Why is the Floodplain Risk Management Study and Plan being reviewed?

    We make computer models and maps that show where it could flood and by how much. From time to time, these models are reviewed and predicted levels may change. The reasons why can include:

    • New floods occur, providing additional data to fine-tune the model.
    • More advanced computer models or methods for estimating flood levels become available.
    • Changes in the catchment, such as flood mitigation works or new developments.
    • Changes in policy.

    After we update flood models, we also need to update our understanding of what the risks/damages from floods might be. We then need to update our plan for mitigating (reducing) these. This is what a floodplain risk management study and plan does. It has a prioritised plan of recommended measures to best address existing and future flood problems in the catchment. It also includes guidelines for all future developments in the area. 

    What are the recommended measures for the Towradgi Creek Catchment?

    Upgrade structure (DM06 on the map)
    There are some stormwater pipes under Lake Parade at Parker Creek that could be replaced by either a box culvert or a bridge. A culvert is a tunnel or drain structure built under the road to allow water to flow underneath. This photo shows an example of what a box culvert can look like:

    The image on the left shows the location of the proposed culvert (pink line) and on the right is where the proposed bridge would go (red lines):

    Upgrading this structure would:

    • Allow water to pass more easily under Lake Parade. 
    • Reduce the backwatering along Parker Creek.
    • Lower flood levels north of Lake Parade for frequent storms.
    • Increase road safety during frequent storms for an important access road (Corrimal Beach Tourist Park).
    • May improve water quality.

    To build these structures, the creek may need to be dredged to remove the build-up of silt. A box culvert or bridge would take up more space in this area than the existing pipes do. 

    Widening of the Towradgi Lagoon entrance (CM02)
    The community has previously suggested returning the Towradgi Creek outlet to its historic / original location. Training walls were built on either side of the entrance in the 1980s. This option proposes widening the entrance by moving the existing northern wall 20m north. This would return the alignment closer to where it was originally. In this image, the green line shows where the existing wall is. The blue line in this aerial photo (overhead, looking down) shows where the proposed replacement wall would go:  

    This aerial photo shows you the historic / original location of the lagoon entrance in 1977:

    This aerial photo shows you the location of the lagoon entrance in 2021:

    This option would help to reduce flood impacts, e.g. property damage, up to Pioneer Road and through the Parker Creek area. It would involve digging out a large section of the lagoon entrance and have impacts on dune and native vegetation. 

    Installing “debris control structures” (DCS)
    There are 2 locations on the map with red dots where we are considering installing these structures. These would be installed near existing stormwater drains and inlets that help stop debris (branches, rocks, rubbish etc.) from blocking them. These photos show you examples of these types of structures: 

    If each of these options (DM06, CM02 and DCS) are supported, we would need to do a more detailed investigation, concept design, then detailed design for each and seek a number of approvals before we could go ahead with the work. We’d also seek further community input on the design and construction of each option. 

    Additional option - build an overland flow path at the bank and shops in Corrimal town centre (CM01)
    Overland flow happens when a lot of rain and water runs across the land. These are natural paths where water flows along and into stormwater drains or local creeks after running off neighbouring properties and driveways. Any structures in the way of overland flow can be damaged or flooded. For this option, a building on the Princes Highway would be removed to create an overland flow path between Bertram Lane and Princes Highway. It would help channel stormwater away from the shops and into stormwater drains. There would be a minor increase to flood levels downstream and to the east of the property on public land. This option has a low benefit-cost-ratio (overall value for money) but is somewhat beneficial to the community. It could go ahead if there is enough funding, and community and political will.

    Other options
    Other options recommended to help manage flood risk in this catchment include:

    • Improving flood warnings.
    • Controls to make sure new developments don’t increase flood impacts. 
    • Improving emergency management. 

    Where can I get information about flood levels on my property?

    We have historical flood level records and/or our completed flood studies for some properties, but not all. Please contact our Customer Service team on (02) 4227 7111 to find out what’s available for your property.

    What happens next?

    After we’ve completed the Floodplain Risk Management Study and Plan, more work will be done to develop concepts and detailed designs for the recommended stormwater structures. We’ll take these out to the community to seek further input before the designs are completed.

    How will my feedback be used?

    At the end of the engagement period, we read and consider all feedback. We write a report about the engagement and what we heard. It is provided to the project team and Northern Floodplain Committee for consideration in making a decision.

    How can I join the conversation?

    • Online  www.our.wollongong.nsw.gov.au                           
    • Email    engagement@wollongong.nsw.gov.au                                
    • Write    Locked Bag 8821, Wollongong DC 2500                
    • Phone   (02) 4227 7111                                      
    • Drop-in Information Session (no presentation)
      When: Wednesday 2 November 2022 - drop in anytime between 3:30-6:30pm
      Where: Towradgi Surf Club Function Room - 1 Murranar Road, Towradgi    

    If you’re d/Deaf or have a hearing or speech impairment, you can contact us through the National Relay Service. If you need an interpreter, you can contact us through the Translating and Interpreting Service on 131450. You’ll need to provide our phone number 02 4227 7111 for either service.