Hydrogeophysical assessment of existing boreholes field of Bayero University Kano new site campus, Kano State Nigeria

Abstract

Bayero University main campus in Kano State, Nigeria is bedeviled with the shortage of water supply to cater for its water needs, as the main source of supply is mainly boreholes-based stations. An estimate of more than 3 million liters per day is needed in the campus, but the supply from the three boreholes fields was estimated to be less than 600,000 liters per day making a shortfall of 2.4 million liters supply. A Build, Operate and Transfer (BOT) boreholes field is the largest with 15 boreholes of which only nine are functioning. However, there is no available geophysical and hydrological data of the boreholes to determine their capacity and productivity. The research aimed at using geophysical method in diagnosing the geological sections/layers of aquifers in the existing boreholes in the BOT fields. This is to understand weather the boreholes were drilled to maximum aquifer thickness or not. A geophysical survey using Vertical Electrical Sounding (VES) was conducted adjacent to each borehole to determine the drilled subsurface geoelectrical sections. The location of the boreholes was taken using Global Positioning System (GPS) and the resultant VES data was interpreted using Interpex 1XD resistivity software. The results show that there are four to five geoelectric sections inferred as topsoil, lateritic soil, clayey soil, highly weathered decomposed rock, fractures crystalline basement rock and fresh crystalline basement rock with varying thickness across the fifteen (15) VES data set. The results were correlated with the drilled boreholes depths, and it was found that there is a mismatch of some surveyed geoelectric depths with the drilled depths, indicating that some of the boreholes were not adequately drilled to maximum aquifer depths. The findings from this study is significant in the proper designing and management of borehole fields for optimum underground water supply in basement complex areas.