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

The development of a 2D hydraulic model of the River and                   Sunshine Coast Council commissioned consultants, Projex
its associated floodplains will also provide an insight into               Partners, to undertake a detailed flood investigation4 of the




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the anticipated overbank flood flow velocities. Knowledge                  site. Subsequently the Sunshine Coast Council undertook




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of the anticipated overbank flood flow velocities will assist              a follow up study to develop a detailed (TUFLOW) flood




                   DR
Council and local builders and developers with identifying                 model of the Daintree Estate reach and determine flood
locations suitable for applying the national Standard for                  mitigation options for the estate. The results of this model
the construction of buildings in flood hazard areas. It will               form the basis for the current disaster management
also provide a more accurate estimation of design flood                    mapping.
velocities in high velocities locations where the Standard
                                                                           Recent flood mitigation works have significantly improved
does not apply. Knowledge of the anticipated magnitude of
                                                                           the flood immunity of affected properties. The Daintree
flood flow velocities is important in structural calculations
                                                                           Estate flood model has been amended to include these
for designing buildings, walls and fences located within
                                                                           works. The resulting inundation extents for the 1% AEP
flood prone areas.
                                                                           (future climate) scenario form the basis of the 2016 Flood
To address the deficiencies of the original 1D flood                       Hazard Area Planning Scheme amendment.
study required it to be upgraded to a contemporary 2D
modelling approach. Where possible, improvements to the
calibration and extents of the flood modelling are being
pursued although there are relatively limited additional
flood records available.

The completion of the upgraded Noosa River flood model
will provide an improved understanding of the distribution
of both tidal velocities and flood flow velocities throughout
the waterway and associated floodplains of the lower
reaches of the Noosa River.

The updated modelling will allow for variations in the shape
of the river’s bathymetry to be modelled to determine the
sensitivity of the waterway’s velocity distributions to these              5.1.4       Ringtail Creek
changes. This will assist with understanding if natural or
                                                                           In 2002 consultants Lawson and Treloar were commissioned
man-made changes to the shape of the river can have a
                                                                           to undertake the Ringtail Creek Hydraulic Investigation5.
demonstrable effect on flow velocities and erosive forces
                                                                           The flood models adopted for this investigation were
along the foreshore.
                                                                           RAFTS for hydrological modelling and DELFT-FLS for 2D
5.1.3         Noosa Daintree Estate                                        hydraulic modelling.

Noosa Daintree Estate is a 97 lot residential estate                       Anticipated inundation extents for a 100 year ARI local
constructed in circa 2000. The estate has been subject to                  catchment event combined with a 20 year ARI Regional
significant flooding on three occasions, with the most                     catchment event were used to inform the existing flood
severe impacts occurring from an event on the 24th                         hazard area of the Planning Scheme Natural Hazards
February 2012.                                                             Overlay map.

4
    Noosa Daintree Estate Report 1 July 2013 by Projex Partners for Sunshine Coast Regional Council
5
    Ringtail Creek Hydraulic Investigation, Lawson and Treloar Pty Ltd 2002




                                                                                              Noosa Council | Flood Management Plan | Page 17