Turbidity distribution in the Brisbane river estuary during the 2010-2011 Queensland floods

Yingying YU, Hong Zhang, Charles Lemckert

Friday 3 july 2015

12:15 - 12:30h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling

Parallel session: 15B. Sediment - Transport

The turbidity distribution within the Brisbane River estuary during the January 2011 flood event was investigated using a validated numerical model. The Brisbane River estuary turbidity maximum zone (ETM) generally extended throughout the mid- estuary under normal weather conditions. However, the turbidity distribution was significantly changed during the January 2011 flood events, from a high-low-high pattern of turbidity distribution to a gradual increasing pattern from upstream to downstream within the estuary. The ETM zone disappeared but the turbidity approached approximately 2000 NTU. In addition, it was found that the flood impact on sediment transport in the estuary was more significant than the tidal effects. An estimated 1,000,452 tonnes of sediment were delivered into Moreton Bay through the Brisbane River mouth during the January 2011 floods. These outcomes will be further applied to develop Moreton Bay models, thereby investigating the sediment settling in the coastal area following the flood and will also be used to inform the implementation of catchment management strategies.