How is ARR used?

With national applicability, balancing the varied climates of Australia, the information and the approaches presented in Australian Rainfall and Runoff are essential for policy decisions and projects involving:

  • infrastructure such as roads, rail, airports, bridges, dams, stormwater and sewer systems;
  • town planning;
  • mining;
  • developing flood management plans for urban and rural communities;
  • flood warnings and flood emergency management;
  • operation of regulated river systems; and
  • estimation of extreme flood levels.

What is new in ARR 2019?

Geoscience Australia, on behalf of the Australian Government, asked the National Committee on Water Engineers (NCWE) - a specialist committee of Engineers Australia - to continue overseeing the technical direction of ARR. ARR's success comes from practitioners and researchers driving its development; and the NCWE is the appropriate organisation to oversee this work. The NCWE has formed a sub-committee to lead the ongoing management and development of ARR for the benefit of the Australian community and the profession. The current membership of the ARR management subcommittee includes Mark Babister, Robin Connolly, Rory Nathan and Bill Weeks.

Following the 2016 release, the team received a lot of feedback from industry and practitioners, ranging from substantial feedback to minor typographical errors. Much of this feedback was addressed and where a decision has been made not to address the feedback, advice has been provided as to why this was the case.

A new version of the ARR was released at the Floodplain Management Association Meeting in May 2019. ARR 2019 was a result of extensive consultation and feedback from practitioners. Noteworthy updates include the completion of Book 9, reflection of current climate change practice and improvements to user experience, including the availability of the document as a PDF.

Recognising this effort, Engineers Australia’s National President awarded the Australian Rainfall and Runoff editors and technical committee the Presidents Prize at the National Congress and National Awards Dinner on 18th November 2019 in Melbourne. Congratulations were extended to the ARR team: Mark Babister, Rory Nathan, Erwin Weinmann, Bill Weeks, Monique Retallick, Martin Lambert, George Kuczera, James Ball, Isabelle Testoni, Peter Coombes, Michael Leonard, Bryson Bates, Steve Finlay, Ashish Sharma and Steve Roso. The team gave thanks to everyone who have made contributions over many years in developing, reviewing, testing and publishing the ARR which is now a free and open resource. Particular mention is made to Engineers Australia National Committee on Water Engineering.

Key updates in ARR 2019



ARR 2019

Book 9

Available as “rough” draft

Peer reviewed and completed

Guideline formats

Epub version

Web-based version

Following practitioner feedback, a pdf version of ARR 2019 is now available

User experience

Limited functionality in web-based version

Additional pdf format available

Climate change

Reflected best practice as of 2016 Climate Change policies

Updated to reflect current practice

PMF chapter

Updated from the guidance provided in 1998 to include current best practice

Minor edits and reflects differences required for use in dam studies and floodplain management


Examples included for Book 9


Updated reflecting practitioner feedback

What was new in ARR 2016?

ARR was previously accessible only as a book on a fee for access basis. It is now publicly available online and free of charge.

Data standards are now established to provide a consistent approach to collecting, analysing and managing flood information.

Terminology for concepts, measurements, methodologies and products for flood studies is now standardised.

Previous versions of ARR were developed when computer technology was emerging and calculations were often done by hand. Since the last update in 1987, there have been many developments in the understanding of rainfall-runoff processes and many new tools available for catchment simulation. ARR 2016 takes advantage of the significant advancements in computer technology, techniques and understanding of rainfall-runoff processes since 1987 and introduces changes to current practice. It is also based on Australian data, when previously it was based on USA data.

Key changes in ARR 2016

Design Input

ARR 1987

ARR 2016

Intensity Frequency Duration (IFD)

Used BoM rainfall gauges

Presented as static A2 maps

Uses BoM and other agency gauges


Areal Reduction Factors (ARF)

Based on USA data

Not available for long durations

Based on Australian data


Based on jurisdictional based advice (personal communication only)

National advice for rural and urban catchments


Methods but no ungauged catchment advice

Australia wide advice

Temporal Patterns

Average Variability Method Peak Burst

Patterns for less than 30 year average recurrence interval (ARI) and rarer than 30 year ARI

Temporal patterns based on historic records, multi pattern for each design quantile and complete storms, with pre burst considered.


ARR 1987

ARR 2016

At site Flood Frequency analysis

  • Gauged
  • Ungauged

Probable Rational Method in some states

Bayesian of L moments

Regional Flood Frequency

Hydrograph Estimation Methods

Simple Design Event

Ensemble and Monte Carlo

Interaction of Coastal and River Flooding

Not considered

ARR Project 18


Not considered

Blockage Guidelines

Safety Design Criteria

Not considered

People, vehicle and building hazard curves