scholarly journals Geoelectrical Assessment of the Impact of the Ilokun Dumpsite, Ado-Ekiti Southwestern Nigeria, on Surrounding Groundwater Aquifers

2015 ◽  
Vol 40 ◽  
pp. 41-47
Author(s):  
T.A. Lateef ◽  
Akinola B. Eluwole ◽  
Dare J. Adewa
Keyword(s):  
Electrode Spacing ◽  
Contaminant Plume ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Contaminant Plumes ◽  
Low Resistivity ◽  
Resistivity Method ◽  
Weathered Layer ◽  
The Impact ◽  
Aquifer Unit

The area around the Ilokun dumpsite, Ado-Ekiti was investigated with the aim of establishing the possible impact the contaminant plumes emanating from the dumpsite have on the subsurface aquifers. The Vertical Electrical Sounding (VES) field technique of the electrical resistivity method was adopted for the study, and the half-electrode spacing AB/2 varied from 1 to 65 m. A total of eight VES stations were occupied and a control VES point was located on the refuse dump. The VES data were interpreted quantitatively by partial curve matching and computer iteration, after which the geoelectric parameters were used to evolve a 2-Dimensional geoelectric section beneath the study area.The weathered layer beneath the control VES point was identified to be the aquifer unit, but the anomalously low resistivity of 18 ohm-m within the unit was interpreted as an evidence of pollution from conductive contaminant plume. The geoelectric section beneath VES 1 to 7 delineated four layers, these include the topsoil; the weathered layer; the fractured basement and the fresh basement. The resistivity and thickness range of the layers are 177 – 399 ohm-m and 0.7 – 1.2 m; 29 – 842 ohm-m and 1.0 – 3.4 m; 16 – 446 ohm-m and 4.5 – 45.5 m; and 289 – 2144 ohm-m respectively. The fractured layer constitutes the main aquifer unit beneath the seven VES points, but the anomalously low resistivity of 16 – 47 ohm-m within the fractured layer beneath VES 4, 5, 6 and 7 is suspected to be as a result of pollution from conductive contaminant plume emanating from the dumpsite. The fractured layer beneath VES 2 and 3 which does not show any evidence of pollution yet is at a risk of being contaminated, due to its interconnection with the polluted zone.

scholarly journals Investigation of groundwater potential using integrated geophysical methods in Moloko-Asipa, Ogun State, Nigeria

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
A. A. Alabi ◽  
S. A. Ganiyu ◽  
O. A. Idowu ◽  
A. F. Ogabi ◽  
O. I. Popoola
Keyword(s):  
Geophysical Methods ◽  
Low Frequency ◽  
Sampling Interval ◽  
Groundwater Potential ◽  
Groundwater Exploration ◽  
Protective Capacity ◽  
Southwestern Nigeria ◽  
Industrial Growth ◽  
Geoelectric Section ◽  
Weathered Layer

AbstractWater is essential for livelihood, development, and industrial growth. Its exploration in sufficient quantity is required where it does not freely occur on the surface. This research was aimed to delineate aquifer regions and provide information on the subsurface lithology of Moloko-Asipa Southwestern Nigeria. A combination of eight traverses investigated with very low frequency electromagnetic (VLF-EM) method at 5 m constant sampling interval and ten vertical electrical sounding (VES) were carried out in the survey. Measurements from the VLF-EM survey were processed with Karous and Hjelt filtering to give the resistivity contrast across the selected profiles. The VES data processing involved an automatic approximation of the initial resistivity and thickness of the geoelectric layers with IPI2Win and further filtering by WinResist iteration. Estimation of Dar-Zarrouk parameters was also employed to investigate the aquifer protective capacity of the area. The processed VLF-EM results showed the geology of the area to an average depth of 25 m. The geoelectric section of the VES data revealed minimum of 3 layers from sandy top soil to weathered layer and fresh basement with an average resistivity values of 1,816, 926 and 17,503 Ωm, respectively. The integration of VLF-EM and VES in the investigation revealed that the potential for groundwater exploration in the study area is poor due to the thin nature of the weathered layer and its shallow depth to basement. The aquifer protective capacity of the area was likewise inferred to be poor.

scholarly journals Evaluation of Topsoil Competence, Aquifer Types, Groundwater Prospect and Flow Pattern using Geoelectric Characterization for Part of Ogbomoso, Nigeria

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
O. G. Bayowa
Keyword(s):  
Groundwater Flow ◽  
Flow Pattern ◽  
Flow Direction ◽  
Groundwater Potential ◽  
Water Levels ◽  
Groundwater Prospect ◽  
Southwestern Nigeria ◽  
Fractured Bedrock ◽  
Resistivity Method ◽  
Weathered Layer

Part of Ogbomoso Southwestern Nigeria was assessed using electrical resistivity method with a view to obtaining the subsurface geoelectric parameters (resistivities and thicknesses), categorizes the topsoil into different competence zones and evaluates the aquifer types, groundwater prospect and flow pattern. Fifty-four Vertical Electrical Sounding (VES) data were quantitatively interpreted using the partial curve matching technique to obtain the preliminary layer parameters which were further refined through 1-D forward modelling WinResist software package. The resulting final layer parameters were used to generate 2D geoelectric sections, isopach and isoresistivity maps and subsequently used to categorize the study area into different topsoil Competence, Aquifer types and Groundwater Potential zones. Static water levels of hand-dug wells in the area were used to generate the groundwater flow pattern. Four subsurface geoelectric layers were delineated. These were the topsoil, laterite, weathered/partly weathered layer (main aquifer) and fractured/fresh bedrock. The resistivities and thicknesses of the layers were 76-1858, 649-2021, 17-880 and 260-33385 Ωm and 0.4-4, 0.7-1.9 and 1.9-25.2 m respectively. The groundwater flow pattern in the area was NE-SW. The study concluded that incompetent to highly competent topsoil, weathered bedrock (main) aquifer unit/partly weathered/fractured bedrock aquifer and generally low groundwater potential with NE-SW flow direction underlay the study area.

scholarly journals Spatial Resistivity Mapping of Ureje Dam Floor, Southwestern Nigeria

2020 ◽  
Vol 66 (4) ◽  
pp. 245-255
Author(s):  
J.O. Fatoba ◽  
A.B. Eluwole ◽  
O.A. Sanuade ◽  
M.T. Aroyehun
Keyword(s):  
Storage Capacity ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Water Storage Capacity ◽  
Fractured Bedrock ◽  
Resistivity Method ◽  
Cumulative Response ◽  
Weathered Layer ◽  
Electrical Sounding

AbstractUreje Dam, Ado-Ekiti has witnessed drastic reduction in the water storage capacity of its reservoir. It became imperative to determine the possible cause(s) of the reduction in storage capacity. Geophysical investigation involving the vertical electrical sounding technique of the electrical resistivity method was conducted in the upstream part of the dam. Five lithologic units that include the mud/suspended materials, such as sandy clay, clay, weathered/fractured bedrock and fresh bedrock, were delineated. The respective resistivity and thickness range of the units are 2–19 ohm-m; 147–206 ohm-m, 2–38 ohm-m; 47–236 ohm-m and 455–1516 ohm-m and 0.4–1.9 m; 0.5–2.5 m; 1.0–12.2 m; 7.3–16.4 m and ∞. The thickness of suspended materials, resistivity/thickness of weathered layer and the presence of near-surface impervious layer were used as the main indices for the spatial demarcation of the dam axis in terms of vulnerability to loss of impounded water. Using the cumulative response of the indices, the study concluded that the eastern to southeastern parts of the dam axis showed the highest indications of vulnerability to loss of impounded water.

Impact Assessment of Dumpsite Effect on Groundwater Quality Using Geophysical and Geochemical Techniques in Balogun Iwaya, Lagos Southwestern Nigeria

2021 ◽  
Vol 47 (2) ◽  
pp. 225-234
Author(s):  
A.A. Alabi ◽  
O.I. Popoola ◽  
O.T. Olurin ◽  
A.S. Ogungbe ◽  
A.O. Adewale ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Quality ◽  
Impact Assessment ◽  
Great Influence ◽  
Physicochemical Analysis ◽  
World Health ◽  
Southwestern Nigeria ◽  
Low Resistivity ◽  
Subsurface Layers ◽  
The Impact

Waste disposal and management is a challenge in developing countries and has great influence on the groundwater quality. This research aimed at assessing the impact of leachate on nearby wells within the vicinity of active dumpsite in Yaba, Lagos, Nigeria. Four vertical electrical sounding and four electrical resistivity tomography using Schlumberger and Wenner electrode configurations respectively were carried out at the dumpsite. Physicochemical analysis of water samples from neighbouring wells were also conducted. The geo-electric curve showed four different subsurface layers. The electrical resistivity surveys revealed low resistivity values of s uspected leachate between 1.77 and 39.1 Ωm at a maximum depth of 20.8 m from the subsurface. The leachate polluted area is characterized by low resistivity values ranging from 1 to 10 Ωm, the thickness ranged from 0.5 to 9.2 m and the dir ection of leachate flow is from the northeast to southwest of the canal. The physicochemical analysis revealed that SO42- (70 - 89 mg/l) and Cl- (115.7 - 190.5 mg/l) have values within the World Health Organization (WHO) permissible limit. The pH (5.08 - 6.07), Electrical conductivity (774-1028 μS /cm) and the total dissolved solids values fall below WHO limit. The impact assessment of dumpsite effect revealed that the groundwater quality was affected by the leachate flow.

scholarly journals Integrasi Metode Resistivitas, Seismik Refraksi, Geologi Berbasis Geospasial untuk Identifikasi Potensi Longsor di Srimartani, Yogyakarta

2021 ◽  
Vol 1 (2) ◽  
pp. 109-122
Author(s):  
Besse Nurul Luthfiani Azis ◽  
Ketut Arya Wikranta ◽  
Nur Siti Anifah ◽  
Wihdah Syamsiyah Q Syamsiyah Q ◽  
Dirga Wahyuzar
Keyword(s):  
Slip Plane ◽  
Seismic Refraction ◽  
Research Area ◽  
Potential Zone ◽  
Resistivity Method ◽  
Site Survey ◽  
Weathered Layer ◽  
Dipole Configuration ◽  
Subsurface Resistivity ◽  
The Impact

Kabupaten Bantul merupakan salah satu kabupaten yang berpotensi terjadi tanah longsor, tepatnya di daerah Srimartani, Kecamatan Piyungan. Penelitian ini dilakukan dengan tujuan untuk mendapatkan data dan informasi mengenai parameter metode geofisika daerah longsor dan mengetahui dugaan zona potensi longsor. Metode yang digunakan dalam penelitian ini adalah survei lokasi, akuisisi metode seismik refraksi, akuisisi metode resistivitas, dan pemetaan foto udara (geospasial). Dari penampang bawah permukaan seismik refraksi metode hagiwara didapatkan bahwa lapisan lapuk pada daerah riset berupa soil dan pasir tuffan dikarenakan memiliki sifat permeable dan bidang gelincirnya yang bersifat impermeable. Pada penampang bawah metode seismik refraksi lapisan pertama yaitu soil dengan kecepatan V1 sekitar 313.8 m/s – 461.6 m/s dan lapisan kedua yaitu pasir dengan kecepatan V2 sekitar 459 m/s – 1567 m/s. Sementara penampang bawah permukaan metode resistivitas konfigurasi dipole – dipole didapatkan lapisan lapuk tersebut memiliki nilai resitivitas yang kecil dikarenakan lapisan tersebut bersifat lunak sehingga ada kemungkinan lapisan tersebut dalam kondisi basah. Pada penampang resistivitas memiliki nilai 126 ohm.m hingga lebih dari 301 ohm.m, daerah tersebut diperkirakan terdapat batuan breksi batuapung dari formasi semilir yang diduga sebagai bidang gelincir. Dari segi geologi, daerah penelitian sangat rentan terjadi tanah longsor dikarenakan kondisi lereng searah dengan kondisi struktur regional di daerah penelitian yaitu barat-timur, didukung oleh kondisi batuan yang ada berupa breksi batuapung dan tuff yang sangat rawan terjadi longsor. Dengan adanya penelitian ini, diharapkan dapat menambah pengetahuan mengenai antisipasi masyarakat dalam meminimalisir dampak yang ditimbulkan dari adanya tanah longsor. Bantul Regency is one of the districts that have the potential for landslides to occur, precisely in the Srimartani area, Piyungan District. This research was conducted with the aim of obtaining data and information about the parameters of the geophysical method of landslide areas and knowing the alleged landslide potential zone. The methods used in this research are site survey, seismic refraction acquisition method, resistivity method acquisition, and aerial photography (geospatial) mapping. From the subsurface seismic refraction of the Hagiwara method, it was found that the weathered layer in the research area was soil and sand due to its permeable properties and impermeable slip plane. . In the lower section of the seismic refraction method, the first layer is soil with a V1 velocity of around 313.8 m/s – 461.6 m/s and the second layer is sand with a V2 velocity of about 459 m/s – 1567 m/s. While the subsurface resistivity method of the dipole - dipole configuration found that the weathered layer has a small resistivity value because the layer is soft so there is a possibility that the layer is in a wet conditionIn the cross section resistivity has a value of 126 ohm.m to more than 301 ohm.m, the area is estimated to contain pumice breccia from the breccia formation which is thought to be a slip plane. In terms of geology, the research area is very susceptible to landslides because the slope conditions are in line with the regional structural conditions in the research area, namely west-east, supported by the existing rock conditions in the form of pumice breccia and tuff which are very prone to landslides. With this research, it is hoped that it can increase knowledge about community anticipation in minimizing the impact of landslides.

scholarly journals Assessment of Hydrogeological Potential and Aquifer Protective Capacity of Odeda, Southwestern Nigeria

2020 ◽  
Vol 66 (3) ◽  
pp. 199-209
Author(s):  
J.O. Aina ◽  
O.O. Adeleke ◽  
V. Makinde ◽  
H.A. Egunjobi ◽  
P.E. Biere
Keyword(s):  
Groundwater Resources ◽  
Electrode Array ◽  
Electrode Spacing ◽  
Protective Capacity ◽  
Clayey Sand ◽  
Southwestern Nigeria ◽  
Current Electrode ◽  
Ogun State ◽  
Weathered Layer ◽  
Longitudinal Unit Conductance

AbstractHydrogeological assessment of groundwater resources was carried out with a view to evaluate the potential of the aquifers to provide portable water supply and access the distribution of electrical parameters of hydrogeologic units in some areas in Odeda, Ogun State, Nigeria. A geophysical survey using vertical electrical sounding (VES) with the Schlumberger electrode array, with half-current electrode spacing (AB/2) varying from 1 to 132 m was carried out at 30 different stations in the study area. The VES data were interpreted qualitatively and quantitatively. Three-to-five sub-surface layers consisting of topsoil, weathered layer consisting of clay, sandy clay, clayey sand and sand layers, and fractured/fresh basement were delineated. Layer resistivities and thicknesses obtained on the curves within the study area showed one main aquifer type, which is the fractured basement. The longitudinal unit conductance (ranging from 0.049720 to 1.4520000 mhos) of the study area aided the protective capacity to be rated into good, moderate and weak. About 33% of the study area falls within the weak protective capacity, 57% falls within the moderate protective capacity and 10% falls within the good protective capacity.

scholarly journals Geophysical Assessment of Groundwater Vulnerability to Diesel Contamination at a Telecommunication Mast in Adebayo Area, Ado-Ekiti, Southwestern Nigeria

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olaseeni Olayiwola ◽  
Fagbemigun Tokunbo ◽  
Ojo Bosede ◽  
Amosun Joel ◽  
Oyebamiji Ajibola
Keyword(s):  
Electrical Resistivity ◽  
Groundwater Vulnerability ◽  
Diesel Oil ◽  
Vertical Electrical Sounding ◽  
Geophysical Investigation ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Resistivity Method ◽  
Electrical Sounding ◽  
Electrical Resistivity Method

Abstract An appraisal of the groundwater vulnerability to contamination risk at Adebayo in Ado-Ekiti, Southwestern Nigeria, was carried out using the electrical resistivity method of geophysical prospecting. Two traverses of length 100 m each were established for both vertical electrical sounding (VES) and dipole-dipole. Six (6) Vertical Electrical Sounding (VES) and 2-D dipole-dipole profiling techniques of the electrical resistivity method were adopted for the geophysical investigation. The results show variations in resistivity values, depicting four to five geologic layers: the topsoil, laterite, weathered layer, fractured, and the fresh basement. It was observed from the correlation of the geoelectric section and 2-D resistivity image along traverse 1 (TR1) that the groundwater in the study area flows towards the southwestern part, and the fractured basement serves as a migration pathway to the diesel oil in the same direction as groundwater flow. The fractured basement (Well 2) with no lateritic cover has higher resistivity values compare to the fracture zone that was found directly under the mast which was overlain by the laterite. Comparing the resistivity values of Well 1 and 2, Well 2 that was drilled into the fractured basement has more traces of the contaminant than Well 1.

scholarly journals Geoelectrical and geotechnical investigation of foundation failure in and around Oroke high school, Akungba- Akoko, southwestern Nigeria

2020 ◽  
Vol 8 (2) ◽  
pp. 237
Author(s):  
Odundun O.A ◽  
Fagorite V.I ◽  
Rogbitan E.O
Keyword(s):  
High School ◽  
Shear Zones ◽  
Structural Features ◽  
Building Structures ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Geoelectric Section ◽  
Effective Measure ◽  
Resistivity Method ◽  
Sandy Clay

Engineering structures are designed and constructed with an air of lifelong expectancy. Moreover, building foundation may experience failure due to presence of concealed geologic features such as cavity and shear zones which can lead to subsurface subsidence. Hence, it is imperative, prior to building construction, to investigate the physical properties of foundation soils and determine its suitability for design and construction of building structures. In the light of this, a geoelectric survey, involving three (3) electrical dipole - dipole array and geotechnical analysis methods were carried out around a distressed building at Oroke High School, opposite Adekunle Ajasin University, Akungba Akoko to establish the cause of failure for the structures foundation via delineating the subsurface structural features. The field electrical data were plotted on log –log graph sheets and the resulting curves were interpreted qualitatively by visual inspection, and quantitatively via partial curve matching and computer iteration techniques. For the geotechnical analysis, a total of twelve (12) soil samples were taken from different locations of about 30 meters intervals, at the depth of 1.5 meters. The pseudo – section and electrical sections indicate that the subsurface is heterogeneous in geological composition. The 2D dipole- dipole resistivity and pseudo – section delineated zones having resistivity values ranging from 200 to 700ohm meter, and those approaching infinity all within a depth of 0-5 m, the resistivity values of 27 to 139ohm meter suggest the presence of clay. The geoelectric section identified three subsurface geologic layers comprising clay /sandy, clay top soil / sub grade soil, clay / sandy clay and sand weathered layer and the basement (fresh) beneath the failed segment. Additionally, prominent fractures were discovered within some areas on the pseudo-sections. The results of the laboratory tests also included those of natural moisture content, specific gravity, grain size distribution curves, Atterberg limit, compaction test and California Bearing Ratio (CBR). In conclusion, electrical resistivity method was found to be an effective measure or tool in the site characterization. The soil/rock in these zones may require reinforcement in order to enhance its bearing capacity and increase the life span of the engineering foundation.  

scholarly journals Application of Electrical Resistivity Method in Site Characterization along Ado – Afao Road, Southwestern Nigeria

2018 ◽  
pp. 1-16
Author(s):  
S. O. Ilugbo ◽  
A. D. Adebiyi ◽  
S. O. Olaogun ◽  
T. Egunjobi
Keyword(s):  
Clay Content ◽  
Geophysical Investigation ◽  
Clayey Sand ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Resistivity Method ◽  
Sandy Clay ◽  
Geophysical Study ◽  
Weathered Layer ◽  
Subsurface Layers

A geophysical study was carried out at a proposed location for the construction of a structure along Ado-Afao road, Southwestern Nigeria. The aim of the study is to evaluate the electrical properties of the soil for Founding of Engineering structures. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration with a total of twenty-one (21) VES within the investigated area. The electrode separation varies from 1 to 100 m. The geoelectric sections identified three to five geoelectric/geologic subsurface layers along the traverses. The topsoil comprising of clay, clayey sand and sandy clay with the resistivity values range from 28 to 800 Ω-m with its thickness varying from 0.4 to 1.9 m. The second layer was found to be lateritic with resistivity ranging between 200 to 800 Ω-m and thickness ranges from 1 to 7.5 m while the weathered layer comprising of clay, clayey sand and sandy clay with resistivity varies from 30 to 220 Ω-m and its thickness varies from 1.2 to 54 m. The fractured basement with resistivity value of 763 Ωm and thickness value of 8m while the fresh basement has a resistivity value ranging from 365 to 2964 Ωm with depth to basement ranging from 8 to 58 m. The resistivity values of the topsoil are indicative of clay, sandy clay and clayey sand. This layer may not be of any special interest since topsoil is normally excavated. Hence, foundation of the proposed structures cannot be found on this layer. Based on the investigation, the subsurface of the study area can be generally classified as incompetent. There is a presence of lateral inhomogeneity of the subsurface layers and geologic features such as fractures and faults. The construction in the area should be founded on the lateritic layer or fresh basement layer coupled with pile foundation to ensure the stability of the building. The choice of foundation material, clay content and topography elevation should be put into consideration.

scholarly journals Hydro-geologic, Corrosivity and Geotechnical Implications of Geoelectric Sounding Survey at FUTA Cooperative Housing Estate, Ilaramokin near Akure Southwestern Nigeria

2020 ◽  
pp. 40-50
Author(s):  
I. A. Adeyemo ◽  
V. O. Iwuala ◽  
T. S. Fadare ◽  
E. O. Otayemi
Keyword(s):  
Groundwater Potential ◽  
Housing Estate ◽  
Engineering Structures ◽  
Southwestern Nigeria ◽  
Low Resistivity ◽  
Cooperative Housing ◽  
Weathered Layer ◽  
Subsurface Layers ◽  
Electrical Sounding ◽  
Structural Failures

Aim: Groundwater potential evaluation, corrosivity and geotechnical competence investigations of the subsurface layers were carried at FUTA Cooperative Housing Estate, Ilaramokin near Akure Southwestern Nigeria in order to facilitate proper positioning of facilities within the estate. Methodology: A total of 14 vertical electrical sounding (VES) data was acquired across the estate using Schlumberger array. Results: The VES survey results delineated 3 - 5 geoelectric layers across the estate which corresponds to the topsoil, weathered layer, partially weathered basement, partially fractured basement and the presumed fresh bedrock. The groundwater potential map of the estate revealed that the groundwater potential is moderate (GWP of 0.5 - 0.75) to high (GWP of 0.75 - 1.0) in the western and southeastern parts of the estate. The depth slice corrosivity maps (1.0, 2.0 and 3.0 m) of the estate indicated that the corrosivity of the subsurface layers within the estate reduces with depth. The 0.5 m depth slice isoresistivity map of the estate indicates that the central and a segment of the southwestern parts of the estate are characterized with low resistivity (50 - 100 Ωm) indicating incompetence, while the estate flanks (west and east) are considered to be moderately competent (100 - 350 Ωm). Likewise, the 1.0 m depth slice isoresistivity map of the estate reveals that the central and western parts of the estate are characterized with low resistivity (50 - 100 Ωm) suggesting incompetent layer, while the northern, southern and eastern parts of the estate are moderately competent (100 - 350 Ωm). Conclusion: These results suggested that structural failures can be expected on any engineering structures sited at the central, northern, southern and eastern parts of the estate. Groundwater efforts should be concentrated at the western and southeastern parts of the estate.

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