Computational modelling

Healthy Estuaries WA uses computer models to better understand how our rivers, catchments and estuaries work, and how they might change in the future. These computer-based models are powerful tools that help us test ideas, predict outcomes and make evidence-based decisions to protect the health of our waterways. 

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What is computational modelling?

Computational modelling is a way of simulating real-world systems using complex mathematical equations and environmental data. Our models integrate data such as rainfall, river flow, nutrient inputs, tides, sea levels and bathymetry to predict how catchments and estuaries behave over time. By adjusting variables in the model, we can test different scenarios – such as land-use changes, management actions or future climate conditions – and see how they might affect water quality, ecosystem health and estuary dynamics. 

For these models to work well, they rely on accurate data collected at the right time and scale, along with a sound understanding of how the system functions. When done correctly, the models provide valuable insights that would be difficult or impossible to gain through field measurements alone. 

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Why modelling matters

Computational modelling gives us an insight into potential real-life scenarios. By combining field data, statistical analysis and modelling, we can: 

  • Predict how catchments and estuaries will respond to changes in climate, land use and management. 
  • Identify where nutrients are coming from and where to focus actions to reduce them, so they do not cause algal blooms and fish kills. 
  • Have a more detailed spatial and temporal understanding of how estuaries change (e.g. salinity or current speeds), which cannot be achieved by measurements taken at multiple individual sites.  
  • Understand how physical processes like tides, waves and river inflows influence estuary condition. 
  • Test different management actions before they are implemented, saving time and resources. 
  • Evaluate our programs at a catchment-wide scale and provide information for cost-benefit analysis. 
  • Support evidence-based decisions that protect estuaries for people, wildlife and future generations. 

Modelling our catchments

Catchment models simulate how water and nutrients move across the landscape and into rivers and estuaries. They help identify where nutrients like nitrogen and phosphorus are coming from and how they travel through the catchment. This is crucial because excessive nutrient runoff can lead to problems such as algal blooms, oxygen depletion and fish kills, and it allows us to identify land uses and prioritise waterways that are susceptible to high nutrient runoff. 

Healthy Estuaries WA supports the development of catchment models using the eWater Source platform, adapted for Western Australian conditions. These models allow us to test how different land uses – such as urban development or changes in farming practices – affect water flow and nutrient loads. They also help us assess how management actions, such as improved fertiliser use or riparian restoration, could reduce nutrient inputs and improve water quality. 


Through Healthy Estuaries WA we have produced catchment models for:

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Modelling our estuaries 

Hydrodynamic models of estuaries simulate water levels, currents, temperature and salinity in the estuary. They may show how tides, river inflows, sea levels, and sandbar openings influence water circulation, salinity and temperature.  Hydrodynamic models can be combined with catchment models to calculate the movement of sediment, nutrients and phytoplankton. Modellers also work closely with estuary ecologists to understand how outcomes of modelling scenarios could potentially affect the health of the estuarine ecosystem. 

Healthy Estuaries WA works with technical monitoring equipment, and partners with universities from Australia and overseas to develop cutting-edge estuary models. 
 

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Through Healthy Estuaries WA we have produced estuary models for: 

  • Peel-Harvey estuary (in progress) 
  • Wilson Inlet 
  • Hardy Inlet 
  • Vasse Wonnerup Wetlands 
  • Leschenault Estuary