The City's response to PerthNow about C.Y. O'Connor Beach erosion, 18.2.26
Question: What has been happening to the sand on the beach? Is it due to ocean currents or recent weather events i.e. winter storms?
Answer: Severe erosion of the northern section of C.Y. O’Connor Beach, and sand drift issues in the Rollinson Road Park area, occurred over the recent summer holiday period.
Strong sea breezes blew a significant amount of sand up the beach and over the dune, accumulating on the shared path adjacent to the Rollinson Road Park area. The sand has been removed from the path and excess sand is being moved from the dunes to recover smothered vegetation.
Sand which eroded from the beach on the northern side of the Catherine Point groyne due to wave action, is also currently being replenished during sand nourishment operations.
Question: What did the results of the UWA monitoring assessment from 2022-2025 find?
Answer: Preliminary UWA research indicates the reef’s first stage (completed in 2022) contributed to a 10 per cent reduction in wave height, while reducing wave energy reaching the shoreline by 20 per cent. You can read more about that here: Engineered fringing reef doubles scale of erosion reduction trial - City of Cockburn
The assumption following installation of the 2nd stage (completed in November 2024) is that a further reduction in wave energy will reduce sand erosion and movement from the adjacent section of beach. While the early results are promising, the effectiveness of the reef will be determined when UWA completes its multi-year monitoring program.
Question: What’s involved in the restoration process?
Answer: Approximately 20,000m3 of sand has eroded from C.Y. O’Connor Beach on the northern side of the Catherine Point groyne.
A large volume of sand has accumulated at the northern end of the beach on the south side of Island Street Groyne.
Sand is being ‘back-passed’ from the accumulation zone down the beach from north to south by the City’s contactor, via excavators and trucks.
Work to restore the beach profile began on 11 February with an estimated completion date of 2-3 March. The beach is closed to the public on weekdays during this period, reopening around 5pm each Friday and through the weekend.
Question: How much will it cost?
Answer: The total cost for sand nourishment work varies from year to year and season to season, depending on various factors, such as the extent of erosion, the source and method of sand extraction, and the availability of contractors.
The City has a current annual budget of $590K for sand nourishment and beach re-profiling works along its coastline, which can include C.Y. O’Connor north and/or south beaches, Coogee Beach, and/or Ngarkal Beach.
Question: What will be included on the new CHRMAP to manage coastal risks/ when will this be decided?
Answer: The City is currently developing a Coastal Hazard Risk Management and Adaptation Plan (CHRMAP) to replace its Coastal Adaptation Plan and create a holistic and up to date plan to manage its coastal risks and assets.
This is a planning document that will influence all management and development along the City’s coastline. This document will include technical data and modelling to identify risk areas as well as consider the results of community consultation in the recommended actions for future coastal adaptation and management.
Community consultation is scheduled on the CHRMAP for this March and April to ensure the community continues to be informed and has a say about the future of our coastline. Information of the consultation process will be made available once details are confirmed.
A draft CHRMAP and report will be completed for consideration by Cockburn Council this year.