Mr Chris Sharples1, Ms Hannah Walford1, Dr Christopher Watson1, Dr Joanna Ellison1, Dr Quan Hua2, Mr Nick Bowden3, Professor David Bowman1
1University Of Tasmania, Hobart, Australia
2Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, Australia
3Antarctic Climate and Ecosystems Co-operative Research Centre, Hobart, Australia
Renewed global sea-level rise (SLR) is expected to eventually cause recession of many shores, however most swell-exposed sandy beaches have not yet shown evidence of receding in response to this cause. A 70-year air photo and beach profile record for swell-dominated Ocean Beach (western Tasmania) demonstrates an abrupt change of long-term shoreline position variability circa 1980, from episodic erosion and accretion (since at least 1947) to persistent recession up to the present. Some of the processes that elsewhere confound expected sandy coast responses to SLR – such as episodic reversals of alongshore or onshore-offshore sand transport causing beach changes large enough to mask any sea-level rise effects – are not significant on the Tasmanian west coast. Instead, Ocean Beach exhibits conditions likely to cause earlier recession in response to SLR than most beaches. We have identified two changing processes capable of explaining the change of behaviour at Ocean Beach, namely sea-level rise and increasing onshore wind speeds. Both are likely to contribute to the observed change of beach behaviour. The factors causing an early shoreline response to sea-level rise at this site are probably applicable much more widely as indicators of beaches likely to respond earlier than others to SLR.
Chris Sharples is a geologist who has specialised in coastal geomorphology as a contractor /consultant since 1998. He is currently completing a PhD study on differentiating the coastal erosion effects of global sea-level rise on coastal landforms.