ABEM SAS Research Articles

Geoelectrical Investigation of the Groundwater Potential in Eti-Osa, Lagos State, Nigeria

An electrical resistivity survey was conducted in Eti-Osa, Lagos State, Nigeria, to characterize the subsurface lithologic units, delineate the underlying aquifer, and assess groundwater potential. The study utilized an ABEM SAS 1000 terrameter for the data acquisition. Eight vertical electrical soundings were carried out using the Schlumberger electrode configuration. Data interpretation, both qualitative and quantitative, was presented through tables, charts, and sections. The interpreted geoelectric models revealed three to five layers with varying lithologies, including topsoil, sand, silty sand, sandy clay, silty clay, and clay. The first geoelectric layer, with resistivity values ranging from 8 Ωm to 320 Ωm, is relatively thin, with a thickness between 0.4 m and 3 m. The second layer exhibits thicknesses of 1.3 m to 15 m and resistivity variation between 1.5 Ωm to 185 Ωm. The third layer varies in thickness from 1 m to 36 m, with varying resistivity between 9 Ωm to 335 Ωm. The fourth geoelectric layer has a thickness range of 5 m to 20 m and resistivity values between 1.6 Ωm and 193 Ωm. The basement resistivity ranges from 3 Ωm to 361 Ωm. The study identified the sand layers, particularly at VES points 1, 2, 3, and 8, as the most promising for groundwater extraction. In contrast, VES points 4 and 5 are less favorable, and points 6 and 7 may yield lower-quality water. It is recommended that boreholes be drilled to depths greater than 20 meters at VES sites 1, 2, 3, and 8 for optimal water quantity and quality. However, sites 3 and 8 may be at risk of contamination due to shallower depths.

Application of Electrical Resistivity Method in Building Foundation Study around Ansarudeen Primary School Adehun Area of Ado-Ekiti, Southwestern Nigeria.

The study evaluated the structural competency of the subsurface geological materials around Ansarudeen Primary school in Bolorunduro community, Adehun area of Ado Ekiti, Ekiti State, Nigeria to delineate the area that is suitable for building development. The ABEM SAS 1000 was employed for transmitting current and recording the resistivity value of the subsurface layers across the two traverses using the dipole-dipole and the Schlumberger arrays for horizontal profiling and vertical electrical sounding of the survey area respectively. Five VES points were occupied along traverses 1 and 2 with AB/2 of 150m. The field resistivity data were processed using Win RESIST and the Dipro software to generate the geoelectric sections of the survey area. The sounding curves generated were HK, KHA, and A, with HK having the highest number of occurrences. The interpreted result showed that the geoelectric section consist of five layers which are the topsoil, weathered layer, fractured basement layer, partly fractured layer and the fresh basement rock. The resistivity value and subsurface layer thickness for the top soil varied from 115.3 - 752.7 Ωm and 0.3 - 2.1 m respectively. The general overburden thicknesses were estimated at 11m and 23m respectively for traverse 1 and 2. The pseudo section of the horizontal profiling and the geoelectric section of the Vertical electrical sounding revealed similar subsurface lithology along traverse 1 and 2. The result however suggested foundation placement on traverse 1along VES 3 and VES 2 of the geoelectric section or point 16-19 of the horizontal profiling pseudo section.

Application of Combined Geoelectrical Techniques for Groundwater Exploration at Federal University Gusau, Zamfara and its Environ, Northwest Nigeria

Study’s Excerpt Integrated approach combining Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) is used to delineate groundwater potential in the study area. The results revealed that the water bearing aquifers in the study area are fractured basement layers at varying depths between 15 and 105 meters. This research provided a robust framework for groundwater exploration in arid and geologically complex terrains. Full Abstract The area of study is currently facing an acute water shortage due to the dominant lithological framework that underlies the region and its fragile climate condition. As such, this study aimed at unearthing the groundwater potential of the area using a combined three geoelectrical techniques. Techniques such as Electrical Resistivity Tomography (ERT), Natural Electric Field (NEF) method, and Vertical Electrical Sounding (VES) were employed in the delineation of the groundwater potential of the area. Using an ABEM SAS-4000 Resistivity meter and a PQWT-TC150 water-detector equipment, respectively. Wennar array was employed for the conduct of ERT while Schlumberger configuration was used for VES data collection. The measured apparent resistivity value was inputted into RES2DIV software and subjected to an inversion process to generate the resistivity structural image of the subsurface. However, IP2WIN software was used for the VES data interpretation. The result of the ERT method revealed two to three geoelectrical resistivity layers: an overburdened layer of topsoil/laterite with resistivity values ranging from 6.86 Ωm to 1095 Ωm and thicknesses of 1-13 meters, a weathered/fractured basement layer, interpreted as the aquifer unit, with resistivity values between 28.7 Ωm and 345 Ωm, and thicknesses ranging from 6 - 30 meters; and a fresh/slightly fractured basement layer with resistivity values from 367 Ωm to 6899 Ωm. NEF method revealed the thickness and depth of the aquiferous layer across the six profile lines to range between 15-60m, 30-90m, 15-85m, 20-80m, 45-105m, and 20-40m respectively, with points on profile five (5) identified as the most promising site with regards to groundwater development. VES result identifies weathered and fractured layers as the major aquiferous units with resistivity values ranging from 9.965 Ωm to 9651 Ωm and 21.7 Ωm to 859 Ωm respectively with fracture thickness reaching up to 60m in some instances. The result goes in line with the outcome of both NRF and ERT techniques. The geological interference of this lithology on groundwater exploration reveals both the weathered overburden and fractured basement as aquiferous units in the study area. The study identified several promising aquiferous zones at depths ranging from 15 to 105 meters, with fractured basement layers serving as primary reservoirs for groundwater development.

The Result of Electrical Resistivity Investigation of Solid Waste Landfill Conducted at Nsukka Municipality Using Electrical Resistivity Measurments

Solid waste landfill management has been a significant issue for Nigerian urban areas and other developing countries across the globe.Similar to most other cities, Nsukka also generates waste on a daily basis, much of which is dumped in poorly designed and positioned dumping sites. The majority of the disposal sites are found on roadsides, at marketplaces, on farms, and in residential neighborhoods, among other places. The road infrastructure and groundwater are under danger, and the beauty of the impacted communities are not spared. Undoubtedly, the unchecked citation of boreholes as the source of potable water in the majority of our rural and urban communities—given that the government doesn't seem to be providing water to the people—has become a significant challenge. An investigation using electrical resistivity method was conducted around a solid waste dumpsite at Nsukka in Nsukka L.G.A of Enugu State, Nigeria with an aim to investigate the level of groundwater contamination and the objectives to determine the subsurface geoelectric layers, depth to water table, lithology delineation and map out the contamination zones. The scope of this study provides an overview of some of the approaches used to assess the aquifer vulnerability and aquifer potential using Vertical Electrical Sounding (Schlumberger array) and 2D resistivity imaging (Wenner array) in different locations around Nsukka municipality dumpsite. Both methods were used for this study in order to provide a geophysical database for exploration of the study area’s groundwater resources and also they are less expensive and less time consuming. VES has proved to be effective in solving groundwater problems in most places in Nigeria (Ezeh and Ugwu, 2010; Ugwu and Ezeh, 2012; Nzemeka et al. [1,2]. Electrical Sounding (VES) and 2D resistivity imaging were carried out with a digital read out resistivity meter (ABEM SAS 1000) to acquire data in the area and were interpreted using the Schlumberger automatic INTERPEX analysis software and the RES2DINV software respectively, which generates model curves using initial layer parameters and display the variations of electrical resistivities respectively. A total of eight (8) sounding and six (6) 2D resistivity imagings were carried out in the area. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones while the VES shows the depth of aquifer. In 2D pseudosections where bluish colours with low resistivities (less than 20.80\(\Omega\)m) with the depth ranging from 1.28m to 17.1m in the Line 1 and 2 are seen as contaminated zones. The rest of the lines are not contaminated because of their high resistivities (greater than 20.80\(\Omega\)m). The result of the electrical resistivity survey also showed 4 - 5 layers geo-electric sections and an AA and AK type sounding curves. The VES result shows that VES 1A, 1B, 2A and 2B which are carried out on line 1 & 2 of the wenner lines showed signs of contamination with low resistivity values less than 20.80\(\Omega\)m complementing the wenner results. The contamination has not yet got to where the aquifer is located on the lines. Since the depth to the aquifer ranges from 30.26m to 155.43m while maximum depth of contamination is 17.1m. It is believed that the leachate has not percolated down to the aquiferous zones as such aquifers are presumed to be free. As such, it is recommended that boreholes around the study area should not be less than 30m deep to avoid exploiting polluted water.

Estimation of Groundwater Potential and Aquifer Protective Capacity Within Old Ikenga Hotel, Nsukka, Enugu State, Nigeria

A geophysical survey using electrical resistivity method was conducted around Old Ikenga Hotel, Nsukka in Enugu State, Nigeria to investigate the groundwater potential and aquifer protective capacity of the area. The project area lies within latitudes 6°50'4.0''N – 6°57'52.0"N and longitudes 7°21'6.3"E – 7°28'12.0"E, and covers an area of about 89.6 km2. Vertical Electrical Soundings (VES) were carried out with a digital read out resistivity meter (ABEM SAS 1000). The VES points were marked at 25 m and 75 m along a 100 m line. A total of eight soundings were carried out in the area. The VES data collected were interpreted using INTERPEX software and the results presented in terms of resistivity, thickness, depth and lithology. The lithology was inferred by correlating the result to the lithology log of the borehole drilled in the hotel and the geology of the study area. The VES result shows lithologic layers varying from 4 to 5. Aquiferous sand and Aquiferous sandy shale constitute the aquifer units in the area at depth of 30.26 m to 188.20 m, with their thickness ranging from 30 m to 74 m as shown by their isopach map. The aquifer protective capacity was determined by calculating for longitudinal conductance and matching the values to known standards. The calculated longitudinal conductance varies from 0.0409 to 3.1235 mhos. The interpreted VES results reveal poor, moderate, good and very good aquifer protective capacities of the overburden layers.

Geoelectric Investigation for Groundwater in Imo State University Campus and Environs using Direct Current Electrical Resistivity Method

Eighteen, vertical electrical soundings (VES), were carried out in Imo State University and Environs to delineate the potential site for groundwater. Data were acquired using ABEM SAS 300 resistivity meter. Schlumberger array and maximum electrode spread of 700m were adopted. Data were interpreted with IP2WIN software. Contour maps were done using Sulfer 20 software. Geoelectric cross-sections constructed along three profile lines delineated subsurface stratification. Sediments consist of sequence of sandstone/gravel, silty sand/sand and clay with geology representing the Benin Formation. Groundwater was delineated within the zone interpreted to be sand with quartz making up more than 95% of all grains. Resistivity of aquifer varies across study area and ranges from 159Ωm, observed around Library and Information Department (VES 11) to 100000Ωm recorded at IMSU Plaza (VES 10). Depth to water table also varied across study area with higher values of 150m and 130m observed at College of Health Science (VES 3) and Behind Old ETF (VES 4). A relatively shallow aquifer is delineated behind Senate Building and Okwu-Uratta with water table at depths of 23.5m and 26.5m. The transmissivity values are moderately high except at some locations. The variation in longitudinal conductance and transverse resistance values show that part of the study area such as Aso Rock, Female Hostel, Law Faculty and IMSU Plaza are underlain by relatively resistive (low longitudinal conductance) aquifer material. Distribution of hydraulic conductivity and electrical conductivity values indicates that in some of the VES points, the values are fairly constant. This could be seen as areas with similar geologic settings and water quality. Storativity of study area ranges from 0.00003 at VES 1 and 12 to 0.00028 at VES 4. Study area shows a good prospect for groundwater development, except at Library and Information Department, where the zone delineated is an aquitard.

Geospatial analysis of soil resistivity and hydro-parameters for groundwater assessment

Groundwater is a precious resource for irrigating the crops in developing countries. This research was governed in Faisalabad District of Pakistan to assess the groundwater strata using GIS cum geoelectric resistivity method approach. The IX1D computer model was calibrated with root mean square error (up-to 5%), to obtain true soil layers’ resistivities and thicknesses model for each VES point based on apparent resistivity data collected by ABEM SAS 4000 Terrameter using the most common Schlumberger electrode array setting. Knowledge of geo-hydraulic parameters (hydraulic conductivity, transmissivity, and porosity) aids in identifying the quality and potential of groundwater repositories, estimated based on modeling results (soil layers resistivities and thicknesses). Most common interpolation (inverse distance weighted) method in ArcGIS Pro was used for mapping the soil aquifer layers resistivities/thicknesses and geo-hydraulic parameters. Transmissivity, Porosity, and hydraulic conductivity values ranged from 365.46 to 1888.503 m2/day, 31.84 to 39.72% and 4.05 to 15.27 m/day for all surveys, respectively. Based on these results, aquifer layers with thicknesses 30 to 103.5 m, were distinguished as comprised of saline to low marginal quality (fine sand and clay formation), marginal to fresh quality (fine sand and gravel formation) and fresh quality groundwater (coarse sand and gravel formation).Graphical

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


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

A Geo-Electric Survey of Potential Aquifer in Some Parts of Amaigbo, in Imo State, Using Vertical Electrical Sounding and Well Log Data

A geo-electric survey in some parts of Amaigbo in Imo State was conducted for the determination of potential groundwater aquifer. Using the Schlumberger Array techniques, Vertical Electrical Sounding along with Self-Potential Well Logging was carried out at six (6) VES in Amaigbo using the ABEM SAS 1000 Terrameter and ABEM SAS 1000 Logger respectively. The field data obtained was analysed using the computer software IPI2win. The result obtained revealed the heterogenous nature of the sub surface geo-electrical sequences in the study area. The results revealed the aquifer resistivities in the study are ranges from 352 ohm-meter to 7514 ohm-meter and aquifer thickness from 45m to 119m which indicates that the study area has high aquifer potentials for groundwater exploitation. The result from this study would therefore assist indigenes of Amaigbo in reducing the high cases of borehole failure due to improper drilling a d inadequate hydrogeological; data here in provided.

2D Resistivity Imaging for Leachate Migration in Nkwelle-Ezunaka Farm Estate, Southeastern Nigeria

Leachate effluence from wastewater Leachate migration and solid waste are major sources of soil and groundwater pollution. Assessing the impact of leachate is an active area of soil and groundwater research. This study evaluated the extent of leachate migration at Nkwele-Ezunaka Farm Estate in Anambra State of Nigeria using a 2D resistivity imaging technique. The study area lies within longitude 6° 51' 27'' − 6° 59' 37'' E and latitudes 6° 13' 18'' − 6° 20 '27" N and covers an area of about 60 km2. A total of five profile lines were carried out in a resistivity survey using a digital read-out resistivity meter (ABEM SAS 1000). The data obtained were interpreted using RES2DINV software. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones (less than 80.0 Ωm). The maximum depth of penetration of leachate determined was 10.6 m and hence could not penetrate the groundwater in the study area. The groundwater flow in the study area was revealed to be in the West-East direction.

Evaluation of Factors of Soil Resistivity in the Niger Delta

Soil conductivity is responsible for its aggressive behavior to metallic objects either in contact or buried in the ground. Rapid deterioration and eventual rupture of pipelines leading ultimately to crude oil spillages have been of economic as well as environmental concern. Although many factors contribute to soil resistivity, these relationships have hardly been quantitatively expressed. This paper explores the factors affecting soil resistivity firstly by matching the spatial regional distribution with each of the identified factors of influence, including ground elevation soil type, depth to water table and undrained strength. 183 Vertical Electrical Sounding VES with the ABEM SAS 1000, using Schlumberger electrode configuration were carried out along a pipeline route to generate resistivity distribution across a linear alignment that traverses three geomorphic sub-environments in the Niger Delta Region. The apparent resistivity values averaged over depths of 3 m and 10 m were plotted against the co-ordinates using Surfer-16 and overlaid on Google earth Pro to produce a spatial distribution with enhanced location visibility. The results show that apparent resistivity is influenced by depth to water table with lower values in areas of shallow water table occurrence. Furthermore, it is shown that changes in resistivity below the water table are more due to variation in soil type. Within a soil type above the water table, soil resistivity increases monotonically with depth until the depth of probe extends to a different soil horizon. Results of this study provide guidance as to what ground resistivity to expect in different part of the delta as well as provide valuable information to assess the risks to assets either as a means of prioritizing maintenance or of improving design for new installations in the Niger Delta Region.

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.

Groundwater exploration using vertical electrical sounding techniques in parts of Etche Local Government Area of Rivers State, Nigeria

Vertical Electrical Sounding (VES) was carried out in parts of Etche Local Government Area, Rivers State, Nigeria to investigate availability of groundwater. An ABEM SAS 1000 terrameter was used. Schlumberger configuration was adopted for the sounding to acquire a 4 point data, with the use of ID Interpex software in order to know the subsurface variations in resistivity with respect to depth. The investigation revealed the subsurface, thickness of lithology, prolific aquiferous zones, the resistivity curve portrays an overall increase in resistivity trend ranging from 228.7Ωm - 5872Ωm. The resistivity trend in the form of ρ1< ρ2< ρ3< ρ4< ρ5, indicates the presence of conductive materials present at a shallow depth of the point of survey. The highest resistivity value is observed in the fifth layer and it is believed to have gravely sized particles. A stratigraphic layer with gravely sized particles in this area revealed a good aquifer quality with reasonable quantity of aquifer fluid contained within the interconnected pore spaces. This zone of the studied area contains rock units from the geoelectric section such as silt, medium sand, coarse sand and gravel. The fifth layer is the prospect zone for aquifer delineation. A geoelectric section drawn from the resistivity data shows that the first layer is silt, the second layer is fine sand, the third layer is medium sand, the fourth layer is silty sand, the fifth layer is fine sand and the sixth layer is medium sand. The sixth layer is believed to be the prospect zone for aquifer characterization. A suitable data from drilled boreholes should be introduced to this study so as to have a profound knowledge and views about the grain size, sphericity, roundness and parking. These characteristics will be useful to determine the dominant grain size existing in these aquifers and characterize them appropriately.

Analysis of Water Quality of Saket by using Geophysical Logging Located in Saket, New Delhi

Geophysical logging application was incorporated for the perusal of the groundwater analysis. The study area involves the parts of the Saket area, situated in the Indian capital Delhi. For the purpose of study VES(vertical electrical sounding) method was adopted to reach to desired analysis. The study carries the objective of an analysis of the condition of groundwater along with the investigation of the geological situation. Abem Terrameter SAS-300c system with the with Geomac II, ABEM SAS log200 system with Geomac III were used in the study to perform the VES of the Schlumberger configuration along with the tubewell geophysical logging. Lithological investigation of the tubewell depicts the presence of alluvial topsoil, Badarpur sand, fractured and weathered rock along with the sandy silt and silty sand for subsurface of soil. Also, the presence of four geoelectric layer found. In these layers the fourth layer that is observed at a depth range from 15 ft to 450 ft, were found with the aquifer and 50 to 2000 Ωm resistivity were observed for this layer consisting aquifer. Geophysical logging analysis depicts the observation results for total dissolved solid in aquifer as 430 ppm. the obtained limit of TDS is found to be in standard limits, as the standard limit is 500 ppm set for the potable water by standard organization of India. Ground water development is found to be feasible for the fourth layer, since the layer is observed as potential non-conductive zone in the study area.

Geophysical investigation of the effects of waste dump on groundwater quality in Rukpokwu, Port Harcourt Metropolis

Vertical Electrical Sounding (VES) was carried out in Rukpokwu, Obio/Akpor Local Government Area, Rivers State, Nigeria to investigate the effect of waste dump on groundwater quality in the study area. An ABEM SAS 300 terrameter was used. Schlumberger configuration was adopted for the sounding to acquire a 4 point data, and at Rukpokwu adjudged to be free from waste dumps which served as control. The result of the resistivity survey was interpreted by IPI2WIN computer software, revealing the subsurface lithology, thickness of lithology, prolific auriferous zones, curve types and zones of contamination. The Niger Delta has a shallow water table which makes it prone to easy contamination. Different resistivity values were obtained; high resistivity values are an indication of uncontaminated subsurface lithologic zones while low resistivity values are an indication of contaminated subsurface lithologic zones as a result of dissolved ions and metals from waste dumps decomposing through biochemical reactions, hydrolysis, oxidation and reduction processes which subsequently leads to the formation of leachate. This leachate is in hydraulic continuity with groundwater flow which eventually leads to groundwater contamination. Therefore a geophysical survey is essential and necessary before a borehole drilling project is carried out in order to ascertain the depth to prolific aquifer which will give potable water free from contamination.

Evaluation of Geophysical and Geochemical Characteristics of Soil and Groundwater Resources in Yenagoa Environs, Niger Delta, Nigeria

The problem of potable water has increased in recent time due to increase in population density, petroleum exploration activities and spillages along the creeks. Thus, three (3) Vertical Electrical Soundings (VES) were made using Schlumberger array in the study location to obtain geophysical data, using the ABEM SAS 1000 terrameter, in order to investigate the occurrence of groundwater in relation to the depth and thickness of viable aquifer. Six (6) surface water samples and six (6) subsoil samples were obtained from the study area. Both subsoil and surface water samples were analyzed to determine the concentration of contaminant. Analysis was performed using the Atomic Absorption Spectroscope (AAS) method which was compared with the World Health Organization Standard. Result and interpretation of analyses revealed high contaminant contents of lead (Pb) with values of subsoil samples at S2 (18 mg/l) and S6 (8.1302 mg/l), while Mn show very high concentration of contaminant values for all subsoil samples which exceeded the WHO permissible standard which indicates that aquifer may likely be polluted by intrusion. Cr for subsoil samples and Mn of surface water samples are likely within or slightly higher concentration value when compared with WHO limit. It is advisable to carry out proper water treatment from source and soil degradation, for potable drinking water and cultivation of agricultural product respectively.

Assessment of groundwater potential using vertical electric sounding technique at Faculty of Medicine and Engineering, Federal University Dutsin-ma Katsina State, Nigeria

Geophysical exploration is used to locate boundaries between different elements of the subsoil as these procedures depend on variations in the gravitational, magnetic, electrical, radioactive or elastic properties of the subsurface. Electrical resistivity method was employed to investigate the groundwater potential of the Faculty of Medicine and Engineering at permanent site of Federal University Dutsin-ma, Katsina State. The study was carried out using ABEM SAS 300 Terrameter, Schlumberger electrodes configurations were used to acquire 9 Vertical Electrical Soundings (VES) soundings. The VES data obtained were interpreted using Winresist computer software which reveal five (5) geoelectric layers, namely; the topsoil, laterite, weathered basement, fractured basement and fresh basement. The weathered and fractured layers constitute the aquiferous zone in all the stations. The results of the interpreted VES data showed that the resistivity of the topsoil varies from 17.1 to 109.8 Ωm with an average value of 137.7 Ωm. The thickness of the weathered basement varied from 1.7 to 7.9 m with an average value of 4.67 m, while depth to this layer varies from 4.6 to 13.8 m with an average value of 10.6 m. The thickness of the fractured basement varied from 3.0 to 15.6 m with an average value of 8.01 m, while depth to this layer varies from 6.3 to 33.7 m with an average value of 18.85 m. The depth to aquifer ranges from 17 to 69 m, the resistivity of the aquifer unit ranges between 35 and 830 Ωm. Based on the results, the potential VES points for groundwater exploitation in the study area includes VES 02, 03 and 05 which indicates low to moderate resistivity at greater depth and are therefore recommended for borehole establishment.

Geoelectric Investigation of Groundwater Potential within Mubiand Environs, Adamawa State, Northeastern Nigeria

In this paper, ABEM SAS 4000 Terrameter with Schlumberger configuration was used to determine the groundwater potential within Mubi and its environs. The Schlumberger configuration with maximum current electrodes of 100 meters was adopted and a total of twenty-five Vertical Electrical Sounding (VES) was carried out. The results show that the geologic sequence beneath the study area consists of top soil, partly weathered/fractured basement, highly weathered/fractured basement, aquifer with fresh water and presumably fresh basement. The weathered/fractured and aquifer with fresh water horizons constitute the water bearing zones referred to as aquifer with a thickness value of 10.06m to 77.32m and resistivity value of 16.19Ωm to 150.40Ωm. In addition, six distinctive curve types namely H, KH, HK, K, HA and KQ were identified. The results reveal that H curve type dominates the study area with 48%, HK and K curve type have 12% and HA and KQ curve type have 4%. Furthermore, the result shows that out of twenty-five (25) locations considered within Mubi town and Environs, nineteen (19) of them have potentials for ground water.

Characterization of aquifer system using electrical resistivity tomography (ERT) and induced polarisation (IP) techniques

Groundwater plays a major role as an alternative freshwater resource for irrigation and industrial purposes. This study aimed to characterize the subsurface of aquifer systems in TelukIntan district, Perak, Malaysia using Electrical Resistivity Tomography (ERT) and Induced Polarization (IP) methods. The horizontal profiling (TL1 and TL2) was conducted at length of 400 m. The estimated depth is 150 m below ground level (b.g.l.). An ABEM SAS 4000 Terrameter and ABEM LUND ES464 Imaging System were applied to create a resistivity pseudo-section using polar-dipole configuration. The collected geo-electrical data was interpreted using RESIST software with partial curve matching and computer iteration. ERT and IP survey profile results were validated with in-situ borehole data from borehole 2 (B2). Eleven samples of soil profile were collected at depth from 5.6 m to 61.2 m, with average percentage of sand, silt and clay are 93.77 %, 5.78 % and 0.02 %, respectively. The geology of subsurface settings is the key factor in determining the aquifer system characterized by interlayer sand-silt sequence indicating the saturation zone of aquifer underlain by shale at the bottom. Further study on hydraulics perspective is important to understand the overall capacity of the aquifer.

Integrating Resistivity Techniques for Optimum Groundwater Exploration and Development within a Hotel Facility in Osogbo, Southwestern Nigeria

This work is an attempt to combine dipole-dipole profiling and vertical electrical sounding techniques of electrical resistivity methods to investigate the groundwater potential within the premises of a 3-star hotel facility in Osogbo, Nigeria by delineating the geoelectric layers, delineating the low resistivity layers, determining the lithologies and hence, delineating the groundwater bearing zones. The five vertical electrical sounding data were collected along two pre-surveyed dipole-dipole traverses at right angle to each other beside the fences of the premises using the ABEM SAS 300c terrameter. The observed data were interpreted quantitatively using curve matching and computer-assisted iteration method using the WinResist and Dipro software. The results of the inversion show that the lithology comprises of the top soil and an intermittent sequence of sand and lateritic clay having varying resistivity and thickness. The aquiferous layer was observed to be located at a depth of 23 m to 25 m due to the low resistivity and high thickness of the aquiferous layer. The result of the 2-D imaging closely correlates with the result of the vertical electrical sounding. Thus, combining these techniques in groundwater investigation has achieved similar result as the Werner technique and has reduced ambiguity and error in positioning for drilling.
 Keywords: Resistivity, Groundwater Exploration, Dipole-Dipole