The response of the river plume to the flooding in Moreton Bay, Australia

Abstract

Coastal zones are important ecological regions and popular areas for human recreational activities. The regions also act as receiving environments for contaminants and sediment discharged from coastal rivers. In Australia, the Brisbane River, and more particularly its estuary (Costanzo et al.), is an example of one such environment as it is a complex coastal system with ecological and commercial significance. While Moreton Bay has been the focus of recent intense scientific research, little is known about its physical processes, such as the behaviour of the Brisbane River plume that enters the bay following storm events. In this study, a three-dimensional hydrodynamic model with an unstructured mesh is employed to simulate the generation and development of the flood-driven plume near the mouth of the Brisbane River. The model results are verified by field measurements and satellite observations. The results show that the river discharge is the determinant effect on the plume extension alongshore and offshore. A high correlation coefficient of 0.87 demonstrates that the plume size typically increases with the growth of the river discharge. Following 3 days extension of flood-driven plume, both the salinity and temperature, within the region that 1 km wide and 3.5 km long off the river mouth, decreased by approximately 3.6%.