A systematic review of climate change science relevant to Australian design flood estimation

Abstract

Abstract. In response to flood risk, design flood estimation is a cornerstone of planning, infrastructure design, setting of insurance premiums and emergency response planning. Under stationary assumptions, flood guidance and the methods used in design flood estimation are firmly established in practice and mature in their theoretical foundations, but under climate change, guidance is still in its infancy. Human-caused climate change is influencing factors that contribute to flood risk such as rainfall extremes and soil moisture, and that there is a need for updated flood guidance. However, a barrier to updating flood guidance is the translation of the science into practical application. For example, most science focuses on examining trends in annual maximum flood events, or the application of non-stationary flood frequency analysis. Although this science is valuable, in practice design flood estimation focuses on exceedance probabilities much rarer than annual maximum events, such as the 1 % annual exceedance probability event or even rarer, using rainfall-based procedures, at locations where there are little to no observations of streamflow. Here, we perform a systematic review to summarise the state-of-the-art understanding of the impact of climate change on design flood estimation in the Australian context, while also drawing on international literature. In addition, a meta-analysis, whereby results from multiple studies are combined, is conducted for extreme rainfall to provide quantitative estimates of possible future changes. This information is described in the context of contemporary design flood estimation practice, to facilitate the inclusion of climate science into design flood estimation practice.

Fostering Science–Industry Connections in Australia’s Severe Storm Science Community

“…Convective winds also differ from larger-scale (cyclone) winds and there are knowledge gaps in understanding these winds and their impacts on built structures. Estimates of extreme convective rainfall and its climatic changes-important for subdaily rainfall extremes-feed into design flood estimation, a cornerstone of flood planning (e.g., DCCEEW 2023; Wasko et al 2023).…”

“…Convective storms affect water services (e.g., dam safety and flood operations), the power grid, and agriculture in Australia. Subdaily rainfall data are crucial for water services but require substantial quality assurance and control, and possible changes in subdaily rainfall amounts in a warming climate affect engineering decisions (e.g., Wasko et al 2023). The power grid is a highly interdependent system susceptible to outages caused by storm events (e.g., Ausgrid 2023).…”

Unveiling the Evolution of Extreme Rainfall Across Space and Time in a Warming Climate

“…Changes in intensity and frequency of rainfall have significant implications for ecosystem services, water resources availability and agricultural production. Accumulating evidence points towards an increase in intensity and frequency of extreme precipitation events within a warming climate along with a change in its distribution in time and space (Fischer & Knutti, 2016;Guerreiro et al, 2018;Masson-Delmotte et al, 2021;Wang et al, 2017;Wasko et al, 2023;Westra et al, 2014). This trend raises legitimate concerns as floods may become potentially more frequent and severe (Sharma et al, 2018;Wasko & Nathan, 2019).…”