Reference Document - Coastal Hazard Assessment - MCU24 0094 · MCU24/0094

                                33 Ross Crescent, Sunshine Beach – Coastal Hazzard Assessment | 33 Ross Crescent Family Trust




Figure 6-10 Dune heights and beach profile


6.4.6.   Sediment size
BMT (2018), RHDHV (2024) and the assessment herein adopted a median sediment grain size (D50) of
0.22mm.


6.4.7.   Storm Tide
BMT (2018) stated that a 100-year ARI design storm tide level (inclusive of wave setup) for Sunshine Beach
of 2.61m AHD was adopted based on a storm tide assessment by Aurecon (2013). However, when
reviewing the assessment summary provided it appears that a design storm tide level of 2.2m AHD was
used by BMT (2018) for assessment of the short-term erosion component of the erosion prone area. There
is no clear explanation provided by BMT (2018) for the different storm tide levels described in their report.

Vellinga (1983) provides an empirical method for estimating beach erosion associated with a design storm
event. The input parameters for the design storm event described in Vellinga (1983) include the deep-
water significant wave height (Hos) and storm surge. The description described in Vellinga (1983) suggests
that the storm surge is exclusive of wave setup which is implicitly included in the empirical model. Figure
6-11 shows an example hydrograph of storm surge from Vellinga (1983) indicating the surge and tide effects
and no indication of wave setup. RHDHV (2024) therefore adopted a 100-year ARI storm tide level of 1.74m
(exclusive of wave setup) from Aurecon (2013).




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