Lake Wollumboola Flood Study

Lake Wollumboola Flood Study

A flood study is currently being prepared for Lake Wollumboola.  Shoalhaven City Council has appointed WMAwater to undertake this Study.

Community Workshop Presentation

On the evening of Thursday 7 August 2014, Council held a community workshop at the Culburra Beach Community Centre to discuss the progress of the study and to receive feedback from the community on the flood modelling results.  The workshop was attended by over 30 Culburra Beach residents.

Consultants WMAwater provided a 30 minute presentation which was followed by questions and discussion with Council staff and the consultants from those in attendance.  A copy of the presentation slides can be downloaded here.

A video can be viewed here.

The Floodplain Management Process

The State Government's Flood Policy aims to reduce the impacts of flooding and flood liability on individual owners and occupiers, and to reduce private and public losses resulting from flooding.  Under the Policy, local government is responsible for managing flood liable land.

The Policy encourages the development of solutions to existing flood problems in developed areas, and strategies for ensuring that new development:

  • is compatible with the flood hazard, and
  • does not create additional flooding problems in existing developed areas.

The State Government's Flood Policy provides for technical and financial support for a number of floodplain management activities. Funding for this study was provided from the State Government's Flood Risk Management Program and Shoalhaven City Council.

What's Happening Now?

The Flood Study aims to understand and determine the nature and extent of potential flooding in Lake Wollumboola and the town of Culburra.  The first stage of the Flood Study will collect, compile and review all available information, including valuable community knowledge and experiences.

As part of the study, computer models will be established to determine the extent and nature of flooding around Lake Wollumboola and in Culburra.  In order to determine the accurancy of such models, historical data such as observations and photos of flooding behaviour from the public are required.

Study Area

Lake Wollumboola is situated just north of Jervis Bay with the town of Culburra on its northern shoreline. The catchment has an area of approximately 4027 hectares and is the largest shallow lagoon on the NSW South Coast.

Approximately 50% of its catchment, the bed of the lake to 0.86m AHD and its entrance barrier beach are within the Jervis Bay National Park.  The remaining makeup of the catchment includes State Forest, some distributed areas for grazing, some forested areas in private ownership and the urban areas of Culburra.

Lake Wollumboola is an ICOLL, and the below photo shows the lake closed to the ocean.  The entrance to the lake is actively managed by the National Parks and Wildlife Service.  The trigger level for manual opening of the lake entrance is a lake level of 2.75m AHD.

What is an ICOLL?

Many coastal lakes and lagoons alternate between being open or closed to the ocean.  These are known as Intermittently Closed and Open Lakes and Lagoons (ICOLLs).  About 70 of the coastal lakes and lagoons in NSW are ICOLLs.

ICOLLs are located all along the NSW coast.  Most occur south of Sydney where catchments are generally smaller in size and experience lower average rainfall than the north coast.  Average wave activity is also generally high, pushing sand into the estuary mouth.

ICOLLs are separated from the ocean by a sand beach barrier or berm.  This entrance barrier forms and breaks down depending of the movement and redistribution of sand and sediments by waves, tides, flood flows and winds.  The barrier will sometimes open naturally to the ocean when there are major freshwater inflows from rain in the local catchment.

For further information regarding this project please contact:
Matthew Apolo
P: (02) 4429 3354
F: (02) 4422 1816

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