Evaluation of water quality with application of Bayes' rule and entropy weight method

Abstract

The quality of water of the river has a significant impact on human population and livestock in basin area. Six water quality indicators are monitored from the gauging stations of Brahmani River to assess the changing trends in the quality of water. The conventional Aggregative Index Evaluation method is applied to know the overall water quality index for its intended use. Further, in this study, Bayes’ rule is applied for comprehensive assessment. The likelihood estimates are obtained from the normal distribution and is pre-owned for posterior probability calculation through Bayes’ rule. Finally, the indicator weights are estimated by Shannon’s entropy weight method. The consequences of analysis specified that the indicator, COD_Mn, is affecting the quality of water more in Panposh downstream. Biological oxygen demand, TA as CaCO₃, NH₄–N and Nitrate-N are closely related to domestic pollution and agricultural non-point source pollution. The overall quality of water is improved during dry seasons than during wet seasons due to the dilution of pollutants. Comprehensive evaluation indicates that the water is acceptable for second grade surface source protection zones for centralised drinking water.

Keywords:

• water quality
• Brahmani River
• Bayes’ rule
• normal distribution
• Shannon’s entropy
• likelihood

Acknowledgements

The research was encouraged by National Institute of Technology, Rourkela, India. The data were collected from Central Water Commission, Bhubaneswar, Orissa, India, and Orissa State Pollution Control Board, Bhubaneswar, Orissa, India. We are thankful to the editors and incognito reviewers for careful review of this research, who have contributed significantly to improving the manuscript.