Numerical Study of Brisbane River Estuary and Moreton Bay, Australia: Proposed Coastal Reservoir for Flood Adaptation

Floods are more likely to occur due to global warming and climate change. In Australia more than 85 %, the population is living in coastal areas, which are exposed to the impact of climate change. Brisbane, the capital city of Queensland has been selected as the study area to analyze the adaptation measures against flood through a Coastal Reservoir (CR) technique. Extreme weather events are one of the significant aspects of South East Queensland (SEQ). The floods history starts from 1806 to recent 2011, after a decade-long drought, the Brisbane River catchment experienced an extreme rainfall event during January 2011 that gave rise to the so-called ‘2011 Brisbane flood’. The catchment rainfall-runoff and flow releases from Wivenhoe Dam augmented and caused excessive flooding in the Brisbane city, causing significant damage to lives and property. The existing studies have considered flood mitigation measures upstream of the Wivenhoe dam. However, half the catchment of the Brisbane River lies above the Wivenhoe dam and almost half of the area below the dam, and the Wivenhoe dam for flood control cannot regulate catchment flows associated with the latter. The aim of this paper is to analyses lower Brisbane River flood dynamics for flood adaptation through a Coastal Reservoir technique at the mouth of the Brisbane River in the Moreton Bay, so when a significant climate event occurs in future, its effects on the regional community are lessened. A numerical model (MIKE-21) will be used to study the feasibility of proposed CR for flood adaptation. The gate operation of the CR will be analyzed under different flow conditions (riverine and tidal flows) to see how the flood levels can be reduced in the Brisbane city. The hydrodynamic simulation of the Brisbane River Estuary (BRE) will be performed with and without proposed CR. For this paper hydrodynamic model will be calibrated and validate of the Brisbane River and Moreton Bay, which will give the water levels variation inside the BRE. Further, CR gate operation will show the quantity (flood volume) of floodwater inside the CR. Thus, the paper would provide useful information for the feasibility and design of the CR technique for floodwater storage and water resource development in Brisbane River estuary. It will provide a practical solution for flood adaptation and also possible water resource development for water shortage areas affected by saltwater intrusion near estuaries.