Principal Component Analysis in Groundwater Quality in a Developing Urban Area of Andhra Pradesh

Principal component analysis (PCA) of the chemical variables of groundwater is employed to interpret the relationships with specific processes that control the quality of water. Groundwater samples collected from the Guntur urban area, Andhra Pradesh were analyzed for major ion chemistry. The PCA separates the chemical variables into three principal components, which together account for 77.20% of the total variance. The principal component-I (PC-I) is dominated by TDS, Na⁺, Cl^-, SO₄^2- and K⁺. The principal component-II (PC-II) is influenced by pH and CO₃^2-. The principal component-III (PC-III) is governed by NO₃^-. These three principal components are identified with the processes of salinity, alkalinity and pollution, which are considered as lithologically and non-Lithologically controlled factor, lithologically controlled factor and non-Lithologically controlled factor, respectively.

Areal distribution of the principal component scores show that the higher positive scores of PC-I, PC-II and PC-III are randomly distributed, but do not coincide with one another, which suggest the local modifications of PC-I due to the regional flow system of groundwater, whereas PC-II and PC-III are the pathways of recharge zones via soil and anthropogenic activity operated independently, following the natural environmental hydrogeochemical evolution of groundwaters. Identification of these zones helps to take appropriate management measures to improve the quality of groundwater for sustainable development of the area.