Author(s): Monique Retallick; Mark Babister

Linked Author(s): Monique Retallick, Mark Babister

Keywords: Floods; Risk mapping; Hazard mapping; Resilience

Abstract: There is a continuing push to map flooding for the whole of Australia to help manage natural disaster risk. This has resulted in a common approach where national coverage is given priority over quality mapping in areas of risk. This trade-off between extent and population at risk has seen limited funds spread thinly over a broad area. There is also a move to adopt an all hazards approach where all natural disaster risks are presented on one map, including floods, fire, storm surge, earthquake, hail, landslide and wind. There are many good reasons to invest in flood mapping as it can lead to informed decision making, better planning, setting insurance premiums and the community having a better understanding of risk. However, are any of these end users served by unreliable maps? The public and private business’s use of this information is based around an assumption that this information is of a reasonable quality and can be relied upon for decision making. When some of this information is not reliable or low quality these groups question the quality of all the information. Low quality broad-brush mapping is being used for important investment decisions. It is important that this information is reliable. The counter argument is that low reliability mapping leads to further detailed assessments. This paper analyses the advantages and disadvantages of broad-brush flood mapping and the arguments used to justify their use. A number of examples of the use of broad-brush mapping are analysed. Alternative ways that risk can be mapped other than probability including historical floods and soil type based maps, are discussed. Recommendations are made based on accuracy of the mapping and the underlying hydraulic model on the appropriate the use of different mapping types.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022996

Year: 2022