Assessment of water quality of a hilly river of south Assam, north east India using water quality index and multivariate statistical analysis

Abstract

The River Jatinga, Assam, north east India is the only river that caters to the needs of the people of the Dima Hasao district of Assam but lacks information about its water quality. For ascertaining its quality, water samples were collected seasonally from five sites of the river during 2018–2019. Analyses of 13 environmental variables of water following standard methods found most of the variables well within the acceptable limit of drinking water quality standards prescribed by Bureau of Indian Standards/World Health Organization. Water Quality Status (WQS) of the river considering nine parameters (potential of hydrogen, electrical conductivity, total dissolved solid, biological oxygen demand, dissolved oxygen, total alkalinity, total hardness, nitrate, phosphate) was evaluated using Water Quality Index by weighted arithmetic index method. WQS across the sites and seasons were either good or excellent and suitable for domestic, irrigation and industrial purposes. Principal component analysis (PCA) classified the three PCs as I: electrical conductivity, total dissolved solid, total alkalinity, biological oxygen demand (anthropogenic, organic); II: transparency, flow rate, dissolved oxygen (natural); III: nitrate, phosphate (agricultural runoff). For improvement and maintenance of water quality of the river a co-operative participation of the authorities and local bodies is imperative.