This document summarizes a study on the hydrogeochemistry and environmental implications of the Periyar River in southern Western Ghats, India after severe flooding in 2018. The study analyzed water and soil samples from different areas in the Periyar River basin to understand changes caused by the flood. Water samples were tested for various chemical parameters and compared to WHO and BIS standards. Soil samples were analyzed to determine Loss on Ignition (LOI) and composition through X-Ray Fluorescence (XRF). The results provide insight into the current water quality and soil composition/properties in the river basin following major flooding.