Fairy & Cabbage Tree Creeks Catchment Flood Study

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Consultation has concluded

As part of our commitment to managing flood and stormwater in our region, we’re working on a flood study for the Fairy & Cabbage Tree Creeks catchment. The updated Study explains the ways flooding happens in the Fairy & Cabbage Tree Creeks catchment, which covers an area between Towradgi and the southern end of Wollongong.

We’re sharing the draft Study with the community during the public exhibition from 6 April to 11 May 2020.

In line with NSW Health guidelines about Novel Coronavirus, we’ve made some changes to the way we’re engaging the community, to keep our staff and people in our community safe. Instead of having face-to-face conversations with people, we’re offering the following opportunities to learn more about the flood study and ask questions of the floodplain engineers who are working on it:

On this wepbage, you can

In addition, you can email engagement@wollongong.nsw.gov.au to book in a time to speak to a flood engineer about the Study via phone or Skype.

Following our conversations with the community, the Fairy & Cabbage Tree Creeks Flood Study will go to Council for adoption. After that, we can start working on a Floodplain Risk Management Study that looks at what the risks and damages from floods might be, and what we could do to mitigate (reduce) those risks. We’ll again be inviting the community to contribute to that process when the time comes.

Feedback closes on 11 May 2020.

As part of our commitment to managing flood and stormwater in our region, we’re working on a flood study for the Fairy & Cabbage Tree Creeks catchment. The updated Study explains the ways flooding happens in the Fairy & Cabbage Tree Creeks catchment, which covers an area between Towradgi and the southern end of Wollongong.

We’re sharing the draft Study with the community during the public exhibition from 6 April to 11 May 2020.

In line with NSW Health guidelines about Novel Coronavirus, we’ve made some changes to the way we’re engaging the community, to keep our staff and people in our community safe. Instead of having face-to-face conversations with people, we’re offering the following opportunities to learn more about the flood study and ask questions of the floodplain engineers who are working on it:

On this wepbage, you can

In addition, you can email engagement@wollongong.nsw.gov.au to book in a time to speak to a flood engineer about the Study via phone or Skype.

Following our conversations with the community, the Fairy & Cabbage Tree Creeks Flood Study will go to Council for adoption. After that, we can start working on a Floodplain Risk Management Study that looks at what the risks and damages from floods might be, and what we could do to mitigate (reduce) those risks. We’ll again be inviting the community to contribute to that process when the time comes.

Feedback closes on 11 May 2020.

CLOSED: This discussion has concluded.

Please submit your questions about the flood study and we'll get back to you shortly with a response.

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    Is it possible to have pedestrian and cycling access along the side of these creeks? Creeks usually provide pleasant green space for people to walk. Also, could we have paths that follow these two creeks under the major roads? An example of this is the Minnamurra bike path which follows the Minnamurra River. It also passes under a major road.

    Sian Morgan asked 6 months ago

    The intent of a flood study is to describe flood behaviour and identify areas that are flood prone. This work helps to inform the next stage of our flood risk management process, where we look at what the risks/damages from floods might be and what we could do to mitigate (reduce) those risks. 

    Council has a number of strategies and plans that inform where our cycleways and shared paths are built, the main one being the Bike Plan 2014-2018, which we will soon be asking people in our community to help us refresh – keep an eye out for the public exhibition of the Cycling Strategy 2030. These are developed with input from people in our community, which helps us to prioritise the areas where cycleways are most needed. 

    There are existing plans along the Fairy Creek corridor, and we may consider others in the future, although they are a relatively low priority given they are not regionally significant like the project noted at Minnamurra which forms part of the NSW Coastline cycleway.

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    Have any properties that have previously been declared flood prone now been removed from that classification after this new study? If the answer is yes how do we find out which properties they are?

    Balgownie asked 7 months ago

    Any changes to the flood coding of a property will be formalised after Council adopts the draft Study. Council will notify property owners of any changes via mail. 

    The Section 10.7 Planning Certificates will also be updated following Council adoption. You can apply for a Section 10.7 Certificate through Council's website

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    How do we get information regarding any changes in flood modelling to our individual owned properties?

    Balgownie asked 7 months ago

    The draft Fairy and Cabbage Tree Creeks Flood Study mapped the difference of 1% AEP event peak flood level between the current study and the previous study. Please refer to Figure 25-1 and Figure 25-2 of the Draft Fairy and Cabbage Tree Creeks Flood Study Volume 2 Part 3

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    There seems to be a significant increase in areas that were reported as previously dry now wet, and increased flood height areas shown in Figure 25-1 and Figure 25-2. These changes predominantly occur in places with no validation against 1998 flood levels. How have these changes been validated against actual 1%AEP flood data? Have validation points included in the previous study been omitted, and if so, what is their justification for exclusion? What is the expected confidence in results? For instance, is a flood level of 0.15m statistically significant given it would appear a tolerance of +/- 0.3m against measured points appears to be considered a valid prediction?

    ValidationAndConfidence asked 7 months ago

    The main reason there is a big increase in areas previously dry, now wet is that the 2D hydraulic model area has been increased significantly. This area was previously only modelled in a hydrologic model which only provides flow, rather than a depth and velocity. The changes are largely in the upper catchments, where there is less model validation data.

    All the validation points from the previous study were available and have been considered in the latest flood study.

    We are confident this study represents the best available flood information for the entire catchment. There are always challenges with LIDAR and historic flood marks and that is why we report error bounds for this kind of data. We are confident the model is well calibrated and we have confidence in the design flood levels. At a lot scale, data such as detailed site survey may increase the confidence for an a flood level.

    For more details, please refer to Model Calibration included in the Draft Fairy and Cabbage Tree Creeks Flood Study Volume 1