Vertical Electrical Sounding Method Research Articles

Delineating leachate-groundwater interaction at Gyadi-Gyadi dumpsite, Kano, using natural electromagnetic (EM) field detector and Vertical Electrical Sounding (VES)

Geophysical investigations are mostly used for hydrogeological studies, mining, geotechnical investigation and environmental surveys. Geophysical investigation of groundwater within the dumpsite is highly critical because the extent of interaction between leachate plume/contaminated zone and aquifer zones could significantly reduce groundwater quality. The textural complexity and clay content of soils could change their electrical properties, thus reflecting inconsistent resistivity values using the resistivity method. This research investigates the extent of leachate infiltration from waste dumpsite into groundwater at Gyadi-Gyadi Kano State, using natural Electromagnetic (EM) field and Vertical Electrical Sounding (VES) methods. Six natural EM profiles were obtained in various locations within the study area using PQWT-TC 150 model. Six VES data points were occupied along the EM profile lines using SAS 1000 ABEM resistivity meter. The two techniques employed revealed some intercalations of low resistivity (conductive) as well as very low electrical potential differences in the study area. The low resistivity media are mixtures of leachates into groundwater units, thereby creating formations from the surface to a depth of about 40 m. The first and second layers have experience leachate-aquifer interaction in the northern, southern and eastern parts of the study area to about 40 m depth, and the leachate-aquifer interaction has extended to the deep aquifer of about 70 m depth at the western part. Shallow aquifer has not been infiltrated by leachate at about >100 m away from the waste dumpsite. Therefore, for potable groundwater exploitation in this area, it is advised that boreholes should be sited >100 m away from the dumpsite, where leachate-aquifer interaction has attenuated. The natural EM field detector is evidently constrained by issues of over-generalization and summation of potential values, probably due to its relatively low resolution. Hence it might not be capable of precisely delineating varying geological units. In contrast, the resistivity method is able to delineate and discretize the subsurface into sub-units of different resistive zones. This implies that VES is better suited for accurately defining the true subsurface geology, while the NEF detector is effective for determining the extent of a leachate plume.

Application of VLF-EM response and geoelectrical sounding in groundwater investigation around an active dumpsite

An integrated geophysical method combining very low frequency electromagnetic (VLF-EM) and vertical electrical sounding (VES) methods were carried out around Adaland, Southwestern Nigeria, located within latitude 7° 54’ 0” and longitude 4° 43’ 0”, with a view to investigate the possible impact of dumpsite on groundwater. This is the major study in the environment to offer extensive evidence regarding the suitability of obtaining quality groundwater. In this research, eight VLF-EM and twelve VES data sets were generated, which were then used to estimate the linear structure, bedrock formation, subsurface geological characteristics, and identification of leachate pathways. The VLF-EM data were analyzed by employing Karous_Hjelt and Microsoft Excel, while the VES data were investigated using the WinRESIST software. TheVLF-EM results confirmed the presence of conductive zones, which might be due to fracture, fault and contact zones or weathered basements. The lithological units acquired from the electrical resistivity results revealed four geoelectrical layers such as topsoil, weathered-based, fractured basement and fresh basement. However, the identified weathered layers and fractured basements from the geoelectrical sections and the corresponding Karous and Hjelt (K-H) pseudo sectionresults around the dumpsite, constitute the main passages for the possible impact of the open dumpsite on groundwater quality, since leachates from the dumpsite could slowly percolate downwards from the topsoil to the water table. Therefore, the impact of the dumpsite on the groundwater is caused by the inadequate clay materials, near-surface features such as fractures/faults, and lateral in-homogeneity. Thus, integrating both methods has been recommended in site characterization for accessing quality groundwater around a dumpsite environment.

Groundwater Study Using Vertical Electrical Sounding (VES) Data Based on Resistivity and Porosity of Rocks in Kampung Melayu, Bengkulu City

This research aims to identify groundwater based on the value of resistivity and porosity of rocks, which are important parameters in the management of groundwater resources and Development Planning in the region. This groundwater research using Vertical Electrical Sounding (VES) data based on the value of resistivity and porosity of rocks was carried out by measuring resistivity using the (VES) method at 20 sounding points located in Kampung Melayu District, Bengkulu City. The VES method is one of the approaches in the geoelectric method to determine the lithological characteristics of subsurface rocks. Resistivity Data obtained were then inverted and analyzed and interpreted to obtain lithology of subsurface rocks and groundwater level distribution in Kampung Melayu, Bengkulu City. The results showed the presence of groundwater based on low resistivity anomaly values with a range of values from 5 to 30 meters in the West and 10 to 50 meters in the East, with resistivity values ranging between 5 Ω.m up to 45 Ω.m. This research is expected to make a significant contribution to the management of groundwater resources in the District of Kampung Melayu, Bengkulu City and can be the basis for development planning in the area. In addition, it is hoped that the results of this research can be a reference for further research in the field of hydrogeology and groundwater modeling. Keywords: Aquifer; geoelectricity; groundwater; porosity; resistivity

Aquifer potential investigation applying vertical electrical sounding in Bango sub-catchment area

The freshwater requirement in the Bango sub-catchment is rising along with land use change. The main source of freshwater that can be used is groundwater in the aquifer layer. The research on aquifer potential was conducted using the vertical electrical sounding (VES) method. Vertical electrical sounding is a geoelectric method to measure the resistivity of the rocks. This instrument is used to obtain subsurface information about aquifer depth. The measurements along fourteen measurement points that the length of each track used is a maximum of 4 km. The layer which is the potential to be an aquifer is a tuff layer with resistivity values for tuff layer at each measurement point varying from 20,2 to 78,16 Ωm. The results showed that the rock lithology is influenced by volcanic activity and there is a layer suspected of being a potential shallow aquifer. The potential shallow groundwater in the Bango sub-catchment is approx. 5,73 billion cubic meters.

Computer Modeling of the Electrical Conductivity of the Geological Environment in Problems of Monitoring the Reliability of the Foundation of Roads, Buildings and Engineering Structures

Main problem: Monitoring the reliability of the foundation of roads, buildings and engineering structures is an important aspect of geophysical research. Modeling of geological heterogeneities is relevant. Moreover, the use of computer modeling in this problem is associated with computational costs. Purpose: Analysis of the vertical electrical sounding (VES) method for modeling the physical properties of soil and their changes when exposed to elastic vibrations. Methods: To achieve the goal, the vertical electrical sounding (VES) method was used, using a one-dimensional model of the geological environment. The direct VES problem was solved by calculating the Hankel integral. Results and their significance: The study made it possible to model a large number of soil layers using the VES method. The results obtained make it possible to determine the parameters of detected objects and changes in the characteristics of the controlled environment when exposed to elastic vibrations. The significance of the results lies in the possibility of improving the method for modeling the physical properties of soil and taking into account their changes under the influence of elastic vibrations, which helps to increase the efficiency and accuracy of monitoring the reliability of the foundation.

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.

Evaluation of Physicochemical and Geoelectrical Parameters of Soil and Water around Electronic Dumpsites in Selected Locations of Aba, Nigeria

Electronic waste can be harmful to human health as it contains some heavy metals which alter the wellbeing of people. Aba being a commercial city in Southeastern Nigeria is lying on permeable soil. The indiscriminate disposal of these items makes it expedient for the investigation to be carried out by studying the characteristics of the soil and groundwater quality in order to ascertain the concentration of some of these heavy metals which pollute the water. Resistivities of the soil were determined by employing the vertical electrical sounding method and using some appropriate computer modeling software such as ip2win, surfer12, grapher 8, etc. to interpret the geoelectric sections. Water samples were collected from twenty different locations (BH1 to BH20 and leachate site), then, analyzed using atomic absorption spectrophotometer which revealed the concentration levels of some elements including heavy metals and some compounds such as Al (4.5–40.26 mg/L), As (0.0–3.78 mg/L), Cd (0.0–3.78 mg/L), Cr (0.0–0.543 mg/L), Cu (0.0–21.54 mg/L), Fe (0.15–9.27 mg/L), Pb (0.0–5.604 mg/L), Hg (0.0–2.688 mg/L), Ni (0.0–0.504 mg/L), Ag (0.04–1.2 mg/L), Zn (0.0004–5.2 mg/L), CN (0.84–2.63 mg/L), NH3 (0.004–2.74 mg/L), PO4 (0.3–8.4 mg/L), SO4 (0.0–35 mg/L), etc. The soil resistivities range from 500 Ωm to 1000 Ωm and the depth to water is between 20 m to 40 m. The results revealed that water level is very close to the ground surface and hence, the groundwater is prone to pollution. Also, the percentage concentration of some of the heavy metals is high, which points to a serious threat to life.

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.

IDENTIFIKASI AKUIFER DI DAERAH RAWAN BANJIR DENGAN METODE VERTICAL ELECTRICAL SOUNDING DI KECAMATAN MUARA BANGKAHULU (Identification of Aquifers in Flood-Prone Areas using the Vertical Electrical Sounding Method in Muara Bangkahulu sub-district)

Muara Bangkahulu Subdistrict is a flood-prone area in Bengkulu City, Bengkulu Province. This study aims to identify the depth of aquifers in flood-prone areas. Flood-prone areas in the Muara Bangkahulu sub-district were analyzed using the Vertical Electrical Sounding (VES) method with Schlumberger configuration of as many as 40 VES points in residential areas. Data acquisition was carried out using the Geoelectric IP Meter MAE X612-EM. The obtained data was then processed using Progress 3.0 software to get a 1D Resistivity Log cross-section. The log data was then modelled using Voxler 4 software to find an overview of the distribution of aquifers and subsurface structures in 3D. The distribution of resistivity values at depths of 2, 5, 10, 15, 30, and 40 meters using ArcGIS 10.8 are mapped to see the distribution of aquifers. The aquifers in the Muara Bangkahulu sub-district are sand and gravel with a value of 0-25 Ω.m. The intrusion of seawater influences this value. Flood-prone areas are located at shallow aquifer, namely depths of 2-5 m in the villages of Rawa Makmur, Rawamakmur Permai, and Bentiring Permai.

Integrated electrical resistivity methods for evaluation of fracture terrain groundwater potentials, case study of indurated shale of Lower Benue trough, Southeastern Nigeria

The incessant borehole failure in the Abakaliki area suggests that the application of vertical electrical sounding (VES) in prospecting for groundwater within the fractured terrain is relatively inefficient. Therefore, this research aimed at using integrated resistivity methods (azimuthal resistivity survey (ARS) and VES) to defined the structures and porosity parameters in the area to overcome the lapses experienced in applying VES method alone. The data acquisition was done along four azimuthal angles (0°,45°, 90°, and 135°), adopting the Wenner electrode array expanded symmetrically about the center point in increments of 5, 7, 10, 14, 20, 28, 40, and 50 m, whereas VES data was acquired using routine Schlumberger array and the resistivity of the subsurface was recorded using resistivity meter. The data was processed with IPI2WIN™, INTERPEX™, GRAPHER™, and SURFER™, and interpretated with respect to the geology of the area. The data delineated the fractures based on mean resistivity contrast. The fractures strike within the area are NW-SE, NE-SW and N–S, E-W (37.07%, 33.33%, 18.52%, and 11.11% respectively). The interconnectivity of the fractures was portrayed in some locations and they define the permeability of the area, coefficient of anisotropy, transmissivity, and longitudinal conductance defines the groundwater possible yield. The coefficient of anisotropy ranges from 1.05 to 9.54, and fracture porosity extends from 0.0006 to 1.95, with an average of 0.34. The transmissivity of groundwater in the area support withdrawal of marginal regional importance. Therefore, groundwater yield and recharge in the area is contingent on the variability and interconnectivity of the subsurface fractures, the number of existing boreholes being recharged by this fracture, and the baseflow dynamics and dipping angle of the major fracture at the borehole site.

Investigation of Groundwater Potential Zone Using Geophysical and Geospatial Technology in Akuku-Toru Local Government Area, Rivers State, Nigeria

Background of the Study: The study area is located within four communities in Akuku-Toru Local Government Area, which is a coastal region within the Niger Delta. The study area is heavily reliant on groundwater for domestic, industrial, and agricultural purposes. The hydrogeological dynamics of the area are complex, with diverse geological formations and intricate subsurface structures. As a result, an innovative and integrated approach is necessary for effective groundwater management. The study investigated the potential of groundwater resources in the study area and identification of fresh water zones using electrical resistivity, remote sensing, and GIS which employs geophysical surveys, remote sensing techniques, and geospatial analysis to explore the interplay between aquifer characteristics, geological formations, and topographical attributes. The fresh water zones are regions with low saline content.
 Aim: This study aims to assess groundwater potential in some parts of Akuku-Toru Local Government Area by integrating the geophysical data from Vertical Electrical Sounding (VES) surveys with geospatial analysis from GIS and Remote Sensing Technology. The research seeks to provide a comprehensive understanding of groundwater availability and its correlation with geophysical and geospatial parameters.
 Study Design: A thorough methodology was employed to investigate the possibility of freshwater resources in the study area. The approach involved gathering Vertical Electrical Sounding (VES) data from 8 locations, as well as incorporating geospatial data such as elevation, drainage density, geology, apparent resistivity, and slope maps. The collected data underwent rigorous processing, correlation analysis, and reclassification to explore the potential of freshwater resources in the study area.
 Place and Duration of the Study: The research was conducted in four communities (Abonnema, Ekulama, Jacobkiri and Belema) within the Akuku-Toru Local Government Area over a span of 18months. The area's hydrogeological context and topographical features are investigated to determine groundwater potential zones.
 Methods: The research utilized the Vertical Electrical Sounding (VES) method to obtain aquifer resistivity data, reflecting subsurface Lithological variations. Geospatial analysis involved accessing elevation and drainage density patterns. Correlation analysis was also performed to link the geophysical and geospatial data with qualitative interpretations, facilitating the assignment of numerical values representing groundwater potential zones.
 Results: The Correlation analysis revealed insightful patterns. Aquifer resistivity, elevation and slope were identified as influential parameter affecting groundwater potential. The geology of the study area, categorized into dominant formations, exhibited varying degrees of potential for freshwater resources. The Correlation of geophysical and geospatial data provided a comprehensive understanding of groundwater availability across the study region.
 Conclusion: The integration of geophysical and geospatial analysis offers a robust approach to groundwater potential assessment. The research findings contributed to valuable insights into the spatial distribution of potential freshwater resources in the study area. The correlation between aquifer resistivity, elevation, slope, and geology enhanced our understanding of hydrological conditions and provides a foundation for future groundwater studies and management strategies.

Investigation of Groundwater Quality using Vertical Electrical Sounding and Dar Zarrouk Parameter in Leihitu, Maluku, Indonesia

The goal of this research is to obtain information related to aquifer quality, including aquifer protection capacity, transmissivity, and aquifer thickness based on vertical electrical sounding (VES) data and Dar-Zarrouk parameter analysis. The research area is located in Leihitu District, Ambon with 8 measurement points. The Leihitu region is included in the geological map of the Ambon sheet, Maluku, which consists of Late Pliocene - Holocene lithology, specifically Ambon volcanic rocks, reef limestones, and alluvial deposits. The rock resistivity measurements and layer thickness information were obtained using the VES method and analyzed with IP2WIN software. Based on VES data, aquifer properties were identified using Dar-Zarrouk parameters. That parameter consisted of longitudinal conductance, transfer resistance, longitudinal resistivity, and transfer resistivity. Longitudinal unit conductance is applied to evaluate the protective capacity class of the aquifer, the transfer resistance is beneficial for analyzing rock type and aquifer transmissivity. Based on the Dark-Zarrouk parameters, the longitudinal conductance (S) ranged from 0.0278 to 5.1213 mho and was classified as moderate to good protective capacity. The high S value results from a thick layer of clay at the observation point. This area also has a high enough transverse resistance (T) and then if related to aquifer transmissivity, this area is classified as a good transmissivity aquifer, especially at VES 2, VES 5, VES 6, VES 7, and VES 8. If correlated to rock formations, areas with limestone and volcanic rocks have better transmissivity than areas with alluvial deposits.

Estimasi Kedalaman Batuan Dasar di Kampung Yabaso Kabupaten Jayapura Menggunakan Metode Vertical Electrical Sounding Konfigurasi Schlumberger dan Metode HVSR

Research on the estimation of bedrock depth in Yabaso village, Jayapura district using the Schlumberger configuration Vertical Electrical Sounding (VES) method and the HVSR method has been carried out. The total observation points are three points where VES is one point and VHSR are two observation points. VES measurements used a set of resistivity meter model AK HV 500 with a maximum spread length of the current electrode is 100 m. HVSR measurements use a portable seismograph set and the measurement time for ambient seismic waves is 60 minutes. VES and HVSR data processing respectively using IPI2Win and Geopsy software. The model parameters resulting from the inversion of the VES data show that there are nine layers with a resistivity range between 18 – 25,260 Ωm. Layer 1 is a heap of sandy gravel with a resistivity value of 92 Ωm. Layers 2 to 7 are part of alluvium formations and coastal deposits (Qa) with resistivity values of 18 – 264 Ωm. While layers 8 and 9 are fragments of weathered ultramafic rock (um) and compact and dry ultramafic rock respectively. The source rock (bedrock) is layer 9 which is at a depth of 42 m. The results of HVSR data processing show that the natural frequencies at the two observation points are very small (<2.5 Hz), namely 0.85 Hz and 0.83 Hz. According to Kanai's classification, this frequency value is type I, class IV, namely alluvial rock. The depths of source rock based on the HVSR method at measurement points 1 and 2 are 43 m and 44 m, respectively. There is agreement in the estimation of the depth of the source rock obtained from the VES and HVSR methods even though the two methods utilize two different physical parameters.
 Keywords: HVSR; VES configuration Schlumberger; Resistivity; Jayapura

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.

GEOELECTRIC INVESTIGATION USING VERTICAL ELECTRIC SOUNDING METHOD TO DETERMINE UNDERGROUND WATER AQUIFERS IN THE CASE OF PUDAK AND ITS SURROUNDING AREAS

Resistivity is a determinant of the type of rock and the electrical properties of the rock or water-carrying layer. Primary data is the main source of data for the investigation of the subsurface with the Vertical Electric Sounding (VES) method. The purpose of the study is to determine the resistivity of subsurface geological conditions to detect aquifer and reservoir lithology types designed as planned wells. The data of geoelectric investigation point was carried out on as many as 10 (ten) points and produced in the form of (1) Claystone: resistivity of 1.4-6.4 Wm and thickness of 4-4.6 meters, (2) Sandstone: resistivity of 7.5-40 Wm and thickness of 0.2-55 meters, (3) Breccia: resistivity of 45-1088 Wm and thickness of 0.5-33.2 meters. For a depth aquifer of 5.8-68 meters and resistivity of 12.40-23.60 Wm with a shallow well condition around reaching a depth of 15-19 meters and freshwater results are obtained.

Groundwater Potential Mapping Using Geophysical Techniques: a Case Study in Hosanna Area, Western Margin of The Central Main Ethiopian Rift, Ethiopia

In this study, Vertical Electrical Sounding (VES) and magnetic methods are applied for mapping the groundwater potential and aquifer system in the Gode area, the western margin of Central Main Ethiopian Rift. The VES is used to map the depth to potential aquifer zone of the groundwater and its distribution over the area, whereas, the magnetic survey is applied to delineate contact between lithologic units and geological structures. A total of 12 VES data points and more than 400 magnetic data points at about 10m station intervals along seven profiles are collected, processed and analyzed. Our results from interpretation of the VES data, geoelectric sections, and 2D magnetic modeling results respectively revealed the vertical stratification of the subsurface geoelectric layers and the presence of subsurface weak zones, which control the groundwater flow and storage system where the potential aquifer in the area obtained at a depth range from 45m to 92m. Overall, areas in the neighborhood of four VES points, i.e.VES-2, -3, -10, and -11, show good water-bearing zones in the study area associated with the highly weathered/fractured ignimbrite and pumice layers.

Vertical Electrical Sounding Method to Detect Groundwater and Design of A Tubular Well for the Pampas District – Peru

Vertical Electrical Sounding Method to Detect Groundwater and Design of A Tubular Well for the Pampas District – Peru

Exploring the Geological Formation and Sub-Surface Lithology Modelling of Hadejia, Jigawa State Nigeria

This research aims to explore the geological formation and sub-surface lithology modelling of Hadejia, Jigawa State using the VES (vertical electrical sounding) method. The VES method is a geophysical technique that measures the electrical resistivity of the subsurface, which is related to the lithology of the rock units. The study area is located in the north-western part of Nigeria, on latitudes 12025’23.73‘‘N and longitudes 10°04’06.74‘‘E, and is characterized by a chad formation geological setting with a variety of rock units, including sandstones, shales, and limestone. The research was conducted using a total of 50 VES stations, which were distributed over the study area in a grid pattern. The data collected from the VES stations were analyzed using the IPI2WIN software. The results were used to create a subsurface electrical resistivity model, which was then used to infer the lithology units present in the subsurface. The results showed that the study area is characterized by a complex subsurface structure, with several rock units present, including sandstones, silt, and clay. The subsurface electrical resistivity model revealed that the sandstone units are located at shallow depths, while the silt units are found at deeper depths. The clay is present at intermediate depths and is interbedded with sandstones and clay. The results provide valuable information for hydro-geological and mineral exploration in the area.

Application of VES and 2D Resistivity Methods for Groundwater Exploration in Kutigi-Enagi Region, Northern Bida Basin, Nigeria

The study integrates electrical resistivity tomography (ERT) and vertical electrical sounding (VES) methods for investigation of the groundwater potential of the study area. Five ERT was conducted to determine the variation in resistivity of the shallow subsurface rocks both vertically and laterally in order to infer aquifer zones therefrom while twenty-four VES was carried out to compliment the information obtained from the ERT, determine vertical variation in resistivity, infer lateral variation in resistivity, identify depth to aquifer and infer groundwater prospect of the area. Three geoelectric layers were obtained with layer resistivity and thickness increasing northwards with shallower depth to aquifer obtained at Kutigi. K (ρ1<ρ2>ρ3) and Q (ρ1>ρ2>ρ3) resistivity type curves constitute 75% of obtained curves signifying increasing groundwater saturation and salinity, and are indication of increasing aquifer prospect with depth. The groundwater prospects in the area is generally high with properly constructed boreholes in these areas will produce prolific groundwater at 40 meters with higher yield expected at the southern regions of the study area around Enagi.

THE LITHOLOGY OF FLOOD PRONE AREAS USING THE VERTICAL ELECTRICAL SOUNDING (VES) METHOD

Rock lithology modeling of flood-prone areas has been carried out using the Vertical Electrical Sounding (VES) method in Rawa Makmur village, Bengkulu city. Field data acquisition using a stretch length of 160 with the MAE X612-EM Geoelectric tool forming a straight line. VES method, using Excel software for resistivity variations with depth and Progress lithology modeling. This research aims to determine the subsurface condition of flood-prone areas and the characteristics of rocks that make up flood-prone areas. The results of this study can be concluded that the Rawa Makmur village is dominated by sand (0,2-50 Ωm), silty sand (1-35 Ωm), gravel sand (20-150 Ωm) and clay (65-250 Ωm) at several points. VES 1, VES 2, VES 3, VES 4, VES 5, VES 8, and VES 9 have a shallow water table of 1-10 meters, close to the Rawa Makmur river and have a rock structure that is saturated with water so that it cannot absorb moisture on the surface and becomes a flood puddle. The characteristics of rocks that make up flood-prone areas are porous stones such as sand and gravel saturated with water. Sites that are not prone to flooding in the Rawa Makmur village at points VES 6 and VES 7 are dominated by the rock structure of sand (20-65 Ωm), gravel sand (100-200 Ωm), and dry gravel (100-1000 Ωm).