| description abstract | This study presents a framework for water-quality-based ranking of river stretches by employing a modified multicriteria decision-making method, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), that coupled water-quality indicators with their prescribed standards. The methodology was applied to rank a total of 468 river stretches located across 19 states in India based on eight water-quality indicators. These indicators were dissolved oxygen (DO), temperature, conductivity, pH, biochemical oxygen demand (BOD), nitrate (NO3−), fecal coliform (FC), and total coliform (TC). The surface water classification based on “designated best use criteria,” which classify water bodies into five classes, namely A, B, C, D, and E was used to develop the standard matrix for use in TOPSIS. The results revealed that out of the top 10 best river stretches for water quality, the first four were located on the Beas River in the state of Punjab. These best stretches were located at Harike, Gowindwal, d/s Pathankot, Talwara, and G.T. Road near Kapurthala. The next best five in ranking were located on tributaries of the Indus river, passing through the northern states of Punjab and Himachal Pradesh. The bottom/worst 10 river stretches were all located in urban areas with high levels of population and industrialization. These were the Yamuna at Okhla, downstream of Shahdara Drain in Delhi; Vasishta at Salem in Tamilnadu; Arkavathi d/s of Kanakapura in Karnataka; the Yamuna at Nizamuddin in Delhi; and Ghatprabha at the town of Gokak in Karnataka state. It was observed that the best stretches were those with high DO, low BOD, and low FC and TC, whereas the worst polluted stretches were those with very high levels of BOD, FC, and TC. To the best of the authors’ knowledge, this is the first attempt wherein a modified TOPSIS involving the coupling of water-quality indicators and their prescribed standards has been used to rank river stretches. The findings of this study will have implications for the pollution control authorities and researchers in applying the proposed approach in the development of effective and robust river water-quality management plans. | |
