The June 2016 Australian East Coast Low: importance of wave direction for coastal erosion assessment

Thomas R. Mortlock*, Ian D. Goodwin, John K. McAneney, Kevin Roche

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)
18 Downloads (Pure)

Abstract

In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen-Collaroy, a well-known erosion hot spot on Sydney's Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.

Original languageEnglish
Article number121
Pages (from-to)1-22
Number of pages22
JournalWater
Volume9
Issue number2
DOIs
Publication statusPublished - Feb 2017

Bibliographical note

Copyright the Author(s) 2017. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • East Coast Low
  • nearshore processes
  • coastal erosion
  • coastal management
  • climate change
  • numerical modelling
  • Southeast Australia

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