SOUTH EAST QUEENSLAND
PALM BEACH ARTIFICIAL REEF TRANSFORMS SANDY SUBSTRATE TO UNDERWATER WONDERLAND
Zoe Elliott-Perkins Senior Coastal Engineer Transport and Infrastructure City of Gold Coast
The Palm Beach Artificial Reef (PBAR) on the Gold Coast was constructed in 2019, as part of a two-phase project to protect Palm Beach from coastal erosion. The PBAR is a submerged control structure, meticulously designed and constructed to provide coastal protection outcomes, with the added bonus of enhancing surf amenity. In just a year, the PBAR has also had a positive impact on the local marine ecology, transforming the site from a sandy substrate to an underwater wonderland alive with marine flora and fauna. Background For decades, significant erosion events along Palm Beach have threatened beachfront infrastructure, exposing seawalls and jeopardising the lifestyles of locals through the temporary loss of beach amenity. While erosion events are part and parcel of coastal living, coastal data
monitoring had shown that Palm Beach, in particular, had the lowest volume of sand to buffer the beach against high energy storm events. This made it more vulnerable to erosion than other Gold Coast beaches. To address this ongoing issue, the City of Gold Coast began the Palm Beach Shoreline Project in 2013. The project became a collaboration of a talented team of scientists, coastal management experts, engineers, environmental officers, and dredging experts to find a sustainable solution to protect Palm Beach. The project aims were to: • r educe vulnerability of the beach and beachfront development to storm damage, •p rotect, and if practical, enhance the beach amenity for the community, •p rovide a sustainable, cost effective and integrated solution, and •a void or mitigate adverse environmental social impacts of erosion. Designing the solution The project went through a comprehensive design process spanning several years. An initial feasibility assessment developed and evaluated a total of 18 management options. Each option was assessed and compared based on expected cost, coastal protection benefits,
and impacts on a range of aspects such as coastal processes, ecology, surfing, and beach amenity. Following this investigation three options were assessed during the concept design study, which included numerical modelling investigations. After much investigation and consideration, the City followed a ‘design with nature approach’ and sand nourishment stabilised by an artificial reef was adopted as the best solution for Palm Beach. This option was favoured, largely due to its low visual impact and the long-term retention of nourished sand. Final detailed design investigations of the preferred solution were led by Royal HaskoningDHV and incorporated a ‘multiple lines of evidence’ approach including a combination of field data collection, numerical modelling and physical modelling. This method allowed for crosschecking between the results of the various design investigations and provided confidence in the unique design solution. The artificial reef is designed to work by influencing the surrounding waves and currents to promote a long-term increase in sand along vulnerable sections of Palm Beach. The detailed design investigations predicted that a sustained increase of sand
ENGINEERING FOR PUBLIC WORKS | SEPT 2020
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