24-01-2020 - Appeal No. 245 of 2019 - Final Order of Judge Rackemann · 51987.2951.01

Working Notes:
M Design and Fourteen Enterprises Pty Ltd as trustee v Noosa Shire Council -
42 Seaview Terrace, Sunshine Beach




Figure 5-3 Conceptualisation of recession due to sea level rise due to Bruun Rule (1962)

The Bruun Rule assumes an equilibrium beach profile is maintained with sea level rise resulting in an
elevation and landward movement of the profile, as shown in Figure 5-3. The Bruun Rule is given by
equation 2 below:

𝑟=                                                       equation 2

Where:
r=     shoreline recession due to sea level rise (m)
B=     horizontal distance of the active beach profile (m)
a=     rise in mean sea level (m)
D=     vertical height of the active beach profile (m)

The Bruun Rule assumes that the beach and dune consist of a uniform loose sand material. It is also
applicable to long straight sections of beach. The geotechnical assessment which is supported by
aerial photography from 1974 has shown the underlying soil profile includes indurated sand layers
(i.e. coffee rock).

The assessment of recession due to sea level rise is presented in Table 5-3. The profile adopted has
been based on ETA 602.0 for Sunshine Beach supplemented with site survey and bathymetric LiDAR
data for the Sunshine Coast obtained from the QSpatial Catalogue. Based on the information
available an active beach height of 29m has been adopted from the depth of closure of -12m AHD to
the dune height at the rear of the subject property of 17m AHD. This provides an active beach
profile width of 550 metres.

Two sea level rise scenarios have been assessed; 0.3 metres by 2050 and 0.8 metres by 2100. The
2050 scenario accommodates the projected asset lifespan of the proposed swimming pool. This
shows that the position of Highest Astronomical Tide will be 5.7 metres closer to the site’s property
boundary by the year 2050.



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