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 system;
  • 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 2016?

ARR was previously accessible only as a book on a fee for access basis. It is now publically 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