Groundwater is the primary source of domestic and agricultural use in Chinnalapatti Firka, Dindigul district, Tamil Nadu, India. This study assesses the suitability of groundwater for drinking and irrigation. A total of 120 samples were collected and analysed for physicochemical parameters during the pre-monsoon (PRM) and post-monsoon (POM) seasons, and the contaminants were mapped using GIS-based interpolation. The potential of hydrogen, electrical conductivity, total dissolved solids, total hardness, calcium, magnesium, sodium, potassium, chloride, sulphate, bicarbonate, and fluoride exceed the most desirable limit in both seasons. The Piper diagram indicates that the PRM water type is Mixed HCO₃--Cl−-SO₄2−, whereas in POM, the water type is Na+-K+-SO42−-Cl−. Gibbs indicates that rock-water interaction is the primary mechanism controlling the groundwater chemistry in both seasons. The Pearson correlation highlights seasonal shifts in groundwater chemistry, revealing natural processes in PRM and potential anthropogenic influences during the POM season. The groundwater quality index indicates 53% poor and 47% good water in the PRM season, whereas in POM, 70% good and 30% poor water, indicating improved water quality during POM. Wilcox and other irrigation indices indicate improved groundwater suitability for irrigation during the POM season, with reduced sodium and chloride hazards. In contrast, a slight sulphate-related risk arises from increased filtration and oxidation. Overall, weathering, rock-water interactions, and anthropogenic activities are significant factors that affect groundwater chemistry in the study area.
Kannan et al. (Wed,) studied this question.