Identifying major factors controlling groundwater chemistry in predominantly agricultural area of Kattumannarkoil taluk, India, using the hydrochemical processes and GIS

Abstract

Hydrochemical investigation was carried out in predominantly agricultural area of Cuddalore district, South East India. The objective was to determine the potential factors controlling groundwater chemistry and their seasonal variation. Fifty samples obtained from 37 agricultural boreholes and 13 surface waters were used for analyses of 13 physico-chemical parameters. Qualitative and quantitative methods such as titration methods, flame photometry and Ultra-violet visible spectrometry were used to define the major ions; Na+, Ca2+, Mg2+, Cl−, K+, SO42+, PO4, Si(OH)4 and NO3−. The results further were subjected to geographic information system (GIS), statistical analysis and geochemical plots. The evaluation of factors controlling water chemistry was accomplished by interpreting Gibb’s diagram, Piper diagram, Index of Base Exchange (IBE) and factor analysis. The interpretation proved that salts percolation, agriculture, weathering and dissolution as predominant factors controlling water quality of the study area. A Piper diagram classified the study site’s water types into Ca-HCO3 water type, Ca-Cl water type and mixed Ca-Mg-Cl water type indicating freshwater recharge, mineral dissolution and reverse ion exchange, respectively. Factor analysis extracted four significant factors, namely leaching of secondary salts, weathering, and mineral dissolution as well as anthropogenic factors, that cumulatively responsible for 80.34% of the total variance of the taluk’s groundwater chemistry.

Keywords

• kattumannarkoil
• hydrogeochemistry
• groundwater quality
• statistical analysis