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 for Average Recurrence Intervals (ARIs), from one to 100 years, 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.

Updating IFD information

The Bureau is revising the Intensity-Frequency-Duration (IFD) information using nationwide rainfall data and statistical methods, and incorporating information on the likely impacts of climate change on the IFDs (both point and area estimates).

Revised IFD information will be made available to hydrologists and engineers via the Bureau's web pages in user-friendly formats such as shape files for use with GIS. It will also be included in the next edition of the Engineers Australia publication Australian Rainfall and Runoff.

New IFD products are scheduled for online publication in mid-2012.