2016-07-18 General Committee Meeting - Item 3 - Attachment 1 - Flood Management Plan

Between 2003 to 2005 additional investigations were                   5.2 Kin Kin Creek
undertaken to assess the impacts of proposed developments




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in the catchments.                                                    In 2002 consultants Lawson and Treloar were commissioned




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                                                                      to investigate the flooding characteristics for the Kin Kin




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5.1.5      Lake Entrance Boulevard                                    Township7. This investigation prepared a flood model
                                                                      using the Delft FLS 2D hydraulic modelling software.
Following flooding resulting from the February 2012 rain
event, Sunshine Coast Council engaged Projex Partners6 to             In 2013 the Sunshine Coast Council commissioned Water
review a number of areas within the Sunshine Coast region             Technology Pty Ltd8 to undertake an update of the 2002
affected by this flooding. The objective of the exercise was          Kin Kin Flood Model. The earlier Delft FLS 2D model was
to provide a review for each affected area and subsequent             converted to an updated TUFLOW model. The updated
recommendations for Council’s consideration on possible               TUFLOW model has a model grid size resolution of 5m.
further investigation requirements and possible future                The model is described as a sub-model covering a relatively
rectification/mitigation measures.                                    small extent of Kin Kin Creek and extending approximately
                                                                      2km downstream and approximately 600m upstream of
The review of the drainage regime and approved flood study            Kin Kin township.
established that the drainage system has been constructed
in accordance with the development approvals and that                 The hydraulic model is also described as being “partially”
the existing Finished Floor Levels are above the previously           calibrated as it has demonstrated some calibration to
calculated and approved Q100 flood level.                             historical peak flood debris levels and flood profiles
                                                                      however has not been informed by calibrated hydrologic
The February 2012 rain event caused significant flooding
                                                                      inflows and/or downstream water surface elevation
to some properties within the estate. It appears that this
                                                                      boundary conditions. The 2013 investigation also included
flooding was a result of the excessive flows created by the
rain event and potentially exacerbated by downstream                  consideration of the potential impact on anticipated
tailwater conditions within the receiving downstream                  flood levels of re-vegetation within the waterway corridor
channel, as well as the impact of Eumundi-Noosa Road                  immediately upstream of Kin Kin township.
allowing water to back up.                                            The 2013 Sunshine Coast Council flood hazard mapping
The February 2012 rain event has been calculated by                   project utilised the updated Kin Kin Flood Model to
Sunshine Coast Council to exceed a 1 in 100 year                      generate a suite of flood results for existing and future
recurrence interval.                                                  climate scenarios.

                                                                      Future climate scenarios were used as the basis for the 2016
                                                                      amendment to the Planning Scheme flood hazard area.
                                                                      Existing climate scenarios are used to inform the disaster
                                                                      management mapping for Kin Kin township.




6
  Lake Entrance Boulevard Report by Projex Partners for Sunshine Coast Regional Council, August 2012
7
  Kin Kin Flood Study by Lawson and Treloar Pty Ltd 2002
8
  Kin Kin Flood Model Revision and Revegetation Hydraulic Impact Assessment, Water Technology Pty Ltd 2013




                                                                                                 Noosa Council | Flood Management Plan | Page 18