Hydrogeology and Water Quality Assessment (WQA) of Ikhueniro and Okhuahe Using Water Quality Index (WQI)

Abstract

About half of the people that live in developing countries do not have access to safe drinking water and 73% have no sanitation, thus some of their wastes contaminate their drinking water supply leading to a high level of suffering. In view of the foregoing, this study was carried out in two suburbs in Benin City, Edo state Nigeria in order to examine the hydrogeology and water quality of these communities. Three boreholes were drilled to the depth of 57.60, 60.35 and 45.68 meters respectively while soil samples were taken at 4.57 meter intervals in order to determine the soil properties, aquifer geometry and subsurface geology. Water samples from these wells were collected including two other existing boreholes and a sample from a nearby river in order to evaluate the water quality, using water quality index (WQI). The water samples were analysed for physico-chemical parameters such as TDS, pH, TH, EC, NO3-, SO42-, Cl-, Mg2+ using standard laboratory procedures while the heavy metals were analysed using Atomic Absorption Spectrometer (AAS) model 969 unicam series with air acetylene flame.The results obtained from physico-chemical analysis were used to compute the values for water quality index and the results revealed that three of the wells were extremely contaminated, two were of good quality and the other poor. The hydrogeological study revealed that the aquifer geometry is unconfined basically of fine to coarse sands grains with high porosity and permeability which enhance water percolation. The groundwater flows from North West towards South East; and it was observed that water quality increases from adjacent landfill towards the river in the study area which suggest that the leachate emanating from the unprotected landfill coupled with the geography and geology of the terrain is a  major factor contributing to the poor water quality. The authors advise a proper legislature and enforcement of existing environmental laws to arrest the situation.