Johnson, F and White, CJ and Van Dijk, A and Ekstrom, M and Evans, JP and Jakob, D and Kiem, AS and Leonard, M and Rouillard, A and Westra, S, How and why are floods changing in Australia?, 36th Hydrology and Water Resources Symposium: The art and science of water, 7-10 December, Hobart, Tasmania, pp. 1284-1291. ISBN 9781922107497 (2015) [Refereed Conference Paper]
One of the open questions about climate change is how future flood risk in Australia will change.
Although changes to rainfall extremes are expected in most locations, it is not clear how these
changes translate into flood risk due to the potential additional feedback of altered catchment
characteristics (e.g., storage volumes, soil moisture, vegetation cover, fire disturbance) on runoff due instrumental period in Australia but it is not known if this is due to changes in population densities,
increased infrastructure in flood prone locations (the exposure), improved reporting or actual changes
in the occurrence of flood-producing meteorological events (the hazard).
This paper reviews the existing literature on historical and expected future flooding in Australia,
focusing on the flood hazard. Trends and changes in flood-producing mechanisms are also reviewed.
Three flood case studies, namely the 2007 Pasha Bulker storm, the flood characteristics of the
Fortescue Marsh area in the Pilbara and the 1956 Murray River floods are used to highlight the
complexities of flood behaviour and to illustrate some open research questions.
We show that short instrumental records, large natural variability and the interrelated nature of other
catchment changes limit our ability at this stage to understand how the flood hazard has changed in
the historical period. Research efforts to both address this gap and continue to develop methods to
best use projections from climate models are required to quantify future flood hazard. This information
can then serve as an input to risk models that combine flood hazard with projections information, flood
exposure and vulnerability.