Application of Sequential Analysis and Geographic Information Systems for Hydrochemical Evolution Survey, Shagari Environ, Southwestern Nigeria
Joshua Oluwasanmi Owoseni, Elisama Ugeh Tamarautobou, Yinusa Ayodele Asiwaju-Bello

Abstract
Integrated multivariate statistical, spatial, and graphical methods were applied to some hydrochemical data in Shagari area, Akure, southwestern Nigeria with a view to elucidating groundwater hydrochemical evolution. Water samples from 23 dug wells were clustered into distinct groups by hierarchical cluster analysis to depict different hydrochemical facies. Factor analysis reduced bulk hydrochemical data to principal components explaining possible dominant processes controlling water chemistry. Three factors which together explain 83.48 % of the total variance in the dataset were retained and interpreted. Factor 1 explains 35.82 % of the total variance and indicates atmospheric controls and silicate mineral weathering processes. Factor 2 explains 35.41 % of the total variance and reflects atmospheric controls, acid rain and speciation reactions producing inorganic carbon ions in solution. Factor 3 explains 12.24 % of the total variance, indicating silicate mineral weathering processes resulting in elevated pH. Generally, water types tend towards sodium chloride bicarbonate.

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