An attempt to estimate the Curie-point isotherm depths in the Nupe Basin, West Central Nigeria

An estimate of Curie-point isotherm depths has been made in the northern part of the Nupe Basin, west of Central Nigeria, from the spectral analysis of aeromagnetic data. Curie-point, the temperature at which rocks lose theirferromagnetic properties, provides a link between thermal models and models based on the analysis of magnetic sources. The result of this study shows that the Curie isotherm depth varies between 12 and 30km in the study area. In the southern portion of the study area, the curie-depth was found above 28km while it was found to be less than 14km in the northern part. It had previously been discovered by earlier workers that Curie-point depths are shallower than 15km for volcanic and geothermal fields, between 15 – 25km for island arcs and ridges, and deeper than 20km in plateaus and trenches. Therefore, when the values for the study area are compared with these values, the areas with variations less than 15km maybe recommended for further geothermal reconnaissance studies

Estimation of Hydraulic Parameters from Dar-zarrouk Parameters for Aquiferous Zone Characterization in Iyesi Axis, Ota, Ogun State Nigeria

The cost of estimating hydraulic parameters from slug test, pumping test, soil sample analysis etc is expensive. However, these parameters such as transverse resistance and longitudinal conductance can be estimated from geophysical parameters which are cost effective, noninvasive and inexpensive. In this present study, twenty (20) geoelectric sounding were carried out in Iyesi- Jackross axis with the use of ABEM 1000 series terrameter using schlumberger array and AB/2 ranges from 240m to 420m. The result revealed that there are six lithological layers in the study area namely; topsoil, lateritic clay, clayey sand, kaolitic clay, clayey sand (low yield aquifer) and sand (Main aquifer). The aquifer’s depth ranges from 45.1m to 114.7 m with resistivity values ranges from 19.5 Ωm to 850.8 Ωm. Furthermore, transverse resistance and longitudinal conductance were estimated from geophysical parameters and it was observed that longitudinal conductance is low which ranges from 0.0127 Ω−1 to 0.0941 Ω −1 . Consequently, the aquiferous unit is characterized with high transmissivity and hydraulic conductivity. Transverse resistance ranges from 12246.00 Ωm2 to 124878.61 Ωm2 and increase in transverse resistance that was observed generally indicating high transmissivity and high yield of the aquiferous units. It is therefore signifies that the study area is characterized with good groundwater potential. Further study can be carried out to estimate the boundary of aquifer thickness and the possible intrusion of Basement complex using magnetic technique

GEO - SOLUTION TECHNIQUES FOR GROUNDWATER EXPLORATION

Groundwater has been one of the major purest sources of water in the world. This is because the source is been stored in an aquifer beneath the earth’s surface. However, exploring this source require certain skills or techniques in order to ease the trauma experienced by the searcher. Over the years various geophysical techniques have been applied to explore this source but with little or no success due to the approach. In this research therefore, aeromagnetic and electrical resistivity techniques were integrated to explore this source in Dahomey basin, southwestern Nigeria. The result established that no single geophysical technique can be used for detailed geophysical studies of an area. But the combination of these geophysical techniques yields better result because they complement each other

Regional Groundwater Studies Using Aeromagnetic Technique

Geophysical techniques have played a major role in subsurface investigation. These techniques include seismic, electrical, ground penetrating radar, gravity, electromagnetic, magnetic, etc. The problems that have been buffeting the geologist or geophysical researchers are in the wide coverage of any area of interest when investigating subsurface using these ground geophysical techniques. But the aeromagnetic technique has proven to be successful in this regard. Although the magnetic technique (aeromagnetic) has been applied successfully for mineral resources and hydrocarbon exploration, this study examins in detail the uniqueness of this technique (in terms of universality, acceptability and coverage) and its application to regional groundwater studies, especially where hydrogeophysical related equipment is not available. Furthermore, this aeromagnetic technique has been applied to determine the depth to magnetic source of Ado-Ota and environs in southwestern Nigeria. The result revealed that there are two geological environments in the study area, namely sedimentary and basement complex terrain which are very significant in groundwater studies. The shallow sources characterized the basement complex with depth ranges from 102.8 m to 246.1 m, and deep sources characterized sedimentary terrain from 710.0 m to 1,980 m

ESTIMATION OF AQUIFER TRANSMISSIVITY FROM GEO-PHYSICAL DATA. A CASE STUDY OF COVENANT UNIVERSITY AND ENVIRONS, SOUTHWESTERN NIGERIA

The combination of geoelectric resistivity layer and thickness in the Da-zarrouk parameters (such as longitudinal conductance and transverse resistance) has been proved to be useful in the evaluation of aquifers transmissivities around Covenant University and its environs. It was observed that the study area is underlain by the unconsolidated to semi-consolidated Coastal Plain Sand (Benin Formation). Geoelectrical resistivity method was used in the study. Sixteen geoelectric soundings known as Vertical electrical Sounding data was acquired in the study area using Schlumberger array configuration at maximum electrode spacing of 420 m. Four (4) geoelectric soundings were carried out in the area that near existing boreholes. Inverse resistivity model software was employed in processing the data. The result showed that the aquifer is shallow at depths that ranged from 30.6 m to 67.6 m, semi-deep at depths ranged from 70.8 m to 95.0 m and deep at depths that ranged from 96.0 m to 107.6 m. The thickness of the aquifers ranged from 14.0 m to 48.0 m. The hydraulic conductivities values ranged from 0.94 m/day to 12.83 m/day and transmissivity values ranged from 13.16 m2/day to 515.04 m2/day respectively. It is therefore hoped that this result would help the residents of the study area in terms of groundwater development planning and management

Groundwater for Sustainable Development Integration of aeromagnetic and electrical resistivity imaging for groundwater potential assessments of coastal plain sands area of Ado-Odo/Ota in southwest Nigeria

This study aims to investigate the groundwater potential of Coastal Plain Sands area of Ado-Odo/Ota within Dahomey Basin using the integration of aeromagnetic method and electrical resistivity imaging. The aeromagnetic method is applied to reveal the possible hydrogeological structures (such as lineament or fracture) buried in the subsurface. The lineaments which are interconnected are observed in the eastern part of the study area while the western part is void of the interconnectivity of lineaments. Resistivity technique is applied in regions where there are interconnectivity and noninterconnectivity of lineament to delineate occurrence of groundwater about the observed lineament. The depths to magnetic sources range between 102.6 and 1965.2 m. Furthermore, the result of resistivity technique shows that the depth to aquifer ranges from 40 to 100 m with corresponding resistivity values that range between 150.0 and 350.0 Ωm in the region of the interconnectivity of lineament, which is the eastern part of the study area (Igboloye-Covenant University area) and had high groundwater potential. The western part which is void of the interconnectivity of lineaments (Alapoti area) ranges from 80 to 130 m with resistivity values that range between 250.0 and 450.0 Ωm suggesting that the area has low groundwater potential. The study, therefore, shows that the occurrence of groundwater in Ado-Odo/Ota community is a function of hydrogeological structures such as lineaments or fractures, and as a result, this information could serve as guide for borehole drillers, civil engineers and resident of the study area for proper planning before siting borehole either for domestic or industrial use

Geo-investigation on groundwater control in some parts of Ogun state using data from Shuttle Radar Topography Mission and vertical electrical soundings

Groundwater is a vital natural resource that plays a significant function in sustainability of living things on earth. Its exploration requires special skill for optimum exploitation. Shuttle Radar Topography Mission (SRTM)and Vertical Electrical Sounding (VES) were used to detectthe stratigraphy and subsurface structures controlling the groundwater system around Iju – Ota, Ogun State, Southwestern Nigeria. Nineteen (19) VES points were carried out where there were dense concentrations of lineaments and interconnected to establish the connection of the observed lineaments with groundwater occurrence in the study area using Schlumberger array, with electrode spacing of AB/2 varying from 180 to 320 m. The analysis of SRTM data revealedthe dominating structural NE-SW and NW-SE trends, which control aquifer structure. The geoelectrical parameters from the VES results were used to map the stratigraphic sequences in the study area. Six (6) units that comprisethe topsoil, lateritic clay, clayey sand, mudstone, sand (main aquifer), and shale or clay were identified in the study area. The aquiferous unit around Iju – Ota axis ranged from 30 to 80 m. Theextracted from the hill shaded SRTM data and the result of VES revealed that the thickness of the aquifer is as a result of interconnectivity of the lineaments observed in the SRTM data suggesting that the groundwater occurrence in the study area is chiefly controlled by these fractures

Environmental Geochemistry and Heavy Metal Assessment in Soils, Surface and Groundwater from Eastern Niger-Delta, Nigeria using Multivariate Pollution Indices

In recent times, there have been increasing interests regarding heavy metal contaminations in the environments, apparently due to their toxicity and perceived persistency within the aquatic systems. Land and water are precious natural resources on which rely the sustainability of agriculture, industrialization and the civilization of mankind. They have been subjected to severe exploitation and contamination due to anthropogenic activities resulting from industrial effluent, refuse dumps, gas flaring, oil spillage and petroleum refining leading to the release of heavy metals into the environment. The results of the analyses indicate a low pH (3.84 – 7.74) and high concentrations of electrical conductivity (28.00 – 752.00), chloride (12.00 – 721.00) and heavy metals in the decreasing order of: Fe > Ni > Cu > Zn > Mn > Cd > V > Co > Pb > Cr > As > Hg. The heavy metal pollution index revealed that the metal pollution in the soil and water ranged from slightly polluted to very highly polluted. The poor sanitary condition coupled with the high degree environmental abuses in terms of oil spillage, gas flaring and industrial effluent in the area are responsible for the low pH, wide range in the concentration of EC, TDS, Chloride, E.coli, total coliform and  heavy metals in the soil and water system in the area. Good sanitation, use of welllined soakaway, treatment of industrial effluent before discharge and putting an end to gas flaring and oil spills are advocated. The use of environmentally friendly techniques such as bioremediation and phytoremediation in remediating the contaminated soil and water in the area is recommended

Comparative Assessment of Groundwater Suitability for Irrigation and Drinking Purposes in Agbara and Ota area of Southwestern Nigeria

The quality of water is measured in terms of its physical, chemical and bacteriological characteristics. Agbara and Ota area of southwestern Nigeria hosts many industries. These industries generate effluents which are discharged into the environment without any form of treatment, hence the need to ascertain the quality of water in the area for domestic and irrigation purposes. Water samples were collected and analyzed using standard laboratory techniques for physico-chemical and bacteriological parameters and the results were subjected to geostatistical analysis. The result revealed that the pH in the area is slightly acidic (5.70-6.90). The concentration of the major cations and anions falls within the permissible limit postulated by WHO. The high concentration of BOD. COD, total coliform and E.coli in water are testimonies the water in the area is poor bacteriologically and an indication of the presence of human faeces in the water. Prolong drinking of such kind of water can result to water borne diseases in the area. The high concentration of manganese in the water may be attributed to the industrial effluent from the in the area. The water index for irrigational suitability (SAR, SSP, PI, RSC, MAR and KR) suggest that the water in the area to be fairly good. The overall water quality index calculated also confirmed the poor quality status of water in the area. Good sanitary habit and proper treatment of industrial effluent before discharge into the environment is advocated. Boiling of water before use is recommended to ameliorate the effect of bacteriological contamination of the water

Integration of aeromagnetic and electrical resistivity imaging for groundwater potential assessments of coastal plain sands area of Ado-Odo/ Ota in southwest Nigeria

This study aims to investigate the groundwater potential of Coastal Plain Sands area of Ado-Odo/Ota within Dahomey Basin using the integration of aeromagnetic method and electrical resistivity imaging. The aeromagnetic method is applied to reveal the possible hydrogeological structures (such as lineament or fracture) buried in the subsurface. The lineaments which are interconnected are observed in the eastern part of the study area while the western part is void of the interconnectivity of lineaments. Resistivity technique is applied in regions where there are interconnectivity and non-interconnectivity of lineament to delineate occurrence of groundwater about the observed lineament. The depths to magnetic sources range between 102.6 and 1965.2 m. Furthermore, the result of resistivity technique shows that the depth to aquifer ranges from 40 to 100 m with corresponding resistivity values that range between 150.0 and 350.0 Ωm in the region of the interconnectivity of lineament, which is the eastern part of the study area (Igboloye-Covenant University area) and had high groundwater potential. The western part which is void of the interconnectivity of lineaments (Alapoti area) ranges from 80 to 130 m with resistivity values that range between 250.0 and 450.0 Ωm suggesting that the area has low groundwater potential. The study, therefore, shows that the occurrence of groundwater in Ado-Odo/Ota community is a function of hydrogeological structures such as lineaments or fractures, and as a result, this information could serve as guide for borehole drillers, civil engineers and resident of the study area for proper planning before siting borehole either for domestic or industrial use