Aquifer vulnerability using geophysical and physiochemical methods in parts of Ethiope West Local Government Area of Delta State, Nigeria

Supply of potable water in Oghara communities in particular and parts of Ethiope West Local Government Area of Delta State in general is inadequate as a result of increasing population and development activities in the area. This can be resolved and sustained if groundwater resources are effectively managed. This study was carried out to determine the aquifer vulnerability and groundwater quality using geophysical and physiochemical methods in parts of Ethiope West Local Government Area, Delta State. Thirty vertical electrical soundings and four dipole–dipole profiling were administered using Abem Terrameter SAS 1000 AB. The field data were curve matched and iterated using WinResist and Dipro software. The aquiferous zone was found in the fourth layer with resistivity ranging from 159 Ωm to 100234 Ωm, thickness ranging from 12 m to 156 m, and depth ranging from 32 m to 162 m except VES 25, whose aquifer is in the third layer. The dipole–dipole resistivity structure shows low resistivity values along areas where waste dump was sited with resistivity ranging from 300 Ωm to 630 Ωm. This finding suggests that the leachate from the dumpsite is affecting the characteristics possessed by the subsurface close to it. The first order geoelectric and Dar-Zarrouk parameter study of aquifer protective capacity revealed a protection capacity value less than 0.1 for VESs 1–18 and 20–30, while VES 19 revealed a value of 0.24. Thus, Oghara communities are extremely unprotected, and the aquifer is prone to contamination. The physiochemical analysis carried out indicates that groundwater is slightly acidic with a pH value ranging from 5.40 to 6.40 when compared with the WHO permissible limit. The groundwater flow direction is depicted from the east to the west; this will assist policy planners to decide where dumpsites and companies generating waste could be sited to preserve groundwater potential.