Effect of tropical cyclone characteristics and landfall angle on Brisbane flooding potential

Abstract:

Although it is unusual for tropical cyclones to occur as far south as Brisbane (Australia), it is not unprecedented. The Great Flood of Brisbane (1893), resulting in flood levels of over 9 meters, is believed to have been due to a tropical cyclone. Since this first recorded event, eight more tropical cyclones impacted Brisbane (1998, 1954, 1974, 1984, 1990, 2013, 2017, and 2019). Because the area is on the southern end of what is typically considered the tropical cyclone region, building codes are not as stringent as they are further north. Therefore, the potential impact from landfalling storms has a higher potential to cause significant damage. In addition, three of the nine recorded storms have occurred in the last six years, so a potential link to climate change makes it vitally important to understand the potential impact of future tropical cyclones.

Tropical cyclones are rare in this area, so it makes it hard to study the potential impact without many observations. Therefore, this study uses the Hybrid WRF Cyclone Model to generate an ensemble of physically plausible tropical cyclones with varying intensities and landfall angles. Tropical cyclone simulations that create significant amounts of precipitation around Brisbane are chosen to investigate which characteristics, such as intensity, direction, size, and translation speed cause a more significant flood potential.