2019-12-16 GC Agenda - Item 5 - Attachment 1 - Noosa Spit Shoreline Erosion Management Plan-Part 1

 Noosa Spit SEMP Final Report                                                                              23
 Numerical Modelling of Entrance Configurations




3        Numerical Modelling of Entrance Configurations
3.1      Background
         The numerical modelling described in this Chapter follows the analysis of recent shoreline trends
         described above and a data collection campaign completed in March/April 2019. Technical
         summaries of the metocean and bathymetric data collection campaigns are provided with this report:

         • Appendix A: Metocean Data Collection

         • Appendix B: Bathymetric Survey (Acoustic Imagery, 2019).

         The Model is comprised of several numerical components that simulate coastal and estuarine
         processes and can be used in uncoupled or coupled modes. Key elements and an initial application
         of The Model to assess various river entrance configurations are described below.

3.2      Waves (SWAN)
         SWAN (Delft University of Technology, 2006) is a third-generation spectral wave model, which
         simulates wave growth by wind and wave energy dissipation by whitecapping, depth-induced wave
         breaking and bottom friction. SWAN simulates wave/swell propagation in two-dimensions, including
         shoaling and refraction due to spatial variations in bathymetry and currents. This is a global industry
         standard modelling package that has been applied to many investigations worldwide.

         In this study SWAN is used to transform measured directional wave data from the Mooloolaba
         Waverider Buoy into shallow water within Laguna Bay. Validation of the modelling approach using
         directional wave data from an Acoustic Doppler Current Profiler (ADCP) deployed in Laguna Bay
         and is presented in Section 3.5.2.

3.2.1    Nested Model Domain & Bathymetry
         A nested wave modelling system has been established to investigate the wave climate within Laguna
         Bay. The model extent and wave data recording locations are shown in Figure 3-1. The modelling
         system includes a 400 m resolution regional model and two nests of increasing resolution to 25 m to
         resolve waves within Laguna Bay.

         Bathymetry for the wave model has been derived from the following sources in descending priority:

         • Acoustic Imaging high-resolution (0.5 m) survey captured in March 2019 (see Appendix B).

         • SKM 2 m Digital Elevation Model (DEM) created from a 2011 bathymetric LiDAR survey of the
           Sunshine Coast (Queensland Government 2012).

         • High-resolution depth model for the Great Barrier Reef (Geoscience Australia 2017).

3.2.2    Model Configuration
         The wave modelling has used a two-dimensional (2D), nonstationary configuration of SWAN the
         following configurations and parameterisations:

         • Third-generation with default settings; and

         • Bottom friction described by Collins (1972) with default coefficient.

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