Attachment C_R.B23636.001.02.SEMP_final_lowres

Noosa Spit SEMP Final Report                                                                               6
Noosa Spit Shoreline Erosion




        The continued effectiveness of a north-east to south-west running channel is affected by southward
        growth of the northern spit. As the channel progressively shoals, the channel dominance switches to
        the southern channel immediately next to Dog Beach. This is further assisted by the presence of two
        “near permanent” scour pockets at each end of the southern channel (i.e. at the western end of the
        Noosa River training wall and at the end of the Noosa Spit training wall at the western end of Dog
        Beach).

        Under easterly winds, the northern and southern spits at the river mouth are pushed westwards,
        effectively holding the channel in a coastline parallel (approximately north-south) alignment which
        tends to maintain the dominance of the southern channel (next to Dog Beach). This dominance is
        then shifted by a storm event or flooding that causes one of the spits to be breached, thereby
        increasing flows through one (or more) of the other channels. Whether the other channels then
        become the dominant channel depends on the processes described above.

        At Dog Beach, the southern channel could be expected to dominate particularly after:

        • A sustained period of northerly to north-easterly winds (typically August to December); and/or

        • A lack of river flooding to carve a new “east-west” oriented channel.

        Dominance of the southern channel immediately adjacent to Dog Beach results in sustained erosion
        pressure along the central to eastern end of the beach.




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