Application of principal components analysis to the study of salinization on the Castellon Plain (Spain)

The high salinization in some sectors of the Castellon Plain aquifer (Spain) has been erroneusly attributed to seawater intrusion, because of the high and increasing contents of chloride ions. However, recent studies of this aquifer have shown that the chemical characteristics of groundwaters are the result of three different components: intruding seawater, freshwater from rainfall infiltration and saline water with a characteristic sulphate-calcium-magnesium facies, derived from bordering aquifers. The division into sectors according to hydrochemical features, in addition to the inclusion as variables of both certain minor ions and the ionic deviations of the theoretical mixing of freshwater and seawater, have provided a clear characterization of the salinization processes affecting the aquifer. The present study shows the application of statistical methods to the characterization of the salinization processes in the coastal aquifer of the Castellon Plain. The application of these statistical methods (cluster analysis and principal components analysis) has lead to the corroboration of the hypotheses developed from the previous hydrochemical study. Inclusion of specific variables (certain minor ions and ionic-Δ) into the PCA enhances a definition of the degree of the salinization processes.