Development Application - Part 2 of 2 - Report & Plans · OPW11/0116

Numerical modeling [Figure 14] of the existing situation shows that tidal velocities in the southern channel adjacent to the
Noosa River Spit typically peak at 0.5 - 0.6m/s on both the flood and ebb tides. The velocities directly adjacent to the shore
range depending on the location and the state of the tide. The areas directly adjacent to the existing rock wall experience
low (<0.25m/s) velocities on the flood tide, but experience velocities up to 0.6m/s during the ebb tide. Further upstream the
Noosa River Spit experiences higher velocities (0.5 -1 m/s) on the flood tide and much lower (0.25m/s) velocities on the ebb
tide. The end of the Noosa River Spit is again very sheltered during the flood tide, but experiences high velocities (0.5 -
1m1s) during the ebb tide.




                                                                                              Cu;u it*   ayeed Im/sl



                                                                                                    080.100
                                                                                                    070.080
                                                                                                    060.070
                                                                                                    050.060
                                                                                                    040.050
                                                                                                    035.040
                                                                                                     330.035
                                                                                                    025-030
                                                                                                    020-025
                                                                                                    015.020
                                                                                                    010.015
                                                                                                    005-010
                                                                                                     000.005
                                                                                                    r4Wow 0 00
                                                                                                    Ur defined Value




                                                                                                    080 1 00
                                                                                                    070.080
                                                                                                    060.070
                                                                                                    050.060
                                                                                                    040.050
                                                                                                    035.040
                                                                                                    030.035
                                                                                                    325.030
                                                                                                    320.025
                                                                                                    010-020
                                                                                                    010.015




Figure 14: Results of MIKE21HD model [ebb & flood tide] for Existing situation

It is likely that these velocities are lower than experienced previously given dominance of the middle channel and the partial
closure of the southern channel at the end of the Noosa River Spit, but that erosion is still occurring at a reduced rate. It is
noted that areas of greatest erosion are typically vulnerable during the ebb tide, although upstream areas of the Noosa River
Spit are vulnerable during the flood tides [Figure 15].