Coastal Hazard Assessment · MCU25/0087

                                           17 The Esplanade, Sunshine Beach                              Report


The beach profile adopted by BMT (2018) for ETA 602 is shown in Figure 5-11 and was derived from
(LIDAR, 2016) data combined with the Sunshine Coast Bathymetric (Department of Environment and
Science, 2011) for the nearshore section.
The beach profile for this assessment (refer Figure 5-11) was based on detailed site survey (refer
Appendix C) supplemented with a Digital Elevation Model (ELVIS, 2024) for the stable high dune
areas. The profiles are different and this impacts on the extent of erosion that may occur during the
adopted design storm event.




                           Figure 5-11 ETA 602 Beach profile and storm ETA 2100

5.3.2   Depth of Closure
The depth of closure adopted BMT (2018) was -11.5m AHD. However, M&N has adopted a depth of
closure of -12m AHD. This difference is unlikely to significantly alter the Bruun Rule calculation.
5.3.3   Dune of Toe
BMT (2018) determined the dune toe position by utilising the manually digitised coastline from the
Department of Resources and incorporating the Highest Astronomical Tide (HAT) contour.
M&N have adopted a level of 2.3m AHD as the toe of the dune based on site inspection (seaward
edge of vegetation) and detailed survey (refer Section 2.4).
5.3.4   Active beach width and height
The active beach width represents the horizontal distance from the dune crest to the depth of closure.
According to BMT (2018) and M&N, the adopted active beach width measures 525m and 520m,
respectively. The variation in these measurements is attributed to BMT's approach of taking the dune
location as the frontal dune.
5.3.5   Dune height
Figure 5-12 Dune heights and beach profile shows the dune heights adopted by BMT (2018) and
M&N against the beach profile adopted for the assessment in this report. BMT (2018) adopted 4.9m
AHD which corresponds to the frontal dune and therefore underestimates the reserve of sand
available in the dune system. M&N adopted a dune height of 15m AHD which was determine over an
iterative process (see Section 5.2.3).




                                                               252662-MN-RP-CO-0001B | 10 November 2025 | Page 32