Coastal hazards adaptation strategy
Rising sea levels over the 21st Century will put many of Australia’s coastal cities and economic centres at risk of tidal, coastal and estuarine inundation, and coastal erosion, shoreline recession and sea leave rise.
The United Nations’ Intergovernmental Panel on Climate Change has adopted different Representative Concentration Pathways (RCPs) to model climate change, based on future greenhouse gas emissions levels. By the end of the century, the average sea level rise is projected to be between 0.3 m and 0.6 m in the lowest of the four scenarios (RCP 2.6), and by 0.6 m or more in the highest of the scenarios (RCP 8.5) and continue to rise for centuries.
Actions of the sea can damage residential, commercial and industrial property, as well as essential infrastructure. The average household costs of a flood up to 1 m are between $60,000 and $80,000. Without action, the costs of coastal inundation are expected to rise rapidly. It is estimated that the costs of coastal inundation double under a high emissions scenario as compared to a low emissions scenario,. The costs of larger and sustained flooding leading to forced relocation would also be greater.
Rising sea levels also have significant environmental consequences, such as coastal squeeze, where intertidal (seashore) habitats are disrupted and lost.
The proposal is for a proactive infrastructure strategy involving all levels of government. The strategy will need to consider which areas should be protected for continued use, modified to accommodate actions of the sea, or withdrawn from altogether.
Depending on these decisions, infrastructure options could include:
- nature-based methods
- buffer zones or physical barriers, such as seawalls to protect populations
- retreat and protect approaches
- infrastructure to facilitate early response to coastal hazard warnings and evacuations.
The strategy should also consider policy responses, such as actions to reduce exposure to coastal hazards, setting appropriate sea level rise benchmarks and planning controls for vulnerable areas.
Infrastructure Australia has received several submissions for localised coastal hazard issues. This proposal calls for higher-level program submissions that consider coastal hazards at a jurisdictional level.
We encourage relevant authorities to fully assess this problem in their respective locality, state or territory (Stage 1 of Infrastructure Australia’s Assessment Framework) prior to identifying and analysing potential investment options (Stage 2 of Infrastructure Australia’s Assessment Framework).
Refer to Infrastructure Glossary for terms and definitions.