Prediction of drinking and irrigation chemical water quality indices using a multilinear regression approach in Cuddalore district, Tamil Nadu, India

Agriculture is predominantly practiced in the Cuddalore district, Tamil Nadu, India. The aim of this research work is to examine the groundwater suitability for drinking and irrigation activities and identify the factors influencing the groundwater quality. Physicochemical parameters such as pH, total dissolved solids, calcium, magnesium, sodium, potassium, chloride, sulphate, bicarbonate and nitrate are obtained for 62 groundwater samples (pre-monsoon and post-monsoon seasons). Based on the drinking water quality index (DWQI), most of the groundwater samples were good for drinking purposes in the region. The groundwater with elevated DWQI needs treatment before consumption. The parameters such as EC, Na%, SAR, MH and KR were integrated to produce a single irrigation water quality index (IWQI); it showed that most groundwater in the region is good for agricultural usage. Only a few samples were poor for agricultural usage. In these poor water quality areas, surface water and rainwater should be considered as alternative sources. There is a slight decrease in the concentration of groundwater ions during post-monsoon due to the dilution and dissolution processes. A multilinear regression model is also developed to predict the DWQI and the IWQI. The scatter diagram between various ions depicts that the geochemical process and anthropogenic sources influence the groundwater quality.