A southeast Queensland tropical cyclone scenario

Tropical cyclones are devastating events for the communities they affect. Realistic disaster scenario analysis is a simulation technique that can be used by disaster management agencies to understand the potential impacts of these storms and help them better prepare for their inevitable occurrence. This report describes research undertaken to develop such a scenario and detail its impacts. 

The primary aim of this project was to assess the potential impacts of a category 4 storm impacting the populous region of southeast Queensland. A perturbed version of the track taken by Severe Tropical Cyclone Dinah in 1967 was chosen for simulation and the key findings of this work are as follows: 

• The simulated scenario track remained off shore throughout its life, but makes its closest passage to the mainland near Harvey Bay. While not making official landfall it does pass over the holiday destinations of Fraser and North Stradbroke Island causing widespread damage to buildings in those areas. 
• Maximum simulated wind speeds over land were approximately 60 m/s, which is greater than the 500 year design wind speed for the region (wind region B). 
• The worst affected region was Harvey Bay and its surrounds (including Fraser Island). 
• Approximately 50,000 buildings were simulated to experience moderate structural damage, which may lead to occupants needing to seek emergency shelter. A further 8,000 are expected to suffer major structural damage and in many instances will need to be completely rebuilt. 70-90% of this damage is to older homes built prior to any stringent wind resistant design requirements. 
• As a result of the extensive damage to residential buildings 50,000 occupants are expected to seek alternate accommodation following the storm. In the worst impacted areas along the northern beaches of Harvey Bay, 60-70% of residents will need to do this. Such numbers cannot be able to be accommodated locally. 
• Losses will run into the tens of billions. For the wind-induced structural building damage simulated here, approximately $12 Billion in loss is expected. 
• Impacts are highly sensitive to simulated storm parameters such as track and intensity, so the highest quality event information is needed if realistic impact results are to be generated. 

Future work will further develop both the wind hazard and vulnerability models used in the current simulation and will seek to include new model components that simulate tropical cyclone induced rainfall, coastal inundation and their impacts.