Case study Improving Australia’s resilience to storm cluster disaster events and coastal erosion

How we got there 

Collating topographical, geographical, bathymetric, geological and geomorphological data

As the coast is forever changing under the forces of the tide, waves and wind, the project needed to understand how storm clusters may cause beach erosion. This was undertaken in the context of the coastal compartment, which defines the physical and process boundaries within which sediment movement occurs.

As such, the following material was collated for both the Old Bar and Adelaide beach sites:

• Locational information from the Australian Sediment Compartments Dataset
• High-resolution digital elevation data using Geoscience Australia’s Elevation Information System (ELVIS).
• Information on local infrastructure from Geoscience Australia’s National Exposure Information System (NEXIS) spatial and survey dataset.
• National Coastal Geomorphology Classification (NCGC) and Smartline dataset  analysis which identified the nature of each location’s coastal landforms and determined its landform vulnerabilities.
• Storm history information for each site – gathered from waverider buoys, models which use wind records to estimate past wave heights, and open-source software Stormwavecluster to simulate synthetic storm events – used to model sediment movement along the coast.
• Shoreline EVOlution modelling, which estimated the response of each site’s sandy shoreline to successive storm events, accounting for cross-shore sand movement from the beach to the nearshore, and long-shore sand movement along the beach. It also factored in changes in wave direction and height that occurred as waves enter shallow water.
• Geological data showing how the locations had evolved over time, including beach profiles (the measurement of the beach elevation from the dune to the ocean), beach thickness measurements from Ground Penetrating Radar surveys and sediment classifications from beach samples
• Satellite imagery and aerial photography.

Looking forward

A nationally applicable method for assessing coastal erosion impacts

• By demonstrating an understanding of the impact of storm clusters on the beach environment at two coastal-erosion-affected Australian locations (Old Bar, NSW and Adelaide, SA), Geoscience Australia and partners can now apply the methods used during the study at any location nationally where suitable data is available. This decision-making support to better protect valuable Australian coastal assets is invaluable.
• Coastal managers across Australia are now using a toolkit consisting of proven scientific methods and technical guidelines to find site-specific solutions to coastal erosion, particularly in areas where storm clusters are a possible driver of shoreline change. Infrastructure assets found to have a high exposure risk level are now readily identifiable and have included residential buildings, surf clubs, roads, carparks, beach access paths, stairs, sea walls, groynes and sewer outflows. Management strategies have been instigated to prevent future damage to these structures.
• Government and council coastal managers now have access to modelling techniques to show estimates of the shoreline position and sand volumes that may be eroded from the beach during individual storms or a storm cluster, and the subsequent effects of repeated cycles of storm erosion. They can now calculate the volume of sand required to maintain a buffer of sediment to protect their beaches or dunes against large storms. Access to this new information is helping them develop more targeted beach replenishment programs and recovery plans for specific sections of coastline.
• Scientific estimates of beach erosion caused by storm clusters can now be used to inform management strategies for mitigating the hazard into the future.