Assessment of groundwater quality in and around Vedaraniyam, South India

Groundwater from 47 wells were analyzed on the basis of hydrochemical parameters like pH, electric conductivity, total dissolved solids, Ca2+, Mg2+, Na+, K+, Cl-, CO3 (2-), HCO3 (-), NO3 (-), PO4 (3-) and F- in the Cauvery delta of Vedaraniyam coast. Further, water quality index (WQI), sodium percentage (Na %), sodium absorption ratio, residual sodium carbonate, permeability index and Kelley's ratio were evaluated to understand the suitability of water for drinking and irrigation purposes. The result shows significant difference in the quality of water along the coastal stretch. The order of dominance of major ions is as follows: Na+ a parts per thousand yen Mg2+ a parts per thousand yen Ca2+ a parts per thousand yen K+ and Cl- a parts per thousand yen HCO3 (-) a parts per thousand yen CO3 (2-) a parts per thousand yen PO4 (3-) a parts per thousand yen F-. Na/Cl, Cl/HCO3 ratio and Revelle index confirmed that 60-70 % of the samples were affected by saline water intrusion. WQI showed that 36 % of the samples were good for drinking and the remaining were poor and unsuitable for drinking purpose. The degradation of groundwater quality was found to be mainly due to over-exploitation, brackish aquaculture practice, fertilizer input from agriculture and also due to domestic sewage.