Coastal dunes in South Australia are advancing inland at a remarkable rate.

Researchers say the phenomenon is going largely unnoticed by communities despite its potential long-term implications.

A study by the Beaches and Dunes Systems (BEADS) Laboratory at Flinders University has shown accelerated movement of dunes on the Younghusband Peninsula, Australia's longest coastal dunefield. 

This dunefield stretches 190km from the Murray River mouth to Kingston South-East. The recent findings indicate a rapid evolution in the dune landscape due to coastal erosion.

Professor Patrick Hesp, an expert in coastal studies, says he is alarmed at the rate of dune development. 

“This is an extraordinary rate of development and, if the shoreline erosion trend continues to expand north and south as it appears to be doing, it will dramatically change the National Park dune system – and may also significantly impact the Coorong Lagoon as dune sands invade it,” he said.

The central region of the Younghusband Peninsula, near 42 Mile Crossing, has transitioned to a significant shoreline erosion phase since the 1980s. 

This shift has resulted in about 100 metres of erosion at an average rate of 1.9 metre per year. A new dunefield developed in less than five years and has extended landwards by more than 100 metres in eight years.

The change marks a significant departure from the previously more stable and vegetated dune system, which had benefited from the cessation of rabbit and domestic animal grazing since the 1940s.

Dr Marcio DaSilva, a Flinders researcher who completed his PhD on the subject, has noted the surprising speed of these transformations. 

“We tend to think of most dune formation phases having developed over a long period of time, but our research has shown the opposite to be true on the Younghusband Peninsula,” he said.

The study looks at various hypotheses for the dune movement, including climate change, increased windiness, and human actions during periods of climate change. 

Sea level rise, particularly during the Holocene transgression, alongside singular massive storms and water table collapses, have been identified as contributing factors.

“This study provides direct evidence that shoreline erosion and subsequent cannibalisation of a formerly vegetated dunefield has produced a new transgressive dune field at an extremely rapid rate and in less than a decade. It’s the proof that there is cause for alarm,” Professor Hesp said.