Analysis of regional variations in groundwater chemical components in South Korea

Groundwater is a vital resource for drinking water, agricultural irrigation, and industrial use. Groundwater systems comprise a diverse set of chemical components with strong interdependencies, which complicates the identification of dominant factors governing groundwater chemistry. Despite the large number of chemical variables measured in groundwater, this study aims to identify the key factors influencing groundwater characteristics across different spatial locations. From this perspective, principal component analysis is a widely used multivariate technique for dimensionality reduction; however, it assumes a spatially constant covariance structure and therefore fails to capture spatial heterogeneity. To incorporate spatial information, geographically weighted principal component analysis (GWPCA) has been proposed. The objective of this study is to apply GWPCA to more accurately investigate the spatial regional variability of groundwater contaminants. The results demonstrate that GWPCA effectively identifies locally dominant variables, highlighting pronounced spatial heterogeneity in the relationships among groundwater chemical components.