2021-11-15 GC Agenda - Item 7 - Attachment 2 - Coastal Hazards Adaptation Plan with tracked changes

The first stage in developing a risk-based plan to respond to coastal hazards is to model and map
the expected behaviour of each hazard. Modelling of a range of hazard events was performed by
expert consultants, consistent with the QCoast2100 guidelines and Queensland Government
technical guidelines. The future climate scenario underpinning the hazard modelling is based upon
a high global greenhouse gas emissions scenariopathway known as ‘RCP 8.5’, which is often
referred to as ‘business as usual’ because it broadly represents anup to now, human emissions
pathway based on our current trajectory of minimal emissions reductionat the global scale have
tracked this pathway most closely12. This scenario results in a projected rise in regional mean sea
level of approximately +0.8 meters by the year 210013. This scenarioThe RCP 8.5 pathway
represents minimal action being taken globally to reduce global greenhouse emissions between
now and the year 210014. The adoption of this scenario is a requirement of the QCoast2100
program.15.

Council acknowledges the need to considervalue in considering a range of possible climate
change scenarios as well as sources of local data in coastal hazard modelling and for these to be
incorporated as part of future modelling reviews where appropriate.

Ongoing localised monitoring and data collection are important inputs to managing coastal hazard
risks, and are discussed further in Section 6 of this plan.



Noosa already experiences periodic tidal inundation and coastal erosion events. The first stage of
the project sought to understand how Noosa may be affected by changes in tidal water, storm
tides, and coastal erosion events due to rising sea levels. These events were modelled using
specialised software across four planning horizons – present day, 2040, 2070 and 2100.

Coastal hazard map layers produced as part of the development of this plan show potential
inundation and coastal erosion extents for each of these time steps. These map layers
should not be relied upon for making detailed design decisions as part of the development
of buildings, infrastructure or other structures at the individual lot scale. The mapping has
been prepared to identify areas of interest that require further investigation for mitigating
potential risks.



What is coastal erosion?
Coastal erosion is the wearing away of land or the removal of beach or dunes by wave action, tidal
currents, drainage or high winds. Coastal erosion leads to the recession of shorelines inland and
the destabilisation of dune systems if the system is not able to rebuild before another erosive event
occurs.

Beaches in south-eastSouth-East Queensland typically consist of sand particles that can be easily
eroded by waves. These deposits comprise terrestrial sediment delivered to the coast by rivers,
sediment produced by the erosion of coastal landforms by waves, and marine sediment that has
been reworked from offshore deposits onto the coast.

12 For a simple explanation of Representative Concentration Pathway (RCP) 8.5 and other emissions

pathways, see Australian Academy of Science (2021): The risks to Australia of a 3° C warmer world. To
understand how they are used in climate models, see Queensland Government’s description at
https://www.longpaddock.qld.gov.au/qld-future-climate/understand-data/.
13 Intermediate projections for sea level rise are +0.2m by the year 2040, and +0.5m by the year 2070.
14 It is important to note, RCP 8.5 presented in the IPCC’s Fifth Assessment Report (AR5) roughly

corresponds to the new Shared Socioeconomic Pathway (SSP) 5-8.5 in the latest IPCC (2021) Sixth
Assessment Report (AR6).
15 For more information, see Noosa Council’s Briefing Note titled: Use of sea level rise projections


Noosa Council – Coastal Hazards Adaptation Plan                                                    Page 19