Beach erosion in estuaries: Port Stephens

Estuarine beaches are more vulnerable to serious coastal erosion than oceanic beaches due to their smaller size.  Dr Ana Vila-Concejo from the University of Sydney and her team have been investigating coastal management problems in the Port Stephens estuary since 2007.  Their project focused on erosion problems on the beaches (Jimmy’s Beach and Shoal Bay) and assessed the changes in the estuary sand shoals (flood-tide delta).  The project was funded by the Australian Research Council as a Linkage Project in collaboration with NSW-OEH, the local councils, Jimmy’s Beach Restoration Society and DHI Water and Environment. This was an innovative project as it looked at the beaches and the sand shoals concurrently. Dr Vila-Concejo and her team combined field observations with numerical modelling, and the results are now being passed on to the managers and local residents to improve the management of the beaches and the estuary.

Major findings from the project suggest that most of the erosion problems in Port Stephens are related to the lack of sediment arriving in the estuary. Over the last few thousands of years, the estuary received large amounts of sand. These days, the same processes that once formed the beaches and flood-tide delta, are pushing the delta further inland and sequestering sand from the estuarine beaches. The processes are more complex at Jimmy’s Beach because there is a river mouth directly to the west. Over the last 60 years, the river mouth has become narrower due to the extension of the adjacent Winda Woppa spit. A large quantity of sand from the system has been used to create that spit and this has exacerbated the erosion problems at Jimmy’s beach.

Winda Woopa and Jimmy's Beach

Historic evolution of Winda Woopa and Jimmy’s Beach undertaken using GIS