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Project 5.2a: Developing a wave model for Cockburn Sound

Understanding wave type and activity in Cockburn Sound through wave modelling

04 February 2025

Westport has partnered with the Western Australian Marine Science Institution (WAMSI) to deliver the $13.5 million WAMSI-Westport Marine Science Program. This 3-year program is developing the latest data, information and modelling on the complex environmental systems and community values associated with Cockburn Sound.

 

Project 5.2a: Hindcast surface gravity wave modelling

Research theme: Hydrodynamic Modelling

Researchers: C Pattiaratchi and I Janekovic

Publication date: October 2024

 

Understanding wave activity in Cockburn Sound through wave modelling 

Over the past two decades, several spectral wind-wave models, known as third-generation models, have been developed globally to understand and predict wave activity.

Cockburn Sound is a semi-enclosed embayment that is relatively sheltered from the open ocean through the presence of Garden and Carnac islands and Success and Parmelia Banks

A key measure of waves is the time between waves. The longer the period between waves, the more powerful the wave, and more likely to be swell conditions. The shorter period between waves usually reflects choppier waves, created by local wind conditions. 

Due to its topographic and bathymetric features, wave activity in Cockburn Sound comes mainly from locally wind-generated waves, and long-period swell generated from distant storms, with some originating as far out as the Atlantic Ocean offshore from Brazil.

The objective of this project was to develop a validated wave model that was localised for Cockburn Sound, to provide inputs and forecasts to inform port and channel design and operations.

 

What the report found

  • Three wind systems dominate in the Cockburn Sound area: sea breezes; storms (wind speeds greater than 15 metres per second); and calm periods.
  • During a typical sea breeze day, the morning wind speed is usually low and directed offshore (easterly). Wind direction then typically changes to south/south-westerly around late morning or early afternoon and steadily increases, with maximum wind speed generally reached by the late afternoon or early evening.
  • Storm systems are most frequent during winter (June-August).
  • The longest wave periods may originate in the Atlantic Ocean offshore from Brazil.
  • Data obtained from the Stirling Channel (on the southern end of the Kwinana Shelf) indicated the highest swell period energy was 15 seconds between waves, with wind wave energy was at 3.5 seconds between waves.

 

How Westport will use the report

Westport will use this localised wave model to accurately simulate wave parameters, provide boundary conditions in Cockburn Sound for the port and channel operability model, and support future port development works.  

 

You can read the full report here:

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