S. Gopinath

Geochemical evolution of groundwater along flow path in Upper Vellar sub basin, Tamilnadu, India: an integrated approach using hydrochemistry, modeling and statistical techniques

Hydrochemical, multivariate statistical, geochemical inverse and flow modeling techniques were attempted to examine groundwater recharge, flow and hydro chemical evolution along groundwater flow path in upper vellar hard rock aquifers. A total of 74 groundwater samples were collected and analyzed for different chemical constituents. Results revealed that three types of water facies were isolated as young, intermediate and matured type. Both hydrochemical and multivariate statistical analyses indicate groundwater in higher elevation observed with lower ionic ratios, plain and low lying areas with medium and higher ionic ratios respectively. Inverse geochemical modeling signify silicate minerals as precipitating and gypsum anhydride and NaCl species tend to dissolve due to limited availability of ions. Hydrochemical alteration seems to be influenced by rock water interaction, ion exchange and anthropogenic processes. .

Investigation of hydrogeochemical processes and groundwater quality in Upper Vellar sub-basin Tamilnadu, India

An attempt has been made in the Upper Vellar sub-basin to assess the hydrogeochemical processes influencing the water chemistry along with suitability of water for domestic and agricultural utilities. A total of 35 groundwater samples were collected for two different seasons, premonsoon (PRM) and post monsoon (POM), and analyzed for major cations, anions, and trace elements. The obtained results indicate that the dominance of silicate weathering, ion exchange process, and anthropogenic and microbial activities alter the chemistry of groundwater. The Piper plot suggests the facies evolution from Ca-HCO3, Ca-Mg-Cl and mixed Ca-Na-HCO3 and Na-Cl fluxes influencing the water chemistry. The ionic ratio plots suggest the predominance of Na+, Ca2+, HCO3− and Cl− indicating the silicate minerals dissolution and anthropogenic activities. All the trace elements are within the scale; however, Zn exceeds the WHO standard. The stability plot suggests samples representing kaolinite field during PRM and evolves towards montmorillonite and chloride field during POM infers the dissolution of silicates minerals and ions from host rocks. According to the WHO standard, 23% of PRM and 6% of POM water samples exceed the maximum permissible limits for drinking purposes.