Geological traversing at Nasarawa State University Keffi, part of Keffi Sheet 208NE, North-central Nigeria, revealed that the area is underlain by the Basement Complex rocks consisting of biotite gneiss, granitic gneiss and schist. The structural trends are mostly in NNW-SSE and NE-SW directions and foliation in the NE-SW direction. Surface geophysical investigation was conducted using the new hybrid Wenner-Schlumberger array, where fifty (50) stations were investigated along seven established profiles to determine the groundwater potential of the area. Six curve types were observed; HA, KA, QH, HAK and KHA; QHA-types has the highest frequency of occurrence while KA and HAK-types has the least. Results revealed that the top soil being the 1st layer with resistivity (62-5800 Ωm) and thickness (1-2 m). Laterite is the 2nd layer with resistivity (20-5550 Ωm), and thickness (2-7 m). The weathered basement is the 3rd layer with resistivity (43-2080 Ωm) and thickness (5-20 m). The fractured basement is the 4thlayer in the five (5) geoelectric layer case with resistivity (115-1700 Ωm) and thickness (25-50 m); while the partially weathered/fractured basement forms the 4thlayer in the six (6) geoelectric layer case with resistivity (66-2059 Ωm) and thickness (10-30 m). The fresh basement forms the 5thlayer in the five (5) geoelectric layer case with resistivity (312-2170 Ωm), while the fractured basement forms the 5thlayer in the six (6) geoelectric layer case with resistivity (139-2800 Ωm), and thickness (10-50 m). The fresh basement forms the 6thlayer in the six (6) geoelectric layer case with resistivity (310-3800 Ωm). The depth to fresh basement or overburden thickness range from 29-79.5 m, which implies that the area is generally good for groundwater development, especially places with distinctive weathered and/or fractured layers thicknesses. Groundwater potentials were zoned into low, medium and high potentials for groundwater development. Wenner data extracted and interpreted have a good degree of correlation with the Schlumberger results, the structural trends observed on the geological structures and with existing geology.

Chad Basin is a fertile area with great agricultural potential located within Chad Basin of Nigeria with high scarcity of surface and groundwater. The research is aim at establishing sources of water supply to the Lake Chad basin and revived the agricultural potential by diverting Benue River to the basin as a result of drying up of both surface and groundwater. The study involves collection of previous data on water level followed by detail groundwater level measurement in 2007 and 2012 during which water level in 87 hand dug wells and boreholes were measured using a water level meter or graduated tape. Global Positioning System (GPS) with accuracy ±8m was used to measure the elevation and coordinates of each hand dug wells and boreholes. Results of depth to water level measured from 2007 to 2012 during dry and wet season for Middle and Lower aquifers revealed that, groundwater depletion in Middle and Lower aquifer of the Chad Formation is higher due to lesser recharge from the infiltration of seasonal rainfall or horizontal flows from flowing seasonal rivers, these indicate higher groundwater withdrawal from the aquifer. The rate of groundwater piezometric heads in the Middle and Lower aquifer are falling annually by 0.19 m/a in the rural areas and as much as 0.77 m/a with large drawdown curve where abstractions of groundwater are higher. From the findings, it is expected that, dewatering of aquifers in the Chad Formation will start to shrink from 649 years to come starting from year 2012 in urban centres to 2632 years in rural areas provided that the rate of depletion is not controlled. From the study, it is concluded that, interregional water transfer from the Benue River to Lake Chad basin is the only solution to the basin where irrigated agriculture will be revived again as food basket of Nigeria with great employment opportunity, agro-allied investment and tourism attraction.

Hydrogeochemical characterization of surface and groundwater at Nasarawa State University Keffi, part of Keffi Sheet 208 NE, North-central Nigeria was carried out. Twenty-five (25) water samples were obtained from hand pumps, hand-dug wells, boreholes and along stream channel in order to ascertain their suitability for human consumption, domestic use and irrigation purposes. Atomic Absorption Spectroscopy (AAS), flame photometry, Macro-Kjeldahl, Turbidimetric, Argentometric and Titrimetric methods were used to analyzed the samples. Results reveal slightly acidic to slightly alkaline water (pH 5.07-8.60), soft to very hard water (TH 28.04-289.32 mg/l), Na+ (5.10- 80.00 mg/l), K+ (2.40-21.00 mg/l), Ca2+ (3.54-35.71 mg/l), Mg2+ (3.68-53.96 mg/l), Fe (0.00-7.26 mg/l), Cu (0.00-0.07 mg/l), Zn (0.00-0.22 mg/l), As (0.00-1.35 mg/l), Pb (0.00- 0.09 mg/l), Cl- (1.50-17.49 mg/l), HCO - (0.00-4.00 mg/l), NO -(1.96-27.44 mg/l), SO 2- 3 3 4 (1.07-16.87 mg/l). Piper trilinear diagram, Schoeller and Wilcox plot reveal four (4) major water types derived from 13 water facies. The mixed water type, Magnesium Chloride water type, Sodium Chloride water type and Calcium Chloride water type, all of which falls within the alkaline earth water. Na+, K+ and Mg2+ were above WHO (2011) and NIS (2007) recommended standard for drinking water in some locations, making them the most dissolved cations in the groundwater which added greatly to the TDS. All the water belongs to good-fair water class for irrigation. High concentration of trace elements; Fe, Zn, As and Pb found in some water samples obtained from certain locations make them objectionable for drinking, although can be made suitable for human consumption/ drinking if treated by the addition of coagulants and the use of reverse osmosis. The dominance of cations/anions and trace elements in the water is in an order of Na+>Ca2+ >Mg2+>K>NO ->SO 2->Cl->Fe>HCO ->As>Zn>Pb>Cu. The need to continuously 3 4 3 monitor, manage, remediate and mitigate against these hydrogeochemical characteristics is called for.

The long-time practice of careless disposal of commercial, electronic and domestic wastes especially along stream channels in Sabon-Layi and its environs, in the ancient city of Keffi, Central Nigeria could lead to groundwater contamination from leachates of some dangerous heavy metals emanating from the open wastes, thereby rendering it unsafe for use since majority of the inhabitants of the area depend on groundwater from shallow hand dug wells. The area comprises of low lying schist and weathered gneissic rocks exposed on the surface, with presence of mainly joint, faults and exfoliations. A groundwater contamination study was conducted with a total of nine water samples - five from hand dug wells and four from boreholes, collected within the area for chemical analysis of some harmful heavy metals. Results obtained revealed the presence of As, Ba, Cd, Cu, Fe, Mn, Pb and Zn with range values of 0.21-0.80, 0.51-0.80, 0.05-0.33, 0.70-4.90, 0.95-1.00, 0.05-1.37, 0.10-0.74 and 2.10-3.90 respectively in five hand dug wells samples, implying that except for Cu and Zn, other metals analyzed are present in amounts above the WHO and NSDWQ quality standards making the water unsafe for consumption. However, heavy metal contents in the four borehole water samples all fall below the WHO and NSDWQ standard with range values of 0.001 – 0.008, 0.02– 0.40, 0.002-0.005, 0.008-0.017, 0.44-1.05, 0.16- 0.52, 0.001-0.014, and 0.038-0.138 for As, Ba, Cd, Cu, Fe, Mn, Pb and Zn respectively which means they are safe for consumption. Results of calculation of contamination status indicate slight heavy metal contamination for waters in shallow wells in the area under investigation. 2D electrical resistivity tomography using dipole configuration was conducted on two profile lines spread across the area to depict plume locations and extent. Results show the presence of plumes in Sabon-layi and Kofar Kokona indicated as areas of appreciably low resistivity values ranging from 1.0 ohm/m to 20 ohm/m at shallow depths of 3 m to 7 m. These areas should be avoided during water well constructions and groundwater should be obtained from wells with depth of 25 m and above in the area.