Recent climate conditions experienced in Australia certainly ring true with the famous words from author, Dorothea Mackellar, ‘of droughts and flooding rains’.

Australian Rainfall and Runoff (ARR) is a national guideline document, data and software suite that can be used for the estimation of design flood characteristics in Australia. This is the 4th edition of ARR, after the 1st edition was released by Engineers Australia in 1958. This edition is published and supported by the Commonwealth of Australia. Geoscience Australia supports ARR as part of its role to provide authoritative, independent information and advice to the Australian Government and other stakeholders to support risk mitigation and community resilience. ARR is pivotal to the safety and sustainability of Australian infrastructure, communities and the environment. It is an important component in the provision of reliable and robust estimates of flood risk. Consistent use of ARR ensures that development does not occur in high risk areas and that infrastructure is appropriately designed.