Geophysical and Hydrochemical Evaluation of Groundwater Potential and Character of Abeokuta Area, Southwestern Nigeria (original) (raw)
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The electrical resistivity method was used to determine the groundwater potential of Ogidi and its environs. Thirteen soundings were carried out at thirteen different locations using the ABEM terrameter (SAS 1000), and adopting the Schlumberger configuration with maximum current electrode spacing of 1000 m. The lithologic logs for the boreholes were used to delineate the geologic sections. The results revealed six to nine geo-electric layers comprising laterite, clayey sandstone, sandstone, water-saturated sandstone and shale. The water-saturated sandstone forms the aquiferous unit. This unit was found to have resistivity values ranging from 363Ωm to 9107Ωm. It is deeply seated in some areas with a depth of 33.2-103 m. It was observed that the hydraulic conductivity varies between 0.001 and 0.066 m/day, while the transmissivity values vary between 0.01 and 4.7 m 2 /day. Among all the VES points studied, it was observed that VES 1 has the highest transmissivity value and the highest aquifer thickness. In view of the foregoing, it is expected that water will flow more from aquifer in VES 1 since groundwater flow from an aquifer is directly proportional to transmissivity.
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Tanzania Journal of Science, 2021
Hydrogeophysical study involving the use of Vertical Electrical Sounding (VES) was carried out in part of the basement complex rocks of Ilorin, central Nigeria, with the aim of determining its geoelectric parameters and groundwater potential. A total of thirty (30) VES were carried out using Schlumberger electrode configuration, with half electrode separation (AB/2) varying from 1m to 100m. Information on the subsurface lithologies, overburden thickness and aquiferous layers were obtained from the different VES locations in the study area. From the quantitative interpretations of the data collected, using the method of curve matching with the Orellana-Mooney master curves and 1-D forward modeling with WinResist 1.0 version software, three to five lithologic units were identified in the study. These include: the topsoil, sandy/lateritic clay/laterite, the weathered basement, the fractured basement and the fresh bedrock which are predominantly of the ‘KH’ curve type (30%), followed by...
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2017
This research involved the use of electrical resistivity technique which is considered most appropriate for subsurface investigation of structures and/or lithologies associated with the occurrence of groundwater; to investigate the geo-electric characteristics of the subsurface formations that underlie the study area. The aim was to provide a data base for sustainable groundwater development in the study area. The geophysical investigation involved the acquisition of twenty two (22) vertical electrical sounding (VES) data via the ABEM terrameter SAS 300C model using the Schlumberger configuration. These were quantitatively and qualitatively analysed using partial curve matching and computer iteration to obtain subsurface information in the study area. The results obtained from the interpretation of the VES data show earth models with geo electric layers ranging from three (3) to four (4). The representative type curves are H, A, HA, QH, HK and KH types. The subsurface is made up o...
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Geophysical Investigation of Groundwater Potential of a Site in Obale Area of Akure, Nigeria
International Journal of Engineering Applied Sciences and Technology
Electrical Resistivity method using Vertical Electrical Soundings (VES) were carried out at a site in Aba-Oyo area FUTA Southgate area, Akure, Nigeria, with the aim to access groundwater potential of the site. The study area is underlain by crystalline rocks of the Precambrian basement complex of the Southwestern Nigeria. Twelve (12) VES were carried out using Schlumberger electrode array configuration with AB/2from 1 to 65m. The VES data generated were processed and interpreted using partial curve matching method and computer iteration techniques. The interpreted data revealed three to four geoelectric sections with varied thicknesses and resistivity. The top soil layer ranges from 44 to 181?m, lateritic clay layer ranges from 20 to 174?m, the weathered horizon resistivity ranges from 20.0 to 424.0?m while the competent rock/fresh rock has resistivity values greater than 424.0.3?m. The top soil layer resistivity and thickness ranges from 44 to 181?m and 0.4 to 2m, the lateritic cla...
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Geoelectrical, hydrogeochemical investigations were carried out in order to determine the groundwater potentials of Ehandiagu in Enugu state, southeastern Nigeria. Ehandiagu is underlain by the Nkporo Shale, which is a low permeability formation. Four vertical electrical sounding (VES), employing the Schlumberger electrode configuration, was carried out in the study area, with a maximum electrode separation of 580m. The VES data were modeled with the IPI2 WIN software. The VES curves were predominantly of the QH type. The lithologic succession consists of lateritic top soil, weathered bedrock, fractured shale (the aquifer) and compact carbonaceous shale. Results show that the depth to water ranges between 6.82m and 20.7m while aquifer thicknesses range between 8.95m and 26.26m. The depth to water obtained from hand-dug wells varies between 6.20m and 15.18m. Aquifer hydraulic conductivity and transmissivity were calculated to be 2.62 x 10-3 m/day and 4.31 x 10-2 m 2 /day respectively. These parameters were used to classify the aquifer as moderately good to poor aquifer. Hydrogeochemical analysis of groundwater samples collected from twelve (12) hand-dug wells in the study area reveals that weathering is the major process that controls the groundwater chemistry and the water type is Sodium-Potassium-Bicarbonate. The concentration of heavy metals (Mn, Fe, Pb) were found to be above the acceptable limits for potability and the SO 4 2-concentration is very low, probably due to sulphate reduction. Both sulphate reduction and high heavy metal concentration suggest a geochemical reducing environment.
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