Exploratory assessment of groundwater vulnerability to pollution in Abi, southeastern Nigeria, using geophysical and geological techniques

The geophysical-based integrated electrical conductivity (IEC) and the groundwater hydraulic confinement–overlying strata–depth to water table (GOD) techniques were used to assess vulnerability levels of aquifers and the extent of aquifer protection in Abi, Nigeria. The IEC indices was generated from constrained one dimensional (1D) inversion of vertical electrical sounding (VES) and two dimensional (2D) electrical resistivity tomography (ERT) data, acquired randomly in the area. The GOD indices were sourced from existing geologic data within the area. Results showed that IEC values vary from <0.1 S in the weakly protected areas to >2.0 S in the strongly protected areas. The GOD indices vary from <0.3 in the lowly vulnerable areas to 0.6 in the highly vulnerable areas. Thus, the groundwater resources in the area need to be properly managed for sustainability and such management practices have been suggested.