Design discharge estimation from urban catchments - a comparison between ARR1987 and ARR2016

Australian Rainfall and Runoff (ARR) is a national guideline to assist engineers and practitioners in estimating design flood characteristics in Australia. ARR is pivotal to the safety and sustainability of Australian infrastructure, communities and the environment. The guidelines and data included in the 3rd edition of the guideline (ARR1987) have been used by the civil engineering industry for many years. However, since the development of ARR1987, there have been major advancements in technology, the availability of rainfall data, the industry’s understanding of rainfall patterns, ground infiltration characteristics and rainfall-runoff routing procedures. In response to these advancements, the 4th edition of Australian Rainfall and Runoff (ARR2016) has recently been released and includes recommended updates to flood estimation methods. This paper presents a comparison of the practical application of ARR1987 and ARR2016 in the regional Queensland city of Bundaberg, focusing on three major updates within ARR2016 which are likely to influence the peak design discharge: updated intensity frequency duration (IFD) data, rainfall temporal patterns (including methodology for application) and climate change recommendations.