Geoelectric investigation to determine fracture zones and aquifer vulnerability in southern Benue Trough southeastern Nigeria

• Published in: Arabian journal of geosciences Vol. 14; no. 22
• Main Authors: Eyankware, Moses Oghenenyoreme, Aleke, Godwin
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2021; Springer Nature B.V
• Subjects: Anisotropy; Aquifers; Contamination; Earth and Environmental Science; Earth science; Earth Sciences; Electrical resistivity; Fracture zones; Freshwater; Geoelectricity; Geology; Groundwater; Groundwater potential; Inland water environment; Iterative methods; Limestone; Mathematical models; Original Paper; Parameter estimation; Parameters; Porosity; Sandstone; Sedimentary facies; Sedimentary rocks; Shale; Shales; Siltstone; Surveying; Vulnerability; Nigeria; Longitudinal conductance; Transverse resistance and Nigeria; Fracture porosity; Anisotropy
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-08542-w

Electrical resistivity method was employed to determine fracture zones, aquifer protection, and groundwater potential of the aquifer within the southern Benue Trough. A total of 22 vertical electrical sounding (VES) survey was conducted using the Schlumberger configuration and a quantitative partial curve matching technique using computer simulations and iterative software were employed in processing and interpreting VES data. Parameters estimated are longitudinal conductance (S), transverse unit resistance (T r ), longitudinal resistance (ρL), anisotropy (λ a ), and fracture porosity ( ϕ f ) and their corresponding estimated values which vary across the study area, range from 0.07 to 37.46 mhos, 328.19 to 16,765 Ω/m 2 , 212.5 to 3586 Ω-m, 0.06 to 1.91, 0.000045 to 0.28, respectively. Results obtained from S showed that 66% of the aquifer units which fell within (moderate to excellent) were considered not vulnerable to contamination, while 31% (poor to weak) was considered vulnerable to contamination from the surface. The variation of these parameters across the area was further illustrated using contour maps which show that (T r ) values in the SE and NE part of the area (Bental, Ibinta, and Oju) suggest high groundwater prospect. This is in agreement with the geology of the area which is underlain by the Asu River Group that comprises of shale, siltstone, sandstone, and limestone facies that are fractured as compared with the NW part that is underlain by the shaly Eze-Aku Formation with low potential. Findings from ρL revealed three groundwater categories, viz saline, brackish, and freshwater. Deductions from ρt showed that the highest value of ρt was observed around Ibinta. Estimated value obtained from λ a revealed that the fracture trend increases towards NW. ϕ f revealed that Ameke, Oganga, Ebele, and Dogu area have good ϕ f, and considered to be of higher aquifer yield when compared to other parts of the study area. It is therefore recommended that water exploitations can be carried out in the eastern, NE, and SE part of the area that showed good prospect for aquifer potential, coupled with high ϕ f .