Geoelectric Layers Research Articles

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.

The Application of Vertical Electrical Sounding for the Geophysical and Hydrogeological Investigation in University of Benin Area, Nigeria

The occurrence and distribution of groundwater in a sedimentary basin are localized and confined to the weathered sandy layer/zone. The study was carried out with the aim of demonstrating the vertical electrical sounding method of investigation in the exploration of groundwater at the University of Benin, around VC’s lodge. A total of six VES points were probed using the ABEM SAS 300C terrameter which was used to generate field data applying the Schlumberger Array with AB/2 of 1.5 m, 215 m. The results were simulated using IPI2WIN software. The results show an average of four geo-electric layers per VES point; superficial layer, duricrust, clay layer, alluvium, sand layer and the weathered sandy layer. For VES 1-6, the thicknesses of the water table are 11.6 m. 16.6 m, 22.5m, 30.5 m 51.4 m and 27.8 m respectively and the depth to the water table is 124.4 m, 124.6 m, 78.4m, 55.2 m, 38.5 m, and 29.4 m accordingly. Going by the results, VES 1 & 5 ranked the highest water prospect due to the thickness of the water table layer, the depth to the water table and most importantly the weathered/fractured layers with resistivity as high as 15,188 Ω and 76,432 Ω for VES 1 & 5 respectively, which also increases the permeability and storage of the groundwater. VES 2, 3, 4, and 6 are also wet reservoirs but for their shallow thicknesses and depth to the water table which will influence the purity of the water. However, further investigation is needed to ascertain the suitability of the water as portable drinking water by examining the physicochemical and hydrogeological characteristics of the existing Boreholes drilled in the vicinity of the study area. The findings of this study are a reminder of the essence of a geophysical survey prior to drilling exercises and the suitability of electrical resistivity as a tool for aquifer delineation.

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.

Efficiency and limitation of vertical electrical sounding in evaluation of groundwater potential in fractured shale terrain: a case study of Abakaliki Area Lower Benue Trough Nigeria.

Water supply in the Abakaliki Area of Southeastern Nigeria and its environs has been a source of worry. The area is marked by a series of abortive boreholes, sparsely productive boreholes, and failed water wells. These problems are a result of the direct and indirect function(s) of the prevailing geology of the area which is underlain by aquiclude (Abakaliki Shale, lenses of siltstone and sandstone) dominantly indurated shale. Sixteen (16) vertical electric sounding (VES) were acquired using a resistivity meter. The acquired data was plotted on a bi-log graph using INTERPEX and SURFER. Quantitative and qualitative interpretations were used in preparing geoelectric layers and layer parameter maps. Three (3) to five (5) geoelectric layers were delineated. The first layer is a compacted lateritic overburden. VES 1, 3, 4, 6, 11, and 15 were observed to have thin layers of clay with very low apparent resistivity values with an average of 2.642 Ωm and average thickness of 1.08m, and depth generally less than 10m. Fractured and non-fractured/baked shale layers were dominant in all points of the study area. The non-fractured consolidated shale has a high apparent resistivity value ranging from 180.3 Ωm to 770.42 Ωm with an average of about 339.53 Ωm while the fractured shale has an average resistivity value of about 21.36-68.79 Ωm and an average of 38 Ωm. The confinement of the aquifer implies that the indurated shale generally underly the Abakaliki Area. The low resistivity value of the fractured shale is an indication of the presence of fluid, possibly water. The results of this research implied that the application of exploration method(s) that could delineate the subsurface fractures should precede groundwater development in the area. Also, there is no specific depth to the water table in the area; however, the area has a generally shallow depth to groundwater on average.

Leachate delineation and aquifer vulnerability assessment using geo-electric imaging in a major dumpsite around Calabar Flank, Southern Nigeria.

A near-surface resistivity investigation was undertaken to investigate soil contamination and aquifer vulnerability due to leachate percolation in a major dumpsite in Calabar. The study was undertaken using 2-D electrical resistivity tomography (ERT) and vertical electrical sounding. Ten traverse lines were created within and outside the dumpsite and geo-electric measurement was conducted using dipole-dipole and Schlumberger electrode configurations. Interpretation of the measured data was carried out using DIPROWIN and WinResist program. 2-D resistivity structures were produced, showing four resistivity layers. Conductive layers with a resistivity of less than 14Ωm were delineated as leachate infiltrated and soil-contaminated zones. The study has shown that leachate has spread across all the survey lines except the two control stations outside the dumpsite. The investigation has further revealed that leachate has percolated the subsurface up to 25m in the area. Subsequently, twenty vertical electrical soundings were carried out to evaluate aquifer protective capacity/vulnerability in the area. The interpretation shows the area is underlain by four to five geo-electric layers. Total longitudinal conductance values were calculated. Two VES points (14 and 19), representing 10% of the sounding points, showed a weak protective capacity rating; eight VES points (1, 7, 9, 11, 12, 13, and 18), representing 35% of the soundings, showed a moderate protective capacity rating; ten VES points (2, 3, 4, 5, 6, 8, 10, 15, 16, 17, and 20), representing 55% of the total soundings, showed a good protective capacity rating. Three (3) hand-dug wells were sampled with the view to obtaining the groundwater and leachate flow direction within the dump vicinity. An electric water level recorder was used to determine the static water level (SWL) of the three wells, and the leachate flow direction was determined to be north-easterly.

Geotechnical Characterization of the Subsurface Using Seismic and Electrical Resistivity Techniques in Mikinduri Meru County, Kenya

Abstract Geotechnical study of the Mikinduri area was conducted with the aim to establish the causes of landslides and ground subsidence during the heavy rainfall. Sounding curves, travel time curves, 2D geoelectric sections, and 2D seismic models revealed 3-5 lithologic units to a depth of 30-250m. The study established thick loose alluvium deposits mixed with clay to a depth of 0.3-15m on an impermeable sub-basement as the possible major trigger of the landslides witnessed during rainy seasons. The thick alluvium deposits are due to erosion. They have been transferred by the location of the Mikinduri area, which lies in the lower regions of the Nyambene domes. Geologically, the domes were formed during Mount Kenya volcanic series and parasitic activities between the early Miocene and late Pleistocene eras. Resistivity modeling revealed deep geologic structures, including possible intrusions extending from 50m deep and faulted regions to a depth of 60-150m in the central and northeast area of study. The faulted area is highly saturated, as revealed by the low resistivity values. The delineated top black cotton soils and alluvium deposit are 40-50% clay and have poor foundation bearing capabilities. In contrast, compacted gravel, silt, and compact basaltic rock basement have good foundation capabilities. Keywords: Geotechnical, characterization, subsurface, seismic, electrical resistivity, foundation, geoelectric layer, Mikinduri Meru, Kenya.

English

Vertical electrical sounding (VES) and 2D electrical resistivity tomography (ERT) employing the Schlumberger and Wenner configurations respectively were combined for groundwater exploration in parts of Enugu metropolis. The area is underlain by Enugu Shale and Mamu Formation. A total of twenty (20) VES and four (4) 2D ERT traverses were acquired in the study area. VES and 2D ERT data were processed and interpreted using INTERPEX 1X1D and RES2DINV respectively. Sounding curves shows dominant decrease in resistivity with depth while 2D ERT inverse model shows lateral variation in resistivity of the rock layers with lower resistivity at increasing depth. VES geoelectric layer sections show top sideritic clay - clay/shale sequence. Resistivity curve analysis also shows predominance of Q and K curve types. 2D map of aquifer layer resistivity, thickness and depth were constructed. Aquifer layer resistivity range from 2.00 to 190 ?m, while the thickness range from 10 to 75 m and a depth range of 23 to 150 m. The 2D ERT shows layer resistivity range of 0.1 to 250 ?m. Based on the combination of the two techniques for groundwater exploration in the study area, a water table depth of 18 m with a maximum drill depth of about 100 m was determined. However, it is recommended that the selection of point of drill should be on the low saturated regolith as observed on the 2D ERT sections.   Key words: Aquifer, groundwater, VES, 2D ERT, resistivity.

Spatial appraisal of aquifer characterization through hydrogeophysical investigations in central part of Bari Doab, Punjab, Pakistan.

The study area lies in Southwestern part of Sahiwal District, Punjab, Pakistan, which is the central part of interfluves system, i.e., Bari Doab. Hydrogeophysical investigations were carried out for the spatial appraisal of groundwater aquifers resources in the study area through electrical resistivity survey. A total of forty vertical electrical soundings through Schlumberger electrode configuration are conducted in the study area. The interpreted results of electrical resistivity survey along with interactive modeling suggest that four to six numbers of geo-electric layers exist in the subsurface in the study area. The alternating alluvium comprised of silt, sand, gravel, and kanker layers has been interpreted. The interpreted resistivities are categorized from very high to very low in the study area. Below the water table, very low resistivity values interpreted mainly as sand and sand-gravel saturated with saline water. Moreover, the interpretation of our developed maps also leads to demarcate the fresh and saline groundwater zones. Interpreted results decipher that this gigantic saline water zone starts below the depth of 150m and extends below the depth of 300m. The models of true resistivities are also calibrated with the lithological logs of test holes and tube wells within the study area. The sandy and gravel layers are the most promising zones for good-quality groundwater that leads to the development tube wells up to the depth of 150m within the study area.

Identification of Groundwater Bearing Zones Using Geoelectrical and Electromagnetic Techniques at Tourah Area, South of Cairo - Egypt

The complex geology of Tourah area, south Cairo is a serious challenge for groundwater exploration, where the risk of unsuccessful groundwater drilling excavation for industrial purposes is well dressed, raising the need for better geophysical subsurface detection and characterization approaches in terms of water bearing and aquitard zones. Datasets from the study area were acquired using integrated geophysical techniques comprising of one Dimensional Vertical Electrical Soundings (1D VES) and one Dimensional Transient Electromagnetic (1D TEM) as well as two-Dimensional Electrical Imaging (2D ERI) which was restricted to the available spreading space as well as subsurface infrastructure noise. The results of 1D VES and 1D TEM soundings detected three to five geoelectric layers used to generate geoelectrical cross sections and maps of resistivity, thickness, and depth to water bearing zone. Moreover, the 2D ERI inversion profiles were able to image the first three layers and the depth of the water bearing zone [A] with significantly greater resolution due to their higher lateral and vertical resolutions compared to the traditional 1D VES and TEM interpolated cross section. The integration of the three geophysical methods displayed a smooth distribution of both marly limestone and fractured shaly limestone and claystone bands water bearing zones [A and B]. Resistivity values of the water bearing zone [A] ranges from 0.1 to 24 Ω m, with average thickness of 4 to 12 m, and depth to water of 1.5 to 13.6 m. In addition, [zone B] is the main water bearing zone of fractured shaly limestone and claystone bands (2 to 14 Ω m) which is detected at deep depth of 40 and 75 m. Two normal fault systems inferred from 1D interpretation are considered responsible for local recharging of the main Eocene aquifer over the study area. In conclusion, the outlined water bearing thickness as well as limited sources of groundwater recharge indicate that these water bearing zones may not provide a sustainable supply for the industrial development purposes in the future.

Characterization of Subsurface Lithology and Aquifer Parameters Using Vertical Electrical Sounding (VES) for Groundwater Development in Igbo-Imabana, Southern Nigeria

Vertical Electrical Soundings (VES) using Schlumberger array was carried out at fifteen (15) different points to evaluate aquifer characteristics within Igbo-Imabana, Abi L.G.A of Cross River State. Resistivity meter and its accessories were used for data acquisition. The maximum current and potential electrode distance were 400 m and 20 m respectively. The field data were interpreted using Interpex software and three to five geo-electric layers encountered within the study area. The dominant curve type was H followed by K. From the result, geo-electric layers delineated were sandstone, clay, saturated sandstone, sandy shale, clayey shale, and shale with average apparent resistivity values of 2249.94 Ωm, 2.86 Ωm, 365.28 Ωm, 222.69 Ωm, 14.60 Ωm and 59.02 Ωm respectively. The top geoelectric layer was dominantly lateritic topsoil, with variation in degrees of compaction and having an average resistivity of 876.33 Ωm with depth and thickness generally less than 5 m. The calculated aquifer parameters hydraulic conductivity (Kc), transmissivity, longitudinal conductance, and transverse resistance from the VES results show ranges values; 3.86×10–4 to 4.69×10–2 m/day, 2.95×10–3 to 2.82 m2 /day, 2.95×10–3 to 2.81 Ωm and 484.33 to 19444.83 Ω2 m respectively. The aquifer thickness and depth values range from 3.60 m to 68.05 m and 5.20 m to 76 m respectively. The study reviewed that the area is made of heterolithic/heterogenou lithofacies, confined aquifer(s), shallow and deep aquifer. Also, from the models and aquifer parameters, the area is characterized by semipervious materials. This integrally explains why the area have have low transmissivity and majority of boreholes drilled in the area failed.

GEOPHYSICAL INVESTIGATION OF GROUNDWATER POTENTIALS USING RESISTIVITY METHOD: A CASE STUDY OF ABU PHASE II STUDENTS’ HOSTEL

Geophysical survey for groundwater was conducted in two newly built halls of residence (hostels) named Dangote and Shehu Idris at the second phase of Ahmadu Bello University (ABU), Zaria in Nigeria. The vertical electrical sounding (VES) technique of resistivity method was employed with Schlumberger array in seven VES points distributed within the two hostels. Results showed that 4 to 6 geoelectric layers exist within the study area for a spacing of at most 200 m between current electrodes. The resistivity values of the geoelectric layers in all the VES points ranged from 26.6 Ωm – 30342 Ωm while the thickness and depth ranged from 0.263 m – 40.34 m and 0.572 m – 50.66 m respectively. However, four VES points (two in each hostel) were identified to be suitable for borehole drilling though, three out of these four VES points have single aquifer in each with resistivity and thickness ranging from 34.4 Ωm – 40.57 Ωm and 2.02 m – 7.49 m respectively. Conversely, the fourth VES point has two aquifers positioned at the third and fifth layers with resistivity values ranging from 26.6 Ωm – 51.4 Ωm and thickness ranging from 1.93 m – 18.7 m. It was recommended that among the four VES points (two in each hostel) identified to contain aquifers, priority should be given to the ones with larger thickness in each hostel.

Aquifer depth determination of low permeability layers using geo-resistivity data: A case study of Enyigba mine area and environs, South Eastern Nigeria

Many geophysical methods have been applied to locate groundwater in Nigeria’s rural and urban villages. Locating groundwater in low permeability formations like shales and siltstones is even more challenging due to the difficulty of mapping fracture zones within these formations. The fracture zones serve as potential aquifers in low permeability formations and have been the object of groundwater search in shales, siltstones and other low permeability formations. The electrical resistivity method has proven helpful in fracture mapping within low permeability formations due to the existing resistivity contrast usually observed between the fractured and non-fractured sections in the Shales and Siltstones. Three vertical electrical geosounding datasets (VES 1, VES 2 and VES 3) were acquired in the Schlumberger configuration, using a maximum current electrode spacing of 200m to delineate the fracture zones based on their electrical resistivities. The acquired datasets were processed and modelled using IP12 Win software, while the processed datasets were correlated with local geology to estimate the depths of the fractured shales in the area. Results show five modelled geo-electric layers with depths to the fractured shales ranging from 17-25m, while aquifer thicknesses range from 7 to 12m. Aquifer resistivities range from 58 - 115 ohm-m. The curves are primarily of the QH type. One of the Vertical Electrical Sounding Data points (VES 2) encountered an anomalously low resistivity zone at a depth range of 5 to 8m which was interpreted as a galena lode. The low resistivity zone has been confirmed through exploratory drilling to tie with Lead-Zinc lodes at a depth of 8m.

Groundwater aquifer assessment using hydrogeophysical investigations: the case of western Al Ain Sokhna area, Gulf of Suez, Eastern Desert, Egypt

This study aims to assess the groundwater aquifer and defined the quality of water in the Gulf of Suez region. Hydrochemical and electrical resistivity techniques have been used for evaluating an aquifer, including its extension and quality, in the western Al Ain Sokhna area, Gulf of Suez. This study collected 16 groundwater samples from wells tapping the upper Miocene aquifer. Laboratory tests, including the estimation of electrical conductivity (E.C.), pH, total dissolved solids (TDS) and major ions such as Ca2+, Mg2+, Na+, K+, CO3 2–, HCO3 3–, SO4 2– and Cl–, were conducted. Most water samples belonged to the category of permissible water (TDS 500–1500 ppm) which represented 62.5% and brackish water which represented 37.5%. A total of 47 vertical electrical sounding stations were measured using the Schlumberger array of AB/2 up to 1500 m to detect the subsurface geologic section and delineate water-bearing layers. The results of geoelectrical interpretation illustrated that the subsurface section has five geoelectrical layers. The third layer represents the freshwater aquifer, and the fourth layer represents the brackish water aquifer. The upper Miocene aquifer represents the first aquifer with fresh groundwater of resistivities ranging from 14.7 to 100 Ω.m and thickness ranging between 28.4 and 86 m.

Integrated Geophysical Assessment of Groundwater Potential in Southwestern Saudi Arabia

Saudi Arabia is seeking fresh groundwater resources to face the increase in anthropogenic activities. The groundwater storage variations and occurrence were investigated and the surface and subsurface structures influencing the groundwater resources in the research area were defined using a combined study of Gravity Recovery and Climate Experiment, aeromagnetic data, and electrical resistivity data with other relevant datasets. Results are: The groundwater storage fluctuation is calculated at −0.34 ± 0.01 mm/yr during the period 04/2002-12/2021. The area is receiving an average annual rainfall rate of 117.6 mm during the period 2002 to 2019. Three structural trends, defined in the directions of NS, NNW, and NNE are cutting the sedimentary cover and the basement rocks. The sedimentary cover ranges from 0 to 1.2 km thick. Vertical electrical sounding results indicate three main geoelectric layers: the surface geoelectrical layer of higher resistivity values (428-9626 Ω. m) is made up of unconsolidated Quaternary sediments; the water-bearing layer of saturated sands with a resistivity range between 5.1 and 153 Ω. m and with depths vary from 1 to 94 m, and highly fractured basement rocks with resistivity values ranging from 813 to 6030 Ω. m. The integrated results are useful in providing a comprehensive image of the study area’s surface and subsurface structures, as well as groundwater potential in the southwestern part of Saudi Arabia. Our integrated approach provides a reproducible model for assessing groundwater potential in arid and semiarid areas.

Depicting of groundwater potential in hard rocks of southwestern Saudi Arabia using the vertical electrical sounding approach

In the hard rock terrains of southwestern Saudi Arabia, vertical electrical soundings (VES) were used to demarcate groundwater potential zones. To map the groundwater potential zones, 16 VES were done using a Schlumberger electrode array arrangement. Zond-IP computer software was used to analyze and interpret field measurements. The pseudo and resistivity cross-sections have been processed. The evaluation of the 1D geoelectrical curves revealed that the area is characterized by three geoelectrical resistivity layers. The topmost layer of unconsolidated alluvium deposits, which has a wide range of resistivities (42.28 to 297.97 Ω·m) and a thickness of up to 6 m, is the first of these layers. This range of resistivity is linked to changes in the layer's lithology and humidity. The second layer's resistivity values range from 372 to 3625 Ω·m, while the third layer's resistivity values range from 1015.37 to 21113 Ω·m. The second layer's resistivity implies fractured and weathered/jointed basement rocks, and the third layer's resistivity indicates broken to huge basement rocks. According to the findings, the worn and fractured horizons of basement rocks found in the vicinity are acceptable groundwater potential aquifers. The degree of weathering and fracture of the foundation rocks, and thus their water saturation, can be linked to vertical and horizontal variations in resistivity.

Characterization of Crystalline Aquifers in Ouaddaï Division (East of Chad) Using Electrical Resistivity Method: A Case Study of Waguiré and Anourchi

This study aimed to locate suitable aquifers that can be exploited with their structural and hydraulic characteristics. So for this aim, combination of geoelectrical and drilling techniques was used. Eight electrical trailing and Vertical Electrical Soundings (VES) were carried out with Syscal R1 - Plus resistivimeter, using Schlumberger array. VES data were interpreted using the Ipi2win software, and geohydraulic parameters (conductivity, transmissivity, and porosity) were estimated based on geoelectric parameters computed. Results show four favorable shapes of electrical trailing (W, U, V, and H -shapes) and four types of VES curves (H, HA, QH and HKH). Three to five geoelectric layers were delineated from analysis of VES curves with aquifer resistivity influenced by clay content, varying from 6.09 to 33.84 Ω.m and thickness from 5.54 to 17.35 m. Computed hydraulic conductivity, transmissivity, and porosity vary from 14.19 to 70.93 m/day, 92.36 to 429.13 m²/day, and 37.44 to 44.68% respectively. The groundwater potential of the area ranges from moderate to high potential. Based on these geohydraulic parameters, two points (VES4 and VES7) were chosen to drill a hole. Drillings were a success and yield ranging from 2.72 m3/h to 3.12 m3/h. This study reveals that geohydraulic parameters could be an alternative to choose where to drill a positive borehole in the area with a similar geological context.

Mapping of aquifer hydraulic properties in Ogbeje and Umeghe in Abraka, Delta State Nigeria: insights from geophysical and hydrogeological methods

Vertical Electrical Sounding (VES), Pumping test, well logging and grain size analysis were conducted with the aim of studying the subsurface geophysical formation in order to determine aquifer characteristics such as hydraulic conductivity, transmissivity and other parameters for groundwater exploration purposes around Ogbeje and Umeghe, Abraka Delta State. Nine (9) VES stations were occupied and the results obtained from the computer iterations suggest 4 to 5 geoelectric layers. The aquiferous layers wwerefound at a depth ranging from 20.0 m – 38.3 m with resistivity ranging from 2200 ?m to 8500 ?m and thickness varying between 6.7 and 20.0 m. The VES study reveals the possibility of having a maximum drill depth the o water table of about 38 m. The results obtained from the pumping test and well logginwereas used to estimate the transmissivity value of T = 0.0722 m2/min, storativity S = 0.00063, specific capacity of the well = 0.39 m2/min and hydraulic conductivity, K= 8.5 m/day while the result from the grain size analysis gave hydraulic conductivity as Kmin= 12.96 m/d to Kmax = 26.96 m/d respectively. Thus, these results indicate that the aquifer is capable of proda ucing sufficient amount of water for both domestic and industrial purposes for the people in the area. 

Geoelectric and mineralogical studies for foundation soil characterization in new Luxor city, Upper Egypt

The new Luxor city was proposed by the Egyptian government as a new constructional and building site in order to face the increasing population density around the two banks of the river Nile. It is important prior construction of buildings to characterize the foundation soil. So, vertical electrical resistivity survey and mineralogical investigation were conducted for this purpose. The results obtained from the interpretation of the sounding data indicate that the lithological succession of the study area consists of four geoelectric layers. The top layer corresponds to the surface loose sediments of conglomerate, gravel, and sand. The second geoelectric layer is composed of sand and gravel. The third layer is composed of silty clay, sandy clay, and clayey sand. The fourth geoelectric layer is composed of dry sandstone. The X-ray diffraction (XRD) results of samples collected from the clay-rich layer revealed the presence of smectite mineral as predominate clay minerals which is characterized by its swell potentiality on wetting. Accordingly, the clay zone recorded within the third layer must be taken into consideration during designing the foundations at new Luxor city especially this layer was located at shallow depth range between 1.6 and 7.5 m and attains a relatively big thickness that reach up to 33.5 m in some parts. This study emphasizes the importance of the integration of geophysical investigation and mineralogical analysis of the foundation soil for optimal characterization of a site.

Near-surface groundwater exploration using the geoelectrical resistivity method: A case study of Wadi Nisah, Riyadh, Saudi Arabia

In desert regions like Saudi Arabia, groundwater exploration is critical for drinking, household, and agricultural purposes. The purpose of this study is to use Vertical Electric Sounding (VES) to assign near-surface groundwater sources in the Wadi Nisah area of central Saudi Arabia. Twenty VES stations were installed in the central part of Wadi Nisah, with a maximum half current electrode separation (AB/2) of 100 m, utilizing a Syscal R2 resistivity-meter with Schlumberger electrode design. The interpretation of these VES's revealed five geoelectric layers, the first of which is formed of dry sand with greater resistivity values and has a depth of around 3 m. The groundwater-bearing aquifer is represented by the fifth layer, which is the deepest, with depths ranging from 37.8 to 52.25 m below the surface and resistivities ranging from 47 Ω-m to 115.3 Ω-m. Six geoelectrical cross-sections were also mapped to show the lateral and vertical heterogeneities of the underlying lithology in the study area. These findings suggest that the groundwater bearing layer is a hydrologically promising zone capable of delivering optimal groundwater yield for drinking and agricultural use in the study area; the VES technique is a useful tool for identifying groundwater prospective zones.

Electrical Resistivity Survey on Two Waste Dumpsites at Nguru, Potiskum, Yobe State, Nigeria to Determine the Effect of Leachates on Ground Water Aquifer

The research intends to bring out the contribution of leachate on groundwater in two dumpsites in Nguru and Potiskum all in Yobe state, Nigeria. A total of seven (7) and eight (8) VES by Schlumberger electrode with the use of Wenner electrode configuration. The results were interpreted by the use of WinRESIST for VES and IPWIN2INV for ERT. The study pointed out that, the area in question is comprised of four layers of geoelectric such as the topsoil, clay, sand, sandy clay and sand. The range of the first resistivity layer was from 6.16 Ωm to 332 Ωm in the first geo-electric layer and its thickness range from 2.77 m to 37.7 m and a depth range of 2.77 m to 37.7 m. the range of the second resistivity layer was from 16.5 Ωm to 37.9 Ωm which has the range of its thickness from 4.1 m to 10.7 m. The range of the third resistivity layer was from 101.2 Ωm to 288.2 Ωm which has the range of its thickness from 38.9 m to 99.7 m, and the first aquifer in the area. The range of the first resistivity layer was from 100.7 Ωm to 214.3 Ωm which has the range of its thickness from 28.5 m to 94 m. The fifth layer which is the second aquifer and has resistivity from 254 Ωm to 350 Ωm with a very large thickness. The range of the first resistivity aquifer is from 101.2 Ωm to 288.2 Ωm and the range of the second resistivity aquifer is from 253.8 Ωm to 350.1 Ωm. The 2D ERT profiles unveiled areas with low resistant zones and later discussed as zones penetrated by contaminants originated from dumpsites whereas high resistant zones represent areas of low or non-conductive materials in the area. Data obtained from four dumpsites indicated that leachate of the waste dumpsites penetrated into aquifers and polluted the groundwater. The existence of contaminants in the water was noted by a decrease in the formation resistant values. It is seen, from the results of the survey (geophysical) that the water in the area is polluted and it accounts for the prevalence of any disease related to water that are common in the area