PA3660-Coastal Hazard Assessment - 4 arakoon

                                                    Project related




Figure 3-9 from DEA indicates that the position of the shoreline in the immediate vicinity of the site has
prograded by approximately 0.4 metres annually (±0.3 metres at 95% confidence interval). However,
minimal progradation (less than ±0.1m/yr) is reported at transects nearby to the north and south. Further,
the location/s where accretion is reported (i.e. blue dots in Figure 3-9) generally coincides with the
location of drainage channels across the beach. The shoreline position from the DEA dataset in Figure
3-10 indicates that the beach has generally been stable from 1990 to present (only ~30m of shoreline
movement). At locations where progradation has been reported in Figure 3-9, the shoreline was generally
further landward in 1988 with rapid progradation from 1988 to 1989. Given the progradation during this
time was localised, it is inferred that freshwater flows and/or rip heads caused localised erosion of the
beach around 1988, which is otherwise stable. The localised erosion at commencement of the reporting
interval has resulted in the reported accretion.

The CoastSat time series in Figure 3-11 indicates that the shoreline at this location was relative stable.
Figure 3-11 indicates the shoreline fluctuated by approximately ±30m from the mean shoreline position
annually, some of which may be due to the RSME of the dataset. However, it is likely that episodic
recession and progradation would occur due to annual beach rotation and storm events.

Care should be taken when analysing shoreline recession to ensure the data captures long term trends
rather than annual or interdecadal variability. Long-term shoreline recession is adopted as 0m/yr.




Figure 3-9: DEA recession analysis near the site.


11 April 2024         4-6 ARAKOON CRESCENT, SUNSHINE BEACH            PA3660-RHD-XX-ZZ-RP-Z-0001   15