Published works

This report describes research undertaken to develop a modified Severe Tropical Cyclone Marcia (2015) scenario and details its wind and storm tide-related impacts on buildings and society in Livingstone Shire and the Rockhampton Region. A perturbed version of the original track taken by Cyclone Marcia was chosen to create an ensemble event set of possible worstcase wind and storm tide inundation scenarios for the region of interest and the key findings of this work are as follows:

• Fifty storm scenarios were generated using modified 72 hr European Centre for Medium-range Weather Forecasting (ECMWF) ensemble storm track and intensity forecasts. Several scenarios caused widespread wind and storm tide-induced impacts.
• In Byfield, Rockhampton and Yeppoon, 90% of the simulated maximum site-relative three-second gust wind speeds were at or below 75 ms-1, 59 ms-1 and 68 ms-1 respectively.
• At the 90th percentile, roughly 43% of all residential homes experienced severe structural damage.
• The total number of inhabitable homes decreased for both pre- and post-1981 residential building construction with increasing percentile range.
• The maximum simulated storm tide for the entire ensemble event set was 5.83 m.
• Total loss ratios maxed out across the towns of Bangalee, Cooee Bay and Rosslyn for all percentile storm tide heights calculated for the entire ensemble event set. This led to many homes becoming inaccessible due to high flood waters.
• Both wind and storm tide 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 seek to improve the exposure dataset used in this scenario. Improvements will include adding critical infrastructure such as power lines and water distribution networks, as well as, updating Geocoded – National Address File (G-NAF) building level estimates of property value, contents value and population using ground truth data. The wind, rainfall and storm surge hazard models and associated vulnerability models used in the current multi-hazard model framework will also be updated. The wind hazard model will include new environmental parameters (i.e. sea surface temperature and deep layer wind shear) that influence tropical cyclone formation and maintenance. This improvement will help generate more realistic cyclones wind fields. The rainfall hazard model will be calibrated to Australian surface terrain and topography to simulate inland rainfall enhancements and will be paired with a hydrodynamic runoff model to simulate inland flooding damage and impacts to buildings, critical infrastructure and society during the post-landfall phase. The storm tide hazard model will be updated to simulate inland flooding impacts (e.g. surge-induced riverine flooding) by including the influence of the underlying surface roughness overland and expanding the mesh inland. Updates to the wind and flood vulnerability models will be made as new results surface from Bushfire and Natural Hazard CRC projects aiming to develop and improve these types of models. The flood vulnerability model will be updated to include flow velocity and wave effects. Finally, combined or joint hazard impacts (i.e. wind driven rain) will be evaluated to develop joint-hazard damage functions in future model releases.