Coastal Management

Help shape our coastline for the future

The review of our Coastal Hazard Risk Management Adaption Plan (CHRMAP) commences as we stirve to protect our coast environment. Community engagement closes 6 October 2024.

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The City’s beaches and coastline are invaluable natural and community assets. Our beaches are however vulnerable to natural processes such as erosion and inundation, the impacts of which are predicted to increase in severity with climate change and sea level rise.

C.Y. O’Connor Beach is at present an erosion hot-spot, requiring ongoing active management in the form of annual sand replenishment to maintain a useable beach and prevent the loss of land and coastal assets.

The City’s other beaches, such as Coogee Beach, are expected to experience significant erosion problems as sea levels rise as predicted over this century.

A Coastal Adaptation Plan (CAP), developed in collaboration with Cockburn Sound Coastal Alliance (CSCA), guides the management of coastal risks and adaptation to coastal changes in a sustainable and flexible manner including:

• A Coastal Monitoring Program to track shoreline movements and identifies changes in the condition of beaches and coastal assets
• Periodic sand replenishment of eroding areas such as C.Y. O’Connor Beach
• Planning and design for responses to coastal hazards at specific sites, such as the design of long-term erosion protection measures for C.Y. O’Connor Beach
• Ensuring planning schemes and controls are appropriate to the latest hazard information
• Engagement with the community and stakeholders to raise awareness of coastal hazards and adaptation planning.

Current Projects

Engineered Fringing Reef

An engineered fringing reef located offshore at C.Y. O’Connor Beach is part of an ongoing coastal management project trial. Locally-made precast concrete reef modules, a sample of which can be seen at C.Y. O’Connor Reserve, have been installed offshore to break down wave energy reaching tan erosion ‘watchspot’ on the shore and slow erosion rates. The engineered fringing reef was the first of its kind in Australia.

Stage 1, installed in 2022, forms a 100 m long row made up of 135 modules. Stage 2, installed in November 2024, consists of a second 100 m row placed in parallel with stage 1. 

The City and the University of Western Australia (UWA) are monitoring the reef for a further three years following the installation of Stage 2 to understand how it performs and affects the surrounding coastline. The reef could be reconfigured, reduced or expanded over time, depending on the outcomes of the trial.

Image: Engineered fringing reef located offshore at C.Y. O’Connor Beach

While erosion is a complex issue with multiple causes, preliminary analysis of findings by UWA indicate the reef is helping to reduce wave heights and energy. The reef is equipped with extensive sensors in and around its components to monitor wave energy. This research indicates the reef’s first stage contributed to a 10 per cent reduction in wave height, while reducing wave energy reaching the shoreline by 20 per cent. The assumption following installation of the 135 2nd stage modules is that a further reduction in wave energy will reduce sand erosion and movement from the adjacent section of beach.

Within 12 months of the installation of stage one in March 2022, marine diversity had increased significantly, with surveys showing fish species had tripled. The reef has blossomed into a healthy underwater habitat and popular snorkellers’ and divers’ paradise, about 100 m offshore in about 2.5 m of water. The reef’s concrete modules are perfect for marine flora and seaweed growth which is providing habitat for an abundant range of sealife. Covered in macroalgae, seaweed and mussels, it has become a significant recreational destination for locals and the wider Perth population.
 
A habitat mapping report, commissioned by the City of Cockburn, to monitor marine life found in and around the artificial reef, observed 68 species of fish now inhabiting the reef compared to 29 species before the reef was installed, and 57 species of non-fish such as molluscs, starfish, sea urchins, sea anenomes and jelly fish.

Stage 1 of the reef was part-funded by the WA Department of Transport Coastal Adaptation and Protection grant scheme. Stage 2 was part-funded by the Australian Government’s National Emergency Management Agency Coastal and Estuarine Risk Mitigation Program. The reef has been designed and built by MMA Offshore (previously Subcon) with coastal engineering support from M P Rogers & Associates and UWA.

Using the Reef Responsibly

To help protect this sensitive marine environment and ensure it remains safe and enjoyable for everyone, please follow the guidelines below.

More information and contact

For more information contact 08 9411 3444 or at [email protected]