The multivariate statistical analysis, hydrogeochemical modelling using visual MINTEQ software, indices of base exchange and Gibbs ratio were simultaneously applied to groundwater hydrochemical data of the Tirupati area. These techniques were applied to know the principal processes controlling the water chemistry. Fifty groundwater samples were analyzed for pH, electrical conductivity (EC), Ca, Mg, Na, K, HCO3, CO3, Cl, and SO4. The results showed that the abundance of the major ions in the water samples is in following order: Na > Ca > Mg > K and HCO3 > Cl > SO4 > CO3 > F. From this study, it is clear that there are five main processes that are responsible for this hydrochemistry namely: (1) weathering of silicate minerals, (2) dissolution of chloride salts, (3) Ion exchange between (sodium, potassium) and (calcium, magnesium) during the infiltration of reclaimed water, (4) precipitation of carbonate minerals and (5) anthropogenic activities (agricultural activities such as irrigation practices and fertilizers). Further, this study clearly demonstrates that the multivariate statistical techniques are potential tools and provide with greater precision clues to the processes that control water chemistry.
