Cluster analysis of groundwater quality data of Venkatagiri Taluq, Nellore District, Andhra Pradesh

An assessment of the quality of groundwater for the Venkatagiri taluq of Nellore district has been carried out with an objective to determine the hydrogeochemical variability. A total of 120 samples of groundwater were collected from wells distributed over different geological formations such as gneisses, schists, phyllites and quartzites. The groundwater samples were analysed for the major chemical constituents, viz. Ca, Mg, Na, K (Cations); CO3, HCO3, SO4, Cl (Anions); pH and EC. Cluster analysis, a multivariate statistical tool, has been used in the study as a qualitative means for differentiating groundwaters into distinctive types. Based on hydrogeochemistry, chemical variability deciphered from Cluster analysis suggests three distinct types of groundwaters, viz. Mg-Cl-Ca type, Na-HCO3 type and CO3-pH type. Distribution of these groundwater types and their quality have been found to be in direct relation with the host rocks of the area.