Intensity–Frequency–Duration

The 2016 Intensity–Frequency–Duration (IFD) design rainfalls are provided for use in conjunction with the 2016 edition of Australian Rainfall and Runoff (ARR2016) http://arr.ga.gov.au/arr-guideline

The 2016 IFDs:

  • are based on a more extensive database, with more than 30 years of additional rainfall data and data from extra rainfall stations;
  • are more accurate estimates, combining contemporary statistical analysis and techniques;
  • have an increased probability range from 12 exceedances per year to 1-in-2000 annual exceedance probability;
  • provide better estimates of the 2% and 1% annual exceedance probability IFDs than the interim 2013 IFDs.

While access to the ARR87 IFDs will be maintained for a short period, use of these previous estimates should be limited to the guidance provided below.

2016 IFDs (new)

Should be used:

  • in conjunction with ARR2016
  • for new flood studies and flood assessments but must be used with the other ARR2016 design inputs
  • for sensitivity assessments of older studies and studies already underway

ARR87 IFDs

Should be used:

  • for old flood studies
  • to compare changes between 2016 IFDs and ARR87 IFDs
  • if adopting the ARR87 Rural Probabilistic Rational Method

IFD questions and answers

Feedback

Subscribe to email updates about IFD


Creative Commons By Attribution logo
Unless otherwise noted, all material on this page is licensed under the Creative Commons Attribution 4.0 International Licence