A national view of storm tide flood risk in Australia

Dr Thomas Mortlock1, Andrew Gissing1, Dr Mingzhu Wang1

1Risk Frontiers, Sydney, New South Wales


Research by Risk Frontiers in conjunction with the Insurance Council of Australia has showed that approximately 30 % of all insured losses in Australia since the 1960s have come from tropical cyclones. Storm surge associated with tropical cyclones can cause significant damage to property and loss of life when they coincide with high tides. Recent research undertaken by Risk Frontiers provides an up-to-date national view of storm tide flood risk in Australia for the first time since the National Coastal Risk Assessment was undertaken in 2011. Results indicate there are approximately 179,000 addresses at risk of the 1% AEP storm tide flood (i.e. properties that have a 1% probability of coastal flooding in any given year under current climate conditions) around Australia. This increases to around 243,000 (+ 36%) by the 2090s with sea level rise projected under a low emissions scenario (RCP 2.6) and 271,000 (+ 51%) under a high emissions scenario (RCP 8.5). This national picture of storm tide risk shows that, while most of the present day risk is concentrated in Southeast Queensland, suburbs in Sydney and Brisbane may see significant increases in future storm tide flooding, depending on the rates of sea level rise that occur over the coming century. The rate of sea level rise that may eventuate over this period, however, remains deeply uncertain. This research forms part of Risk Frontiers’ multi-hazard Risk Rating Database, and is suitable for national to suburb-level risk scoping.


Thomas is Senior Risk Scientist at Risk Frontiers where he leads the development of climate risk modelling services and Risk Frontiers’ coastal, flood and tropical cyclone loss modelling. He has worked for over 12 years in the field of climate science, catastrophe risk, and coastal, flood and windstorm modelling and monitoring. Thomas is a Chartered Engineer and an Adjunct Fellow in the Department of Earth and Environmental Sciences at Macquarie University. He holds a PhD in the field of Coastal Geoscience.

Thomas’ background is in coastal engineering, flood hydrology, oceanography and climate science. He maintains an active research profile and has authored over 20 scientific papers in the field of climate and coasts. His current research interests include: climate change impacts on coastal waves and water levels, in particular the role of atmospheric circulation changes on coastal vulnerability; and, understanding the role of low amplitude climate variability on coastal and flood risk.

He is a member of the Editorial Board of the Journal of Marine Science and Engineering, and has reviewed for journals including Nature Scientific Reports and Earth Science Reviews. He currently sits on the Australia Pacific Climate Partnership (APCP) Expert Panel. Between 2016 and 2018, Thomas was on the steering committee of the (Australian) Coastal Processes and Responses Node of the New South Wales Adaptation Research Hub.