Assessment of river water quality through application of indices: a case study River Sabarmati, Gujarat, India

Sabarmati is a major river in Gujarat which serves as the primary source of drinking and other domestic purposes. It also carries industrial and sewage discharges from nearby industries and areas of municipal corporations due to which it is prone to deterioration. Therefore, it is necessary to continuously monitor to restore and sustain the quality and the quantity of the river. The objective of this study was to assess the pollution levels in the river and assess the levels of various parameters with respect to drinking water standards. Here, a total of 10 physicochemical parameters were selected namely pH, turbidity, total dissolved solids, total alkalinity, total hardness, chloride, ammoniacal nitrogen, BOD, dissolved oxygen, and conductivity. These were analysed in samples collected from 11 stations along the course of the river Sabarmati in pre-monsoon and post-monsoon seasons from January 2015 to January 2016. Further, the water quality indices Weighted Arithmetic Water Quality Index (WAWQI) and Canadian Council of the Ministers of the Environment Water Quality Index (CCMEWQI) were selected to give an overall indication of pollution. Cohen’s d test was applied to test for any significant differences between the parameters in pre-and-post monsoon seasons. Water quality through WAWQI was found to be highly polluted and ‘unsuitable for drinking’. Using WAWQI, it was also found that, the water quality deteriorated further during post-monsoon season, while using CCMEWQI, it was found that the water quality ranged from ‘Fair to marginal’. Statistical analysis revealed significant differences in all the parameters during pre-and post-monsoon season at different locations. From the above indices and analysis, it can be concluded that appropriate measures must be taken for the improvement of the quality of water in River Sabarmati.