Water quality characterization and pollution source apportionment in the Himalayan river flowing through Jammu City, India, using multivariate statistical approach and geospatial techniques

The present study evaluates and characterizes the water quality of River Tawi in Jammu city of Union Territory of J&K, using water quality index, multivariate statistical methods, and geospatial techniques. Water quality parameters were measured at fourteen selected sites along a 12 km (approx.) stretch of river (passing through the city) over two seasons (pre-monsoon and post-monsoon) using standard methods. Water quality index (WQI) results demonstrated spatial and temporal variations and the pollution level of the river increased from upstream to downstream sites. Calculated WQI revealed 35.71% of the water samples in the unfit for drinking category, 28.57% in good and poor category each, and 7.14% samples in very poor drinking water category during the study period. Comparison of analysis results with the drinking water standards prescribed by the World Health Organization and Bureau of Indian standards recorded elevated ranges of parameters like turbidity, BOD, total alkalinity, nitrate, and faecal coliform beyond the permissible limits. Hierarchical cluster analysis has transformed the sites into two clusters during pre-monsoon and three clusters during post-monsoon season indicating more water quality variation during post-monsoon season. Principal component analysis resulted in two PCs for the water quality, explaining 80.827% and 73.672% of the variance for pre-monsoon and post-monsoon periods. The prepared WQI maps confirmed and depicted deterioration of river water quality towards the midstream and downstream sites of the river basin. Entry of major sewage drains from the city particularly at the midstream sites and dumping of solid waste and agricultural runoff towards the downstream sites of the river constituted the main anthropogenic sources that decreased the river water quality. The study establishes first step towards spatial zoning of River Tawi based on pollution level which would help in improving the river water quality through proper basin management. The study also recommends installation of sewage treatment plants particularly at the midstream and downstream sites.