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

 Noosa Spit SEMP Final Report                                                                               47
 Numerical Modelling of Entrance Configurations




3.6.1    Impact to Water Level
         Maps showing the impact to peak water level are shown in Figure 3-16 to Figure 3-19 and indicate
         the following:

         • The comparison between the existing peak high tide water level and 1987 scenario (Figure 3-16)
           and 2010 scenario (Figure 3-17) show only minor differences beyond the entrance and within the
           lower river. This suggests that the tidal prism and tidal attenuation is relatively insensitive to the
           entrance channel configuration.

         • The Dog Beach breakthrough scenario (Figure 3-18) causes high tide water levels within Noosa
           Sound and the lower river to increase by up to 0.08 m. This morphological change increases the
           tidal prism and reduces the freeboard for waterfront locations.

         • Following the 1 in 100 (1%) AEP flood event and associated scour, the cross-sectional area at
           the entrance and tidal prism increases. This causes lower river high tide water levels to increase
           by up to 0.1 m. It is noted that the ‘post flood’ condition is temporary, and the entrance cross-
           sectional area would gradually return to it’s equilibrium conditions under the prevailing conditions.




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