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

 Noosa Spit SEMP Final Report                                                                              34
 Numerical Modelling of Entrance Configurations




3.5.3    Laguna Bay Water Level & Currents
         The bottom-mounted ADCP temporarily installed within Laguna Bay also recorded water level,
         current speed (magnitude) and current direction. Hydrodynamic model calibration results to these
         datasets are shown in Figure 3-6 and indicate the following trends:

         • The water level within Laguna Bay is accurately represented by the model during neap and spring
           tide conditions.

         • The magnitude and direction of tidal currents are modelled in a general sense however the data
           shows significantly more scatter than the model. This is likely due to a combination of the
           following:

             ○ The influence of wind on the water column not being precisely represented by the model. For
               example, the CFSR wind field applied as a boundary condition will not accurately resolve the
               local orographic effects associated with the Noosa Headland;

             ○ The influence of wave radiation stress on the current patterns; and/or

             ○ Vertical gradients in the water column not represented by the 2D modelling approach.

3.5.4    Noosa River Water Level
         Within the Noosa River, the model has been calibrated to the six tide recording locations indicated
         in Figure 3-4. Tidal water level comparisons, covering a period that includes neap and spring tides,
         are provided in Figure 3-7 and Figure 3-8. These figures illustrate that the phase and amplitude of
         the tide is predicted well at each location, noting a tendency to slightly overpredict high tide at the
         river mouth (Tide Recorder 1). The recordings and model output also show the attenuated tidal
         conditions within the lower river compared to Laguna Bay (top panel of Figure 3-6).

         It is noted that Tide Recorder 2 (middle panel of Figure 3-7) appeared to have been moved on
         retrieval of the instrument. The raw data suggested that this occurred during the first week of
         deployment. Data recorded before this time has been discarded.




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