Hydrochemical assessment of groundwater quality in Sagamu area, Southwestern Nigeria

Abstract

Groundwater samples from 39 wells in different geological settings in Sagamu area, Southwestern Nigeria were analysed for their hydrochemical properties, to determine their suitability for domestic and irrigation purposes. The samples were subjected to chemical analysis involving the Induced Coupled Plasma Mass Spectrometry (ICPMS) for cation determination, and volumetric analysis to determine the anions. The classification of the groundwater using Piper diagram, Gibbs variation, Wilcox classification and Zhang evolution plot reveals the distribution of groundwater quality in the area. Parameters like Sodium Absorption Ratio (SAR), Magnesium Adsorption Ratio (MAR) Kelly’s Ratio (KR), Permeability Index (PI), Residual Sodium Bicarbonate (RSBC), and chloro-alkaline indices (CAI), were calculated for irrigation purposes. The results were presented as spatial distribution maps for interpretation and further inferences. Comparison of the groundwater quality in the area with local and international standards indicates that 94.9% of the groundwater within the area is generally suitable for domestic and irrigation purposes.

Keywords: Groundwater, hydrochemical assessment, geological settings, Sagamu area, Irrigation