---
title: "Australian Rainfall and Runoff"
canonical: "https://help.innovyze.com/space/infodrainage2021v1/16548149/Australian%20Rainfall%20and%20Runoff"
format: markdown
---
> Macro (anchor)

Australian Rainfall and Runoff ([ARR](http://www.arr.org.au/)) 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](https://help-innovyze.atlassian.net/wiki/spaces/infodrainage2021v1/pages/16548015) topic.

To determine the required values you can use the calculator on the [Australian Bureau of Meteorology website](http://www.bom.gov.au/hydro/has/cdirswebx/cdirswebx.shtml), 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**](https://help-innovyze.atlassian.net/wiki/spaces/infodrainage2021v1/pages/16548087) 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

|  |
| --- |
| ![image](media://07a61d19-d000-4c3f-b371-115b5ddf3e27) |
| <span style="color: #323232">***Figure 3.2 in Pilgrim DH, Kennedy MR, Rowbottom IA, Cordery I, Canterford RP ***</span><span style="color: #323232">***and Turner LH, ***</span><br><span style="color: #323232">***Temporal Patterns of Rainfall Bursts, Chapter 3 in Australian ***</span><span style="color: #323232">***Rainfall and Runoff, ***</span><span style="color: #323232">***A Guide to ***</span><br><span style="color: #323232">***Flood Estimation, Volume 1, DH Pilgrim (ed), The Institution of Engineers, Australia, Barton, ***</span><br><span style="color: #323232">***ACT, 1987***</span> |


**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.