Attachment C_R.B23636.001.02.SEMP_final_lowres

Noosa Spit SEMP Final Report                                                                          72
Shoreline Erosion Mitigation Options




4.3     Multi-Criteria Analysis
        A Multi-Criteria Analysis (MCA) of the shortlisted options has been developed in consultation with
        the PCG. Table 4-4 provides a summary of the MCA categories, weightings and scoring descriptors.

        Building on the outcomes of the rapid assessment and consultation with the PCG and DES, the
        following options were defined:

        • Option 1a – Sand plug at either end of Dog Beach and shoreline nourishment

        • Option 1b – Sand plug at the southern end of Dog Beach and shoreline nourishment

        • Option 2 – Extension of the existing training wall/groyne at western end of Dog Beach

        • Option 3 – Extension of submerged breakwater and two new groynes (full implementation of the
          strategy proposed by Sunshine Coast Council and summarised in Section 2.4)

        • Option 4 – Three new groynes at Dog Beach

        • Option 5 – Shore parallel seawall

        • Option 6 – Do nothing (allow Dog Beach to recede without intervention).

        Discussion on the MCA category scoring and assumptions for each option is presented in the
        following sections. The general approach for scoring within each MCA category is:

        • Effectiveness: Option 1 (a and b) to Option 4 were assessed using The Model with impacts
          quantified by comparing the ‘existing’ and ‘developed’ case scenarios. These outputs are used to
          infer areas where sand deposition, erosion and morphological change may occur in response to
          the option. Option 5 and Option 6 were not assessed with The Model and therefore the scoring is
          based on qualitative assumptions.

        • Whole of life costs (annualised) to 2040: Assumptions based on Council’s experience with
          similar works at Dog Beach and other lower Noosa River locations. Industry advice from dredging
          contractors has also been incorporated to the cost estimates for Option 1a and Option 1b.

        • Environmental values: Qualitative assumptions based on the potential for temporary impact (i.e.
          during construction) or permanent loss terrestrial and/or estuarine habitat.

        • Social values: Qualitative assumptions based on the available beach and land areas available
          for recreation.

        • Risk: In accordance with Council’s corporate risk assessment procedure (full details in Appendix
          D).




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