Geoelectrical Investigation Using Schlumberger Array for Groundwater Occurrence in Part of Bosso Estate Minna Sheet 164 SW North-Central Nigeria

Inadequate potable water supply remains one of the challenges of residents of Bosso Estate in Minna Metropolis, Niger State, Nigeria owing to the Basement Complex terrain underlying the area. Rapid increase in population in the area over the years, which is due to its proximity to Federal University of Technology Minna (Bosso Campus) and the nation’s capital city (Abuja) among others. This has led to increase in the demand for potable water supply for domestic use since public water supply by government is inadequate. Consequently, in a quest to seek for Groundwater as a reliable source of water supply for domestic need, various abortive boreholes have been drilled without proper geophysical survey. This has led to loss of valuable time, energy and money. Therefore, Geoelectrical investigation using Schlumberger array was carried out with a view to delineate zones with good groundwater occurrence.

A locally made Terrameter (resistivity meter) of high precision was used for data acquisition. Schlumberger array was used to obtain geophysical data at ten (10) VES stations in the area. Field data obtained were analysed and interpreted using Win RESIST and Surfer Software which gives an automatic interpretation of the apparent resistivity data. Results from the interpretation revealed these curve types: the HK, H KH and A whereas three to four (4) geoelectric layers which consist of Topsoil layer, Lateritic clay, Weathered/fractured basement and Fresh basement. Fractured/weathered basement has resistivity values ranging from 35.5 to 841.62 Ωm and thickness variation of 13.5 to 48.5 m. This weathered /fractured layer constitutes the aquifer zones in the area. The fresh basement has resistivity values as high as 7336 Ωm and above. The groundwater potential in the study area was classified into high, medium and low/non groundwater potentially occurring zones. High groundwater potential zones were found at VES station 01, 02, 03, 04, 07 and 08 corresponding to the North-Eastern, Central and North-Western parts. This survey revealed aquifer zones having thickness ranging from 20 to 40 m and depth to bedrock ranges from 8.7 to 55 m. A recommended minimum depth for drilling borehole in the study area is about 46 to 60 m. The study however recommends an integrated geophysical method for future groundwater exploration in the area.