Groundwater Chemistry and Quality in an Intensively Cultivated River Delta

The deltaic region of Cauvery River in Tamil Nadu, India is one of the intensively cultivated regions of India. The present study was carried out with the objective of assessing the groundwater quality and to evaluate the suitability of water for domestic and agricultural use in the deltaic region of this river. Groundwater samples were collected from 44 wells once in two months from July 2007 to September 2009. EC, pH, Eh and concentrations of ions (Na, K, Ca, Mg, Cl, SO4, HCO3 and NO3) were determined. Groundwater occurs in the alluvial formation generally in unconfined condition in this area. Na, Cl and are the dominant ions in groundwater. Groundwater is unsuitable for drinking in the coastal part and in few locations in the southwestern part of the area. Relatively high concentrations of fluoride and nitrate near the surface suggest the impact of fertilizers. Groundwater in the coastal region is unsuitable for irrigation due to sodium hazard. High concentration of ions in groundwater of the coastal region is due to poor flushing of groundwater into the sea and due to fine-grained nature of sediments in the aquifer. Hence proper management strategy is required to control salinity buildup either by increasing the rainfall recharge or by maintaining the river flow over a long period.