2019-12-16 GC Agenda - Item 5 - Attachment 1 - Noosa Spit Shoreline Erosion Management Plan-Part 1

Noosa Spit SEMP Final Report                                                                                                                                                                                                                                                                      10
Noosa Spit Shoreline Erosion


 Imagery                                                                           Observed Changes                                         Wind Climate            Notable          Orientation         Northern Spit    Southern Spit      Dominant Flow       High Tide             High Tide
   Date                                                                          (since previous image)                                  Compared to Average        Rainfall        and Condition         Length and       Length and          Channel          Recreational          Recreational
                                                                                                                                            (since previous          (since            of Mouth            Condition        Condition                              Beach                Beach
                                                                                                                                                 image)            previous                                                                                    Availability at       Availability at
                                                                                                                                                                    image)                                                                                     central Doggie          eastern
                                                                                                                                                                                                                                                                   Beach             Doggie Beach


August                                             Major manual interference in the southern channel and along Doggie Beach              Double Island Point:   Significantly       Multiple             Average, wide,   Non-existent       Central,    but   Wide         (post-   Wide      (post-
2013                                               occurred in the lead up to this image. A training wall was constructed at the         Typical winds          higher   than       disconnected         patchy                              multiple          groyne,               groyne,
                                                   western end of Noosa Spit to control channel migration and limit further erosion                             average:            NE-SW                overwash,                           channels          nourished)            nourished)
                                                                                                                                         Tewantin:
                                                   of Doggie Beach, accompanied by nourishment along the length of the beach.                                   December            channels             submerged                           through shoals
                                                                                                                                         Typical winds
                                                   Manual infilling of the channel near the submerged geobag groyne at the eastern                              2011,   January                          shoals to west
                                                   end of Doggie Beach is visible. Nourishment material was sourced from the                                    2012,     March
                                                   shoals near the new training wall. The dredge holes created in this process                                  2012,      June
                                                   appear to have naturally re-filled.                                                                          2012, January
                                                                                                                                                                2013     (ex-TC
                                                   Very little change was observed in the central channel, which is dominant now
                                                                                                                                                                Oswald),
                                                   that the southern channel has been partially infilled. The exit channel has
                                                                                                                                                                February 2013,
                                                   remained close to the Noosa Woods training wall, assisted by the training wall
                                                                                                                                                                July 2013
                                                   scour pocket, and reduced sediment supply from Noosa Main Beach due to
                                                   sand shifter activities between February and May 2013 (approx. 30,000 m3).

                                                   Sediment supply to the northern spit appears to have reduced, and localised
                                                   breaching of the northern spit at higher water levels is evident.


June 2014                                          Very gradual increase in length and height of northern spit sand mass, with the       Double Island Point:   Nil. Dryer than     Multiple             Average, wide,   Non-existent       Central,    but   Average               Average
                                                   spit blocking flow of the northern channel. Visible increase in dune grass            Typical winds          average. 2014       disconnected N-      submerged                           multiple
                                                   colonisation.                                                                                                close to lowest     S channels           shoals to west                      channels
                                                                                                                                         Tewantin:
                                                                                                                                                                rainfall    on                                                               through shoals
                                                   The central channel remains dominant, although some shoaling is occurring just        Typical winds
                                                                                                                                                                station record.
                                                   upstream of its intersection with the southern channel, forcing development of a
                                                   currently short section of new channel aligned to N-S. The channel exit remains
                                                   close to the Noosa Woods training wall, although minor development of the
                                                   southern spit has occurred.

                                                   The southern channel has remained largely stable, although redistribution of the
                                                   nourishment material placed in the southern channel has exposed the upper
                                                   layer of the submerged geobag groyne. The scour pocket at the end of the
                                                   Noosa Spit training wall has become well developed.




September                                          Consolidation of the northern spit continued, with easterly winds expanding the       Double Island Point:   Nil. Dryer than     Poorly     defined   Average, wide,   Minimal   above    Multiple          Average               Average
2015                                               spit to the west, almost connecting with Frying Pan Island above the high-water       Spring 2014 more E     average. Ex-TC      N-S channels         submerged        HWM, minimal       channels
                                                   mark. This spit growth was assisted by further dune grass stabilisation. The          than average           Marcia in area                           shoals to west   submerged          through shoals
                                                   northern channel largely remains a backwater. Shoaling of the eastern end of                                 February 2015,                                            shoals to north-
                                                                                                                                         Tewantin:
                                                   the central channel has progressed to a stage where the channel, although                                    heavy    rainfall                                         west
                                                                                                                                         Typical winds
                                                   dominant, is no longer continuous through the flood-tide delta.                                              recorded      for
                                                                                                                                                                one day only.
                                                   Further exposure of the submerged geobag groyne has occurred, with the entire
                                                   length of the structure now visible. The scour pockets at the ends of both training
                                                   walls (i.e. at each end of the southern channel) are well developed.

                                                   Gradual narrowing of Doggie Beach above the high-water mark has occurred,
                                                   although no further loss of vegetation is evident.




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