2019-12-16 GC Agenda - Item 5 - Attachment 1 - Noosa Spit Shoreline Erosion Management Plan-Part 2

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2.3       Offshore ADCP, Noosa Main Beach
Figure 1-1 shows the Noosa Main Beach Offshore ADCP deployment location. The instrument was bottom-
mounted at a depth of approximately 9.5 m below AHD.

2.3.1     Currents
Recorded current magnitude and direction offshore from Noosa Main Beach and within Laguna Bay are
presented as time series and polar plots over the following vertical segments:

• Depth-averaged over the entire water column (Figure 2-3 and Figure 2-4)

• Bottom third of the water column (Figure 2-5 and Figure 2-6)

• Middle third of the water column (Figure 2-7 and Figure 2-8)

• Top third of the water column (Figure 2-9 and Figure 2-10)

The deployment period current characteristics include:

• The depth-averaged currents were typically less than 0.2 m/s except for the final week of deployment
  which coincided with increased winds. The currents align NE to SW with the ebb and flood phases of
   the tide and show a weak residual to the SW. The prevailing wave energy is likely to enhance the net
   SW current direction at this location (refer Section 2.3.2).

• The bottom third of the water column currents were typically less than 0.15 m/s and not strongly
  influenced by winds. The currents align NE to SW with a very weak residual to the SW.

• The middle third of the water column currents were higher in magnitude and show a stronger residual
  toward the SW compared to the bottom currents.

• The highest magnitude currents occur in top third of the water column where they are influenced by wind
  shear at the water surface. The current direction at the surface is more variable due to the wind.




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