2018-05-08 Services & Organisation Committee Agenda

SERVICES & ORGANISATION COMMITTEE MEETING AGENDA                                      8 MAY 2018


While these works included a thorough investigation of the potential solutions at the time, using
numerical modelling, the project scope was limited to the rehabilitation of these critical areas of
erosion. The investigations that were undertaken at the time of this project were never developed
into a formalised Shoreline Erosion Management Plan and there remains considerable
opportunity to better understand this region under current and future climate conditions.

The works constructed by SCRC were effective in mitigating erosion loss in the areas they were
designed to (i.e. the western tip and eastern end of the beach); however, since September 2017
the middle section of the beach has been experiencing severe erosion. Council staff have been
closely monitoring and evaluating this erosion in order to more thoroughly understand the ability
of Noosa Spit to perform as a coastal defence to Noosa Sound.

2.   Loss of Coastal Defence Risk Assessment

Council staff conducted a study in early 2018 to quantify the extent of erosion of the Noosa Spit
Foreshore using three-dimensional survey analysis to quantify the volume of sediment lost and a
two-dimensional aerial photography analysis to quantify the magnitude of shoreline recession.

The survey analysis indicated a loss of nourishment of approximately 18,000m3 between
November 2016 and July 2017, with an annual rate of erosion of 27,000m3/year.

Further survey work will be repeated in July 2018.

The aerial photography analysis (Figure 1 & 2) below compares the high water mark for all the
data points and uses this to predicatively forecast the shoreline position in the future.

Figure 1 shows the shoreline position in April 2015 with the shoreline measurement lines
overlayed, while Figure 2 shows the same measurement lines overlaying a December 2017
aerial photograph, the latest such image available.




                                Figure 1: April 2015 Shoreline position




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