A recent study by Flinders University has revealed new insights into the continually developing strategy for coastal management in South Australia. By examining the way Cape Dombey’s rocky headland in Robe influences waves, currents, and sand movement, Flinders Uni researchers have identified key patterns in sand movement on the Limestone Coast.
Through data analysis, the researchers have put together a detailed framework for understanding “headland bypassing”, a process in which sand moves past the headland. Their findings provide insights into why Robe’s popular beaches are either building or eroding at various times.
Described in a new Marine Geology article, the study found that headland structure and submerged features significantly impact the behaviour of waves as they shift inshore and offshore. While bending around the headland or breaking over underwater reefs during low water levels, waves lose their energy, which changes the amount of sediment being moved towards beaches on the sheltered side of the headland.
The article, titled Sediment bypassing around a headland in a high-energy coastal environment, then outlined three ways sand is transported around Cape Dombey:
Slow movement in mild conditions
When water levels are low and waves are small, currents flow around the headland and cause minimal sand movement. This process helps build up the level of sand on the sheltered side of the headland.
Strong transport across the bay
When water levels rise and waves get bigger, currents move sand across the bay at rates 30 times higher than during mild conditions.
Powerful offshore transport
During storms, especially those that cause waves to come from the northwest, strong currents pull sand away from the coast at rates up to 40 times higher than under mild conditions, significantly reducing sand levels on beaches.
With these three forms of sand transportation now outlined, researchers can develop greater strategies for coastal management, ensuring that South Australian beaches remain stable in the face of changing wave and weather conditions on the coast.
Charlotte Uphues, author of the study, said the research “provides a deeper understanding of the forces at play along the coastline of Robe.”
“By studying how Cape Dombey’s headland shapes the movement of sand, we can better predict changes to the local beaches and develop more effective management strategies.”
“The findings from this study provide valuable insights into the dynamic processes that shape our coastline. Understanding how the Cape Dombey headland affects the movement of sand is crucial as we work on our Coastal Adaptation Strategy,” District Council of Robe Mayor, Lisa Ruffell, said. “This will help us better manage our beaches, protect the natural beauty of Robe, and ensure a resilient coastal environment for the future.”
In addition to the research from Flinders University, local government and the public continue to develop future coastal management strategies to help safeguard Robe’s coastline and adapt to climate change and coastal erosion.
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