Estimation of aquifer parameters from electrical resistivity data and lithologs in Idah area, Northern Anambra basin, Nigeria

Abstract

The parameters of the aquifers in Idah area were characterized by integrating resistivity and litholog data. To achieve this, a total of twenty-three (23) Soundings were conducted by applying the 1-D Schlumberger resistivity array and integrating it with borehole lithologs to empirically determine the aquifer parameters in the Idah area, Northern Anambra Basin, Nigeria. The results of the analyses indicate that the aquifer zone resistivity ranges from 36.65 – 2065.31 Ωm while the aquifer thickness is between 15.60 m and 66.66 m. Its values of the longitudinal conductance (S), transverse resistance (TR), and hydraulic conductivity (k) are 0.01-1.13 mhos, 1518.90-90265.88 Ωm² , and 0.31-13.44 m/day, respectively. The transmissivity (T) values vary from 4.88 to 2 557.78 m /day. T is inversely proportional to TR with a correlation coefficient of 0.28. The result of the reflection coefficient is in the range of -0.79 to 0.66, while that of the fractured contrast is between 0.11 and 5.06. The results suggest that an aquifer system that is predominantly fracture-based is underlying the region. Lithification and diagenesis influence the hydrological properties. The northern–central portions of the map are more suitable for groundwater exploration /exploitation than the southern/eastern ends.