Evaluation of Geological Formation for Sustainable Groundwater Resources in Parts of Aguata, Anambra State, Southeastern Nigeria, using Electrical Resistivity Method.

Abstract

Onyenweife Geraldine Ifesinachi and Omezi Ifeanyi

The study was designed to evaluate the geological formation for sustainable groundwater resources in Aguata, Anambra State, Southeastern Nigeria. Geological formation of the subsurface were investigated using the electrical resistivity methods. The study undertaken incorporates compilation and integration of the acquired VES data of 14 locations in Aguata Local Government Area and consideration of factual reviewed literature in the study area. The outcomes of the IPI2WIN modelled apparent resistivity of the near surface in this research highlight hydraulic properties of water bearing units as thus; depth 50 m – 300 m, thickness 35 m – 400 m, transmissivity 49.70 m2/day – 384.37 m2/day, hydraulic conductivity 1.5 m/day – 9.1 m/day and hydraulic resistance 36764 - 431034. Evaluation of protective capacity rating of the water bearing unit to proffer the sustainability of the groundwater resources of the study area involved knowledge of volume of shale/clay of the overburden layers which is their longitudinal conductance which ranges from 0.003 – 8.10, except VES 7 that good protective capacity (PC), other locations revealed low protective capacity (PC). The research assessed the vulnerability the water bearing units in the study area to potential sources of contamination for sustainability. The hydraulic resistance rate to contamination was evaluated extremely low as the formation of the study area do not constitute much filtering agents. The indexed low resistance of the aquifer proved the vulnerability rate of the aquifer in the study to contamination very high, only few locations tend moderate which was assessed using Groundwater occurrence, Over-layering and Depth (GOD) Indexing.

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