Characterization of Groundwater in the Unconfined Aquifers of Chennai City, India, Part 2 - Factor Analysis

Hydrogeological studies of the groundwater in Chennai area have shown that the alluvial aquifers have several geochemical facies with distinct characteristics. Factor analysis of the data has been helpful in characterising these facies, since it is noticed that the factor 1 measures salinity, hardness and alkalinity, while factor 2 measures pollution. It is observed that lithology, land use and hydraulic characteristics exercise significant control on the geochemistry of groundwater. The behaviour of groundwater quality in coastal areas, river banks and surface reservoirs is also well explained by factor scores and many of these form distinct hydrogeochemical facies. The study further shows that the geochemistry of the groundwater in these categories gets much more distinct in the pre-recharge periods indicating the effectiveness of the rock-water interaction in the aquifers.