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

3. Catchment Description
A catchment is an area of land where all surface water resulting from rainfall falling within that area
will accumulate and flow to (or past) a point at the end of the defined catchment.

For the purposes of this report and the associated investigations the end of the catchment is
defined in the vicinity of Highland Drive. The entire Six Mile Creek catchment extends downstream
beyond the Noosa Council boundary to a confluence with the Mary River south of Gympie.


3.1      Catchment Area to Highland Drive
The total upstream contributing catchment area to Highland Drive is approximately 4,500 hectares
and extends approximately 11km upstream. Refer to Figure 1 for contributing catchment extent.


3.2      Contributing Sub-Catchments
The upstream contributing catchment includes the sub-catchments of:
   •   Cudgerie Creek

   •   Cooroy Creek (including Cooroy township)

   •   Six Mile Creek Left Branch and

   •   Two local drainage tributaries

3.3      Contributing Catchment Land Use
Land uses within the contributing catchment are predominantly rural and rural residential with
urban (commercial and residential) land uses within Cooroy township. The total urban area of
Cooroy township, as defined by the ultimate urban footprint of the SEQ Regional Plan, is
equivalent to approximately 7% of the contributing catchment area.

The contributing catchment and associated waterways and drainage lines also includes several
road crossings and the north coast rail line. The influence of each crossing on local and regional
flooding depends upon the size of the bridge or culverts at each crossing and the elevation of the
roadway and associated embankments. Significant road crossings in the contributing catchment
include: the Bruce Highway, Garnet Street, Elm Street and Mary River Road.

Depending upon the size of a flood event and hence the volume of flood waters, road crossings
often act as ‘control’ within a catchment where water can only pass through or over the structure at
a rate determined by the size of the crossing opening and elevation of the roadway and
embankments.




Lake McDonald Flooding Community Reference Group Report                                         Page 5