Case study

The Challenge

The Pioneer River overflows to the adjoining streams of Bakers Creek, Goosepond Creek and Sandy Creek at several locations along its length during large flood events. The key challenge for this project was to develop design flood discharges and flood levels along the Pioneer River from Mirani Weir to Mackay including its tributaries taking into account the breakout flows and the impact of the Mirani, Marian and Dumbleton in-stream weirs.

Approach and Key Activities

The Pioneer River catchment has 16 stream gauges and 35 daily and continuous rainfall gauges available for model calibration. Each of the stream gauge rating curves was reviewed and the differences between the Bureau of Meteorology and Department of Natural Resources and Mines ratings were reconciled. The eight rating curves within the hydraulic model area were updated and extended. Flood frequency analyses of the revised annual peak series of the recorded data were undertaken and an URBS rainfall runoff routing model of the catchment was developed and calibrated to four historical flood events to estimate design discharges.

Design discharges along Bakers Creek and Goosepond Creek were estimated for design storms located over their local catchment as well as storms centred over the Pioneer River catchment.

A TUFLOW hydraulic model was used to estimate design flood levels along the Pioneer River from Mirani Weir to the Coral Sea including across the in-stream weirs at Marian and Dumbleton. The hydraulic model was also used to assess the impact of sediment transport rates and different tailwater levels, such as tidal impacts, on design levels at Mackay.

Outcomes

Mackay Regional Council received a comprehensive set of flood level, depth and extent maps for a range of design events across the entire Pioneer River floodplain including its tributaries of Bakers Creek and Goosepond Creek for use in landuse planning.