SEBA ROY AND ABHIK GUPTA
Abstract
River Barak and its tributaries are major sources of usable water in the densely populated Barak valley of Assam, India. This paper makes an assessment of the physical, chemical and biological characteristics of R. Barak and its tributaries during 2002 to 2006 at 12 sites. Habitat scores (based on RBP III) at all the sampling sites mostly ranged between the suboptimal and marginal categories, thereby indicating their neither pristine nor heavily impacted nature. Among the twelve stations of the Barak River system, R. Chiri had the highest value of pH, total alkalinity and dissolved oxygen. At the same time, it also had the lowest value of water temperature, electrical conductivity, total dissolved solids and BOD, thereby revealing that this site, located in the upstream area of the Barak Catchment in Cachar district, was the least disturbed. As the river flowed further downstream to enter Silchar, the largest urban center in this area, there was an immediate decline in pH, total alkalinity and DO and a concomitant increase in water temperature, TDS and BOD. BOD (5 days) remained below the acceptable limit in R. Kushiara. Possible correlations were made between the habitat score and water quality parameters. Habitat degradation in River Barak and its tributaries might have occurred due to anthropogenic activities like agriculture, disposal of sewage and other waste, mass bathing and washing of clothes in the river and its catchment.