Vertical Electrical Sounding Points Research Articles

PROTECTIVE CAPACITY ASSESSMENT OF A SHALLOW AQUIFERAT THE EASTERN PART OF ADO-EKITI, SOUTHWESTERN NIGERIA

Vertical Electrical Soundings (VES) survey has been undertaken at the eastern part of Ado-Ekiti, southwestern Nigeria to assessthe aquifer protective capacity of the overburden units of the area. The Schlumberger electrode array was adopted with a maximumcurrent electrode spread (AB) of 300 m.Thirty-six(36) VES points wasoccupied and processed through a partial curve matching technique and 1-D forward modelingcomputer-assistedsoftware.The interpretation revealed H, A, KH and HA-type curves and threemajor geoelectric layers overlying the resistive basement. The groundwater potential and overburden protective capacity maps were prepared. The groundwater in the area was categorized into high, medium and low groundwater potential zones. About 80% of thestudy area falls within the moderate/low groundwater potential zone while the remaining 20% constituted the high groundwater potential zone (Agric Olope area). Hence, thegroundwater potential rating of other areas is considered to be low. The values of longitudinal conductance (ranging from 0.01 to 2.01 mhos) of the area enabled the overburden units to be rated into good, moderate and weakprotective capacity. About 75% of the area falls within the good/moderate rating while 25% constitutes the weak/poorprotective capacity rating (Agric Olope area), suggesting that the groundwater around Agric Olope isvulnerable to contamination.

Integrated groundwater exploration in basement complex terrain for sustainable regional water supply in Abuja, Nigeria

This study integrates geophysical and geological analyses to identify potential areas for regional water supply in newly developed sites and regions lacking coverage from the lower Usuma Dam. Covering an expanse of approximately 5200 km2, high-resolution aeromagnetic data were collected, analyzed, and interpreted alongside thirty-five (35) vertical electrical sounding (VES) data points, utilizing the Schlumberger array with current electrode separations (AB/2) ranging from 100 to 140 m and potential spacing MN/2 varying from 0.25 to 5m. The aeromagnetic data, reduced to the equator, reveal anomalies characterized by variations in magnetic susceptibility, indicative of changes in rock composition. Total magnetic field intensity ranges from 435.7 nT to 568.3 nT, with variations attributed to the presence of diamagnetic materials, specifically magnetite and quartzite in basement rocks. Residual data, ranging from −92 to 41.4 nT and high residual values correspond to granite gneiss and coarse porphyritic biotite hornblende granite. First vertical derivative results expose lineaments with lengths ranging from 894.4m to 11.627 km, supported by tilt derivative lineaments of 1.131–11.400 km these delineate potential zones for urban and regional groundwater supply, emphasizing the role of lineaments and faults in controlling structural geometry for groundwater flow. Geological mapping affirms high fracturing with conjugate faults in the area. Interpreted VES curves identify 65.7% as H-type, 22.9% as KH, and 5.7% as QH curves, with HK- and A-type curves at 2.9%. Overburden thickness varies from 6 to 44 m at specific VES points. Iso-resistivity maps exhibit high resistivity values (6000 to 9000 Ωm) due to geological outcrops, while low resistivity values result from a partially or highly fractured basement. Recommendations include drilling 31 VES points for regional water supply in Abuja's urban area, offering a diversified water source and reducing dependence on potentially vulnerable surface water supplies.

Lithological and Structural Factors Affecting Groundwater Occurrence in Eruwa, South West Nigeria

The subsurface Lithological and Structural framework was investigated to understand its effects on groundwater aquiferous occurrence in this study, underlined by the Precambrian Basement Complex of Nigeria, with granite, gneiss, and schist occurring as the dominant rock types. To successfully map the subsurface, fifty-two (52) Vertical Electrical Sounding points were probed to a depth of current electrode spacing of 100m depth to obtain the variation in the resistivity measurement of the underlying weathered basement and basement rock in the subsurface. Apparent resistivity values and current electrode spacing are plotted on a bi-logarithm plot and correlated to standard curves to estimate subsurface layers' depth, thickness, and resistivity values. WinResist software uses a mathematical algorithm to estimate further the geoelectric parameters to find the best-fit model that matches the observed data. Golden Surfer software was used to represent the geoelectric parameters to aid in geospatial representation. Results show 3-5 lithological layers, which include Topsoil, Clay, Laterite, Sand, Sandy Clay, and Fresh Basement with resistivity value range 82.1Ωm - 2648.2Ωm, 21.8Ωm - 98.4Ωm, 102.3Ωm -167.5Ωm, 404.6Ωm - 2468.2Ωm and 606.8Ωm - 20,535.90Ωm indicating a weathered and fresh unweathered basement rocks layers with H, KH, HA, HKH, KHKH, QH and A geophysical curve which are also typical geometry of weathered material and limited or no fractures basement rock layer. Basement rock resistivity, Overburden thickness, Reflection coefficient, longitudinal conductance, Anisotropy coefficient range (606.8Ωm-20535.9Ωm, 2.6m - 35.6m, 0.3-1.0, 0.01-0.86 and 0.7-3.3) respectively which a typical value of shallow to deep overburden layer with limited or no-detected fracture basement rock). Incorporating the geoelectric parameters value obtained and calculated reveal limited structural deformation of the basement rocks to yield fracture capable of creating secondary porosity in the area while the lithology of the weathered layers becomes the exploitable source for groundwater recovery in the study area.

Groundwater Potential Evaluation and Aquifer Characterization using Direct Current Resistivity Method in Wasinmi South-West Nigeria

The effectiveness in near-surface characterization makes geoelectrical resistivity techniques viable for groundwater exploration, geotechnical studies and environmental investigations. Geo-electric soundings were carried out in 25 different locations in Wasinmi, South-West Nigeria to acquire aquifer properties required for groundwater production of the study area using Direct Current Resistivity (DCRE) of Vertical Electrical Sounding (VES) utilizing AGI Super-sting Earth Resistivity meter with schlumberger configuration; current electrode spacing (AB) ranging from 1 to maximum of 100 m and the potential electrodes (MN) were consequently changed from 0.25 m to 5 m respectively. The simulated results of the 25 VES points reveal the presence of 3 to 4 geo-electric layers. The top layer comprises clay, sand, siltstone intercalations. Layers underneath the top soil are the Lithified Laterite, Clayey Sand, Clay/Shale, Sandy Clay and Limestone/Sandstone, Saturated, Sandstone Aquifer. The area is also characterized with relatively high depth to sandstone aquifer which varies from 20 m to 69.1 m. This can be attributed to the thick water saturated Shale/Clay and Clayey Sand in the area. However, at the extreme of North-Western part of the study area, depths to aquifer are far lower, with VES location VESWAS15 having a thickness of about 14.4 m. Aquifer thickness in the study area varied from 14.4m to 63.5m. VESWAS19 has the highest aquifer resistivity value (2473 Ωm) in the study area, with depth to aquifer of 69.1 m. The transmissivity varies between 0.17695×/s in VESWAS4 to 8.97654×/s in VESWAS13. This study further shows that aquifer resistivity values vary from 284 Ωm to 2473 Ωm with a range of 2189 with the resistivity values suggesting lithology in the suite of Sandy Clay, Sandstone and Karst Limestone found to be widespread in the study area with mean aquifer thickness value of 32.25 m and a variance of 124.63 m...

Application of Vertical Electrical Sounding (VES) for the Determination of Water-Bearing Zone in Karaworo, Lokoja Kogi State, Nigeria

The importance of water in our various communities and the difficulties faced so far to get good and clean water for both domestic consumption and industrial purposes can never be overemphasized. For these purposes to be accomplished, it is necessary to survey the area of study to know more about the geology of the area, which is characterized by the Lokoja Formation, Patti Formation, and Agbaja Ironstone and the possible reasons why there is a lack of water in the area. The geoelectric survey was conducted at Karaworo with the objective of determining the sedimentary formation's geoelectrical features and analyzing the potential of the groundwater in the study area. The most frequently used type of array for Vertical Electrical Sounding (VES) is the Schlumberger array, which needs a lot of space at both ends to yield deeper subsurface information. The Schlumberger configuration was used for data acquisition. About fifteen (15) VES points were acquired at different locations within the study area. For the different VES positions, the maximum AB/2 is within 100m to 180m. Partial curve matching was used to determine the layer parameters as part of the quantitative interpretation of the VES curves. The IP2WIN software was used in the final data analysis. The depth sounding interpretation revealed subsurface layers which comprises of topsoil/clay with a resistivity range between 1.42 ohm-m to 81.0ohm-m and a thickness of 0.253 m to 70.4 m, lateritic clay with a resistivity range between 01.06ohm-m to 1730 ohm-m and a thickness of 0.236 m to 19.2 m, siltstone with resistivity range between 0.423 ohm-m to 5069 ohm-m and a thickness of 4.09 m to 28 m and sandstone with resistivity range between 0.664 ohm-m to 137 ohm-m with the thickness at infinity. Sandstone constituted the aquiferous zone. In conclusion, different types of curves which include HA-type, H-type, KH-type, QH-type and HAK-type characterize the area and hence it is suggested that boreholes be placed in low resistivity zones and considerable depth and thickness as revealed in VES 4 and VES 8 but those with low resistivity without considerable depth, for example, VES 2, VES 5, VES 6, VES 7, etc. can be developed into a hand dug well.

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.

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.

Geo-electrical investigation for characterizing the shallow Quaternary aquifer parameters and vulnerability to contamination: a case study from semi-arid Khanasser Valley region, Syria

Abstract Schlumberger configuration was used to carry out 34 vertical electrical sounding (VES) measurements for estimating and characterizing the shallow Quaternary aquifer parameters and its vulnerability to surficial contamination in the region of Khanasser Valley, Northern Syria. The data of VES are interpreted by the curve matching technique (CMT) and WinResist software package to get one dimensional (1D) geoelectrical solution model for each study VES point. The electrical conductivity (EC), total dissolved solids (TDS), porosity (Ø%), the overburden protective capacity (OPC), and the corrosion (Corr) of the study aquifer were revealed by parameters of longitudinal conductance and transverse resistance of Dar-Zarrouk results. The protective capacity for the shallow Quaternary aquifer is classified as 56% poor, indicating high vulnerability to contamination, 5.9% weak, 14.7% moderate, 20.6% good, and 2.9% excellent. The ratings of corrosivity for the study region are classified as 26.5% slightly corrosive (SC), 61.8% moderately corrosive (MC), 5.9% very strongly corrosive (VSC), and 5.9% practically noncorrosive (PNC).

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

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

Delineation of aquifer promising zones and protective capacity for regional groundwater development and sustainability

Water security is the central mission of the sustainable development goals. The demand for potable and clean water has skyrocketed due to frequent borehole failures and population expansion, which requires adequate groundwater resource management strategies. Identifying groundwater potential zone, overburden protective index capacity and installations of alternative/artificial storage support mechanisms for water security and sustainability under the growing water challenge and demand is critical. This study identifies; (i) aquifer promising zones (ii) aquifer protective capacity through geophysical investigation and suggests (iii) improving aquifer recovery management strategy as the top three targets for groundwater development. An electric resistivity technique was applied to acquire a total of sixty (60) vertical electrical sounding points with Schlumberger arrays. The study indicates the resistivity layer of the aquifer unit ranges from 21 to 294 Ωm, while the aquifer layer thickness values spread from 8 to 59 m and the overburden thickness overlays the aquifer unit extends from 3 to 20 m. The deeper aquifer zones were encountered between 30 and 59 m, which could be suitable for groundwater development, and the shallow aquifer occurs between 8 and 14 m, which is not encouraging for groundwater development and may be susceptible to surface contaminations. However, for water security and sustainability, multiple boreholes should be sited at the delineated aquifer promising zone where the aquifer is fractured and occurs within a depth of 30 m and above. The weathered/fractured units constitute the regional aquifer units, which are largely responsible for the groundwater potential. The hydraulic conductivity of the regional aquifer was estimated to vary between 0.337 and 10.62 m/day, which invariably enhances the aquifer recovery processing. Groundwater quality and the risk of surface contamination were examined through overburden protective index capacity.

Groundwater Investigation Using Electrical Resistivity Method at New Borg El-Arab City, Alexandria, Egypt

New Borg El-Arab is a city located on the northwestern coast of Egypt, where the increasing anthropogenic activities have led to an increase in water demand. Groundwater is the main source of water in this area, but it is seriously affected by the Mediterranean saltwater intrusion. This causes a substantial impact on the water quality of the coastal aquifer. In this study, the electrical resistivity method was applied to delineate the shallow groundwater aquifer and its quality. Twenty vertical electrical soundings (VES) distributed along 6 profiles were measured. To observe the seasonal groundwater variations, 14 VES points were measured at the end of the rainy season, while the measurements of 6 VES points were repeated at the end of the dry season. The results revealed 4 geoelectrical layers; the first layer is a surface dry zone with variable resistivity values, followed by a water-bearing layer; while the third is a limestone layer, followed by a clay deposits zone. In comparison to the winter season, the water-bearing layer records lower resistivity values at the end of summer. Optimal locations to drill new groundwater wells have also been determined with a depth varying from 1.8 m north to about 30 m south.

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

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

GROUNDWATER EXPLORATION FOR WATER WELL SITES IN ABATA ASUNKERE COMMUNITY, ILORIN, NIGERIA

In this study, Electrical resistivity investigation was carried out at different sections of Abata Asunkere Community, Ilorin, Nigeria with the aim of evaluating groundwater potential and properties of the aquifers. Geophysical technique adopted in this work were the Vertical Electrical Sounding (VES) and 2-D Electrical Resistivity Tomography (ERT) using Schlumberger array configuration. ERT was established on two profiles at the study area with total distance of 80 m apart with 5 m electrode spacing. Eight (8) VES points were sounded along the established profiles. The results revealed four geo-electric layers which correspond to the topsoil, clayey layer, sandy clay and the last layer to the bedrock in all the VES points sounded. The topsoil has apparent resistivity values ranging from 5 to 437 Ω-m and 0.5 m to 1.7 m while the last layer which is the fractured/fresh basement rock has resistivity ranges of 27 Ω-m to 9800 Ω-m and is characterized by infinite thickness. The curve types obtained are H, QH and HK curve type signatures with the H curve type covering about 60 % of the study area. High potential for groundwater was observed at the northeastern and southern part of the study area. Aquifers in most part of the study areas are relatively shielded from contamination because of high protective capacity of the overburden material. It was hence concluded that, the study area has a promising groundwater potential. Based on these results, groundwater exploration at optimum yield was recommended. Depending on the volume of water available during drilling, the maximum depth of drilling may reach up to 60 m.

Application of Vertical Electrical Sounding in Mapping Lateral and Vertical Changes in the Subsurface Lithologies: A Case Study of Olbanita, Menengai Area, Nakuru, Kenya

Much study has been done in the study area linking Vertical Electrical Sounding (VES) interpreted results to lithologies in the subsurface though only tend to indicate the vertical changes with the aim of mapping the occurrence of groundwater aquifers. Several boreholes have been drilled in the study area, though not much has been done to compare the vertical and lateral lithologic changes in the study area. This research is based on VES modelled geoelectric layers compared from point to point and using borehole logs as control data to establish inferences of certain lithology in the subsurface. The inversion of each VES curve was obtained using an AGI Earth Imager ID inversion automated computer program and resistivities and thicknesses of a geoelectric model were estimated. The analyzed VES data interpretation achieved using the curve matching technique resulted in mapping the subsurface of the area as portraying H-type; ρ1 > ρ2 ρ3, K-type; ρ1 ρ2 > ρ3, A-type; ρ1 ρ2 ρ3, Q-type; ρ1 > ρ2 > ρ3, representing 3-Layer subsurface and subsequently a combination of HK, HA and KHK types of curves representing 4-Layer and 5-Layer in the subsurface. The analysis further deployed the use of the surfer software capabilities which combined the VES data to generate profiles running in the west-east and the north-south direction. A closer analysis of the curve types indicates that there exists a sequence showing a shifting of the order of arrangement between the west and the east fragments which incidentally coincides with VES points 8, 9 and 10 in the West-East profiles. The lateral change is noted from the types of curves established and each curve indicates a vertical change in the subsurface. Control log data of lithologies from four boreholes BH1, BH2, BH3 and BH5 to show a qualification that different resistivity values portent different lithologies. Indeed, an analysis at borehole BH3 lithologies is dominated by either compacted rocks or soils, insinuating a scenario of compression experienced in this part of the subsurface which confirmed compression of subsurface formations. A correlation of the VES curve types and their change from one point to another in the study area are evident. This change supported by the surfer generated profiles from the modeled VES data show that there exists and inferred fault line running in the north-south in the area. The inferred fault line by VES mapping, is magnificently outlined by the geological map. There is exuded evidence from this study that the application of VES is able to help map the lateral and the vertical changes in the subsurface of any area but the evidence of the specific lithologies has to be supported by availability of borehole log control data. The VES data was able to enumerate vertical layering of lithologies, lateral changes and even mapping vertical fault line in the study area.

Groundwater Potential Detection Possibility in Southern Ondo State, Nigeria

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

Analysis of Groundwater Potential in the Coastal Area of Parangtritis using Geoelectrical VES Method

This research was conducted in the coastal area of Parangtritis, Bantul Regency, Special Region of Yogyakarta. This study aims to describe the hydrostratigraphy of aquifers using the Vertical Electrical Sounding (VES) geoelectric method, to calculate the volume of availability and safe yield of groundwater application, and to compare the volume of availability of safe products with the demand for water for domestic and tourism purposes. This study uses a field survey approach and field data analysis. In this study, there were 9 VES measurement points for primary data and 16 VES measurement points from secondary data, five samples of water demand for restaurants, and 74 samples of domestic groundwater needs. The VES point was measured by a purposive random sampling method representing each landform. Hydrostratigraphic analysis and preparation of 2D and 3D cross-sectional models of subsurface lithology were performed on all VES geoelectrical measurement data. The results showed that the aquifer layer is located at varying depths for each landform, with alluvium sand as the constituent material. The most significant potential for groundwater is found in the form of dunes and beach ridges. The second-largest groundwater potential is in fluviomarine landforms, and the most minor is in the alluvial plain. The groundwater availability in each landform is sand dune and beach ridge of 117,776,100 m3; fluviomarine plain (45,422,700) m3; and alluvial plain (25,553,000) m3. Then, the safe yield of groundwater is 3,498,300 m3 in sand dunes and beach ridges, fluviomarine plain (1,566,300 m3), and alluvial plains (580,750 m3). Meanwhile, based on the calculation of the total need for groundwater for domestic and tourism purposes, the availability of safe yield is still in surplus or sufficient for the estimated needs.

Effects of Soil Resistivity Variation with Depth on Crop Yield in a Typical Sedimentary Terrain: A Geophysical Method Application in Agricultural Practice

Accurate knowledge of soil fertility is required to promote global food security for life sustenance. Literatures have shown that electrical resistivity method is effective for agricultural site selection without passing through the rigor of soil test. However, the factor responsible for inconsistence in resistivity signature with soil fertility from one place to another, effect of soil texture and depth variation on crop yield are the questions this work geared at providing answers. Ten Vertical Electrical Sounding (VES) were done across the study area using Schlumberger array. Res1Dinvers was used for the inversion model, using Least Square method. Twenty soil samples were obtained in the VES points, two samples per point. One samples each at first and second layer. Result of the resistivity showed that areas with high-excellent crop yield have resistivity signature above 500 Ωm while areas with low yield are characterized by values less than 500 Ωm. In both areas of low and high-excellent crop yield, the result of geochemical analysis indicated that Nitrogen, phosphate, and Potassium varied as 59-61%, 43-54mg/kg and 49-51mg/kg, respectively except for organic matter content that was above 3.8% in the first layer have high-excellent yield while low yield soil showed less than 3.8% in their first layer and even if the second layer’s organic matter is above 3.8%. This study has shown that organic matter has significant effect on soil resistivity signature than others soil nutrients (Phosphate, Potassium and Nitrogen). The study shows that soil’s first layer (0-0.3m) is the most suitable depth good for soil minerals occurrence for optimum agricultural output, soil texture affect soil fertility and geological terrain is responsible for resistivity signature inconsistency with soil fertility.

Detection of groundwater sources in Lembor village using geoelectrical resistivity method schlumberger configuration

Drought is one of the problems faced by the people of Lembor Village, Lamongan Regency, this problem will be slightly resolved if the area has reserves of groundwater sources. Therefore, this study aims to determine the existence of potential groundwater sources around Lembor Village. The method used is the geoelectrical resistivity method schlumberger configuration. Data acquisition was carried out for 10 measuring points of Vertical Electrical Sounding (VES) with a track length of 310 meters, and a distance between electrodes of 10 meters. The measurement results are then correlated between VES points to produce a 2-dimensional cross-section. The results showed that the measured resistivity value was between 0.03 Ωm to 81.1 Ωm. The structure of the subsurface layer of the study area is dominated by clay and limestone. The indications for the presence of groundwater are found at a depth between 25 to 35 meters at a track distance of 35 to 45 meters, a track distance of 170 to 180 meters, and a track distance of 270 to 280 meters with resistivity values between 0.03 Ωm to 0.32 Ωm. The indications of the presence of groundwater sources need to be investigated in a wider area, to determine the distribution and direction of groundwater flow.

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.

Effects of Soil Resistivity Variation with Depth on Crop Yield in a Typical Sedimentary Terrain, Igieduma-Edo State, Nigeria: A Geophysical Method Application in Agricultural Practice

Accurate knowledge of soil fertility is required to promote global food security for life sustenance. Literatures have shown that electrical resistivity method is effective for agricultural site selection without passing through the rigor of soil test. However, the factor responsible for inconsistence in resistivity signature with soil fertility from one place to another, effect of soil texture and depth variation on crop yield are the questions this work geared at providing answers. Ten Vertical Electrical Sounding (VES) were conducted across the study area using Schlumberger array. Res1Dinvers was used for the inversion model, using Least Square method. Twenty soil samples were obtained in the VES points, two samples per point. One sample each at first and second layer. Result of the apparent resistivity showed that areas with high-excellent crop yield have resistivity signature above 500 Ωm while areas with low yield are characterized by values less than 500 Ωm. In both areas of low and high-excellent crop yield, the result of geochemical analysis indicated that Nitrogen, phosphate, and Potassium varied as 59-61%, 43-54mg/kg and 49-51mg/kg, respectively except for organic matter content that was above 3.8% in the first layer have high-excellent yield while low yield soil showed less than 3.8% in their first layer and even if the second layer’s organic matter is above 3.8%. This study has shown that organic matter has significant effect on soil resistivity signature than others soil nutrients (Phosphate, Potassium and Nitrogen). The study shows that soil’s first layer (0-0.3m) is the most suitable depth conducive for soil minerals occurrence for optimum agricultural output.