Determination of Aquifer Hydraulic Properties, Aquifer Potential and Vulnerability Characteristics Using Pumping Test and Surface Geophysical Data: A Case Study of Udi and Ezeagu Areas, Southeastern Nigeria

A good understanding of aquifer hydraulic properties is vital in the management of groundwater resources and in the determination of aquifer potentiality and its vulnerability to surface environment contamination. Results obtained from the integration of well bore-constrained geo-electric sounding data from Udi and Ezeagu areas, southeastern Nigeria, were utilized in the estimation of vital aquifer hydraulic characteristics such as transverse resistance, longitudinal conductance, hydraulic conductivity, and transmissivity. The correlation of these data sets constrained the sub-surface geology of the study area into five distinct stratigraphic units, namely, from top to bottom: lateritic soil, clayey/shaly sand, fine grained sand, medium grained sand, and clayey sand. Consequently, the resistivities and thicknesses, respectively, of the sub-surface layers range from 524 to 1003 Ωm and 5.10 to 25.50 m; 283 to 524 Ωm and 15.3 to 29.53 m; 765 Ωm to 1523 Ωm and 80.65 to 96.93 m; 180 to 327 Ωm and 80 to 120.50 m; 424 to 718 Ωm. The medium-grained sandstone unit with the least resistivity value is the designated economic aquifer. From the results, the estimated range of distribution of pumped aquifer hydraulic conductivity varied between 50 and 850 m s −1 across the entire study area while pumped transmissivity values ranged from