AR&R Policy Statement

The project team is committed to an open and transparent process with a commitment to having all methods recommended in ARR fully published with full background reports freely available. All reports that investigate methods or make recommendations on approaches will be peer reviewed and published. Contributors are also strongly encouraged to separately publish any improved or new techniques that are developed as part of the updating process.

Technology has changed significantly since 1987. The project team is committed to using technology now available to fully document the data sets used in the development of all methods and delivering information more efficiently.

With methods and approaches continually being improved there is a commitment to having all the data sets available for future researchers. The aim is to have all data sets on-line and available to all parties and researches in the future. In limited cases ownership of data may restrict open access but the data will still be kept in a single location and released for use once consent from the owners has been granted. However it is our intent to seek permisson from the an third party owners for unrestrict access for research into techniques for ARR. Technology will be used to make temporal and spatial information easily available for users. While details of how information will be delivered is still be developed it is envisaged that all mapped data will be provided electronically in GIS format, rainfall data will be delivered electronically via the BoM new information data bases and some methods will be available electronically online.

Practice Advice: Application of Flood Frequency Analysis

Users are reminded that the current edition of Australian Rainfall and Runoff (ARR, 1987, Section 1.1.2) makes the following statement:

"In view of these considerations, firm guidance and specific design data have been included where possible. However, the document is not intended to be entirely prescriptive or a strict code of practice. Where circumstances warrant, designers have liberty, and perhaps a duty, to use other procedures and data. The use of new or improved procedures is encouraged, especially where these are more appropriate than the methods described in this publication. It is certain that within the effective life of the document, new procedures and design information will be developed. Where they are based on observed data or have been shown to reproduce its characteristics, these new methods should be used. Designers are also encouraged to critically evaluate the procedures presented herein, and any procedures developed subsequently, as befits any professional activity. The most appropriate approach for the set of circumstances should be adopted."

This puts the responsibility on practitioners to stay abreast of current research/best practice and not to use out-dated techniques even when documented in ARR. It also makes clear that ARR is not to be treated as a standard where compliance with the published document constitutes acceptable practice. The draft flood frequency chapter of the new version of ARR has been available for some time from the following web site Download Book IV Chapter 2

This draft chapter makes a number of recommendations that currently are considered best practice including:

Where flood frequency analysis is required, users should be aware of the techniques contained in the draft flood frequency chapter, their application, and should use them in an appropriate manner.

Joint Statement by Engineers Australia (EA) and the Bureau of Meteorology (BoM) on IFD data Developed by Other Agencies

The 1987 Intensity-Frequency-Duration (IFD) data was created using an extensive and vigorous process that used data from the whole BoM network and drew upon expert meteorological knowledge. It is currently proposed to update this using the longer records that are now available and more efficient statistical approaches. This is to be done as part of the updating of Australian Rainfall and Runoff (ARR).

In parts of Australia alternative IFD estimates have been produced by other organisations. EA and BoM do not endorse or recommend their use. It is the responsibility of a user to decide whether the alternate IFD's should be used in place of the BoM ARR data in their location.

The user also needs to confirm that the alternative IFD data is compatible with the flood estimation approach and parameters they adopt. Many of the parameters for particular flood estimation approaches recommended in ARR were developed to ensure neutrality of Annual Exceedence Probability (AEP) when used with the BoM ARR IFD data. This may not be the case with alternative IFD data and it is incumbent on the user to ensure the reasonableness of the parameter values adopted.

Tebbits Observatory, Windsor, under flood conditions.