Attachment C_R.B23636.001.02.SEMP_final_lowres

Noosa Spit SEMP Final Report                                                                                 5
Noosa Spit Shoreline Erosion




                    • 7 July 1982                                         • 11 August 2013

                    • 20 May 1986                                         • 17 June 2014

                    • 17 December 1990                                    • 2 September 2015

                    • 25 May 1994                                         • 22 September 2016

                    • 27 May 1996                                         • 17 February 2017

                    • 11 June 2004                                        • 8 December 2017

                    • 21 July 2010                                        • 9 September 2018

                    • 8 November 2011                                     • 24 March 2019

        Figure 2-1 contains the imagery assessed, and summarises the observations recorded around Dog
        Beach and the position of the entrance channels. Following on from Tomlinson and Chamberlain’s
        (2006) historical descriptions of the evolution of the channels in the river mouth, additional details
        are provided for photography captured from 21 July 2010 onwards.

        It is important to note that manual interference has occurred within the assessment area. Two
        separate nourishment campaigns/works implementation have been undertaken to reduce the
        erosion impacts on Dog Beach in 2003 and in 2013. In addition, the sand shifter located immediately
        south of the Noosa Woods training wall intercepts up to 40,000 m3 per annum on an as needs basis,
        recycling the sand back onto Noosa Main Beach.

        Assessment of the imagery concurs that flood events provide the primary mechanism for
        reinstatement of a north-east to south-west running dominant channel. The creation of this channel
        reduces flows in the southern channel immediately adjacent to Dog Beach.

        Longshore transport of sediments along the outer beach to the northern and southern spits also plays
        a role in the position of the channel at the mouth. A dominance of northerly and north-easterly winds
        (and therefore waves) supplies sand from Teewah Beach towards the mouth, while the south-
        easterly winds transfer sand along Noosa Main Beach towards the mouth. The sand supply to the
        southern spit is sometimes interrupted by either the Noosa River training wall, or the activities of the
        sand shifter operating in the area. Under easterly wind conditions, the spits are pushed westward
        into the estuary, resulting in a channel that runs shore parallel (approximately north-south) within the
        estuary before exiting to the ocean.

        This spit growth process from sediment transport is supported by long-term wind data for the
        Tewantin RSL and Double Island Point weather stations (operated by the BoM), which indicates that
        north through to south-easterly wind conditions occur from August to December, while south to south-
        easterly winds dominate from February to June. January and July are highly mixed as the wind
        patterns fluctuate. Northerly winds dominate in spring.

        In addition, the wave refraction processes at Noosa Headland (Noosa National Park) reduce the
        influence of south-easterly waves impacting on Noosa Main Beach, increasing the influence on
        sediment transport of waves from the north-north-east to north-east.




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