ECM_22343537_v1_Coastal Hazard Assessment · 132000.200173.1

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              Reef project (Beaman, 2020). Based on the information available, an active beach height of 36 metres has
              been adopted from the depth of closure of -12m AHD to the dune height at the rear of the subject property
              of 24m AHD. This provides an active beach profile width of 565 metres.

              Recent research undertaken by Geoscience Australia (2021) indicates that 76% of the north-eastern coast
              of Australia has been stable from 1988 to present with 11.3% retreating by more than 0.3m/year and
              12.8% accreting by more 0.3m/year. Similar trends are observed at all locations around Australia, except
              for the western coast and north-western coast. During this period, sea level rise is reported to be
              approximately 2-3mm/yr (5-10cm from 1988 to present). The observations from Geoscience Australia to
              not match to hypothesis of long-term recession due to sea level rise predicted by the Brunn rule.
              Therefore, there is uncertainty and potentially conservatism in this approach. However, it is consistent with
              the Department of Environment and Heritage Protection (2013) requirements.
              Table 6: Summary of Shoreline Recession due to Sea Level Rise.
                                              Profile Width   Dune Height      Depth of Closure   2100 Shoreline Recession
                           Beach
                                                   (m)          (m AHD)            (m AHD)                  (m)

                           Sunshine Beach          565              24               -12                    13


              6.1.4       Dune Scarp Component
              Immediately following storm erosion events on sandy beaches, a near vertical erosion scarp of substantial
              height can be left in the dune or beach edge. Over time the near vertical erosion scarp will slump to the
              natural angle of repose of the sand. Since the short term erosion only accounts for shoreline recession
              due to wave runup for cases where the foreshore is not overtopped, the Queensland Hazard Technical
              Guide (DEHP, 2013) recommends adding this dune scarp component when calculating erosion width.

              Dune slumping erosion is calculated by taking the (0, 0) location on the erosion profile line and using the
              angle of response for sand dunes to find the dune slumping potential (Figure 22). The angle of repose for
              dry sand is 35o and this has been used to determine the dune scarp component of the erosion prone area.
              The results of the assessment are summarised in Table 7 below.




              Figure 22 Dune slumping assessment




              13 February 2023         2 ARAKOON CRESCENT, SUNSHINE BEACH                                    PA3303          30


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