Brisbane River Catchment Flood Study – Comprehensive Hydraulic Assessment

Requirements

Customer: Department of Local Government, Infrastructure and Planning (QLD) with stakeholders from four Local Government Areas and other agencies

The Brisbane River has a catchment area of over 13,600km² with a long history of flooding.  Following the devastation caused by the 1974 flood event, Wivenhoe Dam was constructed in the Brisbane catchment for the dual purpose of water supply and flood mitigation.  The 2011 flood event peaked approximately 1 metre lower than the 1974 event in Brisbane City but caused widespread property damage in the catchment. The Brisbane River Catchment Flood Study (Comprehensive Hydraulic Assessment) is a critical step toward developing a Strategic Floodplain Management Plan for the region. We delivered the hydraulic assessment component of the study.

Solutions

• Development and calibration of hydraulic models, including a 1D one-dimensional (fast) model and a 2D/1D (detailed) model;
• Monte Carlo approach within the hydraulic models to selection of flood events; and
• Flood mapping - automated figure generation (plots and maps) for greater efficiency and standardisation.

Benefits

The Brisbane River Catchment Flood Study is the most detailed and comprehensive flood study undertaken in Australia, and potentially the world. The leading-edge hydraulic modelling (using our TUFLOW software) was successfully calibrated to thousands of flood marks and hydrographs. Due to the complexity of the physical system, methodologies developed for the study were innovative and more comprehensive than current standard practice. A Monte Carlo approach was used to account for the variability in flood producing factors in the catchment. The result is an integrated suite of hydraulic models, rigorous calibration to historical events, and modelling of a comprehensive range of design events to define flood behaviour. Outputs of the study will be used to inform the Strategic Floodplain Management Plan, also by us.