2012 – The Implications for Dam Hydrology of the Revised Design Rainfall Estimates

Janice Green

The Bureau of Meteorology (the Bureau) is revising the current Intensity-Frequency-Duration (IFD) design rainfall estimates which are an essential component in the design of infrastructure. The current IFDs were developed by over 20 years ago using data from the Bureau’s network of rain gauges and adopting techniques for the statistical analysis of the data that were considered appropriate at the time.
The IFD Revision Project, which will provide revised IFD estimates in November 2012, uses a greatly expanded rainfall database in addition to adopting more statistically rigorous methods that are most appropriate to Australian rainfall data. The revised IFD estimates will be provided for durations from 1 minute to 7 days and Annual Exceedance Probabilities (AEPs) from 50% to 1%. The revised IFD information will be blended with the CRCFORGE estimates developed by each state to enable a smooth rainfall frequency curve to be derived from 50% AEP to 0.05% AEP.
Keywords: Design rainfall, Intensity-Frequency-Duration, IFD .


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