Vertical Electrical Sounding (VES. Investigation of Aquifer and Potential Clay Materials in Douala Subbasin (Cameroon, Central Africa) (original) (raw)
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Geoelectrical Prospection of Aquifers in Eseka Region, Center-Cameroon
This geophysical study was carried out in the city of Eseka, the head quarter of Nyong and Kelle Division, Center Region of Cameroon. It had as aims to prospect aquifers and to propose models of geophysical structures of the underground basement in the city. To this effect, the geophysical method of electrical resistivity was chosen, due to the local geologic context, and its easy application. With the aid of a resistivitimeter of mark TERRAMETER ABEM SAS 300, twenty (20) electrical soundings were effectuated in different points in the city. The treatment of data was done through several interpretation softwares, such as Geo-Elect. Mod and surfer 8.0. Qualitative and quantitative interpretations, coupled with field and laboratory observations, permitted: the characterization of the lateritic crust constituted of the model of the terrain, into four and five layers of distinct terrain by their resistivity and thicknesses; the definition of the average depth of the upper aquifer from about three (03) meter in the loose clayey level, and the lower aquifer at about thirty (30) meter in the weathering and fractured gneiss level; the localization of the zone of conduction and resistant anomaly, at chosen depths in the study area. These results are important in future modeling process of the aquifers in this area.
SEG Technical Program Expanded Abstracts 2018
A knowledge of hydrogeophysical parameters of aquifers is essential for groundwater resource assessment, development and management. Traditionally, these parameters are estimated using pumping test carried out in boreholes or wells; but this is often costly and time consuming. Surface geophysical measurements can provide a cost effective and efficient estimates of these parameters. In the present work, geoelectrical resistivity data has been used to characterize and evaluate the aquifer potential at Covenant University, Ota, southwestern Nigeria. Some thirty-five vertical electrical soundings (VESs) were conducted using Schlumberger array with a maximun half-current electrode spacing (AB/2) of 240 m. The geoelectrical parameters obtained were used to estimate longitudinal conductance and transverse resistance of the delineated aquifer. Both the longitudinal conductance and transverse resistance, which qualitatively reflects the hydraulic properties of the aquifer, indicate that the aquifer unit is characterized with high values of hydraulic parameters; consequently a good groundwater potential. Thus, groundwater resource development and management in the area can be effectively planned based on these parameters.
Electrical Resistivity Survey for Predicting Aquifer at Onicha-Ugbo, Delta State, Nigeria
A geoelectric survey employing the vertical electrical sounding (VES) was carried out in parts of Onicha-Ugbo in Aniocha North Local Government Area of Delta State using Abem Terrameter SAS 300C together with SAS 2000 booster. The study was carried out with the aim of delineating the subsurface geologic sequence present in the study area, determining their geoelectrical parameters (layer thicknesses and resistivities), and delineating the structural and geomorphological features present beneath the subsurface. The results of the survey suggest that the subsurface comprises of 5 - 6 layers and that clay and silt content varies vertically and horizontally, thus influencing the apparent resistivity of the area. The geoelectric section developed shows that the subsurface units are dominantly sandy underlying loamy sandy topsoil which is relatively dry. The depth to water table from the sites is above 150 m and suggests that groundwater exploration is encouraging.A geoelectric survey employing the vertical electrical sounding (VES) was carried out in parts of Onicha-Ugbo in Aniocha North Local Government Area of Delta State using Abem Terrameter SAS 300C together with SAS 2000 booster. The study was carried out with the aim of delineating the subsurface geologic sequence present in the study area, determining their geoelectrical parameters (layer thicknesses and resistivities), and delineating the structural and geomorphological features present beneath the subsurface. The results of the survey suggest that the subsurface comprises of 5 - 6 layers and that clay and silt content varies vertically and horizontally, thus influencing the apparent resistivity of the area. The geoelectric section developed shows that the subsurface units are dominantly sandy underlying loamy sandy topsoil which is relatively dry. The depth to water table from the sites is above 150 m and suggests that groundwater exploration is encouraging.
International Journal of Science and Research (IJSR)
This paper presents an investigation of sub-surface layered and ground water characteristics using Vertical Electrical Sounding (VES). The study was conducted in the Mayo Kani area in Cameroon. One hundred VES were carried out using the Schlumberger array in order to determine the nature, characteristics and spatial extend of the components of subsurface layers. The data were analyzed by the software IP2WIN while the isoapparent resistivity maps were plot by the help of the software SURFER. The results gave H, K, A, HK, HA, QH, KH, HKH, HAA, and HKHK types associated to three, four, five and six layers. The geological sequence beneath the study area is composed of topsoil (clayey sandy, sandy-lateritic, gravel, and dry alluvium), weathered layer, unsaturated layer, saturated formation and bedrock. Aquifer is located either in the alterations, sand, or fractured rocks. The resistivity value for the topsoil layer varies from 4.32 Ω.m to 9756 Ω.m with thickness ranging from 0.5 to 13.1...
Groundwater Investigation Using Geoelectrical Method: A Case Study of the Western Region of Cameroon
Journal of Water Resource and Protection, 2013
A geoelectrical survey using the electrical resistivity method was carried out in some villages in the western region of Cameroon to investigate the sub-surface layers and evaluate the characteristics of aquifers. The direct current electrical resistivity method was utilized for the present study. Applying the Schlumberger array, a total of twenty four (24) Vertical Electrical Soundings (VES) were conducted. Quantitative and qualitative interpretations of data were carried out to determine the nature and thickness of the aquifer zone combined with existing litho-logs aided correlation of geoelectric sections to litho-logs. Four to five geoelectric layers were delineated from the survey area. The first layer which is the topsoil has resistivity values ranging from 6-949 Ωm and the thickness is between 0.2-4.2 m. The second layer which is made up of clay and laterite has resistivity values ranging between 9-1862 Ωm and thickness range from 1.0-16.4 m. The third and fourth geoelectric layers are made up of clay and granite/basalts with thickness varying from 2.2-39.5 m which corresponds to an aquifer horizon. Resistivity values of the aquifer ranges from 10 to 70,506 Ωm. The resistivity map drawn from these measurements shows the presence of a low resistivity zone which indicates the reflection in the direction of ground water from northeast to southwest with the recharge concentrated to the south of the study area. This study has revealed for this area, an average depth of the aquifer of 32 m with the average thickness of the aquifer being 22 m. The geoelectric sections of some VES stations demarcated corroborate very well with the geological description of the area.
Electrical resistivity investigation was carried out around Bomo area, Zaria, Kaduna state, in order to study the subsurface geologic layer with a view of determining the depth to the bedrock and thickness of the geologic layers. Vertical Electrical Sounding (VES) using Schlumberger array was carried out at fifteen (15) VES stations. ABEM terrameter (SAS 300) was used for the data acquisition. The field data obtained have been analysed using computer software (IPI2win) which gives an automatic interpretation of the apparent resistivity. The VES results revealed heterogeneous nature of the subsurface geological sequence. The geologic sequence beneath the study area is composed of hard pan top soil (clayey and sandy-lateritic), weathered layer, partly weathered or fractured basement and fresh basement. The resistivity value for the topsoil layer varies from 40Ωm to 450Ωm with thickness ranging from 1.25 to 7.5 m. The weathered basement has resistivity values ranging from 50Ωm to 593Ωm and thickness of between 1.37 to 20.1 m. The fractured basement has resistivity values ranging from 218Ωm to 520Ωm and thickness of between 12.9 to 26.3 m. The fresh basement (bedrock) has resistivity values ranging from 1215Ωm to 2150Ωm with infinite depth. However, the depth from the earth's surface to the bedrock surface varies between 2.63 to 34.99 m. The study further stressed the importance of the findings in civil engineering structures and groundwater prospecting.
2020
The interpretation of 10 schlumberger vertical sounding (VES) data was carried out at Karji area of Kaduna state, Nigeria. It was an attempt to investigate the variation in the resistivity values of earth materials as it varies with depth within the area. Ohmega Resistivity Terrameter was the principal instrument used. No booster was used as the expected depth is within the range of penetration of the instrument. In this instrument consecutive reading are taken automatically and the result averaged continuously and display. The schlumberger electrode configuration was used in the data acquisition. The field procedure consist of expanding AB (distance between current electrodes) while MN (distance between potential electrodes) is fixed. This process yields a rapidly decreasing potential difference across MN, which eventually exceeded the measuring capacity of the instrument; therefore a larger vale for MN was taken to continue with the survey. The VES curves were interpreted using IP...
Geological and Electrical Resistivity Sounding of Olokonla Area in North-Central Nigeria
Geological mapping and Electrical resistivity sounding were carried out in Olokonla area in Moro Local Government of Kwara State in order to determine the apparent resistivities of the subsurface lithologies and correlate them with the exposed rocks observed during the geological mapping. The studies also delineate the pattern of fractures in the area which form prefential pathways for ground water. Three vertical electrical soundings (VES) were performed radially adopting the Schlumberger electrode configuration, with half-current electrode separation (AB/2) varying from 1m to 100m. Anisotropy polygon was also constructed based on the radial electrical sounding. The geoelectric parameters revealed five subsurface layers which were interpreted as topsoil, lateritic soil, dry sand soil, weathered granite and granite respectively. The geological mapping showed that the area is underlain by crystalline rocks comprising biotite granite, granite-gneiss and migmatite. The anisotropy polygon showed that a major fracture direction along 60 0 (northeast to southwest) and the coefficient of anisotropy is 0.79. Based on the apparent resistivities and the structural disposition, a potential aquifer was inferred at a depth of 45m. The fracture pattern in the area was constrained to northeast to southwest direction. The data obtained would be useful in borehole drilling for water within the study area.
Geoelectrical-Geotechnical Studies for Near Surface Characterization , Case History : Lagos , SW
2016
Incessant building collapse and foundation failures in Nigeria have continued unabated in recent years, causing loss of lives and properties worth hundreds of thousands of US dollars. This research in Gioni estate Lakowe, Lekki-Epe, Lagos, Nigeria is concerned with an integrated characterization of near-subsurface geomaterials using geoelectrical resistivity tomography and geotechnical techniques as part of the preliminary investigations for foundations studies and other building construction projects. Four traverses of the geoelectrical resistivity measurements using Wenner array configuration were conducted, and cone penetrating data were equally obtained along the same traverse. A borehole data point was equally acquired for ground thruthing. Based on their geoelectrical properties, three lithologies including loose sand, compacted clayey sand and clay/peat units were delineated with apparent resistivity values ranging 50 – 260 m Ω , 20 – 72.2 m Ω and ≤ 27.5 m Ω respectively. Ave...
2020
Geophysical investigation for engineering and environmental studies has been undertaken at the permanent site of Federal University Dutsin-ma, Katsina state. The study was aimed at assisting in the planning and development of infrastructure at the University, and also to investigate the groundwater potential of the permanent site at Turare which is less than 20km south of the current site the University occupies. Twenty-four Vertical Electrical Soundings (VES) were conducted along predetermined profiles at the permanent site in Dutsin-ma. Terrameter SAS 300 system was used for data acquisition at stations interval of 100m using Schlumberger array. Maximum current electrode separation (AB) of 200m was used. Interpretation was performed using computer software (Ipi2win and surfar7). The interpreted result was used to produce geoelectric and geologic sections. The result of the study indicated that the area is underlain by three to four subsurface layers. The resistivity of the first l...