2020-10-21 Final Order - Approval Conditions and Approved Plans - P&E Appeal No 61 of 2018 - RAL17-0504

                               Rates of Rise
                               To plan for an evacuation case, the 1992 Historic Flood Event was used to inform flood response procedures,
                               as this historic event is a significant event, and has been included as a scenario in Noosa Shire Council’s
                               hydrological/hydraulic model. Modelled hydrographs for the 1992 Historic Flood Event in the Noosa River are
                               shown in Figure A-4, with greater detail of the rising limb of the hydrograph provided in Figure A-5 Figure .
                               Flood levels within Lake Weyba adjacent to the site can rise by up to 120mm/hr.

                               The steepest rate of rise for the 1992 Historic Flood Event is from 0.5mAHD to 1.5mAHD, which is at a
                               consistent rate of 80mm/hr to 120mm/hr.

                               Flooding to approximately 0.5m AHD would start to affect the western portion of the site (which is not proposed
                               to be developed) within 5hrs of the Flood Event starting. The evacuation route to Eenie Creek Road overpass
                               will not become inundated until approximately 14hrs when water levels in Lake Weyba reach 1.5mAHD and
                               will become impassable after approximately 17hrs (approximately 1.7mAHD). This provides adequate time for
                               a reasonable evacuation response should larger flood events occur on the site.




                                                                                                          Water Level Rise in Lake Weyba
                                                               2                                                                                                                                          200


                                                              1.8                                                                                                                                         180


                                                              1.6                                                                                                                                         160


                                                              1.4                                                                                                                                         140
                                 Water Surface Level (mAHD)




                                                                                                                                                                                                                Rate of Rise (mm/hr)
                                                              1.2                                                                                                                                         120


                                                               1                                                                                                                                          100


                                                              0.8                                                                                                                                         80


                                                              0.6                                                                                                                                         60


                                                              0.4                                                                                                                                         40


                                                              0.2                                                                                                                                         20


                                                               0                                                                                                                                          0
                                                                    0                5               10                     15                    20                    25                           30
                                                                                                                 Simulation Time (Hours)
5865_R02_V06_Final_FEMP.docx




                                                                        Water Level at Site (mAHD)    Minimum Evacuation Route Elevation (mAHD)        Rate of Rise (Averaged half hourly) (mm/hr)


                                                                                     FIGURE A-5 1992 HISTORIC EVENT – MODELLED RATE OF RISE




                               Andres Gabarrin | 27 February 2020
                               135 Lake Weyba Drive, Noosaville
                                                                                                                                                                                                                                       43