Abstract
Groundwater quality from a part of lower Vellar watershed has been examined to characterize the geochemical conditions and its suitability for domestic and agricultural uses. The water samples were collected from shallow bore wells at different locations of the study area. The physico-chemical attributes such as pH, electrical conductivity, Ca2+, Na+, Mg2+, K+, HCO3-, Cl-, SO42-, hardness, total dissolved solids (TDS) and nitrate were analysed using standard laboratory tests. The other determinants such as sodium adsorption ratio, percent sodium (Na %), residual sodium carbonate (RSC) were calculated from the observed data. The pH and electrical conductivity varied from 4.47 to 9.46 and 500 µmhos/cm to 6710 µ mhos/cm respectively. The TDS and total hardness ranged from 323.0 mg/L to 4363.0 mg/L and 18.2 mg/L to 964.0 mg/L respectively. The range of chemical concentration of cations such as Ca2+, Na+, Mg2+, K+ was traces to 62.2 mg/L, 19.4 to 196.9 mg/L, 6.3 to 333.90 mg/L, 0.08 to 167.70 mg/L, while that of anions HCO3-, Cl- and SO42- was traces to 6.0 mg/L, 38.0 to 1392.0 mg/L and 5.0 to 80.0 mg/L respectively. Nitrate varied from traces to 1.0 mg/L. The graphical interpretation of modified Piper trilinear, USSL and Gibb’s diagrams represent Ca2+ > Na+ and Cl- > SO42- facies, C1S1 field and rock-water interaction respectively. The result shows that most of the samples were not exceeded the maximum permissible limit of prescribed standard for drinking by ISI and hence, it is suitable for drinking, industrial and irrigational purposes. The level of precipitation, interaction with formation and discharge nature of the study area could have considerable contribution.