Risk Frontiers tropical cyclone model CyclAUS used here to quantify wind speed risk was developed using tropical cyclone observations held by the Bureau of Meteorology. CyclAUS simulates tropical cyclone activity impacting Australia north of latitude 30° South on the east coast, and north of latitude 35° South on the west coast.
The following individual risk measure is considered when calculating the overall risk rating for the tropical cyclone natural hazard:
- The 100-year ARI 3-second gust wind speed (assuming uniform surface roughness and flat topography).
A five-tier scale is used to categorise the risk geographically, based on the wind model in CyclAUS.
- Very High (5) – 100-year ARI 3 second gust > 58 m/s
- High (4) – 100-year ARI 3 second gust between 46 m/s and 58 m/s
- Medium (3) – 100-year ARI 3 second gust between 37 m/s and 46 m/s
- Low (2) – 100-year ARI 3 second gust between 30 m/s and 37 m/s
- Negligible (1) – 100-year ARI 3 second gust < 30 m/s
Areas with risk ratings of 2 or higher may experience some damage in a 1-in-100 year wind event, unless dwellings and other buildings are engineered to cope with such winds.
Proximity to shorelines refers to the shortest distance between an address and shorelines of any coastal waters (e.g., rivers, lakes, lagoons and estuaries) that are directly connecting to open ocean. For addresses located within 25km of the coast, a spatial resolution of 250m was used in the analysis, and for addresses located beyond 25km, the spatial resolution was 500m. The accuracy of this calculation is within 1km (upper integer values are provided).
An indication of storm surge risk can be gained by considering the elevation and the distance from the shoreline together.