2016 Professional engineers and planners, particularly those within local government, are encouraged to make the most of this valuable resource. With nationwide 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 australian rainfall and runoff 2016 rational method. design rainfall. arf rainfall. a guide to flood estimation. A New Chapter for Australian Rainfall and Runoff. COMPLETION OF THE ARR PROJECT. The 2016 ARR is a major achievement as it is the first major update of 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. To determine the required values you can use the calculator on the Australian