Water Quality Assessment of Chhota Rangit River in Darjeeling Himalaya India, using Water Quality Index (WQI) approach

Abstract

The streams and rivers are the only source of water for people living in the mountainous parts of the world. But due to increased population and increased human interferences both the quality and quantity of water has been rapidly deteriorating leading to problems of water scarcity and water pollution in these fragile regions. The study area falls within the hilly region in India that often faces water scarcity and problems of water pollution. Water samples were collected from the predetermined sites of the river basin and then the water samples were sent to the water testing laboratory to measure various physical, chemical and biological parameters. The analytical results were then compared with the water quality standard set by WHO (2004) and Indian Standard (2012).Finally the water quality of the river was measured using the water quality index (WQI).  The analytical result shows that the water in the river basin is highly acidic in nature with pH value ranging between 5.2 -7.1. According to the result of water quality analysis the quality of water in the river basin coincides with four categories of water such as excellent, good, poor and very poor. The water quality index value observed in the sample water collected from Kankibong (94.17) and Bijanbari (76.21) is high which indicates poor water quality. The presence of such high water quality index values in these sites is due to the presence of high chemical and bacteriological parameters. The spatial distribution of water quality in the study area varies from site to site and shows that the poor quality of water is mostly associated with the areas where human interferences such as built up areas, agricultural villages, animal rearing etc are high.