2021-01-18 GC - Item 3 - Attachment 2 - Phase 7 Project Summary Coastal Hazards Adaptation Plan

Noosa Shire Council Coastal Hazard Adaptation Plan: Project Summary                                           5
Methodology




2.2.2.1 Storm Tide
        Storm tide hazard areas were developed using a combination of existing information and inundation
        modelling tools (Aurecon 2013; WMA Water 2017a; WMA Water 2017b), as identified in Table 2-1.
        For land adjacent to the lower Noosa River both inundation depth and velocity hazard information
        were determined.

                    Table 2-1     Summary of CHAP Storm Tide Hazard Mapping Approach

         Mapping product            Present-day             2040               2070                2100
         Open coast storm            Developed           Developed           Developed           Developed
         tide inundation            using present-    using present-      using present-         using 2100
                                   day open coast     day open coast      day open coast         open coast
                                   levels reported     levels + 0.2 m      levels + 0.5 m     levels reported
                                     by Aurecon         SLR reported        SLR reported         by Aurecon
                                     (2013) and          by Aurecon          by Aurecon        (2013) (which
                                       bathtub           (2013) and          (2013) and        included 0.8m
                                       mapping             bathtub             bathtub            SLR) and
                                                          mapping             mapping              bathtub
                                                                                                  mapping
         Lower Noosa River          Previously           Developed          Developed           Previously
         catchment storm tide      completed by        using existing     using existing       completed by
         inundation               Aurecon (2013)      TUFLOW model       TUFLOW model         Aurecon (2013)
                                                       + 0.2 m SLR        + 0.5 m SLR         (which included
                                                         boundary           boundary            0.8m SLR)
                                                          condition          condition
                                                        adjustments        adjustments
         Coincident Noosa           Previously          Previously          Previously          Previously
         River flooding and        completed by        completed by        completed by        completed by
         storm tide conditions     (WMA Water,         (WMA Water,         (WMA Water,         (WMA Water,
                                     2017a)              2017b)              2017b)              2017a)

2.2.2.2 Erosion Prone Areas
        The State Erosion Prone Area plans have been developed by the Queensland Government to assist
        development assessment and to inform the preparation of planning instruments, such as planning
        schemes and regional plans under the Planning Act 2016.

        Erosion Prone Areas (EPA) have been declared for all coastal local government areas in
        Queensland.

        The EPAs apply to land subject to inundation by the Highest Astronomical Tide (HAT) by the year
        2100 or at risk from sea erosion. On land adjacent to tidal water the EPA is defined by whichever of
        the following methods gives the greatest width:

        (1)   40 m buffer from the present-day HAT contour

        (2)   Calculated erosion distance

        (3)   Permanent inundation due to SLR in 2100 (defined by present-day HAT plus 0.8 m).

        The EPAs determined by the State define a hazard extent at a single specified planning horizon (the
        year 2100) and probability (representative 100-year ARI). The State-defined erosion prone areas are
        therefore useful for ‘first-pass risk screening’ however do not provide sufficient information regarding