FAQ

The Council endorses the public exhibition of draft plans and reports to give our community an opportunity to provide feedback before the documents are finalised and adopted by the elected Council.

The exhibition period runs from Saturday 2 March until Saturday 13 April a total of 42 Days.

1.  Online feedback form

2.  Send written submissions to: CEO, Lake Macquarie City Council, Box 1906, Hunter Regional Mail Centre NSW 2310

3.  Email [email protected]. 

Lake Macquarie City Council is committed to building more flood resilient communities across the City.

Under NSW planning laws, councils are responsible for managing local flood planning. Council has prepared a comprehensive Flood Study and Risk Management Study and Plan for the Upper Cockle Creek catchment, which defines the nature of flood risk in the area and provides recommendations for more effective flood management.

This recent flood management assessment updates the previous 1986 Cockle Creek Flood Study, 1993 Cockle Creek Floodplain Risk Management Study and 2004 Cockle Creek Floodplain Risk Management Plan.

The study area includes Edgeworth, Cameron Park, West Wallsend, Barnsley, Holmesville, Glendale and Killingworth.

The Upper Cockle Creek Flood Study determines the nature and extent of the potential flood problem.  Calibrated computer modelling was used to determine flood levels, flows and velocities based on the available design rainfall and streamflow data.

Maps have been produced indicating the peak water depths, contours, velocities, hazard and hydraulic classification for the full range of design flood events, namely:

• 50% AEP event (2 Year ARI)
• 20% AEP event (5 Year ARI)
• 10% AEP event (10 Year ARI)
• 5% AEP event (20 Year ARI)
• 2% AEP event (50 Year ARI)
• 1% AEP event (100 Year ARI)
• 0.5% AEP event (200 Year ARI)
• Probable Maximum Flood (PMF)

Note:

AEP = Annual Exceedance Probability - the chance of a flood of a given or larger size occurring in any one year, usually expressed as a percentage.

ARI = Annual Recurrence Interval - the long-term average number of years between the occurrence of a flood as big as, or larger than, the selected event.

The Floodplain Risk Management Study identified and assessed the flood management options available, potential economic or ecological costs and potential impacts of flooding on local properties.

The Floodplain Risk Management Plan was developed based on the investigations and outcomes of the Study. 

• Historical flood records, started in the 1930’s, show that flooding has periodically occurred in the urban areas of the catchment in response to heavy rainfall. This has resulted in inundation of urban lands and occasionally of building floors.

• Flooding within the Cockle Creek and tributary catchments occurs following heavy rainfall where flood flows in excess of channel capacities results in overbank flooding. Within the lower reaches of Cockle Creek, flooding may also be influenced by high water levels in Lake Macquarie waterway.

• Since the February 1981 flood event there have been changes to the building outlines on the floodplain (extensions to existing houses, new houses) as well as other significant developments on the floodplain (construction of retarding basins, the M1 motorway, expansion of mining activity and creation of residential subdivisions).

• The most significant change has been in the suburb of Cameron Park, which has changed from a largely heavily forested area to predominantly low-density residential development. To compensate for the increased runoff due to the residential development, approximately 20 retarding basins have been constructed.

• There are 229 properties affected by a 1% AEP (Annual Exceedance Probability) flood event with 92 of these properties considered to be in the high hazard category (Refer to Table 5 of the risk management report and Attachment 3).

• Up to 146 building floors in the catchment may be inundated by a 1% AEP flood event (Refer to table 12 of the risk management report and Attachment 4).

• The predicted flood extent (shown in the Flood Study Final Draft Report) matches the community’s experience of flooding in the area;
• The accuracy and appropriateness of the priority ranking matrix; and
• The accuracy and appropriateness of the recommended ranked priority list of actions, of high, medium and low priority.

Council engaged specialist consultant WMAwater Pty Ltd to undertake a flood study and prepare a comprehensive floodplain risk management study and plan for the Upper Cockle Creek catchment and its tributaries.

During stage one of the Flood Study, residents provided Council with their personal experiences of flooding such as photographs, flood marks and recorded observations. This information, along with data on rainfall, past flooding, topography and development within the catchment was used to prepare a sophisticated computer model to predict potential flood hazards within the study area.

This process identified local concerns and values and helped Council understand how floods happen in the catchment.

From your feedback, we have a greater understanding of the flood behaviour in the Upper Cockle Creek catchment and have used this information to inform the Upper Cockle Creek Flood Study and Floodplain Risk Management Study and Plan Final Draft Report.

Impacts of climate change upon flood levels for the rainfall increase scenarios are shown in Table 23 of the report for the 1% AEP flood event. The effects of elevated water levels in Lake Macquarie waterway due to sea level rise have been evaluated in the 2017 Winding Creek and Lower Cockle Floodplain Risk Management Study and indicate that this will not increase flood levels within the Upper Cockle Creek study area.

Further details are provided in Section 8 - Climate Change and Assessment Of AR&R 2016 on page 54 of the Flood Study Final Draft Report.

Community input into Council strategies and plans during public exhibition periods helps to ensure they meet the needs of all aspects of Lake Macquarie community and all views are considered.

Greg Jones, Council's Senior Sustainability Officer (Natural Disaster Management)

Phone: 02 4921 0333 or email [email protected].

Feedback on the Upper Cockle Creek Flood Study and Floodplain Risk Management Study and Plan Final Draft Reports will be reported and appropriately incorporated into the final draft submitted to Council for endorsement. Once endorsed, Council Officers will implement the Plan.