Abrolhos Islands Aquaculture Modelling

Requirements 

Customer: Department of Fisheries, Western Australian Government

We undertook a study with The University of Western Australia to support the preparation of an environmental impact statement on proposed finfish aquaculture activities off the mid-west coast of Western Australia.

We developed a 3D hydrodynamic, particle tracking and water quality model of the Abrolhos Islands, using TUFLOW FV as the hydrodynamic engine and Aquatic EcoDynamics 2 (AED²) as the water quality engine. The particle tracking model was bespoke and developed specifically for this project. The modelling framework was used to determine the distribution of excess feed and faecal pellets arising from aquaculture activities, and the future impact on the environment.

Solutions 

The project was a significant technical undertaking, as the model covered an extensive area of 2.7 million hectares, with a single open boundary of approximately 413 km stretching from Kalbarri in the north to Coolimba in the south. It also required a range of mesh resolution from 3.5 km at the open boundary to less than 40 m in the vicinity of the proposed fish cages.  A particle tracking module was developed for TUFLOW FV to determine the fate of excess feed and faecal matter, which was coupled to a sediment diagenesis model to determine the impact of the particles on the biogeochemistry of the seabed.

In consultation with aquaculture industry representatives, the model was successfully applied to determine an upper limit of aquaculture production, based on the carrying capacity of the surrounding environment.

Benefits

• 3D hydrodynamic modelling;
• Particle tracking modelling;
• Water quality modelling; and
• Environmental impact assessment of aquaculture activities.