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

Noosa Spit SEMP Final Report                                                                                                                                                                                                                                                                         12
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


September                                          Continued expansion of the southern spit has forced the exit channel westward,         Double Island Point:     Wetter        than   Shore-parallel       Short       and   Short and wide     Southern         –   Limited to none   Average
2018                                               scouring out the northern spit and facilitating a breach of the northern spit by the   Less N to E winds than   average but no       west            of   narrow above      above     HWM,     Hard up against
                                                   southern arm of a split northern channel, and by the central channel. The              typical, SE dominant     notable rainfall.    coastline,   then    HWM,              extensive          Doggie Beach
                                                   northern arm of the northern channel is still narrowly blocked by the northern                                                       NE-SW                extensive         submerged
                                                                                                                                          Tewantin:
                                                   spit, which is now significantly shortened but connected to Frying Pan Island                                                                             submerged         shoals to north-
                                                                                                                                          Typical winds
                                                   below high-water mark.                                                                                                                                    shoals to south   west

                                                   The severed southern portion of the northern spit has migrated south, partially
                                                   infilling the central channel and consolidating with the sand shoal separating the
                                                   central and southern channels. The southern channel remains the dominant
                                                   channel, persisting hard up against Doggie Beach before heading northwards
                                                   towards Noosa North Shore where channel migration has undermined
                                                   established vegetation.

                                                   The northern spit has continued to expand to the northwest, and is now well
                                                   developed above the high-water mark, even though nearly 9,000 m3 was
                                                   intercepted by the sand shifter.


March                                              TC Oma affected the area in February 2019, with increased wave action but no           Double Island Point:     2018     Highest     Shore-parallel       Short    above    Short    above     Southern         –   Limited to none   Limited
2019                                               rainfall. While erosion of Noosa Main Beach was observed, the complex wave             Less N to E winds than   October rainfall     west            of   HWM, minimal      HWM, average       Hard up against
                                                   breaking processes over the ebb-tide delta would have limited the passage of           typical, SE dominant     on      station      coastline,   then    submerged         submerged          Doggie Beach,
                                                   large waves through the mouth.                                                                                  record,              NE-SW                shoals            shoals to NW       but    multiple
                                                                                                                                          Tewantin:
                                                                                                                                                                   Significant                                                                    channels
                                                   The northern channel has now completely broken through the northern spit close         Typical winds
                                                                                                                                                                   rainfall                                                                       through shoals
                                                   to Noosa North Shore. The severed portion of the spit has migrated westward
                                                                                                                                                                   November
                                                   to join onto Frying Pan Island.
                                                                                                                                                                   2018.
                                                   The central and southern channels are both operational, with the southern
                                                   channel remaining dominant and largely unchanged, anchored firmly by the
                                                   scour points at the end of the training walls. The eastern end of the central
                                                   channel appears more well-defined than in previous imagery.

                                                   Growth of the southern spit stagnated but appeared to migrate slightly westward.
                                                   Nearly 19,000 m3 was recycled by the sand shifter, including pumping
                                                   undertaken immediately before and after TC Oma.




G:\Admin\B23636.g.mpb.NoosaSpit_SEMP\R.B23636.001.02.SEMP_final.docx