Assessing the Potentiality of fractured shale deposits as an aquifer in the Asu-River Group, Southeast Nigeria

Abstract

Groundwater beneath earth’s surface is stored in pores and rock fractures.Weathering and diagenesis plays vital roles in the enhancement or decrease of rock porosity. To that extent, argillaceous rocks ordinarily considered impervious could earn fracture porosity,enhancing the permeability and substantial storage of water through interconnected matrix channels. Alex Ekwueme University Ndufu-Alike and Gregory University, Uturu are  growing universities faced with challenges of good groundwater for domestic  uses.  Preliminary geophysical studies were carried out within the campuses using  electrical resistivity method. Thereafter, the group recommended drilling at five points ,three at Ndufu-Alike and two at Uturu. The very low resistivity data obtained from the survey confirmed that the lithology of the area is predominantly shale of moderate to high plasticity. The pumping test of drilled boreholes were carried out according to the Cooper-Jacob’s(1946) method. Test results showed that Transmissivity (T) varied from 18.23m²/day to 37.44m²/day at Ndufu-Alike and from 22,85m²/day to 23.04m²/day at Uturu. Storativity (S) was determined to range from 0.22 to 0.32. These values suggest intermediate class associated with confined aquifers.  The study shows that fractured shale aquifers hold a promise for domestic water supply and that the shales can be counted as groundwater prospects to be harnessed after careful site-specific geophysical studies.