ECM_22343537_v1_Coastal Hazard Assessment · 132000.200173.1

                                                                 Internal use only




              Figure 10 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 10) generally coincides with the location
              of drainage channels across the beach. The shoreline position from the DEA dataset in Figure 11
              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 10, 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 12 indicates that the shoreline at this location was relative stable.
              Figure 12 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 10: DEA recession analysis near the site.


              13 February 2023         2 ARAKOON CRESCENT, SUNSHINE BEACH                            PA3303       14


Document Set ID: 22343537
Version: 1, Version Date: 16/03/2023