|Title||Improved predictions of Australian extreme sea levels through a coupled wave-surge model|
|Publication Type||Conference Paper|
|Year of Publication||2016|
|Authors||Hetzel, Y, Janekovic, I, Pattiaratchi, C|
|Publisher||Bushfire and Natural Hazards CRC|
In order to protect life and property coastal planners and emergency managers require accurate estimates of flood risk. Providing reliable predictions of extreme sea levels for this purpose represents a significant challenge due to the range of complex processes that vary from beach to beach, town to town, and state to state around the entire Australian continent. As a result, a reliable comprehensive dataset of extreme sea levels for the entire coastline does not yet exist. Recent technological advances have allowed us to develop a high-resolution numerical model capable of analysing ocean dynamics to better understand how storms will impact local beaches on an Australia-wide scale. The advanced, high-resolution (in the coastal zone ~100m) 3D finite element hydrodynamic model (SCHISM) coupled with the state-of-the art WWMIII wave model included the effects of wave breaking on top of storm surges caused by wind and pressure. Simulations of multiple extreme sea level events, ranging from Southern Ocean winter storms to destructive tropical cyclones revealed that including waves in the simulations raised surge levels between 10–50 per cent, depending on local water depths and coastline orientation. To illustrate the robustness of the coupled wave-surge model we present results from Cyclone Yasi (2011), the largest and most intense storm to impact Queensland since 1913. The cyclone caused extensive damage to property and infrastructure costing $800 million over more than 500 km of coastline. A storm surge of 5.5 m was simulated in Cardwell with waves exceeding 12 m offshore and 6 m near the coast. Wave effects raised water levels by up to 35 per cent, highlighting the benefits of a coupled wave-surge model that includes wave setup effects.