Water Quality Index (WQI) for Evaluation of the Surface Water Quality of Bangladesh and Prediction of WQI from Limited Parameters

Healthy aquatic environment is crucial for preserving aquatic lives in surface waters. Increasing discharge or runoff from industrial or agricultural sources can pollute water leading to an unhealthy aquatic environment that can cause distress in fishes and other aquatic lives. In places with lack of infrastructure and regulatory enforcement, pollution can be particularly challenging to handle. Assignment of an indexing system can be helpful for analyzing pollution pattern in the polluted rivers which can be helpful for remediation purposes and prevention of future pollution. Bangladesh currently does not have any indexing system in place. Assignment of indices in the rivers of Bangladesh can be helpful for remediation of the rivers on a preferential basis as remediation of all the rivers at once will pose challenges with funding and infrastructural allocation. Parameters monitored in the water monitoring stations of ten rivers were extracted from the reports published by the Department of Environment (DOE) of Bangladesh. A water quality index (WQI) was assigned on the rivers across seven years of time period to identify the most polluted rivers. The degree of pollution in the river was in the order of Mayuri > Buriganga > Korotoa > Turag > Shitalakhya > Surma > Halda > Dhaleshwari > Mathavanga > Brahmaputra based on the WQI analysis. The most polluted rivers were in areas with manufacturing, textile etc. industries. Hence, monitoring of industrial discharge intro the rivers and regulatory enforcement is crucial for the prevention of pollution in rivers. Installing more monitoring stations and more frequent samplings can be helpful for better assessment of WQI of the rivers. However, deployment of these strategies can be challenging for Bangladesh due to funding and infrastructural constraints. Hence, a formula was developed in this study to calculate WQI in a resource limited situation (WQI = 4.42-0.42 Dissolved oxygen + 0.11 Biochemical oxygen demand).