MCU25 0087 - Reference Document - Coastal Hazard Assessment (As Published)

                                                                  17 The Esplanade, Sunshine Beach                              Report



                      5        EROSION PRONE AREA
                      The erosion prone areas identify 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
                      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)

                      5.1      Erosion Prone Area Assumptions
                      The assessment of the erosion prone area is based on a number of assumptions associated with the
                      recommended assessment methodology. These assumptions include:

                              Storm events are of a sufficient duration to allow for development of a storm response beach
                               profile;
                              The characteristics of the beach sediment are uniform both across and through the beach profile;
                              the long-term erosion trend is independent of recession due to sea level rise.
                              There are no physical features along the beach that would influence longshore sediment
                               transport; and,
                              The beach has sufficient time to recover following a beach erosion event.

                      The above assumptions, combined with a 40% factor of safety, lead to a conservative assessment of
                      erosion vulnerability.
                      It is reasonable to apply a precautionary approach to erosion vulnerability assessment given
                      uncertainty regarding issues associated with sea level rise and storm events associated with climate
                      change impacts. However, it is important to note that the site is near Noosa Headland, benefiting from
                      the protective influence of this natural feature. Furthermore, Sunshine Beach features deposits of
                      indurated sand (i.e. coffee rock) located beneath the beach and dunes seaward of the properties.
                      Erosion in the early 1970s (refer Figure 3-1) exposed large areas of coffee rock across this section of
                      the beach which would slow erosion and contradict some of the above assumptions.




                                                                                      252662-MN-RP-CO-0001B | 10 November 2025 | Page 21

Document Set ID: 24631530
Version: 1, Version Date: 24/03/2026