Assessment of spatio-temporal patterns of water quality in a tropical river by multivariate statistical analysis and water quality index methods

Abstract

Rivers are facing seasonal as well as long-term changes in their hydro-ecological regime in response to multiple stressors that have affected water quality as well as flow volumes. Ramganga is an important tributary of the Ganga River that provides freshwater to the people of Uttar Pradesh and Uttarakhand. In recent years, industrial discharges, agricultural and municipal wastes and wastewater releases have severely polluted the river throughout its stretch. The contamination index (CI) values at Moradabad in the pre-monsoon, monsoon and post-monsoon seasons were 0.78, 0.86, 0.76-not contaminated, at Bareilly 1.68, 1.65, 1.22-slightly contaminated, at Dabri 2.32, 2.34, 1.76-slightly contaminated while the pollution index (PI) values at Moradabad were 1.76, 2.23, 1.43-slightly contaminated, at Bareilly 4.29, 4.49, 3.95-severely contaminated and at Dabri 13.06, 12.21, 9.49- severely contaminated. The pollutants responsible for high pollution are NH3+, PO4-3, SO4-2, NO2-+NO3- which primarily come from agricultural run-off as the farmers use phosphate, ammonium and sulphate fertilizers and pesticides. The land use type along the banks of the Ramganga in Bareilly and Dabri is primarily dominated by agricultural lands. Hence, the increased CI and PI values at Bareilly and Dabri clearly indicate high agricultural pollution.