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Stable isotopes and geochemical studies have been applied in the investigation of groundwater resources in Sokoto Basin, northwestern Nigeria. Generally, the characteristic hydrochemical classification in the study area is calcium-alkali-bicarbonate. Surface waters are characterized by alkali-calcium-bicarbonate while groundwater is of Ca-Mg-HCO 3. The plot of δ 18 O versus δ 2 H shows that five isotopic groups can be distinguished. Group I-III is of groundwater origin while group IV and V represent surface water. A combination of the hydrochemical and isotope data (14 C, 13 C and 3 H) reveals the Sokoto basin aquifers generally contains good quality groundwater of Holocene age (100 to 10,000 years BP).

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.

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Aeromagnetic and aeroradiometric data covering parts of southern Bida basin, Nigeria and the surrounding basement rocks were processed and interpreted. The research covered both basin and basement rock sections, and was aimed at determining the geothermal heat flow and radioactive heat characteristics of the survey area. The number of data points used for analysis were 2,937, obtained from the digitization of eleven ½ degrees by ½ degrees contour maps. Data processing methods used in the study include determination of heat from radiometric data, regional-residual separation of the total magnetic intensity data, determination of depth-to-top and depth-to-bottom of magnetic sources and estimation of field scaling exponent using the Fractal technique. The research results gave geothermal heat flow values ranging from 69.167 mWm -2 to 124.821 mWm -2 with an average value of 90.959 mWm -2 and radioactive heat values ranging from 0.91 to 4.53 µW/m 3 with an average value of 2.28 µW/m 3 . Deductions made from the survey are, the field scaling exponent varies linearly with depth of downward continuation and Katakwa is a prospect area for geothermal heat.

Aeromagnetic data coupled with Landsat ETM+ data and SRTM DEM have been processed in order to map regional hydrogeological structures in the basement complex region of Paiko, North Central Nigeria. Lineaments were extracted from derivative maps of aeromagnetic, Landsat ETM+ and SRTM DEM datasets. Ground geophysical investigation utilizing Radial Vertical Electrical Sounding (RVES) was established in nine transects comprised of four sounding stations which are oriented in three azimuths. Source Parameter Imaging (SPI) was employed to map average depths of structures from aeromagnetic dataset. Selected thematic layers which included lineaments density, lithologic structure, slope, drainage density and geomorphologic maps were integrated and modeled using ArcGIS to generate a groundwater potential map of the area. Groundwater zones were classified into four categories: Very good, good, moderate and poor according to their potential to yield sustainable water to drilled wells. The results from RVES survey reveal a close correlation to lineaments delineated from surface structural mapping and remotely sensed datasets. Hydrogeological significance of these orientations suggest that aeromagnetic data can be used to map relatively deep-seated fractures which are likely to be open groundwater conduits while remotely sensed lineaments and orientations delineated from the RVES survey may indicate areas of recharge. Regions with high lineament density attributable to thick regolith and highly fractured basement have better groundwater potential. Drill depths in this area should target a minimum of 80 m to ensure sufficient and sustainable supplies to drilled wells. The outcome of this study would act as information framework that would guide the siting of productive water wells while providing needed information for relevant agencies in need of data for the development of groundwater resources.

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Within the hard rock terrains, stream channels are suspected to be controlled by fractures and joints. In the same light, the topographic lineaments and the lineaments observed from the aeromagnetic anomalies are expected to reflect the structural trends within the complex. This study has therefore adopted multi-data sets results first on a regional scale to depict the structural fabric of Ilorin Sheet 223 and then at the chosen location of the University of Ilorin Main Campus, which is made up of the Basement Complex rocks. From the remote sensing map of Ilorin Sheet 223 structural trends have been divided into two: the NE-SW and the NW-SE structural trends. The aeromagnetic anomalies divide the rocks types into metamorphic (low-to-medium magnetic intensity) and igneous (high magnetic intensity) rocks. The resistivity data interpretation reveals the weathered basement at the University of Ilorin ranges from 5m to 20m. The radial sounding results reveal the structural trend to be NW-SE and NE-SW with the interconnection of joints. The radial sounding shows the rock type in the University of Ilorin Campus to be quartzitic, clayey and igneous as judged from the near hexagonal and elongated shapes of the polygons. The results reveal a good agreement between the trends of fractures derived from the radial vertical electrical sounding and that from the lineament maps. Areas with low bedrock resistivity, thick overburden, presence of two or more interconnected fractures, and high co-efficient of anisotropy indicate intense fracturing and thus, indicate areas of high groundwater potentiality and good water quality.