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 Aquifer Protective Capacity and Groundwater Potential in Part of Iju, Akure-North, Ondo State, Nigeria

2020 ◽  
pp. 197-204
Author(s):  
A. Olajide ◽  
S. Bayode ◽  
T. Fagbemigun ◽  
A. Oyebamiji ◽  
J. Amosun ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
Low Frequency ◽  
Groundwater Potential ◽  
Electrode Spacing ◽  
Protective Capacity ◽  
Value Range ◽  
Weathered Layer ◽  
Ondo State ◽  
Geological Units ◽  
Matching Techniques

Groundwater potential and aquifer protective capacity of the overburden unit was evaluated in part of Iju, Akure North, Ondo State using integrated geophysical methods involving Very Low Frequency Electromagnetic (VLF-EM) profiling and Vertical Electrical Sounding (VES). Four major traverses were established of varying length extents. The VLF-EM measurements were taken along the four major profiles of 10 m station interval.Forty two (42) Vertical Electrical Soundings were also conducted with half electrode spacing varying between 1 and 100 m and interpretation was done using the partial curve matching techniques and computer aided iteration. Five subsurface geological units were identified from geoelectric sections, consisting of the top soil, lateritic, weathered, partly weathered and fresh basement layers consecutively. For the first layer, resistivityranges between 23 and 323 Ωm with values of thickness ranging between 0.5 and 2.2 m. The resistivity and thickness of the second (lateritic) layer range from 132 to 430 Ωm and 1.6 to 4 m respectively. The resistivity of the weathered layer ranges from 4 to 94 Ωm and variable thickness between 10 and 24.4 m. The fourth layer has a resistivity value range of 65 to 120 Ωm and thicknesses between 20 and 30 m. The basement bedrock (fifth layer) has resistivity values between 770 and 820 Ωm. The depth to bedrock ranges from 1.8 to 31 m. The geophysical data and the basement aquifer delineated were then used to evaluate the hydrogeological setting and aquifer protective capacity of the study area. The observation from the results shows that close to 70 % of the study area falls within the zones of low groundwater potential, 25 % falls within medium potential zones while only 5 % make up the high potential zones. 75 % of the study area constituted the weak to poor protective capacity zones.  

scholarly journals Hydrogeophysical investigation of groundwater potential and aquifer vulnerability prediction in basement complex terrain – A case study from Akure, Southwestern Nigeria

2016 ◽  
Vol 63 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Opeyemi J. Akinrinade ◽  
Rasheed B. Adesina
Keyword(s):  
Low Frequency ◽  
Groundwater Potential ◽  
Aquifer Vulnerability ◽  
Hydraulic Gradient ◽  
Protective Capacity ◽  
Real Component ◽  
Southwestern Nigeria ◽  
Reconnaissance Survey ◽  
Transverse Resistance ◽  
Optimum Position

AbstractThis study provides a model for the prediction of groundwater potential and vulnerability of basement aquifers in parts of Akure, Southwestern Nigeria. Hydrogeophysical surveys involving very-low-frequency electromagnetic (VLF-EM) profiling and electrical resistivity (ER) sounding, as well as evaluation of hydraulic gradient using three-point method, were carried out. Ten VLF-EM reconnaissance survey traverses, with lengths ranging from 55 m to 75 m, at 10 m station separation, and 12 vertical electrical sounding (VES) stations were occupied. Two-dimensional map of the filtered real component reveals areas of high conductivity, indicative of linear features that can serve as a reservoir or conduit for fluid flow. Interpretation of the VES results delineates three to four geoelectric units. Two aquifer zones were identified, with resistivity values in the ranges of 20 Ωm to 310 Ωm and 100 Ωm to 3,000 Ω m, respectively. Transverse resistance, longitudinal conductance, coefficient of anisotropy and hydraulic gradient have values ranging from 318.2 Ωm2 to 1,041.8 Ωm2, 0.11 mhos to 0.39 mhos, 1.04 to 1.74 and 0.017 to 0.05, respectively. The results of this study identified two prospective borehole locations and the optimum position to site the proposed septic system, based on the aquifer’s protective capacity and groundwater flow properties.

Identification of lithological units using geo-electrical method, Olabisi Onabanjo University Campus, Southwestern Nigeria

2021 ◽  
Vol 20 (1) ◽  
pp. 171-182
Author(s):  
S.A. Adekoya ◽  
H.T. Oladunjoye ◽  
J.O. Coker ◽  
O.A. Adenuga
Keyword(s):  
Subsurface Layer ◽  
Groundwater Potential ◽  
Imaging Data ◽  
Southwestern Nigeria ◽  
Electrical Method ◽  
Type Curves ◽  
Overburden Thickness ◽  
Weathered Layer ◽  
Porosity And Permeability ◽  
Subsurface Resistivity

The study presented the results obtained from estimation of the depth to the bsement bedrock (overburden thickness) in Olabisi Onabanjo University, Ago-Iwoye using two configurations of electrical resistivity methods. The study was aimed to delineate the stratigraphy and thicknesses of the subsurface layer present in the study area for comprehensive study of the lithostratigraphic information of the area. Vertical Electrical Sounding (VES) and 2-D Horizontal Electrical Profiling (HEP) techniques were used to obtain 1-D and 2-D subsurface resistivity images of the study area. The VES data were plotted manually on the Bi-log graph. The curve obtained was partially curve – matched to obtain the layer resistivities and thicknesses for further iteration. The 2-D resistivity imaging data were analyzed and processed to obtain the inverted (true) resistivity image. From the results, five (5) VES type curves weredelineated. These includes H, HA, QH and KH type. The geoelectric sections and 2-D resistivity images showed three to four geoelectric layers. These layers are topsoil/laterite, weathered basement, partly weathered/fractured basement and fresh basement. The study showed that materials with resistivity values that ranged between 10 and 298 Ωm and 152 and 589 Ωm representing clayey weathered layer and partly weathered/fractured basement were delineated beneath some sounding points. The clayey and weathered layer are indicative of soil formations that are inimical to foundation of civil engineering structure. Likewise, they can serve as reservoir for groundwater potential (if the porosity and permeability are high). Due to this, detailed lithostratigraphic evaluation through petrophysical analysis is encouraged for the purpose of mapping and correlation of the rock units before embarking on any engineering construction in the study area. The study concludes in providing assistance to subsequent research on the stratigraphic related studies in the area. Keywords: Geo-electric , Stratigraphy, Lithology, Layer,

scholarly journals Combining Resistivity and Aeromagnetic Geophysical Surveys for Groundwater Exploration in the Maghnia Plain of Algeria

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Djamel Boubaya
Keyword(s):  
Groundwater Potential ◽  
Groundwater Exploration ◽  
Magnetic Data ◽  
Geoelectric Section ◽  
Resistive Layer ◽  
Near Surface ◽  
Groundwater Aquifer ◽  
Geophysical Surveys ◽  
Schlumberger Sounding ◽  
Topsoil Layer

The Maghnia plain in western Algeria is filled by Plio-Quaternary and Miocene sediments that rest unconformably on a basement of Jurassic rocks. Electrical sounding (VES), magnetic data, well information, and hydrogeological data have been used to explore for groundwater potential in the Maghnia plain. The interpretation of Schlumberger sounding data was first calibrated with the lithology of available nearby wells. Four geoelectrical layers were identified within the study area. They are a thin near surface topsoil layer with variable resistivities, a moderate resistive aquifer (15–30 ohm-m), a resistive aquifer (40–70 ohm-m), and a conductive clay layer (1–10 ohm-m). Near Sidi Mbarek, the geoelectric section is reduced to three layers: a topsoil layer, a conductive layer corresponding to the Miocene marls, and a deep resistive layer that correlates with the Oxfordian sandstones. The interpretation of VES data and the enhancement techniques of magnetic data enabled the identification of a number of unmapped faults that occur near recharge zones close to adjacent mountains. This study enabled us to study the extension of the known Plio-Quaternary aquifer of the Maghnia plain and to explore the possible existence of a second deep groundwater aquifer in Oxfordian sandstones.

scholarly journals Investigation of Groundwater Potential Using Electromagnetic Method at a Basement Complex Area of University of Abuja, Gwagwalada

2021 ◽  
Author(s):  
Onoka Adokiye ◽  
Mallam Abu
Keyword(s):  
Current Density ◽  
Clayey Soil ◽  
Low Frequency ◽  
Current Density Distribution ◽  
Groundwater Potential ◽  
Groundwater Exploration ◽  
Electromagnetic Method ◽  
The North ◽  
Overburden Material ◽  
Soil Component

The Very Low Frequency Electromagnetic Method (VLF-EM) was used in view of detecting fractured or weathered zones within the University of Abuja Staff Quarters, Gwagwalada, Federal Capital Territory. The VLF -EM data measured along seventeen profiles of 400m at inter profile distance of 25m and interstation separation of 10m were done using the Scintrex ENVI Instrument. The VLF-EM survey revealed features significant to groundwater potential as conductive zones in the Fraser Filter maps and current density pseudosections. Three distinct zones were delineated based on the current density distribution. The fresh basement terrain corresponds to the highly resistive zone with current density value less than -20. The intermediate zone has current density value range of -20 to 25 typical of rocks and soil component which are slightly resistive to slightly conductive and corresponds to the partially saturated units. The third zone is highly conductive with current density value greater than 30 which includes the saturated weathered or fractured basement, fault zones, clay units and saturated sandy units within the study area. The north eastern, north western (profiles 1-8) and some parts of the southern region (profiles 16 and 17) of the study area show higher conductive zones than the central parts of the study area. This survey has helped in detecting sites that are suitable for groundwater exploration by identifying water bearing fractures and weathered zones in the study area. The areas with high conductivity response are areas with conductive overburden material such as clayey soil, saturated soil, water filled fractures and faults or weathered zone within the basement.

Geophysical Surveys in Engineering Geology Investigations With Field Examples

2018 ◽  
pp. 257-280
Author(s):  
Ali Aydin ◽  
Erdal Akyol ◽  
Mahmud Gungor ◽  
Ali Kaya ◽  
Suat Tasdelen
Keyword(s):  
Geophysical Methods ◽  
Soil Layer ◽  
Low Frequency ◽  
Groundwater Exploration ◽  
Sufficient Information ◽  
Surface Mapping ◽  
Geophysical Field ◽  
Survey Techniques ◽  
Geophysical Study ◽  
Electrical Sounding

This chapter focusses on geophysical survey techniques, employed in engineering geological investigations and it includes case studies. Goal of a geophysical study in an engineering geological research is to display discontinuities in the rock masses, physico-mechanical properties of soils and rocks, groundwater exploration, faults, landslides, etc. It is also helpful to learn type and thickness of soil, layer inclination. These techniques include engineering geological surface mapping, geotechnical drilling and in situ testing.Then the obtained geophysical field data are analyzed and interpreted in conjunction with the results of geological information.The most common geophysical methods namely seismic, magnetometric, vertical electrical sounding (VES), Very Low Frequency (VLF) Electromagnetics methods, ground penetration radar (GPR) provide sufficient information about the subsurface although they have their limitations, setting up the minimum tests requirements in relation to the type of the geological formations.

Bedrock topography from magnetic anomalie—An aid for groundwater exploration in hard‐rock terrains

Geophysics ◽  
1991 ◽  
Vol 56 (7) ◽  
pp. 1051-1054 ◽  
Author(s):  
H. V. Ram Babu ◽  
N. Kameswara Rao ◽  
V. Vijay Kumar
Keyword(s):  
Hard Rock ◽  
Unconfined Aquifer ◽  
Groundwater Potential ◽  
Groundwater Exploration ◽  
Magnetic Method ◽  
Magnetic Response ◽  
Basement Rock ◽  
Bedrock Topography ◽  
Weathered Layer

The role of the magnetic method in groundwater exploration is to locate structures such as dikes, faults, fractures, etc., that control the accumulation and movement of groundwater. In hard‐rock terrains, the thickness of the weathered layer is an important parameter that determines the quantity of groundwater accumulated in the unconfined aquifer above the basement. The basement rock, in the process of weathering, loses its magnetic properties and becomes much less magnetic. Therefore, the magnetic response is mostly due to the unweathered hard basement rock, and the depths of magnetic sources obtained from the analysis give us the top of the basement. Information about the thickness of the weathered layer would help in assessing the groundwater potential of the region.

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.

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