Source identification of spring water mass in the Southern Western Ghats of Kerala, India: Application of biogeochemical tracers

This study investigates the sources and formation of spring water in the southwestern coastal regions of the Indian subcontinent. It involves sampling and analysing spring water, groundwater, rainwater of the region and biogeochemical tracers. The springs of the region were found to be cold (27.2 -29.5 degrees C), acidic (pH = 3.43 -6.83), freshwater dominant (Cl- =10.10 - 43.67 mg L-1 ), and moderately oxygenated (DO = 5.08 -9.43 mg L-1 ). Using a binary mixing model with biogeochemical tracers (total alkalinity and Cl- ), the study identified precipitation and groundwater as primary contributors, with sea water also influencing coastal springs. The binary model indicates a higher precipitation contribution (85 -100%) to spring water compared to groundwater (0 -68%). The basin-wise variability of contribution by different water masses evidenced spatial variation of precipitation is not only acting as the major driving force to build the spring water mass, it is also intricately linked with the geochemical factors controlled by the hydraulic gradient between spring and groundwater systems.