Brisbane River Catchment Flood Study, Australia

Aurecon completes the most comprehensive flood study in Australia, to understand flood behaviour and build community awareness for Brisbane

Widespread flooding occurred in Queensland in 2010 and 2011, causing extensive damage to private and public property, thousands of evacuations and the loss of lives. More than 14 000 properties were inundated in Brisbane, Ipswich and the Brisbane River Valley. In response to the scale of this disaster, the Queensland Flood Commission of Inquiry (QFCOI) was established.

The Brisbane River is unlike any other catchment in Australia. It is highly developed in the floodplain, includes multiple gated and ungated dams, including flood mitigation dams, and several significant waterways interact to produce complex flood behaviour.

As such, one of the recommendations of the QFCOI was for a comprehensive flood study of the Brisbane River catchment to be undertaken to understand the behaviour of potential future flooding that might impact the Brisbane River below Wivenhoe Dam.

The Queensland government engaged Aurecon (hydrology) and WBM BMT (hydraulics) to undertake the Brisbane River Catchment Flood Study.

Working with all levels of government and industry

A technical working group, led by the Department of Natural Resources, Mines and Energy, and consisting of representatives from more than 10 key stakeholder agencies from three levels of Government, was formed to advise and review the study. An Independent Panel of Experts from academia and industry was also assembled to provide rigorous technical scrutiny.

The intent of the study was to deliver best practice estimates of Brisbane River flood behaviour for different probabilities of occurrence.

Aurecon and BMT engaged a wide-ranging and thorough approach by encompassing the latest proven and established techniques, whilst also undertaking an extensive process of innovation and discovery in both the hydrologic and hydraulic phases of the study.

Key outputs of this complex flood study

  • Calibrated hydrologic models for deriving floods from design rainfall events covering the entire Brisbane River catchment.
  • A Monte Carlo joint probability analysis framework integrating the hydrologic and dam operation models for generating tens of thousands of synthetic rainfall and storm tide events.
  • The Fast Model - a one-dimensional hydraulic model - that simulates a flood in around 5 minutes and is capable of accurately reproducing the flood behaviour along the main rivers and creeks below Wivenhoe Dam. 
  • The Detailed Model, a two-dimensional hydraulic model, and the most comprehensive and accurate hydraulic model yet developed for simulating riverine flooding caused by the Brisbane River below Wivenhoe Dam, and lower reaches of both Lockyer Creek and the Bremer River.
  • High resolution maps of peak flood levels, depths, velocities and hazards, and other outputs including tables of peak levels and flows and a variety of charts.

The study has been independently assessed as being “the most complex and comprehensive flood study undertaken in Australia” by the Queensland government appointed Independent Panel of Experts, and the Deputy Premier of Queensland, the Honourable Jackie Trad (on 5 May 2017).

The study benefits are wide ranging

The Brisbane River Catchment Flood Study is crucial to understanding flood behaviour and flood risk in the Brisbane River floodplain.

The study flood mapping and design flood levels for future climate scenarios are being used to develop effective building controls, and land use planning responses, to minimise economic loss associated with future development.

In addition to its crucial role in flood risk management, the study results are being used by insurers for the pricing of premiums, and in the infrastructure sector for the design and optimisation of major projects in and around the floodplain. 

These projects are all of significant value to the state of Queensland and, in some cases, of national economic significance.

The Brisbane River Catchment Flood Study is supporting communities to continue to live, work and recreate safely in the floodplain, now and into the future. The work of Aurecon has positive impacts beyond the study, as they methodologies for this project can be applied to catchments in other regions of Australia and the world.

“Throughout the project, Aurecon and BMT undertook an exciting process of innovation and discovery in collaboration with the Independent Panel of Experts (IPE) and the stakeholders, to develop and implement new methodologies and techniques. This was necessary as a flood study of such significant hydrologic and hydraulic complexity had never before been undertaken in Australia, and possibly the world, and appropriate methodologies did not exist,” says David Wiskar, Executive Director, Water Policy, Department of Natural Resources, Mines and Energy.

Award Winning

This award winning project was recognised at the Australia Engineering Excellence Awards – Queensland Division, winning the RW Hawken Award as the Overall Winner of the Queensland Division for the Hydrology and Hydraulics Phases of the project.

It also won the Queensland Engineering Excellence Award and has been named as an AEEA Finalist.

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