Recurrence of Extreme Coastal Erosion in SE Australia Beyond Historical Timescales Inferred From Beach Ridge Morphostratigraphy

Extreme storms present a major risk to coasts. Increasing populations worldwide, together with sea level rise, exacerbate concerns for coastal settlements, but the low frequency of extreme storms makes an assessment of risk difficult. In southeast Australia, the severest beach retreat on record rela...

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Bibliographic Details
Published in:Geophysical research letters 2019-05, Vol.46 (9), p.4705-4714
Main Authors: Tamura, T., Oliver, T. S. N., Cunningham, A. C., Woodroffe, C. D.
Format: Article
Language:English
Subjects:
Adaptation
beach
beach ridge
Beach ridges
Beaches
coastal conservation
Coastal erosion
Coasts
Cyclones
Erosion
Evolution
Extratropical cyclones
extreme storm
Extreme weather
optically stimulated luminescence dating
Radar
Risk assessment
Sea level
Sea level rise
Storms
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Summary:Extreme storms present a major risk to coasts. Increasing populations worldwide, together with sea level rise, exacerbate concerns for coastal settlements, but the low frequency of extreme storms makes an assessment of risk difficult. In southeast Australia, the severest beach retreat on record relates to a series of extratropical cyclones in the 1970s, but the relatively short observational record hinders assessment of how frequent these events are. At Moruya in New South Wales, four decades of beach monitoring has provided new insights into response of beaches to extreme storms. We augment this recorded history with morphostratigraphic analysis of beach ridge evolution by using ground‐penetrating radar and optically stimulated luminescence dating. We find an episode of extreme retreat over 550 years, proving that the 1970s extreme event is a recurrent phenomenon. Our high‐precision morphostratigraphic analysis provides evidence with which to better plan coastal adaptation. Key Points Short observational history in SE Australia hinders assessment of whether extreme beach retreat in the 1970s is an isolated or recurrent event High‐precision morphostratigraphic analysis of beach ridge evolution augments 40 years of beach profiling at Moruya in NSW Extreme beach retreat is found to have occurred around 1650–1700, revealing that the 1970s event is a recurrent phenomenon
ISSN:0094-8276
1944-8007
DOI:10.1029/2019GL083061