Multivariate statistical analysis of Vaniyar sub-basin, Dharmapuri district, Tamil Nadu

Water quality evaluation is necessary to guarantee that resources should be used safely for drinking, agriculture, and industry. Twenty three groundwater samples were collected systematically according to the standard procedure during pre- and post-monsoon seasons in Vaniyar sub-basin, Dharmapuri district, Tamil Nadu. The main objective of the study is to understand the spatial and statistical variation of groundwater geochemistry seasonal-wise. Vaniyar sub-basin lies between the latitudes 12° 11′ 46″ N and 12° 09′ 39″ N and longitudes 78° 12′ 27″ E and 78° 36′ 65″ E covering an area of 982.25 km2. Out of which plain land covers an area of 591.43 km2. The study area is mostly underlain by Archaean crystalline rocks, the majority of which are charnockite. Quartz and feldspar are the most predominant minerals present in this rock formation. Unconsolidated and semi-consolidated formations, as well as worn and broken crystalline rocks, are the main aquifer formation in this area. The physical and chemical characteristics of the groundwater analysis findings were compared to the Bureau of Indian Standards’ (New Delhi, 2012) guidelines were used to find out the suitability of groundwater for drinking, irrigational and domestic purposes. ARC GSI 10.1and SPSS software is used to find out the spatial and statistical variation of the study area. From the correlation matrix, TDS and EC showing a high positive correlation toward the major cation and anion indicate that origin of major ions in groundwater samples has occurred from rock–water interaction. Factor analysis of two major monsoons shows that Factor 1 pre- and post-monsoon is having a high positive loading strongly suggests that the geogenic process is the main factor that influences the chemistry of groundwater in the area. Most of the major ions are formed by the dissolution of the host rock. Most of the major cation and anion are fall within the permissible limit and the spatial variation of pre- and post-monsoon indicate a high concentration of an ion in the north and northwestern part of the study area. Fluoride concentration in the study area is high, due to the presence of fluoride-bearing minerals in the host rock. In this location, it is required to remove excessive levels of fluoride from drinking water, and efforts should be done to provide water once the fluoride has been removed to improve the area’s life. © The Author(s), under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2022.