Cyclone Yasi storm surge in Australia – Implications for catastrophe modeling

Yasi (2011) is one of the most powerful cyclones to have affected Queensland since records commenced, making landfall near Mission Beach at near category 5 strength (Australia Bureau of Meteorology Scale). A 5-m surge was observed at Cardwell, one of the largest storm surges observed in Queensland. Local damage reports confirm that isolated sections of the Queensland coastline were heavily damaged by the storm surge.

Storm surge can be a significant contribution to tropical cyclone -insured losses – especially for particular insurance client portfolios with significant exposure along coastlines. In this study, the Princeton Ocean Model (POM) with wetting and drying capability is utilized to simulate the storm surge from cyclone Yasi. The modeled over-land water depths are used as input to an advanced vulnerability module and industry exposure database developed at AIR to compute financial losses. Utilizing the default model grid configuration, simulated POM results matched available observations favorably, although the peak did not reach 5-m.

In addition, several experiments are performed in order to assess the sensitivity of the modeled surge heights and financial losses to grid configuration (rectangular vs. curvilinear), model resolution. It is hypothesized that higher resolution simulations will ultimately lead to higher simulated surge heights, and the impact of changes in simulated surge on financial loss will be assessed. Finally, the impact of coastal bathymetry and the Great Barrier Reef on the simulated storm surge is also assessed, utilizing simulations with idealized bathymetry.