The Bureau of Meteorology has updated the Design Rainfall website to provide additional information and improved functionality.

The following features have been included in response to user feedback: 

Subdaily rare design rainfalls
The design rainfall suite has been expanded to include rare design rainfalls for durations from 1 minute to 1 day. This means that design rainfalls are available for durations from one minute to seven days and for probabilities from 12 exceedances per year (EY) to one in 2000 Annual Exceedance Probability (AEP).

Increased number of standard durations
The standard durations for the design rainfall system have been increased to include the durations for which ARR temporal patterns are provided.

Polynomial coefficients available for point locations
The polynomial coefficient values are now available for point locations through the design rainfall system.

Multiple point extractions
For those projects in large catchments or areas with high design rainfall gradients, multiple points (up to 50 locations per request) can now be extracted through the design rainfall system using the template provided.

Tick boxes removed
The tick boxes acknowledging the Conditions of Use and Coordinates Caveat that were present in previous versions of the website have now been removed to improve the efficiency of the system.

Seasonality guidance
Winter factors have been estimated for those parts of Australia which experience winter dominated rainfall (May to October).

Access to ARR87 IFDs
As previously advised, after a transition period, the ARR87 IFDs have now been removed from the website as they have been superseded by the 2016 release of Australian Rainfall and Runoff and the 2016 design rainfalls. These values can still be requested for comparison of historical designs by contacting ifdrevision@bom.gov.au.

The 2016 design rainfalls should be used in conjunction with the 2016 edition of Australian Rainfall and Runoff: A Guide to Flood Estimation (ARR2016). ARR2016 is available from the Geoscience Australia website. Using 2016 design rainfalls and ARR2016 will facilitate infrastructure design for improved flood preparedness and public safety.

Visit the Bureau’s website to access the 2016 design rainfalls, along with technical information and answers to common questions.

Email ifdrevision@bom.gov.au if you have any further questions or feedback about the new design rainfalls.