Multivariate statistical analysis of groundwater mineralization in Daloa and Zoukougbeu, central west, Côte d'Ivoire

Abstract

This study aims to determine the mechanisms of groundwater mineralization in the departments of Daloa and Zoukougbeu (Central West, Côte d’Ivoire). In order to achieve this, a hydrochemical study was carried out from seventeen (17) water samples (wells and sources) collected in March 2018. It was based on the multivariate statistical analysis techniques: The Principal Component Analysis (PCA) and the Hierarchical Cluster Analysis (HCA) were applied to physicochemical parameters. Thus, the average values of temperature, pH, electrical conductivity, Total Dissolved Solids (TDS) and Turbidity measured in situ in source waters are respectively 27.63°C; 4.81; 84.6 μS / cm; 38.45 mg. L^-1 and 40.78 NTU and in well water 27.90°C; 4.78; 81.85μS/cm; 36.61 mg. L^-1 and 27.22 NTU. The average concentrations of the major cations Ca²⁺, Mg², Na⁺ and K⁺ of well water are respectively 2.26; 1.01; 4.58; 1.41 mg. L^-1 and those of spring waters 2.18; 1.03; 5.50 and 2.07 mg.L^-1. The major anions HCO₃^-, Cl^-, SO₄^2- and NO₃^- respectively amount to 8.81; 8.28; 5.33 and 7.67 mg.L^-1 for well water and 11.77; 8.5; 5.27 and 8.25 mg.L^-1 for spring waters. The PCA results show that three phenomena govern the mineralization of these waters. These are the phenomena of mineralization-residence time of water which is acquired by acid hydrolysis of the host rocks, spatial origin of lower quality of water and the grounds throughfall. These phenomena are confirmed by the Hierarchical Cluster Analysis (HCA). This work is therefore a tool for supporting groundwater management.

Keywords: Groundwater, Mineralization, PCA, HCA, Central West, Côte d'Ivoire