Australian Rainfall and Runoff (ARR) is a national guideline document for the estimation of design flood characteristics in Australia. It is published by Engineers Australia. The coefficients entered will describe the rainfall for a particular area of the country.

This method may not be available for your region. For more information, refer to the Regionalisation topic.

To determine the required values you can use the calculator on the Australian Bureau of Meteorology website, which can be accessed by clicking the hyperlink on the form. Once the IFD has been generated for the location the values needed are shown under the Coefficients table.

Enter the ARR variables described below into the form and the select the required set of  Storm Durations to be run by the analysis.


 Return Period
The ARI (Average Recurrence Interval) for the event.
 
MAP 1 2i1, Map 2 2i12, MAP 3 2i72
Log-normal rainfall intensity for 2 year ARI.
  
MAP 4 50i1, Map 5 50i12, MAP 6 50i72
Log-normal rainfall intensity for 50 year ARI.
 
Skewness
Regionalized average skewness.
 
Zone
Location's zone

Figure 3.2 in Pilgrim DH, Kennedy MR, Rowbottom IA, Cordery I, Canterford RP and Turner LH,

Temporal Patterns of Rainfall Bursts, Chapter 3 in Australian Rainfall and Runoff, A Guide to

Flood Estimation, Volume 1, DH Pilgrim (ed), The Institution of Engineers, Australia, Barton,

ACT, 1987


Latitude, Longitude
Location's position as decimal values.
 
F2, F50
Geographical Short Duration Factors for 2 year and 50 year ARI. These can be entered directly or they are calculated from the Latitude and Longitude values.