Abstract:
Estuaries are influenced by both oceanic and catchment forcings are expected to be subject to more frequent and intense coastal storms and heavy rainfall on the southeast Australia coast due to climate change. General circulation models and dynamic downscaling indicate that the 20 year average recurrence interval (ARI) maximum daily rainfall would increase in the order of 25% in this region under the high emission future by 2090. Such increases in extreme rainfall are predicted to cause an average increase of 55% in the equivalent ARI flood discharge into the Georges River, which features one of the largest floodplains and urbanized areas in Australia. This study quantifies consequent changes in extreme estuary water levels using the hydrodynamic model RMA-2. Recorded rainfall and water level data from an observed 50 year ARI flood event were used for model calibrations. Forced by the 20-year ARI historical and high emission future scenario flood conditions, RMA-2 predicts the future peak water levels will rise 1m in the upper estuary in the absence of changes in oceanic forcing. Sea level in the eastern Australia is predicted to rise by 0.66m under a high emission scenario. When combined with a predicted 20 year ARI barometric rise of 0.26m sea level rise, future flood peak water level are predicted to rise 1.3m in the upper estuary and 0.9m in the lower estuary at 20 year ARI. Consequently, under climate change, catchment floods dominate changes in peak water level in the upper estuary while oceanic processes principally determine changes in the lower estuary. The storm wind speeds are shown to have negligible impact on extreme water levels. Climate change storm impacts are predicted to have significant impacts on inundation of densely-populated regions, especially on Australian east coast.

Biography:
Professor Xiao Hua Wang graduated from Ocean University of China, and holds a PhD in Physical Oceanography from James Cook University in Australia. He is the Co-leader of the Sino-Australian Research Consortium for Coastal Management (SARCCM), University of New South Wales (UNSW), Australia, Chair, International Steering Committee, International Workshop on Modelling the Ocean (IWMO), and an associate editor for Estuarine, Coastal and Shelf Science (IF= 3.229 Q1) and Limnology and Oceanography: Methods (2.634 Q1), respectively. He was the Director of International Student Recruitment and Exchange (2018-2020), UNSW Canberra, and the Founding Director of the Sino-Australian Research Centre for Coastal Management (SARCCM, 2010-2020), UNSW. He has over 35 years experience in both undergraduate teaching and postgraduate supervision. His research concerns observing (including satellite remote sensing) and modelling of coastal oceans, sediment transport dynamics, and understanding of coastal management issues impacted by anthropogenic drivers and climate change. He has over 200 publications including eminent international peer-reviewed journal papers, book chapters and four books. His publication rate is 15 journal papers per year over the last five years (2019-2023), 90% of which belong to 1st quartile SJR Journals. His SciVal indexed research outputs in this period are ranked the highest among top international peers in the field. Google Scholar gives his career H-index as 43. GS consistently ranks him in top 15 researchers in ‘coastal oceanography’, ‘sediment dynamics’ and ‘coastal management’. His work has been funded by a variety sources including the Australia Research Council and the EU Framework.  He has been awarded a total of 11 competitive grants in the last five years (2017-2021) with a total cash income of $1.82M (including co-lead Chief Investigator for an industry grant of $1.25M). In 2025, the United Nations Decade of Ocean Science for Sustainable Development has endorsed his five-year project ‘Building Coastal Resilience against Climate Change’.