Comparative study on seasonal variation in hydro-chemical parameters of Ganga River water using comprehensive pollution index (CPI) at Rishikesh (Uttarakhand) India

The assessment of the Ganga River System at Rishikesh was investigated at five different sites for three different seasons (summer, winter and monsoon) using comprehensive pollution index (CPI), considering 10 physicochemical parameters such as conductivity, turbidity, total dissolved solids, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total hardness, Cl, phosphate and sulphate. The CPI was found to be 0.54-2.47, which indicates the variation in pollution level of the River Ganga. The variation in pollution index value clearly shows that water quality was slightly polluted in winter (0.54-0.72) and summer (0.64-0.88) whereas high contamination (1.68-2.47) was observed during monsoon season. Among various sampling stations, Pashulok Barrage (Site 5) was more contaminated than other sites. All the studied parameters were under the permissible limit of W.H.O. (2011) except turbidity, total solids and suspended solids which were higher than the permissible limit. This study also illustrates the correlation between parameters by developing correlation matrix. The result of this study clearly elucidates that the water quality is getting contaminated as we moved from upstream to downstream of river and helps to understand the potential effects of water quality on drinking, irrigation and other purposes.