What is public exhibition?

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.

What documents are on public exhibition?

  • Upper Cockle Creek Flood Study Final Draft report, and
  • Upper Cockle Creek Floodplain Risk Management Study and Plan Final Draft report

How long is the exhibition period?

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

How can I provide my feedback during the public exhibition?

1.  Online feedback form

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

3.  Email council@lakemac.nsw.gov.au

Why has Council developed the Upper Cockle Creek Flood Study and Floodplain Risk Management Study and Plan Final Draft reports?

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.

What suburbs are included in the Flood Study area?

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

What is the purpose of the Upper Cockle Creek Flood Study?

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.


What is the purpose of the Upper Cockle Creek Floodplain Risk Management Study and Plan?

The objectives of the Risk Management Study are to identify and compare various management options, including an assessment of their social, economic and environmental impacts, together with opportunities to enhance the floodplain environments.

The floodplain risk management study builds on the flood study to identify a number of measures, which can be used to reduce flood risks in the catchment in the future such as:

  • setting appropriate floor levels for development;
  • identifying works to reduce flooding; and
  • raising community awareness of flooding issues so that they can take necessary precautions.

The floodplain risk management plan assesses the options considered in the risk management study and recommends options for adoption by Council.

The preparation of the Floodplain Risk Management Study and Plan is the final step in the flood management process and once finalised and adopted will guide Council's actions and future planning.


How was the Upper Cockle Creek Floodplain Risk Management Study used in the development of the Plan?

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. 

What are the key considerations and findings of the Upper Cockle Creek Floodplain Risk Management Final Draft Report?

  • 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).

What are the key aspects of the Flood Study and Floodplain Risk Management Study and Plan to be reviewed?

  • 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.

What are the ‘High Priority’ Flood Risk Management measures in the Plan?

  • Review how the risk of electrocution during floods can be further minimised through additional controls, awareness programs or retro fitting of safety measures;
  • Continue with on-going flood awareness programs;
  • Assess the possible implications of mine subsidence in the area for flood related development controls;
  • Ensure optimal flood emergency management;
  • Limit extent of development into the floodplain;
  • Revise Section 10.7 planning certificate notations, flood certificates and flood control lot certificates as required to incorporate revised flood planning levels and a new permanent inundation planning level;
  • Make flood hazard information available on Council's website; and
  • Continue improvements with flood warning systems.

More information on the recommended priority ranking matrix and subsequent ranked priority list can be found in section 1.2.2. Management Matrix, page 6, and section 1.3. Flood Risk Management Measures in Plan on page 10 of the Report.

How were the Flood Study and Floodplain Risk Management Study and Plan undertaken?

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.

How was the feedback from earlier consultation on the project utilised by Council?

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.

What is the effect of lake flooding and sea level rise?

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.

Where can I view a hard copy of the Final Draft Reports?

  • Lake Macquarie Libraries - Speers Point and Edgeworth branches;
  • Council Administration Building, 126-138 Main Road, Speers Point.

Who is invited to give feedback?

  • Residents affected by flooding in areas surrounding Upper Cockle Creek are encouraged to provide feedback. 
  • It is open to anyone who is interested flood management in the study catchment area, or more broadly, Lake Macquarie.

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

Why is community feedback important?

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.

Who can I contact for more information?

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

Phone: 02 4921 0333 or email council@lakemac.nsw.gov.au.

What are the next steps?

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.