K. Sonaimuthu, N. Arun Nagendran and J. Viji
Abstract
The streams of the Western Ghats are essential freshwater sources that support biodiversity, local populations, and farming activities. Munnar, known for its rich biodiversity and as a tourist spot in Kerala, is experiencing growing human-induced pressures that could impact the quality of stream water. Evaluating its current condition is vital for promoting sustainable usage. This research aimed to investigate the seasonal changes in the physico-chemical properties of four selected streams in Munnar and to determine their overall quality using the Water Quality Index (WQI). Water samples were taken from the Suryanelli, Sivanmalai, Periyavarai, and Kannimalai streams during the winter, summer, monsoon, and post-monsoon seasons of 2023. Nine critical parameters (pH, electrical conductivity, total dissolved solids, dissolved oxygen, total alkalinity, total hardness, calcium, chlorides, and phosphate) were examined following APHA standard methods. The WQI was computed using the weighted arithmetic index method, referencing BIS, ICMR, and WHO standards. The WQI values for different seasons ranged from 26.39 to 43.02 across all locations, categorizing the streams as having âgoodâ water quality. Seasonal differences showed increased hardness and chloride levels in the summer, while phosphate and salinity were higher during the monsoon, influenced by hydrological conditions and agricultural runoff. Correlation analysis revealed significant relationships among parameters, with dissolved oxygen, calcium, and phosphate being crucial in determining WQI results. The results indicate that all four streams in Munnar currently maintain good water quality, suitable for drinking and ecological purposes. However, the rising anthropogenic pressures highlight the need for ongoing monitoring, sustainable watershed management, and awareness initiatives to protect these essential freshwater resources.