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The frequency analysis of rainfall data is an important part of hydrological design procedures. Analysis of rainfall data from single stations is often unreliable, is not temporally or spatially consistent and should generally not be used for design purposes. Instead a set of accurate, consistent intensity-frequency-duration (IFD) design rainfall data has been derived for the whole of Australia. This work was done by the Bureau of Meteorology as part of the revision of Australian Rainfall and Runoff (Inst. Engrs Aust., 1987). Book 2, Section 1 of Volume 1 details procedures for the construction of a set of IFD curves for a specific location. Volume 2 contains a series of maps of intensity-frequency-duration (IFD) design rainfall.
Intensity-frequency-duration design rainfall curves range from 5 minutes to 72 hours in duration and ARI from 1 year to 100 years. A gridded version of the IFD dataset is held by the Hydrometeorological Advisory Service, and an automated procedure known as CDIRS is used for the construction of IFD curves.
A subset of the IFD dataset of 5 minute intensities at ARIs of 20 and 100 years is published in National plumbing and drainage Part 5: Domestic installations (AS/NZS 3500.5:2000) for use in the design of roof and surface drainage systems.
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