Design Rainfalls

Design flood support

Hundreds of millions of dollars are spent annually on hydraulic structures in Australia, ranging from small drains and culverts to bridges and large dams used for town water supply and irrigation.

Rainfall intensity, frequency and duration data plays an integral part in the design of these structures and the Bureau is undertaking a major revision of the information it provides in this domain.

The Bureau currently provides design rainfall data in the form of:

  • Intensity–Frequency–Duration (IFD) information, which is used in the design of gutters, culverts, bridges and stormwater drains
  • Probable Maximum Precipitation (PMP) estimates for the design of large dams and for use in floodplain management.

Revising IFD information

As you are aware, the Bureau of Meteorology has been working to develop new IFD design rainfall estimates. We're pleased to inform you these have now been released.

The new IFDs are based on a more extensive database, with nearly 30 years’ additional rainfall data and data from 2300 extra rainfall stations. By combining contemporary statistical analysis and techniques with this expanded rainfall database, the new IFDs provide more accurate design rainfall estimates for Australia.

IFDs are part of a larger suite of design flood estimation inputs currently being revised by Engineers Australia, to be released progressively over the next two years. Until all components of the Australian Rainfall and Runoff: A Guide to Flood Estimation are revised, the new IFDs can only be used in specific circumstances.

Access the new IFDs and guidance for use.

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