scholarly journals The Use of Vertical Electrical Sounding (VES) for Subsurface Geophysical Investigation around Bomo Area, Kaduna State, Nigeria

2013 ◽  
Vol 3 (01) ◽  
pp. 10-15 ◽  
Author(s):  
B.S. Jatau

Application of geophysical investigation has been carried out using Vertical Electrical Sounding (VES) at the proposed site in wadi Ma’doo, Shabwah Governorate, Yemen to determine the geophysical parameters that can be used to evaluate the subsurface geological layering characteristics of the selection proposed site for dam construction. The Schlumberger array was used for the data acquisition. One-dimensional numerical inversion of individual DC resistivity was used to enhance the processing of the results for better achievement of the aim of the study. Model obtained from the 2D inversion of each VES were used for construction of geoelectric section which exhibit the main geoelectric characteristics of the geological units present in the site. The interpretation of the field data was carried out using the IP12WIN software, which converts the apparent resistivity as a function of electrode spacing to the true resistivity as a function of depth in two dimensions. The interpretation results showed that the geoelectric section consists of three layers namely: boulders and gravels, sandy to pebbly and hard limestone. The layer resistivities and thicknesses range from 18.17 to 746.20 Ω.m/0.20 to 1.084 m, 53 to 60 Ω.m/ 0.20 to 3.059 m and 455 to 1890 Ω.m, respectively. The investigation revealed that the limestone rocks is suitable for shallow foundation for proposed dam engineering structures.


2020 ◽  
Vol 18 ◽  
pp. 35-47
Author(s):  
M.A. Oladunjoye ◽  
K.O. Adejato ◽  
A.O. Ogunkoya

Integrated geophysical investigation involving Ground Penetrating Radar (GPR) and Electrical Resistivity methods were carried out at Medina Estate, Lagos southwestern Nigeria to map the subsurface lithology in order to delineate its peat stratigraphy that has been causing foundation failure in the area. Twenty-one traverses (varying from 35-880 m in length) of Ground Penetrating Radar (GPR) survey were conducted along the streets of Medina trending NE-SW and NW-SE directions using the Mala 250 MHZ bi-static shielded antenna. Thirty-six Vertical Electrical Soundings (VES) were carried out using Schlumberger electrode array at some selected points along the established traverses within the area. The GPR data were processed into radar section using Rad Explorer software. The VES data were interpreted quantitatively using the partial curve matching method and 1-D forward modeling with Win Resist Software. Available litho-logs from boreholes drilled within the area were compared with the geophysical results.  Results of the GPR survey delineated three geologic layers which include the topsoil with high amplitude, parallel to sub parallel, horizontal reflections, with thickness varying from 1 to 2 m across the entire profiles and composed of lateritic clay; peat layer with low amplitude, parallel sinuous/wavy reflections with depth of occurrence ranging from 2.0 to 8 m and clay with low amplitude, planar, horizontal, sub-parallel reflections underlying the peat layer. Vertical Electrical Sounding results revealed the presence of three geological layers which are the topsoil, peat and clay and sandy clay with layer resistivity values ranging from 20- 225 Ωm, 5 – 90 Ωm and 36 to 366 Ωm and thickness values ranging from 0.5 – 2 m, 4.0-29.0 m and infinity respectively. Borehole information confirms the occurrence of shallow peat with depth ranging from 1.5 to 9 m and clay layer with depth ranging from 9 to 21 m beneath the area. The GPR survey results correlates with the well logs acquired in the study area. Based on the correlation of the geophysical results with the well logs, the GPR gives better information about the peat layer compared to the Electrical ResistivityMethod. The information obtained from this study shows that the soils at shallow depth are organic soils which are difficult foundation materials because they exhibit very high compressibility, as such making shallow foundation impossible except some form of soil improvement is carried out. The alternative approach is the adoption of deep foundations in form of piles. Keywords: Foundation Failure, Geophysical Investigation, Ground Penetrating Radar, Vertical Electrical Sounding, Peat.


2019 ◽  
Vol 37 (2) ◽  
pp. 43-58
Author(s):  
A. N. Mumuni ◽  
J. S. Bayor

A geophysical investigation in groundwater prospecting, using the vertical electrical sounding (VES) method in resistivity surveying, was undertaken in the Tolon-Kumbungu district of Northern Ghana. The aim was to evaluate the effectiveness of the VES technique as a low-cost groundwater exploration method. Using the dipole-dipole VES technique, fracture zones that held good prospects for groundwater location were prospectively identified at 15 sites in the Gbullung and Wayamba communities of the district. In addition, retrospective VES data for 6 sites were obtained from previous studies. Geophysical VES data and available drill logs for 3 sites in the prospective study and all 6 sites in the retrospective study (a total of 9 sites) were then evaluated by the VES log-log graph interpretation method to establish a correlation with the groundwater characteristics of the study area. The analyses of the VES curves indicated the presence of anomalous fracture zones occurring within hard sandstone formations that had high groundwater potential. Weathered zones or fresh rock aquifers however did not show potential for groundwater. The dominant formations in the area were found to be thin-bedded sequences of sandstone, mudstone, shale, siltstone and their intercalations. Groundwater was confined to between the depths of 25.0 m and 40.0 m, with major aquifers occurring approximately between the depths of 34.0 m and 45.0 m. These predictions were confirmed by the available drill logs. Using the VES curve interpretation as a means of selecting promising water-bearing sites, 8 out of the 9 sites drilled were successful wells, recording water yields ranging from 14 L/min to 250 L/min, with an average yield of 87.3 L/min. The study thus showed that the dipole-dipole VES technique in groundwater prospecting is effective for the geology of the study area. Keywords: Tolon-Kumbungu; vertical electrical sounding; aquifer; groundwater; apparent resistivity 


Author(s):  
O. J. Airen ◽  
K. K. Oboshenure

A geophysical investigation involving 1D Vertical Electrical Sounding (VES), 2D Electrical Resistivity Imaging (2D ERI) and Multichannel Analysis of Surface Wave (MASW) has been carried out at Agege, Lagos, Nigeria with a view to delineating the subsurface stratigraphy and locate some competent strata/stratum for founding civil engineering structures. Six (6) 200 m long traverses were established within the study area. Along these traverses, 2D ERI were carried out adopting Wenner electrode configuration. Vertical Electrical Sounding (VES) adopting Schlumberger electrode array were carried out at selected points along profiles 1, 2 and 3 to determine the lithological sequence at depth. MASW data also were acquired along traverses 1, 2 and 3. The data were processed and the result yielded interpretable 2D resistivity structure and geoelectrical parameters (layer resistivity, thicknesses and depth) from the VES. The interpreted VES results were used to generate geoelectric section while the MASW resulted in 2D velocity sections. Three subsoils including topsoil, clay and clayey sand/sand were delineated beneath the study area. The resistivity and thickness range of the layers are; topsoil (34.0-54.6 ohm-m, 0.9 – 1.7 m), clay (10.3 – 17.7 ohm-m, 8.9 – 12.3 m) and clayey sand/sand (48.9 – 323 ohm-m) while the S-wave velocity range for the subsoil falls between 40 – 500 m/sec.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olaseeni Olayiwola ◽  
Fagbemigun Tokunbo ◽  
Ojo Bosede ◽  
Amosun Joel ◽  
Oyebamiji Ajibola

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.


Author(s):  
M. O. Ehigiator

Geophysical investigation was conducted at Okada community in ovia North Local Govertment area of Edo state to determine the prospect of aquifer zone. The Petrozenith PZ-02 Terrameter, one of the Electrical Resistivity Equipment was used to conduct a Vertical Electrical Sounding (VES) in the study area. The Garmin Etrex 10 Global Navigation satellite systems (GNSS) was used to acquire Geodetic coordinates of point where VES observations were made. This research was carried out as a pre-drilling Hydro-geophysical survey conducted for the purpose of surveying and studying the proposed water borehole site at Okada Community that has suffered acute water problems for a very long time. There have been series of boreholes drilled in the studied area but all are dry wells. This survey was conducted to investigate the subsurface complexity of the sites in respect of lithology and to recommend the total drill depth based on the prospective aquifer unit so identified. Result of interpretation suggests that the area is underlain with substantive aquiferous formation but at a depth not exceeding 121.60 m (398.95 ft), which is the lower aquifer unit. The value of elevation at point of observation referenced to mean sea level is 94 m.


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