In rivers, reaeration is an important process that occurs at the air-water interface to restore dissolved oxygen (DO) equilibrium and this process is characterised by its reaeration coefficient. Existing empirical equations to predict reaeration coefficient is merely based on natural reaeration (Ku), which refers to the oxygen transfer across the natural free surfaces while reaeration coefficient concerned with artificial reaeration caused by turbulence due to intense boat traffic (Kb) has not been explored previously. This study investigated the influence of boating activities on DO and its associated reaeration coefficient, Kb, along the Brunei River. Spatial analysis of DO distribution indicates that the water is better oxygenated when it travels through areas with boat traffic. Using the DO balance equation, it was discovered that Kb is between 0.19 (day-1) and 1.99 (day-1) while Ku is between 0.20 (day-1) and 0.51 (day-1) which implies the importance of boat activities as an additional source of oxygen for the river. A predictive equation was derived for Kb as a function of boat traffic intensity (N) and water depth (H). This equation is useful for the analysis of purification capacity of a navigated river and water quality modelling.
