Attachment 4 - Option 1 Hydraulic Advice · RAL20/0005

    To:          Trevor Johnson                                           At:          SLR Consulting Australia Pty Ltd
    From:        Michael Della                                            At:          SLR Consulting Australia Pty Ltd
    Date:        23 September 2019                                        Ref:         SLR Memo 23 09 19.docx
    Subject:     Mitti St, Noosa Heads
                 Hydraulic Investigation
                 Channel Widening Option


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1           Introduction

A Technical Memorandum dated 30 November 2018 was previously prepared for this project.                                                       That
Memorandum describes the setup of the TUFLOW hydraulic model for the subject site.

The TUFLOW model has been modified to include the following proposed additional works within the site:
      •     widen existing 700 mm concrete channel to 3 metres;
      •     extend concrete channel to upstream property boundary; and
      •     lift overbank areas adjacent to the channel to a minimum level of 13.7 mAHD generally and to a
            minimum level of 13.8 mAHD between the channel and the southern wing of the existing rear
            dwelling.
This Memorandum describes the results of the updated modelling.


2           TUFLOW Model

As described above, the TUFLOW model (prepared previously for the analysis of the subject site) was modified
to represent the proposed new channel and overbank within the subject site.

Results of the TUFLOW analysis are shown in the following Figures:
      •     Figure 1. Peak Flood Depths – 1% AEP Event
      •     Figure 2. Impact of Proposed Works on 1% AEP Peak Flood Levels
      •     Figure 3. Peak Flood Hazard – 1% AEP Event




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