2018-05-14 GC Agenda Attachment 1 to Item 6 Lake MacDonald Dr Community Reference Group Investigations Report

2. Introduction
In mid-2016 Noosa Council invited residents in the vicinity of Lake MacDonald Drive Estate to
participate in a Community Reference Group (CRG) which was formed following concerns raised
by residents with regards to observed flooding conditions in the local area.

The first CRG meeting was held on 19 July 2016 and was attended by local residents, council
officers and consultants and chaired by Cr Frank Wilkie.

The meeting sought to inform the CRG members of Council’s current understanding of the
catchment with regards to rainfall and flooding and to gather details of flooding observations and
concerns from the local community.

Council’s understandings of the flooding characteristics of the catchment were informed by a series
of flood studies which had been undertaken throughout the previous 15years. The deficiencies of
these studies were noted and a commitment provided to begin to address these through an
upgrade of the relevant flood studies. This upgrade would provide improved confidence in
modelling flooding conditions and also will provide a useful tool to test changes in flooding
conditions due to changes in the catchment or landscape.

Observations and concerns raised by reference group members included:
   •   The severity of the February 2012 flood event;

   •   Observed changes in flooding characteristics over time with regards to the frequency and
       speed of flood waters;

   •   Observed changes in the duration of inundation from flood waters;

   •   The potential for additional runoff due to increased urbanisation of upstream catchments;

   •   Possible flood mitigation works; and

   •   Ability to receive warnings of rising flood waters.

Following the first CRG meeting Council proceeded with preparing a tender to upgrade the Six Mile
Creek Flood Study. This tender was awarded to engineering consultants WMA Pty Ltd in late 2016.

Following the awarding of the tender, site inspections were coordinated by Council to visit CRG
stakeholder’s properties and other key locations throughout the catchment to inform the flood study
upgrade.

Following extensive data collection and development of a new computer flood model of the entire
catchment was prepared by WMA.

The new flood model was used to reproduce the flood event of February 2012 and to test a variety
of flood mitigation options suggested by the stakeholders. The models were also used to
investigate potential increase in runoff due to continued upstream urbanisation.

A second CRG meeting was conducted on 19th September 2017 to present and discuss these
results.

This report summaries these findings.




Lake McDonald Flooding Community Reference Group Report                                       Page 4