MNA_250215_33 Ross Crescent Sunshine Beach_00

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



6.2.       Erosion Prone Area Reassessment
The declared erosion prone area for the Noosa Shire Council area is provided on Department of
Environment and Science Plan Number NOS3A dated 8 July 2015 (refer Appendix B). This shows an
erosion prone area width for Sunshine Beach of 175m measured inland from the seaward toe of the frontal
dune.

Noosa Shire Council has completed a Coastal Hazard Adaptation Study (CHAS) through the QCoast2100
program. Phase 3 of the CHAS involved refining coastal hazard mapping, including reassessment of the
erosion prone area. The study was undertaken by BMT (2018). It should be noted that the assessment by
BMT (2018) was at a beach compartment scale and did not provide site-specific estimation of erosion
vulnerability. The beach compartment which 33 Ross Crescent, Sunshine Beach falls in is based off survey
data from ETA 602. It should be noted that this profile is located 530m to the north of the site.

The following sections will review each component of the Erosion prone area based on site specific
conditions.
6.2.1.      Long-term Erosion (N x R)
The long-term erosion component is based on the selected planning period (N) and the average annual
rate of long-term erosion (R).

In relation to the planning period, the Department of Environment and Heritage Protection (2013) states,
“The long-term erosion component (excluding sea level rise) of the calculation is often cyclical in nature
and typically of a decadal scale. For this reason, it is considered the estimated annual rate of long-term
erosion is only applied for a 50-year period”. Where there is no clear evidence of long-term erosion trends,
the Department recommends a nominal provision of 10m.

The annual rate of long-term erosion (R) reflects changes to sediment supply to a beach and where there
is a long-term deficit in sediment supply this results in a longer-term recession of the shoreline.

BMT (2018) has calculated a long-term erosion rate of 0.03m/year for Sunshine Coast at beach profile line
ETA 602. Table 6-1 provides a summary of BMT (2018) estimated long-term erosion for 2040, 2070 and
2100.

TABLE 6.1: SUMMARY OF LONG-TERM RECESSION RESULTS FROM BMT (2018)
         Beach        Survey       Annual Recession                           Long-term Recession (m)
                      Profile        Rate (m/year)
                                                                   2040                  2070                  2100
 Sunshine Beach      ETA 602              0.03                      0.7                   1.6                   2.5



The subject site is located 1.7km south of Noosa Headland which plays a significant role in sediment
transport processes along this beach as discussed in Section 5.3. This is supported by the aerial and
satellite imagery presented in Section 3 which has shown recovery and progradation of the beach adjacent
to the site since severe storm event related erosion in the early 1970’s. Further, Section 3 highlights
sensitivities associated with reporting intervals for long term recession and the need to select suitable start
and end dates for any analysis, which are not influenced by episodic erosion events.

Given the long-term stability of this section of coast a nominal 10m has been adopted in accordance with
the Department of Environment and Heritage Protection (2013).




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