Restoration Capacity of Dissolved Oxygen Along the Flow Path of Urban Rivers in Dhaka

This is the authors' abstract. We don't add key points for this paper.

Overpopulation and unplanned rapid urbanization with industrial effluent have gradually decreased the river water quality of Dhaka remarkably. The focus of the study is to understand the restoration capacity of dissolved oxygen on the basis of the upstream-to-downstream flow of the rivers of Dhaka. Data were collected from 38 stations covering an area of 81.4 km of the Turag, Buriganga, Dhaleswari, and Shitalakshya rivers along the flow paths. Due to the observation of oxygen deficiency, the Streeter-Phelps equation was used to make the DO sag curve and figure out the profile of oxygen restoration capacity. The DO level lies between 0.28-4.3 mg/L, whereas the DO deficit is about 5.37-7.46 mg/L. The recovery distances have been found around 294-727 km the four rivers. Spearman’s rho correlation confirmed that both ultimate BOD (rho = 0.947, p < 0.01) and Total Dissolved Solids (TDS) are the primary drivers of oxygen depletion and restoration dynamics, significantly influencing the river's self-purification capacity. Furthermore, the linear regression (R² = 0.747) is used to explain the relationship between organic pollution and oxygen deficit. Overall, this study provides insights into the restoration capacity of Dhaka's rivers and will serve as a supporting tool for waste management and environmental restoration.