Impacts of a shellfish restoration reef on wave attenuation within the Glenelg shellfish reef

Author: Giorgia Bovari

Bovari, Giorgia, 2021 Impacts of a shellfish restoration reef on wave attenuation within the Glenelg shellfish reef, Flinders University, College of Science and Engineering

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Shellfish reefs have been an ecological, economic, and engineering resource since the early 1800s, with numerous species of oysters representing a key resource for fishing activities. Due to overexploitation, shellfish reefs are now considered at risk, as are the ecosystem services they guarantee. For this reason, more and more shellfish reef restoration projects are being implemented in the United States, Europe, and Australia. In South Australia there are currently four shellfish reef restoration projects, the Windara Reef in the Yorke Peninsula, the Glenelg Shellfish Reef in Adelaide, and two incomplete oyster reefs in O’Sullivan Beach and Kangaroo Island. Some of the above-mentioned countries, shellfish reef restoration projects have proved to be a sustainable and successful method, not only for the conservation of local species and their biotic and economic importance, as well as for coastal environments. However, it is important to analyse how reefs affect the hydrodynamics of the adjacent environment, in order to evaluate the performance of the structure, regarding its role on potential coastal protection. The current study developed a Delft3D numerical model to estimate the capability of the Glenelg shellfish reef in relation to potential wave energy dissipation, significant wave height reduction and attenuation of wave-driven currents. Furthermore, a two-days FLOW module testing was simulated to highlight the influence of the Glenelg reef on tidal currents and bed shear stress. The obtained results showed a minimal ability of the current reef, to influence the hydrodynamics of the area, with bigger effects during storm periods. The numerical model was subsequently validated by comparing the obtained results with wave data collected by SA Water with a pressure sensor. The validation process showed the ability of the model to pick up the wave trend, mostly during the days defined as "calm" (lower significant wave height), while it showed an overestimation of the data during the days defined as "storm" (higher significant wave height).

Keywords: Shellfish reef, hydrodynamics, numerical modelling, coastline management, coastline protection

Subject: Environmental management thesis

Thesis type: Masters
Completed: 2021
School: College of Science and Engineering
Supervisor: Dr Graziela Miot da Silva