The importance of understanding drivers of hydroclimatic variability for robust flood risk planning in the coastal zone

Abstract

Previous work has established that the risk of climate related emergencies (eg. floods, droughts, bushfires, etc.) in Australia, and many other parts of the world, is non-stationary. That is, the chance of an extreme climatic event occurring is not the same from one year to the next and is in fact dependent on the state of the various ocean-atmospheric phenomena that are responsible for Australia’s hydroclimatic variability. This previous work demonstrated how, on average for New South Wales, the probability of a flood occurring that is equal in magnitude to the 1-in-100 year flood is about five times greater during La Niña events compared to all other years and 12 times greater during a La Niña event that occurs during the negative phase of the Inter-decadal Pacific Oscillation compared to all other years. This work has recently been extended to focus specifically on urban coastal areas where it has been found that the non-stationarity of flood risk is even further enhanced when compared to the non-coastal catchments. Also investigated is whether this non-stationarity of flood risk is due to non-stationarity of antecedent conditions or non-stationarity of extreme daily and sub-daily rainfall events, with the finding being that both are important. This is contrary to recent studies that claim there is no evidence of non-stationarity in extreme daily and sub-daily rainfall across Australia. The implications of these results are significant given the large populations and infrastructure investment along the eastern seaboard and also timely given current updates to Engineers Australia’s Australian Rainfall and Runoff: A Guide to Flood Estimation, the standard for flood estimation in Australia.

Keywords:

• Non-stationarity
• climate variability
• climate change adaptation
• risk assessment

Additional information

Notes on contributors

A S Kiem

Dr Anthony Kiem is a hydroclimatologist and Senior Lecturer in the Environmental and Climate Change Research Group within the Faculty of Science at the University of Newcastle. His major research focus is on understanding the drivers and impacts of climate variability and change in the Asia-Pacific region. Of particular interest are hydrological extremes and how these may change in the future. Anthony has extensive experience in characterising impacts of climate variability and change, seasonal/inter-annual forecasting, extreme event (eg. flood, drought, bushfire, etc.) risk analysis, hydrological modelling, stochastic modelling, and water resources management. In addition to the research mentioned above, Anthony has also been involved in a wide range of consulting projects where insights into the impacts of climate variability and change are used to enable stakeholders from a range of public and private sector organisations to better assess their climate related risk, which therefore enables more informed climate adaptation and mitigation strategies to be developed.

D C Verdon-Kidd

Dr Danielle Verdon-Kidd is a lecturer/hydroclimatologist in the Environmental and Climate Change Research Group within the School of Environmental and Life Sciences. Danielle’s primary research focuses on studying the drivers of climate variability and change in Australia and investigating how to use these insights to improve natural resource management. Of particular interest to Danielle is integrating information from the palaeoclimate records, the instrumental records and global climate models to better assess climate driven risks. Danielle has also carried out a number of projects, within the consulting environment, aimed at helping clients to assess their vulnerability to climate variability/change and their ability to adapt to climate driven risks.