observations can be used to propose predictive models for free swelling, allowable stress, natural water content, and electrical resistivity. Correlations between free swelling (εg) and other variables are not significant, as the degree of significance is lower than the fixed limit, except for models εg - W (R2 = 0.94), εg - ρ (Ώ.m) (R2 = 0.803), and εg - σ adm (R2 = 0.757). Grouping variables in multiple linear regression enables the development of a mathematical model. The predicted values of εg from this model demonstrate good agreement with the measured values for a validity domain of 0–16 %. The soil's natural water content has a strong correlation (R2 = 0.80 and rs = – 0.87) with electrical resistivity, meaning that an increase in water content results in a decrease in electrical resistivity. The permissible stress σadm has a strong correlation (R2 = 0.89 and rs = 0.85) with electrical resistivity. This indicates that changes in soil electrical resistivity are associated with soil stiffness.

Delineation of geological formations and their influence on groundwater in Umunneochi L.G.A of Abia State and Its Environs

For socioeconomic growth and environmental wellbeing of the populace, the availability and sustainable management of groundwater resources is very crucial. Effective management and use of this invaluable resources requires an understanding of the subsurface geological formations and their impact on groundwater. This study was carried out in other to delineate the subsurface geological formations and evaluate their impact on groundwater availability in Umunneochi Local Government Area (L.G.A) of Abia State and its environs using Vertical Electrical Sounding (VES) analysis. The study includes gathering resistivity data via a network of VES surveys carried out at twelve key locations in six selected town within Umunneochi L.G.A. The field data were subsequently interpreted using an iteration software IP2WIN to identify various geological formations and evaluate their potential as aquifers, which substantially impact groundwater occurrence and distribution. The research findings showed distinct geological units with resistivity values ranging from 0.37 - 2000Ωm, which is indicating a variety of lithological properties, with sand and gravel layers showing higher permeability representing potential aquifers. The results of this study have significant implications for groundwater management in Umunneochi L.G.A. and its surroundings, and also provide recommendations for the strategic placement of boreholes and wells to maximize groundwater extraction and long-term use.

Uncovering soil piping vulnerability using direct current geophysical techniques in Awka, Anambra State, Nigeria

In recent times, there have been increasing reports of soil subsidence occurring in various parts of Anambra State, Nigeria. The formation of soil pipes in the subsurface, which has been reported by many researchers globally, is the chief cause of these subsidence incidents. Thus, this research aims to use Direct Current (DC) geophysical techniques to delineate the spatial distribution, pattern, and characteristics of these soil pipes at two sites: Awka Site 1 and Awka Site 2 both in Awka South LGA of Anambra state, Nigeria. Two electrodes array configurations - the dipole-dipole array for analyzing the Electrical Resistivity Tomography (ERT) and the Schlumberger array for analyzing the Vertical Electrical Sounding (VES) - were employed. Nine ERT profiles and eighteen soundings were carried out. The results from the ERT survey divided the subsurface into six distinct structures. The high-resistivity 3000-30000Ωm, the eroded structure with dry pore spaces, which mainly occur at the top of the profile, was interpreted as having the right conditions for the formation of soil pipes. The result from the VES survey revealed two to five different geo-electrical sections and fourteen distinctive sounding curves that are characterized by the vertical changes in the subsurface. The weathered soil with resistivity ranging from 1200-30000Ωm, which aggregates very close to the surface 0-5m of the study areas, was interpreted as having the best soil formations that allow the building of soil pipes. The 2D and 3D iso-resistivity maps obtained from the data of the VES show that soil pipes follow the NW-SE direction. This coincides with the stress direction, fluid migration paths, and sloppy terrains of the study areas.

Aquifer depths and thickness in Ogba/Egbema/Ndoni local government area of Rivers State, Nigeria from vertical electrical soundings

Most parts of the world depend on groundwater for domestic and other uses. Different geophysical methods can be used to exploit these groundwater. In this study aquifer depths and thickness spread in parts of Ogba/Egbema/Ndoni Local Government Area of Rivers State, Nigeria have been determined from 30 vertical electrical sounding survey. An ABEM Terrameter (SAS 300C) was used with Schlumberger array configuration of maximum electrode spread of 500 m. The data were analyzed with an IP2WIN ID software to obtain the strata resistivities, geoelectric layers, aquifer depths and thickness from which the isopach and iso-resistivity maps of the region were obtained. The results show two to four layer formations with resistivity values ranging from 350 to 3895 . Aquifer depths of between 20 m to 75 m and thickness varying from 17 m to 48 m. The isopach map indicates that regions in the north-central part of the study area have shallower aquifer thickness with an average value of 25 m while in the other parts of the study area, the average value is 41 m. The iso-resistivity contour maps at depth intervals of 50 m, 100 m, 150 m and 200 m reveal the trending of the resistivity values for these depths across the region. The general results indicate that the study area has productive aquifers of reasonable thickness at moderate depths from 20 m as in the other parts of the Niger delta region, therefore portable boreholes can be drilled from this depth.

2-D RESISTIVITY IMAGING AND HYDROGEOCHEMICAL ANALYSIS FOR LEACHATE MIGRATION AT DUMPSITES IN SOUTH-SOUTH NIGERIA

Vertical electrical sounding, 2-D tomography and hydrogeochemical analysis was applied to investigate dumpsite leachate plume generation, migration and its impact on the surrounding soil and groundwater aquifer at a municipality in the Western Niger Delta. Twelve vertical electrical sounding (VES) was investigated using the Mini-Res Resistivity Meter with the Schlumberger array. The VES survey result was interpreted with Winglink software. Five hand-dug well water and 5 tap/borehole water samples was collected for hydrogeochemical analysis using the sterile plain bottles and 1-litre plastic bottles. Resistivity results delineated 5 layers of lateritic topsoil, sandy clay, fine coarse-sand, medium coarse-sand and coarse sand. The VES and 2-D tomography mapped and identified 2 distinct zones viz:zone of low resistivity of 91Ωm and 394Ωm at depth of 5m to &gt;28m indicating area of leachate contaminant plume and zone of high resistivity value of 422Ωm and 5102Ωm suspected to be dumpsite gases such as NH3, CH4, SO2 and CO2. The 2-D resistivity imaging also revealed that the generated dumpsite leachate contaminant plume was migrating from the Northern part of the burrow-pit dumpsite towards its Eastern part and to the Northern part of the dumpsite at Scot road/Sakponba road. Hydrogeochemical parameter results showed that colour, pH, iron, Lead and coliform bacteria exceeded permissible standard indicating that the leachate plume has migrated to the groundwater aquifer. Closed municipal landfill whose base is made of concrete and paved surfaces should be adopted in the area to prevent leaching of poisonous substances into groundwater aquifer.

Geoelectrical and Geotechnical Investigations for Development of Superstructures at Nkpologwu Proposed Judiciary Site, Anambra Basin, Southeastern Nigeria

Geophysical and Geotechnical surveys were integrally carried out at a proposed Judiciary site for civil development of superstructures in Nkpologwu, Anambra Basin, Southeastern Nigeria. Nkpologwu falls within 7 ̊06̍ '40” E to 7 ̊08 ' 42” E longitudes and 5 ̊56' 76” N to 5 ̊57' 78” N latitudes at about 320 m above the mean sea level. The study is aimed at interpreting the lithology of the subsurface at shallow depths in order to accentuate the competence of soil formations at the foundation depths of the site. Vertical Electrical Sounding (VES) data were acquired in the geophysical survey while various geotechnical tests were carried out to ascertain the bearing capacity of the site’s subsoil. The registered data from the VES survey were processed with WINGLET software hence, geoelectric models of at least four layers were obtained. Characterized by apparent resistivity values in the range of about 1524 to 96,561 Ωm. Geotechnical results showed values of 10.4% to 12.4% OMC, 1.95 to 2.01g/cm3 MDD, 30.0 to 39.0% CBR, 21.0 to 30.5% particle size distribution, &lt;12% PI and &lt;35% LL Atterberg limit for soil samples within foundation depths at the site. Combined interpretation of the surveys showed that at foundation depths at the site were predominantly sand, laterite and sandstones delineated and these were found to meet the required standard of the Federal Ministry of works and housing for construction of superstructures. Therefore, the study provides the knowledge of the lithology and soil competence at foundation depths for future civil construction works at the site.

Hydrogeophysical investigation using remote sensing and geoelectrical data in southeast Hiw, Qena, Egypt

The current study focuses mainly on understanding the hydrogeological framework of southeast Hiw, Qena, Egypt, as one of the promising regions for land reclamation and future development. This includes defining the groundwater aquifers and delineating their lateral extents, depths, and thicknesses, as well as getting some information on the groundwater quality in the area. These objectives have been accomplished by the integrated interpretation of remote sensing imagery and vertical electrical sounding (VES) data. The digital elevation model (DEM) of the Shuttle Radar Topography Mission (SRTM) was processed to calculate the surface gradient and delineate the structural lineaments and drainage channels. Moreover, VES data were measured at 32 locations using Schlumberger configuration. The result of the VES survey has been presented in the form of 2D cross-sections, 3D fence diagram, and hydrogeophysical contour maps. They reveal that the Quaternary sand is the main groundwater aquifer in the region. It has a depth of 30 to 58 m, a thickness of 30 to 68 m, and a resistivity range of 48 to 93 Ω.m. Furthermore, an empirical resistivity–salinity relationship was developed. Accordingly, total dissolved solids (TDS) values vary from 600 to 1500 ppm. This study improves the understanding of the subsurface geology of the region and serves as a guide for further studies regarding digging new wells and groundwater management in such an arid environment.

Geoelectrical Investigation of Groundwater at Northern Gaza Strip, Palestine

A vertical electrical sounding survey was carried out in northern Gaza Strip (Gaza City, Jibalya, Bayt Lahya and Bayt Hanun), Palestine to study the groundwater conditions and evaluate its quality and distribution. The survey included twenty-six (26) traverses with variable lengths in the range 200-500 m. The geoelectrical survey revealed that the resistivity of the study area varies in a wide range mostly 9 to 850 Ωm, subdivided into three subsurface zones. The first zone represents the dry sandstone and alluvial that attains the highest resistivities (100-850 Ωm) with variable thicknesses in the range 26-80 m beneath the whole study area. This zone is characterized by the presence of thin layers of clay and silt in some localities that reduced the resistivity to 15-25 Ωm. The second zone represents the fresh water saturated calcareous sandstone (locally named Kurkur) with resistivities in the range 22 -39 Ωm). The thicknesses of this zone is about 55-70 m in the western part of the study area and increased to 110 m in the east. The surface of this zone shows a gentle westward gradient, which indicates a general flow of water towards the Mediterranean Sea. The third zone represents saline water saturation with low resistivities, mostly 9 Ωm -10 Ωm close to the Mediterranean shore, located at 60 m below sea level and 100 m beneath the eastern side of the study area. Beneath the eastern part of the study area, an anomalous low resistivity of 2-3 Ωm is observed within the fresh water zone, which indicates groundwater pollution near the buffer zone caused by agriculture activities and untreated pumped wastewater.

Mapping the spatial variability of subsurface resistivity by using vertical electrical sounding data and geostatistical analysis at Borena Area, Ethiopia

Vertical electrical sounding survey has been done to map and visualize resistivity distribution at Borena basin. The area is situated in Southern Main Ethiopian Rift, where Rirriba rift, Mega rift and associated fractures define the structural setting of the area. It is covered by Quaternary deposits, Quaternary and Tertiary basaltic rocks and Precambrian metamorphic rocks. Bullal basaltic formation outstretch in the Rirriba rift and it is thought to be potential groundwater aquifer. About 288 Vertical Electrical Sounding data were collected. Inflection and extreme points were used to identify characteristic points. Variograms are modeled and kriging interpolation is used to map distribution of resistivity, determined from characteristic points, in the area. Very low to low resistivity variations are mapped in northern end of the study area, whereas medium to moderately resistive ground are mapped in the middle and southern part of the area. The low resistivity horizon at the shallow subsurface could be due to salinity since the area occupy numerous saline craters and maars. Approximate mapping of large sets of Vertical Electrical Sounding data with geostatistical treatment has facilitated the interpretation and provided a sound picture of the subsurface.• Inflection and extreme points were extracted from smothed VES curves to identify characteristic points.• Variograms are modeled and kriging interpolation is used to map 3D distribution of resistivity data.

Mapping Of Groundwater Zones Using Vertical Electrical Sounding (VES): A Case Study of Malwah Distributary

In the last two decades, the water requirements for agriculture sector have increased due to high food demand, changes in the cropping pattern, and the increase of evapotranspiration rate due to the climate change. The irrigation water demands are not completely fulfilled by the available surface water, which resulted an increased use of the groundwater in Pakistan. It is essential that before applying the groundwater to agriculture land, its quality should be assessed. In this study, groundwater quality and quantum have been investigated through Vertical Electrical Sounding (VES) for the command area of Malwah distributary, district Shaheed Benazirabad. Total 23 sites were selected in a grid of 3km-by-3km area for the VES survey using Terrameter up to 100-meter depth. The VES results are interpreted in terms of the resistivity and corresponding thickness of various underground zones using IX1D software. The results indicated fresh groundwater up to maximum of 50 m depth, covers 75.65 km2 i.e., 21% of the total command area of 359.94 km2. However, the freshwater is accessible up to 100 m depth near the Indus River. The study suggests that the tubewells should be installed up to 50-meter depth, where the maximum quantity of fresh groundwater is available.

Evaluation and Delineation of Sulfur Groundwater Leakages Using Electrical Resistivity Techniques in Hit Area, Western Iraq

Electrical resistivity methods are one of the powerful methods for the detection and evaluation of shallower geophysical properties. This method was carried out at Hit area, western Iraq, in two stages; the first stage involved the use of 1Dimensional Vertical Electrical Sounding (VES) technique in three stations using Schlumberger array with maximum current electrodes of 50m. The second stage included the employment of two dimension (2D) resistivity imaging technique using dipole-dipole array with a-spacing of 4m and n-factor of 6 in two stations. The 1D survey showed good results in delineating contaminated and clear zones that have high resistivity contrast. Near the main contaminated spring, the 2D resistivity imaging technique was applied in four sections length (100 m) using a dipole-dipole array position coincided with the three points VES. We compared the results of the interpretation of imaging the techniques 2D and VES. We found that the 2D imaging resistivity technique was better than VES survey in determining the distribution of pollution under the surface in the area surveyed. It was also found that the polluted water is located about 5 m below the surface. The largest amount of leakage was found towards the northeast and coincided with the direction of the groundwater movement. Spring water has leaked from outside the region through the Kubaisah area. Most of this water is contained in quaternary deposits and karst gypsum fractures.

Integrated geophysical and geochemical methods for environmental assessment of subsurface hydrocarbon contamination.

Oil spills have become a major source of environmental pollution in Nigeria, especially in the oil-producing communities. Assessment of hydrocarbon contamination within the subsurface is a complex program and requires both field-based measurement and geochemical analysis, to give a precise definition of the extent of pollution. To ascertain the extent of contamination of the subsurface around an oil spill site which was reportedly contaminated by oil pollution, an integrated geophysical method involving 1D vertical electrical sounding (VES) and 2D, 3D electrical resistivity tomography (ERT) techniques supported with geochemical method was employed. Orthogonal set of 2D resistivity data consisting of six (6) parallel and six (6) perpendicular profiles were acquired in a 100 × 50-m2 rectangular grid using the Wenner array. Ten (10) vertical electrical soundings were also acquired in the site to supplement the 2D profiles. 2D resistivity data were processed individually using 2D Earth Imager software. The entire set of 2D resistivity data is collated into a 3D dataset using a 3D collation code and was inverted to produce a 3D resistivity structure of the subsurface, following from which contaminant plumes with high resistivity anomalies due to oil pollution were observed from 2D and 3D resistivity images. 2D resistivity tomography imaged contaminant plume to depth of 17.1 m, while 3D resistivity tomography imaged plumes of hydrocarbon contaminant to depth of 19.8 m within the subsurface. 3D depth slices imaged hydrocarbon contaminants within the third, fourth, and fifth layers at depths of 5.38-8.68 m, 8.68-12.5 m, and 12.5-16.9 m respectively. Thus, hydrocarbon contamination was evidently increasing with depth as observed in VES survey which indicated pollution to depth beyond 24 m, which goes beyond the depth to first and second aquifers in the area, indicating that the first and second aquifers have been invaded by oil pollution. Similarly, geochemical analysis of groundwater samples from three boreholes showed average concentration of total petroleum hydrocarbon (TPH) as 722.75µg/L which is higher than DPR limits indicating high contamination. Poly aromatic hydrocarbons (PAHs) concentration in the samples was summed up to 0.66µg/L in BH1, 0.68µg/L in BH2, and 0.30µg/L in BH3, which are above the DPR target limit. BTEX compounds also showed elevated concentrations in the water samples. These findings validate the result of geophysical investigation; therefore, future research should aim to proffer remediation solutions to oil spill impact on the environment within the study area. The findings of this study can help for better understanding of the subject of electrical resistivity inversion, and particularly on 3D inversion technique for delineating subsurface plumes of hydrocarbon contamination.

Integrated vertical electrical sounding and hydrogeological approach for detailed groundwater pathways investigation: Gökpınar Dam Lake, Denizli, Turkey

Understanding the hydrodynamic systems in the dam lake surroundings is of great importance to protect the lakes feeding zones and maintain their water level. In this study, a combination of hydrogeological and geophysical surveying processes was carried out in order to distinguish the Gökpınar dam lake's recharge ways. The Gökpınar dam lake area is characterized by a very complicated hydrogeological system causing difficulty at distinguishing the groundwater flow pathways feeding the lake. Therefore, a detailed vertical electrical sounding survey was performed in accordance with the Shlumberger array in the surroundings of the Gökpınar dam lake. Results obtained from the resistivity measurements were processed using a partial curve matching technique then inverted in order to build 2D and 3D resistivity models which in their turn were corelated with the geology of the study area. In addition to the geoelectrical measurements 44 boreholes were drilled in order to confirm the vertical electrical sounding results. Data collected from these boreholes were also used for the plotting process of the water table contour map in the study area which highly correlated with the resistivity contour maps. Resistivity data evaluation led to the differentiation between water bearing and dry zones. Results showed that the Gökpınar dam lake is fed by several groundwater flows, deriving from South-West, North-West, and South-Eastern parts of the study area. These flows are generally more important near the surface than they are deeper toward the impermeable bedrock.

Series of 1-D ER and IP traverses reveal vestige of regional geological structure

At the Basement Complex geological province of central Nigeria, in the state of Niger, just northeast of the Bida Sedimentary Basin, there is the character of non-complexity and high uniformity in the local geology over an appreciable linear spread. This appreciation makes it a standard practice to do one-dimensional vertical electrical sounding surveys in the search for groundwater resources at this area with the expectation of reliable results. This seeming “simplicity” means that intense manual labour can be invested in acquiring a large data-field at a local area of survey where resources are not readily available to do a standard two-dimensional survey of the conventional kind. This is especially significant for the proposed area of development at the Gidan Kwano Campus of the Federal University of Technology, Minna, Thus, with this awareness and the use of the ABEM Terrameter 4000 equipment, the aim of this study was to do an intense acquisition of one-dimensional electrical resistance and concomitant induced polarization programme for this proposed area of development so as to achieve the objective of garnering information about exploitable groundwater locations before structural developments cover these points up. Typical point-to-point one-dimensional tandem electrical resistance and concomitant induced polarisation surveys were completed along east-west profile lines for about 309 survey stations of the available 441 principal locations of the 4 km2 extent of the proposed new development. After due processing and interpretation of the data-field of this survey, whilst remarking that the induced polarisation data-set was used herein as quality control “refiner” only, clusters of reliable groundwater locations were observed at the southwest end of the 4 km2 areal extent of the proposed new development. It conforms to the dip of the landform and comparatively significant overburden-material thicknesses observed over there. Interestingly, in a twist of serendipity, the series of diagonal subsurface “fault-lines” that connect one promising groundwater prospect with the other, describable by a prominent northeast-southwest dip, aligns exactly with the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt. In the modern geography setting of the present time, the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt actually traverses a lengthy diagonal across the landscape of Nigeria, cutting through such Nigerian states as Jigawa, Kano, Kaduna, Niger, Kwara, Ekiti, and Osun. There is virtually no surface indicator of this once-prominent schist belt and what this study reveals is its vestigial signature