PA3660-Coastal Hazard Assessment - 4 arakoon

                                                Project related




5               Coastal Processes
The coastal processes of interest to this investigation are water levels (including sea level rise
predictions), wave conditions, and sediment transport processes.

5.1             Tides and Storm Tide
The water levels of interest for a reassessment of the erosion prone area include the astronomical tide,
storm tide and the predicted rise in mean sea level associated with climate change. The following
sections describe the water levels adopted for the assessment.

5.1.1           Astronomical Tides
Sunshine Beach experiences semi-diurnal tides with a tidal range of 1.4 metres at spring tides. Table 5-1
presents the published tidal planes for Noosa Head (Maritime Safety Queensland, 2024) which are
considered consistent with conditions at Sunshine Beach, due to the proximity.


Table 5-1 Noosa Head Tidal Planes (Maritime Safety Queensland, 2024)
                                  Water Level            Water Level
 Tidal Plane
                                (m above LAT)             (m AHD)

 Highest Astronomical Tide            2.35                  1.23

 Mean High Water Spring               1.78                  0.66

 Mean High Water Neap                 1.45                  0.33

 Mean Sea Level                       1.06                  -0.06

 Mean Low Water Neap                  0.71                  -0.41

 Mean Low Water Spring                0.38                  -0.74

 Lowest Astronomical Tide              -                    -1.12


5.1.2           Sea Level Rise
The effects of climate change associated with emission of greenhouse gases has caused a rise in mean
sea level above pre-industrial levels, and sea levels are predicted to continue to rise into the future. The
Queensland Government has adopted a predicted sea level rise of 0.8 metres by the year 2100 above
present day mean sea level. It is noted that BMT (2018) adopted the following sea level rise allowances
(above present day mean sea level) as part of phase 3 of the Coastal Hazard Adaptation Strategy
(CHAS):

     •     0.2 metres by 2040,
     •     0.5 metres by 2070, and
     •     0.8 metres by 2100.

The adopted sea level rise allowances are consistent with industry practice and will be used for this
assessment.

5.1.3           Storm Tide
Storm tide is the total water level associated with the combination of the normal astronomical tide and the
tidal surge from a storm event (e.g., tropical cyclone). There have been several previous storm tide


11 April 2024         4-6 ARAKOON CRESCENT, SUNSHINE BEACH             PA3660-RHD-XX-ZZ-RP-Z-0001    20