Cardno Amended flood report July 2018

  Technical Memo


  5 Results
  The developed case peak, flood depth, water surface level, velocity and hazard maps for the 39%
  to 1% AEP events have been plotted in the attached figures (Attachment B). Afflux maps comparing
  the developed case with the existing are also included in Attachment B. The 1% AEP climate change
  water surface level for the developed case has also been included as Figure 2-0 in Attachment B.
  Changes to the water surface level that can be seen on the extremities of the building footprints are
  a result of the topography modifications blocking water from these cells and in no way effect the
  models reliability.

  It can be seen in the figures provided that Villa No.3 is situated within the flood extent and the flood
  extent encroaches marginally onto Villas No. 2 and 3. The elevated walls simulating debris build up
  did not have an effect on the hydraulic outcomes and at no time do the building finished floor levels
  become inundated. In response to Item 1 of Council’s RFI, the development presents no internal and
  external impacts to the site.

  Table 5-1 shows the peak water surface levels extracted from the centroid of Villa 3. This
  demonstrates that there is no change to the water surface levels due to the development at this
  location. As discussed in the original flood study, peak water surface levels at this site are primarily
  controlled by the weir located nearby on the downstream side of the development.
  Table 5-1 Peak Water Surface levels

                      WSL (mAHD)
    AEP            Existing Developed                  Difference (m)
    39%            8.02     8.02                       0
    18%            8.12     8.12                       0
    10%            8.16     8.16                       0
    5%             8.19     8.19                       0
    2%             8.21     8.21                       0
    1%             8.24     8.24                       0
    1%CC           -        8.28


  6 Conclusions
  Additional flood modelling was completed to respond to issues raised by Noosa Council. The RORB
  and TUFLOW models simulated for the Carramar Tewantin site were adopted and altered from the
  previous Cardno issued flood study to enable the request for information responses. The revised
  model included the 39% up to the 1% AEP event, an updated lot layout of the proposed development
  and included filling proposed.

  The modelling determined that for all design events, no negative impacts were caused by the
  proposed development either on or offsite. Access to the proposed buildings as per the drawings
  shown in Attachment A remains flood free with no impacts on human safety identified.




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