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

Figure 4 shows an example of the potential extent of potential coastal erosion that may occur
during a major oceanic storm event, forby the year 2100, for a portion of Peregian Beach (adjacent
to Peregian Beach Park). Due to the narrow distances between each erosion extent projection, the
results for other years and locations modelled can be explored in detailsdetail using Council’s
interactive mapping website.




 Figure 4 - Erosion Prone Area during a 100 ARI -year Average Recurrence Interval (ARI)16 marine storm event in 2100


In South-East Queensland, significant erosion on sandy beaches is common after high-energy
wave events such as storms, east coast lowsEast Coast Lows and tropical cyclonesTropical
Cyclones. Open sandy beaches such as Castaways Beach are naturally kept in balance as sand is
eroded from the beach and taken offshore by storms, but is then gradually pushed back onto the
beach during calmer conditions. More frequent and severe storm events coupled with sea level rise

16 It is important to note that an ARI of 100 years does not mean that the event will only occur once every

100 years. While for each and every year, there is a 1% chance (a 1 in 100 chance) that the event will be
equaled or exceeded, the chance of this event occurring or being exceeded over a longer period, say 50
years, is around 40%. “That is, a 100 year ARI event has a high chance (40%, or between a 1 in 2 chance
and a 1 in 3 chance) of being equaled or exceeded over a 50 year period.” See Bureau of Meteorology
(2021)’s online article: ‘Why do 100 year events happen so often?’, as well as Noosa Council’s Briefing Note
titled: Natural Hazard Probabilities for more information.


Noosa Council – Coastal Hazards Adaptation Plan                                                             Page 22