Final Engineering services report _62 Lake Macdonald Drive · OPW25/0057

                                                                                         Flood Hazard Assessment
                                                                Intersection of Lake Macdonald Dr and Dianella Crt



1        INTRODUCTION
Noosa Council approached HydraLogic to provide a summary of the design flood conditions at the
intersection of Lake Macdonald Drive and Dianella Court in Cooroy.

The crossing is portrayed as being inundated in Council’s strategic planning and disaster
management maps.

The watercourse and catchment associated with the culvert crossing at this location lie within the
2018 Six Mile Creek flood model prepared by WMA Water for Noosa Council.

An initial review of the flood model results revealed the local tributary was only defined in the flood
study model to determine design flood inflows to the main branch of Six Mile Creek downstream of
Cooroy township. The road culvert crossings along this local tributary were not defined in the flood
model.

To enable a detailed summary of the design flooding conditions of the intersection to be prepared a
higher resolution flood model was developed for the local tributary. This local flood model includes a
higher resolution digital terrain model and the pipe culverts at Lake Macdonald Dr, Curlew Cresent,
and Swift Drive.

This report describes the configuration of the local high resolution flood model and summarises the
hydraulic performance of the intersection under a range of design flood conditions with Annual
Exceedance Probabilities of between 50% AEP and 0.2 % AEP.

The intersection and local catchment are shown in Map 1.




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