EVALUATION OF GROUNDWATER POTENTIAL OF CHANCHAGA AREA, MINNA, NORTH-CENTRAL NIGERIA

Abstract

Inadequate potable water supply remains one of the challenges of residents of Minna Metropolis, Niger State, Nigeria owing to the basement complex terrain underlying the area. The rapid increase in population in the area, which is due to its proximity to the nation’s capital city (Abuja) among others, has led to a corresponding increase in the demand for potable water for domestic, irrigational and industrial uses which public water by government could not meet. Consequently, the inhabitants resort to seeking alternative arrangements for water through hand dug wells and surface water sources which are often of uncertain quality. Objectives: Thus, this study investigates the groundwater potential of Chanchaga area, Minna, North-central Nigeria with a view to delineating the suitable aquifer for groundwater development. Material and Methods: The technique employed for this study was Vertical Electrical Sounding (VES) of the Electrical Resistivity (ER) method. A total number of twenty-three (23) Vertical Electrical Sounding (VES) points were investigated using Schlumberger array configuration and the data obtained were analyzed using partial curve matching and computer iteration techniques. The data were interpreted to reveal various geoeletric layers that characterize the area. Results: The results revealed predominantly H-type curve typical of the basement complex system with three geoelectric layers: the top soil, weathered/fractured basement and fresh basement. The apparent resistivity of the first layer ranged from 25 Ωm – 928 Ωm with a corresponding thickness of 0.5 m – 3.1 m, second layer has apparent resistivity values of 8.3 Ωm – 41.3 Ωm with a corresponding thickness of 2.1 m – 33.0 m and the third geoelectric layer has apparent resistivity values ranging from 74 Ωm – 4173.5 Ωm with an infinite thickness. A careful examination and integration of the isopach map with the isoresistivity maps (at 30 and 40 metres depths) indicated that the central and northern parts of the study area have very low to low apparent resistivity values and shallow overburden which is capable of constituting shallow aquifer units. Conclusions: It is concluded that the central and northern parts of the study area have poor to marginal groundwater potential, and this is supported by the occurrences and concentration of fractures which can constitute weathered/fractured aquifers around these regions. It is recommended that water wells be drilled to an effective depth of 40 to 50 m for optimum groundwater yields, and that pumping test be carried out on the drilled wells in order to further determine the aquifer efficiency and productivity in the area.