The studies aimed at characterising the groundwater system of the Bosso campus of Federal University of Technology, Minna was carried out. Geology of the area was studied using a topographical map on a scale of 1:10,000. Hydrogeological studies were conducted on existing boreholes within the campus and new areas. 1D geophysical study was conducted using a Terrameter employing the Schlumberger array for the Vertical Electrical Sounding (VES). The geological mapping revealed presence of granitic rock with intrusion of quartz vein and joints, major jointing/fracturing is in the NE–SW direction. Geophysical data interpretation was done using computer aided iteration method which enabled the delineation of various geophysical layers in order to reveal the structural control of groundwater and aquifer system. The results show three predominant geoelectric layers: the topsoil, weathered/fractured granite and fresh granite. Apparent resistivity values of the first layer ranges from 14.1Ωm-571.9Ωm with thickness of 0.5m-4.6m, second layer has apparent resistivity values of 10.0Ωm– 406.9Ωm with thickness of 2.0m-13.1m and the third layer having apparent resistivity values ranges from 1467.6Ωm–19031.2Ωm with an infinite thickness. Isopach map with the resistivity maps at 10m and 30m respectively shows very low to low apparent resistivity values with thick overburden which can constitute zones of high groundwater potential at north-eastern and south-eastern parts of the study area. Hydraulic conductivity results range from.7.00×10-5 m/s to 4.31×10-4 m/s. The result falls within standard range for fine grain to coarse grain sand of 2.00×10-7 m/s to 6.00 × 10-3 m/s. It is concluded that the north central parts of the study area have poor to marginal groundwater potential while the northeastern and south-eastern part is supported by the occurrences and concentration of fractures which can constitute weathered/fractured aquifers around these regions.

Maiduguri the State capital of Borno, it is located between latitude 11°47’ N and 11°49’ N and longitude between 13°10’ E and 13°12’ E. It falls within the semiarid region with low rainfall and non-existent perennial surface water except for the Alau Dam. Groundwater is the perennial source of water supply supplemented by treated water from the Alau Dam. Abstraction has increased considerably in Maiduguri because of population explosion, exacerbated by the insurgency. The A-Unit is a phreatic aquifer of the Upper Chad Formation aquifer system. This unit is the most exploited in Maiduguri on account of its low cost and thus the need to evaluate its renewal potentials for sustainable management. Water Table Fluctuation (WTF) model is used to estimate groundwater recharge to the A-Unit aquifer of the study area. Rainfall and groundwater level data for the study area were collected for three years from 2015 to 2017, in addition to lithologic log of the observation borehole. Groundwater recharge in the study area is via diffuse (through the unsaturated zone) and focus (laterally through the river channel) mechanisms. Total groundwater recharge obtained from the WTF method, representing both the diffuse and focus componentsis estimated at 15 – 20 mm/a with an average of 17 mm/a. This recharge rate is about 1.8% of the average annual rainfall of 965 mm for the period 2015 – 2017 in the Maiduguri station. When the 12 km²size of the study area is considered, the amount of recharge is 204 x 103 m3/a. This is in excess of the current local abstraction of about 150 x 103 m3/a, with a net excess of 54 x 103 m3/a. It thus appears that the shallow aquifer in the study area receives total recharge that can sustain present day abstraction levels. Although, caution need to be exercised and the system monitored continuously in view of the variability in rainfall events as a result of the present day climate change, especially in the sahel region.

The present study used different geoscience techniques to determine soil characteristics and subsurface conditions that lead to the gully erosion in Bida area, north central Nigeria. Geological, hydrogeological, geotechnical and geophysical investigations were employed in this study. The geological mapping revealed Bida Sandstone as the principal lithology in the area and it agrees with the stratigraphic configuration of the study area. The well inventory showed a shallow water level (1.4 m to 6.9 m), with groundwater flowing towards the central portion of the area, which coincides with the areas been ravaged by gully erosion. A total of 24 soil samples were collected from four different gully sites in Bida and subjected to geotechnical analyses. The value of Moisture Content (MC) ranged from 2.95% to 18.08% with an average value of 10.66%. The Maximum Dry Density (MDD) varied from 1.89g/cm3 to 2.04g/cm3 with a mean value of 1.94g/cm3 while the Optimum Moisture Content (OMC) is in the order of 10.30% to 11.40% with average value of 10.85%. The low values of MDD and OMC indicates loose formation with little or no binding materials and soils with these characteristics are prone to gully erosion. The results of the sieve analysis indicate that the area is dominated with fine to medium grained sand. The plasticity test showed that the soil samples from the study area are non-plastic except for sample locations L1C and L4C with very low plasticity (plastic limit between 4.40% and 29.60%, liquid limit from 10.78% to 14.40% and plasticity index of 10.00% to 18.82%). This implies that the soil in the study area is non-cohesive soils. The 2D resistivity carried out at gully erosion sites indicate intermediate to high resistivity values of 110 Ωm to 190 Ωm in the profile distance interval of 5m to 60m, this is characteristics of non-plastic soils like sandstone. Underlying the intermediate to high resistivities is the layer flanked by zones of significantly lower resistivities indicating zones of water saturation with resistivity of about 67 Ωm. The study established the dominance of gully erosion in Bida area can be attributed to the presence of non-plastic and friable sandstone formation, increased rainfall, shallow water table, intensity of groundwater flow, saturation of the subsoil, poor drainage system, sand mining along river course and deforestation. Remediation techniques such as construction of concrete terracing and planting of trees, cover crops and wind resistant grasses as well as proper drainage system for the entire Bida town are highly recommended.

The study evaluates groundwater potential in Oke Ata, Abeokuta North Local Government Area, Ogun State, Southwestern Nigeria, using Vertical Electrical Sounding and 2D Electrical Resistivity Imaging (ERI)techniques. The area is characterized by underlain Precambrian Basement Complex rocks of low porosity and permeability of South- western Nigeria. Eleven vertical electrical sounding (VES) using the Schlumberger electrode array and the five 2D resistivity imagining using the Werner electrode array were carried out. The results show four geoelectric subsurface layers which are topsoil, clayey sand, sandy clay, weathered layer, fractured/ fresh basement within the study area. The resistivity of the fractured/fresh basement ranges from 400 to 900Ohm-m.The overburden thickness in the study area varies from9.6 to 15.7m. The field data were employed to prepare the groundwater potential map that was used to classify the area into low, medium and high groundwater potential zones. The study revealed that 63.6% and 36.4% of the study area falls within the medium and low rated groundwater potential zone. The groundwater potential rating of the study area is considered moderate.