The utility of multivariate statistical techniques in hydrogeochemical studies: an example from Karnataka, India.

Quality of groundwater is controlled by many factors amongst which the interaction of river water with adjacent groundwater and mixing/non-mixing of different types of groundwater may be important. An attempt has been made to study these processes using multivariate statistical techniques such as factor and cluster analyses. The Nethravathi catchment (India) which is a tropical river basin draining the Precambrian crystalline province of peninsular India, has been selected for this study. Hydrogeochemical data for 56 groundwater samples were subjected to Q- and R- mode factor and cluster analysis. R-mode analysis reveals the inter-relations among the variables studied and the Q-mode analysis reveals the inter-relations among the samples studied. The R-mode factor analysis shows that Na and Cl with HCO3 account for most of the electrical conductivity and total dissolved solids of the groundwater. The 'single dominance' nature of the majority of the factors in the R-mode analysis indicates non-mixing or partial mixing of different types of groundwater. Both Q-mode factor and Q-mode cluster analyses shows that there is an exchange between the river water and the adjacent groundwater.