Investigation of relationships between geoelectric and Hydraulic parameters in a quaternary alluvial aquifer in Yenagoa, Southern Nigeria

Abstract

In an attempt to establish empirical electric-hydraulic relationships for the purpose of analyzing surface resistivity soundings, geoelectrical soundings using the Schlumberger array were carried out in Yenagoa and environs. Fourteen (14) VES stations were occupied across the study area. The field data were interpreted using Interpex IX1D computer software and the aquifer resistivity (ρ) at each location was estimated. The hydraulic conductivity (K) determined from a reference borehole was combined with the normalized electrical conductivity (σ') to estimate a constant Kσ'. This constant was integrated with the Dar Zarrouk parameters and used to estimate the hydraulic conductivity and transmissivity values at other VES locations where K values were unknown. The results showed that the hydraulic conductivity varied from 11.3 – 120.9 m/day while the transmissivity varied from 218.8 – 2849.9 m² /day. Correlation of geoelectric and hydraulic parameters of the aquifer showed that the hydraulic conductivity (K) exhibited better correlation with the apparent formation factor (F_a ) than transmissivity (T). Transmissivity was linearly related to normalized transverse resistance (T_R) via the equation T = 0.018T’_R + 301.6 while the hydraulic conductivity was related to the aquifer resistivity (ρ) through the equation K = 0.141ρ+413. These empirical equations could be used to predict the hydraulic parameters in groundwater studies in the area.

Keywords: Hydraulic Conductivity, Transmissivity, Aquifer, Transverse Resistance, Apparent Formation Factor