Vertical Electrical Sounding Technique Research Articles

Vertical Electrical Sounding Technique as an Efficient and Rapid Tool for Groundwater Investigation in a Basaltic Environment at Kodana Station for the Shami goats. Case Study from Southern Syria

Geoelectrical survey was conducted by using vertical electrical sounding technique (VES) with adapting Schlumberger configuration, to locate and drill a borehole for groundwater extraction in the Kodana station for the Shami goats, Southern Syria. An integrated approach is proposed to increase the efficacy of the VES technique and to reduce the uncertainties and the high failures in locating and drilling a successful groundwater borehole. The approach is essentially based on analyzing the Dar-Zarrouk (D-Z) parameters with constraining several conditions to obtain the optimum hydro-geophysical model.The 1D inversion quantitative interpretation of twelve VES sounding points and the (D-Z) parameters allowed the characterization of the study area in terms of depth and the Neogene pyroclastic basalt aquifer. The result showed that VES point (V6) has the optimum and favorable properties for drilling a successful borehole in the area. The V6 has GPS coordinates of E: 3589614, N: 3301961 and Z: 770835m. The Neogene (fractured pyroclastic layer with rocks of basaltic composition) aquifer at this V6 point is characterized by a thickness (h) of 217m, a resistivity (ρ) of 227Ωm, a transverse resistance (R) of 49259 Ωm2, and an anisotropy parameter (λ) of 1.15. The advantages of the proposed approach are well proven and documented, in comparing with other techniques that require the combination of VES technique with other available geophysical techniques. The VES technique within the proposed approach is therefore recommended to be easily applied for groundwater investigations, and locating the suitable positions for drilling boreholes in similar worldwide basaltic environments.

Near surface resistivity investigation of regolith of Middle Benue Trough: implications on road pavement along Lafia-Shendam Axis, North Central Nigeria

ABSTRACT Electrical characteristics and subsurface structures associated with the regolith of Middle Benue Trough have been investigated. Vertical electrical sounding (VES) and constant separation traversing (CST) techniques were employed for data acquisition along Lafia-Shendam Road, Lafia, North Central Nigeria. Forty (40) Schlumberger sounding stations and four (4) Wenner resistivity profiles were occupied along opposite sides of the road to delineate and decipher the subsurface geological structures. Second-order Dar Zarrouk parameters (longitudinal and transverse resistivities, mean resistivity and coefficient of anisotropy) computed from VES parameters were also used to evaluate the pseudo-anisotropy characteristics of the regolith cover. Geoelectric sequences delineated within the study area include thin topsoil, alluvium deposit, weathered layer (laterite and saprolite) and fresh basement. The regolith is hosted by a weathered sedimentary rock at an average depth which varies from 10.2 to 37.3 m. The regolith structure is not complex and has a greater proportion of conductive laterite. The saprolite associated with the host sedimentary rock, masked in the VES technique, is revealed as a very thin zone with moderate resistivity in the CST 2-D structures. The predominance of laterite in the regolith is also corroborated by the range of values of the coefficient of anisotropy and mean resistivity.

Using VES and GIS-Based DRASTIC Analysis to Evaluate Groundwater Aquifer Contamination Vulnerability in Owerri, Southeastern Nigeria

This study assesses groundwater vulnerability in Owerri, Nigeria, using Vertical Electrical Sounding (VES) and Geographic Information System (GIS)-based DRASTIC modeling. The research methodology includes literature review, field survey, geological feature mapping, hydrogeological assessment, geo-electrical sounding, and data interpretation. Owerri, a rapidly developing city with flat topography and a growing population, uses the DRASTIC model to construct a groundwater vulnerability map. The model evaluates the risk of groundwater contamination using seven critical criteria, including depth to water table, net recharge, aquifer media, soil media, topography, vadose zone impact, and hydraulic conductivity. Each parameter was given a weight and rating, and the DRASTIC Index (DI) was calculated by summing the products of the weights and ratings for each factor. The results of the vulnerability assessment indicated that approximately 49% of the study area falls into the high vulnerability category, around 45% is classified as moderate vulnerability, and the remaining 6% is labeled as low vulnerability. The study reveals moderate to high vulnerability zones in Owerri, Nigeria, due to factors like lower slope terrain, permeable aquifer media, and vadose zone impact. The use of VES and GIS-based DRASTIC mapping techniques provides insights into groundwater vulnerability, aiding in sustainable resource management and environmental protection. The findings emphasize the importance of understanding potential risks and the need for effective management strategies to safeguard clean water supplies. Further research and mitigation efforts should focus on highly vulnerable areas.

Multi-well clustering and inverse modeling-based approaches for exploring geometry, petrophysical, and hydrogeological parameters of the Quaternary aquifer system around Debrecen area, Hungary.

This research aims to explore the application of an unsupervised machine learning and inverse modeling-based methods to map the aquifers geometry and investigate the petrophysical and hydrogeological parameters of the Quaternary aquifer system around the Debrecen area, Eastern Hungary. The study utilized a limited well-logs, including spontaneous potential, natural gamma ray, and normal resistivity logs. The k-means clustering technique is applied to identify the distribution of lithological facies within the formerly identified basin-scale hydrostratigraphical units of coarsening upward, alluvial, valley incision, and Late Miocene deposits. Based on the mathematical and geological considerations, the analysis revealed three main clusters (C1, C2, and C3), representing different lithofacies of shale, shaly sand, and sand and gravel. The result of the cluster analysis is further validated with a surface geophysical survey using the vertical electrical sounding (VES) technique. Furthermore, an inverse-modeling-based approach using Csókás method is employed to detect the vertical and horizontal distribution of the hydraulic conductivity along these units. Csókás model is empirically modified from the Kozeny-Carman equation that suites the unconsolidated freshwater-bearing units. The results indicated that the petrophysical and hydrogeological parameters widely ranged with the hydraulic conductivity between almost zero in the shaly layers to more than 21.5 m/d in the sandy and gravely layers. However, the valley incision unit aquifers showed a more uniform distribution of hydraulic conductivity. Based on these results, the Quaternary aquifers in the Debrecen area are classified as moderate to highly productive and ideal for groundwater development. The applied methodology contributed to understanding the complexity of the hydrogeological conditions, providing a robust approach to characterize the heterogeneous groundwater systems.

Combination of Vertical Electrical Sounding (VES) and Electrical Resistivity Tomography (ERT) techniques for hydrogeological reconnaissance in the Guigou plain, Tabular Middle Atlas, Morocco

The study site is located in the Guigou plain, which is situated on the south-eastern edge of the Tabular Middle Atlas and is characterised by a particular geology within the mountainous region. Unlike the Tabular Middle Atlas, which is generally covered by Lias carbonate formations, the Guigou plain is characterised by the presence of a different type of cover formed by basaltic flows of plioquaternary age, forming a surface layer that is used extensively for agricultural activities. The main objective of our study is to detect the different geoelectric levels both at the surface and at depth, thus providing indications of the specific aquifer formations in the region studied. The analysis of the results obtained highlighted the presence of a superficial resistant level, attributed to basalts of Plio-Quaternary age, with an estimated thickness of between 30 and 100 m, forming the superficial aquifer of the plain. Next, a conductive level was identified, associated with alternating marl and marl-limestone of Pliocene age, in keeping with the local geology. Finally, at a depth of 225 m, a very resistant level was identified, corresponding to Lias limestone, which becomes a deep aquifer on the Guigou plain. This study provides essential vertical hydrogeological reconnaissance and highlights the need to carry out numerous tomographic profiles as well as electrical boreholes. These combined approaches are crucial to enriching our understanding of the particular geological and hydrogeological characteristics of this region, which forms a transition zone between the MAT and the MAP.

Evaluation of geohydraulic response properties of hydrogeological units in Littoral hydro-lithofacies in Uyo, Southern Nigeria

Aquifer geohydraulic response properties are important parameters in groundwater resource management and exploitation. However, geohydraulic properties in the study area is sketchy and due to wildcat drilling. This practice, which leads to inadequate inventory of groundwater parameters, deprived the area of efficient exploitation, monitoring and management of groundwater resources. This study is aimed at evaluating the geo-hydraulic response properties of hydrogeological units in littoral hydro-lithofacies in Uyo, Southern Nigeria. Vertical electrical sounding (VES) technique was carried out, and a total of fifteen geoelectric soundings were obtained using IGIS Resistivity metre model SSR-MP-ATS and its accessories employing Schlumberger electrode configuration. The interpreted data give sets of geoelectric curves from which the aquifer resistivity and thickness were determined. The results reveal the aquifer bulk resistivity ranging from 23.4 to 1306.2 Ωm with an average of 347.99 Ωm, while aquifer thickness spanned from 7.4 to 56.3 m. The formation factor, fractional porosity and transmissivity ranged from 2.41 to 12.52, 0.20 to 0.46, and 0.001 to 0.037m2/s, respectively. The formation tortuosity also ranged from 1.05 to 1.58; longitudinal conductance ranged from 0.020 to 1.004 Ω−1; and transverse resistance ranged from 549.90 to 69,097.98 Ωm2. These parameters were contoured, and their variations are displayed on the contour maps generated. The graphs plotted showed strong correlation coefficient and earth response function that can be used in modelling the aquifer repositories in areas with similar geomaterials. The results of this study indicate that the survey area has a good prospect for groundwater accumulation, and the results can be useful in installing matching hydraulic pumps in boreholes in the survey area.

Delineating of Groundwater Aquifer Potential Using Vertical Electrical Sounding (VES) Methods in Giriloyo, Wukirsari Village, Imogiri District, Bantul Regency, Special Region of Yogyakarta

The geophysical investigation in Giriloyo, Wukirsari Village, has defined the groundwater potential zones. The research region underwent a geophysical examination utilizing the electrical resistance method, which comprised the vertical electrical sounding (VES) technique and the Schlumberger array system. The study area is surrounded by common rock types such as lava, tuff, agglomerate, and alluvial. In the study region, five lines were explored. Data for subsurface resistivity were gathered with an Oyo McOhm type 2115. IPI2win, a piece of computer software that analyzes data and automatically interprets apparent resistivity, was used to examine the data. The VES data showed the varied nature of the subsurface geological sequence. The geoelectrical cross-sections along the profile of (VES 2-3-4-1) show an aquifer, which stretches from the southeast towards the northwest part of the basin. Tuff is seen to have formed shallow aquifers due to the top weathered part at VES-2 and 3, while Quartz chlorite calcite (VES-4) and Plagioclases (VES-1) are devoid of shallow aquifers. The higher-elevation lithological areas recharge the low-elevation aquifer zones. At VES 2 and 3, relatively low resistivity values (< about 100 Ωm) have been observed. A field observation at these locations reveals that these lithologies are highly fractured with a weathering profile of up to 10 m. Thus, these are the sites where groundwater potential zones can be marked (figure 4). The high resistivity (about 3162 Ωm regions is observed extending at the VES-4; this may be due to the least weathered Quartz chlorite calcite at high elevation. VES-1 is also located on the plagioclase and shows a slight resistivity zone, which could be considered a groundwater recharge zone. This profile shows the high possibility of groundwater potential due to the zone of lineaments.

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.

Assessment of Potential Potable Water Reserves in Islamabad, Pakistan Using Vertical Electrical Sounding Technique

This study aimed to investigate the potential reserves of potable water in Islamabad, Pakistan, considering the alarming depletion of water resources. A detailed vertical electrical sounding (VES) survey was conducted in two main localities: Bara Kahu (Area 1) and Aabpara to G-13 (Area 2), based on accessibility, time, and budget constraints. A total of 23 VES measurements were performed, with 13 in Area 1 and 10 in Area 2, reaching a maximum depth of 500 m. Geologs and pseudosections were generated to assess lithological variations, aquifer conditions, and resistivity trends with depth. Statistical distribution of resistivity (SDR), hydraulic parameters, true resistivity, macroanisotropy, aquifer depth and thickness, and linear regression (R2) curves were calculated for both areas, providing insights into the aquifer conditions. The results revealed that the study areas predominantly consisted of sandy lithology as the aquifer horizon, encompassing sandstone, sandy clay, and clayey sand formations. Area 2 exhibited a higher presence of clayey horizons, and aquifers were generally deeper compared to Area 1. The aquifer thickness ranged from 10 m to 200 m, with shallow depths ranging from 10 m to 60 m and deeper aquifers exceeding 200 m. Aquifers in Area 1 were mostly semi-confined, while those in Area 2 were predominantly unconfined and susceptible to recharge and potential contamination. The northwest–southeast side of Area 1 exhibited the highest probability for ground resource estimation, while in Area 2, the northeast–southwest side displayed a dominant probability. The study identified a probable shear zone in Area 2, indicating lithological differences between the northeast and southwest sides with a reverse sequence. Based on the findings, it is recommended that the shallow aquifers in Area 1 be considered the best potential reservoir for water supply. In contrast, deeper drilling is advised in Area 2 to ensure a long-lasting, high-quality water supply. These results provide valuable information for water resource management and facilitate sustainable water supply planning and decision making in Islamabad, Pakistan.

Evaluation of sedimentary aquifer in tehsil Zehri area using VES technique, Balochistan Pakistan

A geophysical resistivity survey was conducted in Zehri tehsil in the district of Khuzdar for the metering of subsurface hydrogeological properties of aquifers. The Schlumberger electrode arrangement was employed with the vertical electrical sounding (VES) method for subsurface exploration. Two profile lines were designated for the survey. The distance between the two profile lines was about 1500 ​m and each profile contained four VES stations. The results of profile one show the aquifers were encountered in fractured limestone of the Jamburo Formation of Paleocene age at an average depth of 127 ​m, with an average resistivity of 39.7 ​Ωm, and the average aquifer thickness was 54.025 ​m. The result of profile two shows the aquifers were encountered only in VES four in the sandstone lithology of the Ziddi Formation with a resistivity of 79.9 ​Ωm, at a depth of 120 ​m with, and a thickness of 40 ​m. There was no aquifer encountered in the remaining all VES. The main lithology of these VES is thick impervious compacted limestone, shale, and clay of Jurassic age from the Ziddi Formation. The current tube wells were also rapidly depleting in the study area. The main factor behind the decline of aquifers in the study area is an uncontrolled installation of tube wells and continuous pumping of tube wells for agricultural purposes badly puts stress on aquifers and directly deteriorates the quality and quantity of groundwater.

Deployment of Geophysical Technique in Groundwater Search at Guinueaworm Endermic areas in Obubra local government area of cross river state, Nigeria

This study was conducted in the Guineaworm prone areas in Obubra Local Government Area, the study entails the deployment of vertical electrical sounding technique in the search for groundwater. In doing this, measurement was made in 14 profiles of 500m long each, using the IGIS resistivity meter model SSR-MP-ATS. Resist software was used for analysis. The Geoelectric sounding data interpretation revealed characteristic curves with two to six geoelectric layer thicknesses. The predominant curve types in the area were the KH, HKH, and HK. The electrical resistivity of the first layer ranged between 15.8to1626Ωm, which was indicative of clay, shale, or sandy silt, three to six geoelectric layers were obtained from the interpretation of the sounding data. The resistivity of the second layer ranged from 52.3 to 370.7Ωm. This was assumed to be shalestone/shale, and it was overlain by the third layer, which had resistivity values between 121 m to 1491.9Ωm, which was assumed to be sandstone (sandstone materials make good aquifers).The fourth layer, had values between 12.3Ωm. m to 1052.7Ωm, the fifth layer, had values between 11.21Ωm. to 2277.2Ωm, and the last layer, which had a value of32Ωm.The Transmissivity measurements ranged from 16 m2/day to 171 m2/day, Porosities were high with strong storactivity which show that the studied area contains thick and abundant aquiferous zone. Protective capacities (PC) values of (0.01-1.260 seimens) were obtained from the VES data. Borehole depths were recommended for each profile for borehole development. The study was identified to have confine aquifer terrain because of the confining clay layer which had a large vertical extend in the adjacent layers that enclosed the aquifer layer.

Examining tunnel erosion using vertical electrical sounding and ground magnetic geophysical techniques in Awka, Nigeria

Examining tunnel erosion using vertical electrical sounding and ground magnetic geophysical techniques in Awka, Nigeria

Lithologic characterization of Iguosa erosion site using geoelectrical techniques

Considering the devastating menace of gully erosion for which lithology is one amongst several other agents that drives soil loss and gully erosion, Vertical Electrical Sounding (VES) and Electrical Resistivity (ERT) techniques were adopted to investigate subsurface lithology in Iguosa gully erosion site. PASI 16GL model resistivity meter was used in acquiring data for VES and ERT in the area under investigation. VES data acquired were processed both qualitatively and quantitatively, and geoelectric sections were generated using AUTOCAD software by combination of two or more interpreted VES results along a profile. ERT data were processed using Res2dinv software to an inverse model resistivity section. The geoelectric image generated were interpreted to obtain lithology of the subsurface. The analysis and interpretation of the subsurface image reveals presence of topsoil, sand, dry sand, clayey sand and coarse sand. The subsurface lithology within the study location is predominantly sandy. The result obtained from the resistivity of all profiles shows that erodibility increases with depth within this study area with corresponding high resistivity values. Due to the fact that sand within the study area is loose coarse and silty, which can give rise to high resistivity and causes erosion.

Geophysical and geostatistical assessment of groundwater and soil quality using GIS, VES, and PCA techniques in the Jaipur region of Western India.

In present study, geophysical and geostatistical variability of ground water and agricultural soil investigated in the Jaipur region of Rajasthan (Western India) by applying the geographic information system (GIS), vertical electrical sounding (VES) ,and statistical analysis. Ground water and soil samples collected from different sites from the selected study area and variation pattern of quality parameters were assessed. A contour map analysis of distribution of metals and other contaminants in the samples was conducted using GIS. Maximum concentration of metals recorded in the soil samples in order of Fe, 11.25 mg kg-1 > Mn, 8.6 mg kg-1 > Zn, 7.2 mg kg-1 > Cu, 0.455 mg kg-1; however, maximum concentration of metals in the ground water samples was found as Zn, 2.64 mg L-1 > Cu, 0.86 mg L-1 > Fe, 0.39 mg L-1 > Mn, 0.18 mg L-1 > Pb, 0.065 mg L-1 > Ni, 0.016 mg L-1. Observed data emphasis variability in groundwater and soil quality parameter by PCA technique indicated 84.60% and 66.98% of variance, respectively. Soil quality index (SQI) value was observed as 0.482 indicating that 46% of soil sampling sites deteriorated and shown poor quality. Similarly, water quality index (WQI) value indicates good water quality at the sampling sites TW1, TW8, TW10, and TW12; however, TW3, TW4, TW6, TW19, TW20, and TW22 sites showed very poor water quality. The present study concludes that overexploitation of groundwater and unregulated discharge of wastewater leads to depletion of water and soil quality. Further, applying geographical and geostatistical techniques in assessing water and soil quality could be more effective tools in environmental monitoring and management for environmental and health safety.

Delineation of groundwater potential zones in northern Omdurman area using electrical resistivity method

This study is conducted in the northern Omdurman area to delineate groundwater potential zones using electrical resistivity method. Omdurman is the most ancient city known as the historical capital of Sudan. Geoelectric survey employing vertical electrical sounding (VES) technique is carried out to explore the availability of groundwater in the study area. The measurements were conducted using Schlumberger configuration. In this study, twelve VES points are measured along four profiles. The measured data is processed and interpreted using 1D geophysical inversion technique constrained by lithological data obtained from two boreholes. The integration of electrical and geological data led to a reliable interpretation of the geophysical model. The obtained results revealed that the geological succession of the study area is mainly composed of five layers of recent deposits, clay, sandy clay, silicified and ferruginous sandstone, and sandstone. According to the resulting hydrogeological sections, the water-bearing formation is composed mainly of coarse sandstone and varies in thickness under confined conditions. The geoelectrical sounding method successfully fulfilled the aims of the study. Nevertheless, detailed hydrogeological and geophysical investigations need to be carried out for a comprehensive characterization of the groundwater aquifer.

REVIEW OF IDENTIFIED SHORTCOMINGS IN AQUIFER VULNERABILITY ASSESSMENTS

Several studies have successfully carried out aquifer vulnerability evaluations using a combination of geophysical and biogeochemical methods. Unfortunately, some identified shortcomings have often led to inaccurate assessments. This review attempts to identify some of these drawbacks and suggest better ways to improve upon analysis and interpretation of results. Articles reviewed were sourced publicly and subjected to systematic analysis based on fundamental principles. The outcomes of each analysis were discussed, among which was a study that applied Ohmega Resistivity meter to acquire Self-Potential (SP) data without specifying the nature of electrode used. The result indicated large SP readings ≥200mV attributed to high fluid flow. According to analysis, when copper stakes are used, spurious SP readings occur in contrast to lower SP values of roughly 10 mV when suitable non-polarizable electrodes of Cu/CuSO4 porous pots are utilized to collect SP data. The review made clear the importance of providing detailed explanation of the nature of materials used. Another study solely collected samples for groundwater quality assessments during dry season, ignoring the effects of seasonal variation on water parameters. This must have had an impact on the results of the investigations. Research examined the aquifer problems in Gosa area of Abuja, utilizing only the Vertical Electrical Sounding (VES) technique. The study suggested basaltic intrusion as probable cause of borehole failures in the area. A different research which incorporated VES and data from the hill-shaded Shuttle Radar Topography Mission (SRTM), suggested insufficient interconnectivity within the fractures as conditions controlling groundwater occurrence in the area. The study illustrated the need for integrating geophysical methods for effective target detection. To map the infiltration of leachate into the subsurface, a study applied only the VES technique. Studies, however, showed that the VES method only provided average resistivity readings, suppressing some features. The study suggested the combination of VES and 2-D imaging for more accurate results. Another study obtained data via the ADMT Groundwater Detector. At the interpretation stage, the author interpreted ADMT data as VES, which was perceived as inaccurate as their principles and methodologies are different. Another study was noted to have presented results without categorizing the Aquifer Protective Capacity (APC) rating in percentages (%). It was assessed that a framework that accurately categorized the APC of each transversal using common statistics guidelines would have made it simpler to understand and aided decision-making. Future research is advised to take some of the noted flaws into account in order to enhance data processing and interpretation.

Geoelectrical Investigation of Groundwater Potential at Proposed Staff Quarters of FCE Technical, Gusau, Zamfara State, Nigeria

Geoelectric investigation was carried out at proposed staff quarters of FCE, Technical Gusau, located along Gusau – Zaria highway, Zamfara State, Nigeria with the aim of delineating the groundwater potentials. The study area lies in the Basement Complex region of Northern Nigeria and it is situated on Latitude 12o819.64”N to 12o08’24.65’’N and longitude 06o43’28.65’’E to 06o43’37.25’’E with an area coverage of 500 m by 500 m. Vertical Electrical Sounding (VES) technique was employed using Schlumberger array pattern. A total of thirty-six (36) VES points were sounded on Six (6) grided profiles(A-F) separated by 100 m apart with inter VES spacing of 100 m, The VES results depict two distinct curve types namely; H-type and A-type. The results also reveal three distinct geoelectric layers: the top layer, weathered/fractured layer and fresh basement. The top layer has resistivity, depth and thickness range of 10.4 – 158.8 Ωm, 0.4 – 3.6 m and 0.4 – 3.6 m respectively. The second layer has ranges of: resistivity, 6.3 – 525.3 Ωm; depth, 1.4 – 20.8 m, and thickness, 1.0 – 20.4 m. The third layer has resistivity values range of 278.6 – 2726.5 Ωm, its depth and thickness are not defined (to infinity). Seven VES stations (A3, A4, B4, C3, E2, F2 and F5) were delineated for groundwater potential having weathered/fractured resistivity varying between 37.4 and 121.1 Ωm. Depths range were found from 7.9 – 20.8 m and thickness varying between 6.6 and 20.4 m. The results of the study implies that the area has a good groundwater potentials.

Groundwater Potential Detection Possibility in Southern Ondo State, Nigeria

A new simple and quick geophysical method for groundwater exploration of the coastal plains sands and alluvial deposits of parts of Ondo State, Nigeria has been developed. A geophysical evaluation using Electrical Resistivity method for groundwater exploration at the study area was carried out which involved the utilization of Vertical Electrical Sounding (VES) technique with schlumberger array system. About eight (8) points of vertical electrical sounding (VES) survey using ABEM tetrameter (SAS 300) was tabulated in a table which shows the resistivity, the thicknesses and the number of layers for each VES station. The field results were plotted, the curve types and lithologic layers were revealed. The plots showed type-Q, type-K, type-A and type-H curve merging while VES-3 did not reveal any type of curve. This was because of that point understudy being homogenously deposited and non-horizontally layered. Some of the VES points have horizontal layers not more than two for example, VES-1 and VES-3 whiles others have a maximum of four layers within them. The resistivity of the basement within the area ranges from 163.1 ohm-m to 9113.4 ohm-m with an average resistivity of 2627.76 ohm-m. In terms of geological structures and aquifer potential, VES-7 and VES-8 showed to possess characteristically a good geological structures and aquifers for groundwater potentials.

Application of Vertical Electrical Sounding for Subsurface Characterization to Determineslope Instability at Perizie, Nagaland

Vertical Electrical Sounding (VES) technique which employs the Schlumberger depth sounding method was used to investigate the subsurface conditions at the landslide in Perizie colony, Kohima. The interpretation of the VES curves shows differing lithology consisting of weathered shales with associated clay, which is considered an important factor for slope instability. The shear strength of the slope materials, including the country rocks and the soil cover, is also significantly reduced and easily detached due to the effects of weathering and erosion, causing the landslides. Three to six possible geo-electric layers are delineated from the variations in the resistivity values, with the lithologies consisting of topsoil followed by alternate layers of weathered and fractured rocks of varying thickness. The analysis also points to the presence of a weak zone at a depth of about 10 m, which is not apparent from the surface. The formation of groundwater aquifers in the fractured zones indicates high risk for slope failure as this accelerates the weak country rocks to weather. The results obtained by this study correspond well with the available borehole data of the area.

Vertical Electrical Sounding (VES) Technique to Map Potential Aquifers of the Guigou Plain (Middle Atlas, Morocco): Hydrogeological Implications

Vertical electrical sounding (VES) as a geoelectrical method has proven its effectiveness throughout the history of groundwater geophysical investigation. In this sense, VES was carried out 47 in the study area with the aim of determining the geometry and limits of Quaternary basaltic aquifer formations and, above all, the location of electrical discontinuities in the area located in the north of Morocco, between the center of Almis Guigou and the city of Timahdite. This area is experiencing an overexploitation of the groundwater due to excessive pumping and the development of intensive agriculture activities, resulting in a continuous decrease in piezometric levels. The processing of the diagrams by WINSEV software showed the presence of an electrically resistant surface level, attributed to basaltic formations, of the Quaternary age, whose thicknesses reach at least 150 m to the SW of the area. This level is superimposed on a moderately conductive horizon which, according to local geology, corresponds to Pliocene marl and limestone alternations. The correlation of VES interpretation models allowed us to elaborate thematic maps and geoelectrical sections which illustrate the vertical and lateral extension of the basaltic reservoir as well as its thickness, which decreases in general from the south-west to the north-east; however, the main electrical discontinuities also correspond to faults and fractures, and they show a NE–SW direction sub-parallel to the major accidents of the Middle Atlas. A prospectivity map of the local aquifer was generated, coinciding with regional fault lines and confirmed by the alignment of very good flowing water boreholes. This geophysical study by electrical sounding shed light on the geometry and extension of the aquifer and opened avenues to draw further conclusions on its physical and hydrodynamic characteristics, as well as to optimize the future siting of groundwater exploitation boreholes through the elaboration of the local aquifer prospectivity map.