Hydrogeophysical Survey and Aquifer Evaluation: a Case of the Geological Formations in Nsukka Area, Southeastern Nigeria

EasyChair Preprint no. 9658

Abstract

Abstract: Background: The challenges of finding aquifers and having portable water in Nsukka area, Southeastern Nigeria abound. These lead to some geology and hydrogeophysical investigations which targeted the aquiferous Ajali Sandstone and Nsukka Formations that underlies the Nsukka metropolis and its environs. The study area lies within Latitudes 6o 801 N and 6o 891 N; Longitudes 7o 211 E and 7o 301 E, covering an area of about 210 square kilometres. Materials and Methods: Thirty four (34) cross array Vertical Electrical Sounding (using the Schlumberger electrode configuration) and records from four (4) selected boreholes have been used to investigate the subsurface distribution of electrical resistivity and to delineate hydraulic properties of aquifers in Nsukka area, Southeastern, Nigeria. Results: The electrical surveys of the area show high values of permeability, ranging from 0.0075 to 0.015 cm2, hydraulic conductivity, ranging from 8.29 to 16.64 m/s, transmissivity, between 455.87 and 1002.48 m2s-1, and specific yield, ranging from 2.35 to 4.76 m3. A tie with the results of borehole logs analysis reveals the presence of at least four layers of contrasting hydraulic conductivity. Analyses, however, suggests that the Nsukka Formation (which overlies the Ajali Sandstone) is thick and poorly conductive while the Ajali Sandstone unit is homogenous and anisotropic and has higher conductivity (especially beyond the depth of 100 m), suggesting a prolific water-bearing formation at such depth and beyond. Conclusion: The Ajali Sandstone aquifer in the area is thick and prolific. It can also be tapped to serve irrigational and other hydro-energy needs. The distribution of major geological units, well log data, static water level data were shown to have influence on the groundwater occurrence and flow pattern in the area.

Keyphrases: Ajali Sandstone Aquifer, Nsukka Metropolis, resistivity measurements, Well data

@Booklet{EasyChair:9658,
  author = {Emmanuel Ezim and Georgebest Azuoko},
  title = {Hydrogeophysical Survey and Aquifer Evaluation: a Case of the Geological Formations in Nsukka Area, Southeastern Nigeria},
  howpublished = {EasyChair Preprint no. 9658},

  year = {EasyChair, 2023}}