ASSESSING GROUNDWATER HYDROCHEMISTRY OF ATMAKUR, SPSR NELLORE DISTRICT, ANDHRA PRADESH, INDIA

Groundwater from 21 wells were analysed for physicochemical parameters and major ion chemistry in the Atmakur area of Nellore District. Analytical results demonstrated that the majority of the samples can meet the requirement for drinking and irrigation use with few exceptions. The dominant hydrochemical facies of groundwater was Ca-Mg-HCO3 in both Piper and Chadha's classifications. Moreover, Wilcox plot shows that most of the samples fall within the good to permissible followed by doubtful to unsuitable categories for irrigation use while the USSL classification shows that most of the samples fall in C3-S1 and C4-S1 with increasing salinity. Scatter diagram showed that silicate weathering (HCO3- and SO42- dominates over Ca2+ and Mg2+) prevails in the study area. Furthermore, Gibbs diagram confirmed that the majority of samples fall in rock dominance followed by evaporation dominance, while the CAI-1 and CAI-2 indicated that reverse ion exchange is dominant in the region.