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Flood study

South Creek Flood Study

The South Creek Flood Study has been undertaken to define the nature and extent of flooding in the South Creek Catchment for a range of design events. The 466 hectare catchment is located on the north-eastern side of Lake Macquarie on Warners Bay and includes the suburbs of Warners Bay, Eleebana, Mount Hutton, and Tingira Heights. The catchment is defined by the higher elevations in the north, east, and south sides of the catchment. Runoff is conveyed to the main channel of South Creek in the centre of the catchment through several tributaries and drainage depressions from the ridgeline. Landuse in the catchment is predominantly low-density residential and rural-residential with areas of bushland in the higher elevations. A questionnaire was delivered to residents in the catchment floodplain to identify flooding awareness and specific accounts of flood inundation. Sixty-eight out of the eighty-seven responses advised they recalled the flood event of June 2007, twelve recalled a flood event in March 1990, and thirteen in April 1988. Several respondents noted that the June 2007 event was the worst they could recall. Twenty-three respondents advised they had experienced flood inundation in the house. The draft report was placed on public exhibition from 26 April to 21 May 2010 inviting submissions for the Study. Hydrologic and hydraulic modelling was undertaken to assess flood behaviour within the catchment. The SOBEK 1D/2D model from WL|Delft Hydraulics Laboratory was used to model the catchment and to hydraulically route overland flood flows. The SOBEK modelling of the South Creek catchment utilises the Direct Rainfall (‘rainfall-on-grid’) methodology for developing the hydrology. In the model, rainfall is applied directly to the 2D terrain, and the hydraulic model automatically routes the flow. The model was calibrated to flood marks and reports from the June 2007 event. Flood behaviour was modelled for the 50% Annual Exceedance Probability (AEP), 20%, 10%, 5%, 2%, 1%, and 0.5% AEP and for the Probable Maximum Flood (PMF), with the Lake level and rainfall pattern for the same respective AEP event. A 2 hour storm is the critical duration (up to the 0.5% AEP) for the catchment resulting in the highest peak water levels. Figures showing the peak water levels, peak flood depths, and peak flow velocity are included in Volume 2 of the Flood Study report.

Additional Information

Field Value
Title South Creek Flood Study
Publication Date 1 August 2010
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Lake Macquarie City Council
Author/ Prepared by Cardno Lawson Treloar Pty Ltd
Publish date 22 February 2017
Update date 19 October 2017
Place Name Warners Bay
Approval State Approved
Submitted for approval 22 February 2017
Submitted by John Silk
Approved 22 February 2017
Approved by silkj
Data Comment

Legacy data, report only. May have been superseded

Identifier bcee2069-07f0-4cb2-a76b-d33248061c61