Jimblebar Wye Ophthalmia Dam Flood Study

Project: Jimblebar Wye Ophthalmia Dam Flood Study
Client: Calibre Rail for BHP Billiton

For the Jimblebar Wye Ophthalmia Flood Study, a detailed 2D hydraulic model was developed to enable investigation of the potential impacts of various events, including dam break and fuse plug loss, on the existing railways between Port Hedland, Newman and Jimblebar Mine Site, and on the BHP Billiton Iron Ore’s Rapid Growth Project 6 (RGP6) proposed infrastructure.

The detailed modelling using appropriate CFD software included the Ophthalmia dam and its filled reservoir, as well as the existing and proposed railroad alignments and proposed accommodation village. Flood extent plans were developed for the assessment of flood interaction with the proposed alignment, effects of its construction on the existing infrastructure, and suitability of the proposed village location. The hydraulic modelling results were used interactively and directly to improve the rail design, reduce the associated costs and identify the critical locations for additional optimisation.

In addition to the infrastructure flood modelling, a dam break analysis was carried out in accordance with to the ANCOLD guidelines on assessment for dam break failure. The dam break analysis used the international NWS Dam break equation to simulate an overtopping failure with a trapezoidal breach as well as a piping failure scenario. The base scenario for the 2000 yr ARI design flow has confirmed that the accommodation village was in a flood prone area.

The outcome of the simulation with the breach has showed no significant increase in the flood levels in the vicinity of the accommodation village even with the new rail infrastructure in place. Furthermore, the location of the village was proved to remain dry for the 50 and 100 yr ARI design flows. The Hazard category for the accommodation village, population at risk and severity of damage was deemed to be very low and the location of the village was confirmed as suitable based on the modelling outcomes.