Evaluation of Groundwater Quality in the Deep Maastrichtian Aquifer of Senegal Using Multivariate Statistics and Water Quality Index-Based GIS

A regional groundwater quality evaluation was conducted in the deep Maastrichtian aquifer of Senegal through multivariate statistical analysis and a GIS-based water index using physicochemical data from 232 boreholes distributed over whole country. The aim to 1) identify types likely factors influencing hydrochemistry, 2) determine suitability for drinking irrigation. Results showed that sodium, chloride, fluoride are highly correlated with electrical conductivity (EC) reflecting significant contribution these elements mineralization. principal component evidenced: salinization processes (loaded by Na+, K+, EC, Cl-, F- HCO3-) controlled water/rock interaction, seawater intrusion cation exchange reactions; dolomite dissolution loaded couple Ca2+ Mg2+ 3) localized mixing upper aquifers gypsum respectively NO3- SO42-. hierarchical clustering distinguished four clusters: freshwater (EC = 594 μs/cm) mixed-HCO3 type ionic contents below WHO standard; brackish (Na-mixed) moderate mineralization content (1310 μs/cm), (Na-Cl) depicted high EC values (3292 above 4) saline Na-Cl very (5953 μs/cm). mapping indicated suitable zones accounting 54% entire area. occurrence central band its vicinity, which were characterized mineralization, yielded unsuitable agricultural uses. approach used this study valuable assessing irrigation, it can be studies other locations, particularly shallow vulnerable aquifers.