Reassessing Groundwater Potentials and Subsurface water Hydrochemistry in a Tropical Anambra Basin, Southeastern Nigeria

Abstract

This review presented a detailed re-assessment of the hydrogeology and hydrochemistry of the Tropical Anambra Basin. It identified and discussed the major geological formations and their groundwater potentials. The geological examination showed that the Ajali Formation is confined in places forming an artesian condition; the potentials of this aquifer decline in the western basin due to a decrease in thickness. The sandstone associates of the Nsukka Formation are aquiferous and have produced high-pressure artesian boreholes along the Oji River. The Imo Shale is characterized by permeability stability all over much of the intermediate unit. The Bende-Ameki aquifer has a lesser amount of groundwater when equated to other formations; the geologic characteristics do not produce favorable hydrogeological conditions for groundwater occurrence. The stratigraphical and structural framework suggested the presence of an efficient throughflow in the basin. Based on physical and chemical parameters of water quality, the basin holds water of acceptable quality. While there are considerable investigations on the hydrogeology and hydrochemistry, studies are short of analysis of the hydrogeochemical evolution of groundwater, water quality index, heavy metals pollution index as well as total hazard quotient. Suitability of groundwater based on agricultural water quality indices (e.g. SAR) is also salient. Therefore, future studies should address these owing to increasing dependence on groundwater.