Deciphering Groundwater Geochemical Signatures in Central Odisha Using Multivariate Techniques

Abstract

The current study aims at evaluating the hydrogeochemical characteristics of groundwater and its associate geochemical processes occur in different aquifer system in Kaniha Block of Angul District, Odisha, using graphical techniques, multivariate statistical techniques and ionic ratio analysis. The study is carried out by using 81 groundwater samples during premonsoon season. The groundwater in the study area is mostly alkaline, with moderately hard to hard. The order of dominance of the chemical parameters in the study area is Ca2+>Na+>Mg2+>K+ and HCO3->Cl-> SO42->NO3- respectively. The analysed data were plotted in Piper-trilinear, and Gibbs diagrams for the evaluation of hydrochemical facies and the geochemical processes responsible for the water chemistry. The water chemistry of the study area is varied from Ca2+-Mg2+-HCO3- type to Ca2+-Mg2+-Cl- type which controlled by rock-water interactions with the influence of evaporation, particularly in a shallow aquifer. The impact of mineral weathering and ion exchange reactions within the aquifer system is confirmed by Gibbs plots, molar ratios, bivariate plots, and chloro-alkaline indices (CAI-I & CAI-II). This study also utilizes chemometric methods (Correlation Coefficient, Principal component Analysis, Hierarchical cluster analysis) to explore the geochemical evolution and the key factors influence the groundwater chemistry. Three major processes, such as anthropogenic carbonate-sulphate dissolution, ion exchange with silicate weathering, and geogenic fluoride enrichment, which account for a total of 73.72% of groundwater chemistry variance, were extracted using Principal component analysis. Cluster analysis was performed to classify the parameters based on key hydrogeochemical processes occurring on the flow path.