Environmental indices based geochemical assessment of riverine sediments in sustainability perspectives: A study of Chalakudy river, Southern Western Ghats, India during extreme rainfall events for building baseline qualitative databases

ABSTRACT The increased heavy precipitation events associated with climate change can alter the geochemical status of sediments in tropical small catchment rivers, thereby affecting overall ecosystem health. The present study was carried out to understand the responses of sediment geochemistry in the Chalakudy River (CR) to heavy precipitation events, specifically focusing on contamination geochemistry. A total of 25 sediment samples were collected from upstream to downstream sections of the river during the 2019 extreme rainfall period and analyzed for trace element concentrations using X-ray fluorescence (XRF) techniques. The sediments in the Chalakudy river are generally acidic during heavy monsoon periods, and the conductivity values ranged from 18 to 1898 µS/cm. Based on the Degree of Contamination (DC) and Pollution Load Index (PLI), the sediments were found to be slightly polluted during the extreme rainfall period. Overall, contamination in the sediments was minimal and classified as low, except for an increase in barium content, which contributed to a slight elevation in pollution levels. These findings indicate that the increasing intensity and frequency of extreme precipitation events may pose long-term challenges to the sediment geochemical balance and thereby harmful for the aquatic systems. The study provides baseline data that is essential for future monitoring needs and contributes to sustainable river basin management under changing climate conditions.