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

      COASTAL PROCESSES CONSIDERATIONS

      a.   Points of agreement
           i)     The agreed methodologies for calculation of the erosion prone area is outlined in
                  Department of Environment and Heritage Protection (2015), ‘Coastal Hazard Technical
120               Guide’.
           ii)    The prevailing south‐easterly wave climate drives a northerly transport of sand along the
                  beach and Noosa Headland located approximately 400 metres north of the site acts like a
                  groyne trapping sand to the south providing benefit to the northern section of Sunshine
                  Beach
125        iii)   Dune vegetation assists by trapping wind blown sand which builds the volume of sand
                  held in the dune. The dune system in front of the site is vegetated but there has been
                  trees die‐off. A development condition to replant native dune plants on the dunes would
                  assist with maintaining stability.
      LONG‐TERM EROSION

130   a.   Points of agreement
           i)     The long term erosion assessment undertaken by BMT WBM (2018) is considered a
                  reasonable assessment of the long‐term erosion potential of beach. BMT WBM (2018)
                  estimated long‐term erosion of 2.5 metres is based on industry standard practice.
           ii)    The default value of 10 metres for long‐term erosion is conservative given the features of
135               this section of Sunshine Beach, including proximity to Noosa Headland and could be
                  reduced for this location.
      SHORT‐TERM EROSION

      a.   Points of agreement
           i)     The storm tide level of 1.74 metres adopted by BMT WBM (2018) is appropriate for
140               assessment of erosion associated with a 100 year ARI storm tide event.
           ii)    The assessment of short‐term erosion using the methodology developed by Vellinga
                  (1983) provides a conservative assessment of short‐term erosion as it assumes sea level
                  remains elevated for a sufficient period to allow for an equilibrium storm profile to fully
                  develop.
145   b.   Points of disagreement
           i)     PP opinion is that the calculation of the short‐term erosion component of the erosion
                  prone area at the northern end of Sunshine beach should adopt a lower wave height as
                  the criteria for a design storm event. The Department of Environment and Heritage
                  Protection (2015) recommends a combination of a 20 year ARI wave height combined
150               with a 100 year ARI storm tide level. The 100 year ARI wave height adopted by BMT
                  WBM (2018) has not considered the sheltering provided by Noosa Head and is therefore
                  conservative. PP has adopted a 20 year ARI wave height of 5.5 metres based on previous
                  assessment presented by BMT WBM (2013). This results in a short‐term erosion distance
                  of 41 metres from the position of Highest Astronomical Tide (refer Attachment 1).
155        ii)    NC says that until the State Government and Council carry out more details assessments
                  of coastal erosion for regional planning, it would not be appropriate to adopt on an ad‐


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