PA2906-Coastal Hazard Assessment-R1 · MCU21/0212

                                           Internal use only




6           Erosion Prone Area
The erosion prone area identifies land that may be vulnerable to coastal erosion or tidal inundation over a
100-year planning period and are declared under section 70 of the Coastal Protection and Management
Act 1995.

The ‘Coastal Hazards Technical Guide’ (Department of Environment and Heritage Protection, 2013)
provides guidance on the calculation of an erosion prone area. The erosion prone area width is based on
the following:
         short-term erosion from extreme storm events (e.g., a tropical cyclone);
         a dune scarp component to accommodate slumping of the erosion scarp following short-term
          erosion;
         long-term erosion associated with a deficit in sediment supply;
         shoreline recession due to sea level rise; and
         a 40% safety factor.

The Erosion prone area is calculated using the following equation:
𝐸 = {(𝑁 × 𝑅) + 𝐶 + 𝑆} × (1 + 𝐹) + 𝐷                   Equation 1

Where:
E=     Erosion Prone Area (metres)
N=     planning period (years)
R=     rate of long-term erosion (metres/year)
C=     short-term erosion from the design storm event (metres)
S=     recession due to sea level rise (metres)
F=     factor of safety (0.4)
D=     Dune scarp component to allow for slumping of the erosion scarp (metres)

The calculation of the erosion prone area assumes:
         the beach and dune consist of unconsolidated loose sand with uniform physical characteristics;
         physical features (e.g., headland) do not influence sand movement;
         the duration of storm events is sufficient to allow for an equilibrium storm beach profile to develop;
          and
         the long-term erosion trend is independent of recession due to sea level rise.

6.1         Erosion Prone Area Reassessment
The declared erosion prone area for the Noosa Shire Council area is provided on Department of
Environment and Science Plan Number NOS3A dated 8 July 2015 (refer Appendix B). This shows an
erosion prone area width for Sunshine Beach of 175 metres measured inland from the seaward toe of the
frontal dune.

Noosa Shire Council has completed a Coastal Hazard Adaptation Study (CHAS) through the QCoast2100
program. Phase 3 of the CHAS involved refining coastal hazard mapping, including reassessment of the




15 October 2021     66 SEAVIEW TERRACE, SUNSHINE BEACH                 PA2906-RHD-ZZ-XX-RP-Z-0001     20