FAQs

Interative map

The main change is an updated Flood Planning Area. This affects which flood controls apply to a development application, the minimum floor level for new buildings, and the flood information shown on a section 10.7 planning certificate. It does not change flood risk on the ground. Overall, 422 fewer properties are identified as flood affected.

The 2021 study used a coarse modelling method and was always intended as an interim study. To allow for its lower accuracy, Council doubled the freeboard applied to land it mapped, which raised floor levels and limited development on urban lots. The draft study replaces it with a detailed flood model built on 2024 LiDAR survey and checked against the 2007 and 2015 floods.

It is the land covered by the 1% AEP flood plus freeboard, which is a safety margin of 0.3 m for overland flow paths and 0.5 m for major flow paths and waterways. Land in the Flood Planning Area is subject to the flood controls in Council's Development Control Plan.

The Flood Planning Area is a planning tool, not a record of past floods. It is based on a 1% AEP flood, which has a 1 in 100 chance of occurring in any year, or roughly a 1 in 2 chance over the life of a house. Many residents will not have seen one. Freeboard is then added on top. It is deliberately conservative so that new buildings are built to a safe level.

Overland flow paths are the low points and natural drainage lines across the landscape. They are dry almost all the time and only carry water in large storms, when runoff is more than the pipes and gutters can take. The new survey and model pick these up in far more detail than the 2021 study.

There are two reasons, both required by current national guidance (Australian Rainfall and Runoff 2019). Design rainfall has been increased by 11 to 18% to reflect climate conditions, and the way rainfall is distributed through a storm has been updated. Neither reflects a change to the catchment itself.

Better survey data, a more detailed model, and a lot-by-lot review that removed properties with only minor or isolated flooding, obvious errors in the ground data, or flooding contained within the road reserve.

No. Land in the Flood Planning Area can still be developed. The Flood Planning Area sets the controls that apply, mainly minimum floor levels, and in some cases a flood impact assessment.

The Insurance industry uses their own risk assessment processes and their own data modelling from a variety of sources. Flood insurance terms, conditions and premiums are set by the insurance industry. 

Council has no control or influence over flood insurance products or premiums. Floodplain Risk Management Studies and Plans are part of Council's responsibilities to help manage flood risk and the impact of flooding on people and property.

1,022 properties are identified as flood affected for the first time. This exhibition gives owners the chance to check the mapping against what they know of their property and raise any concerns before the study is finalised.

We are asking property owners to view the draft flood mapping and check how it represents their property.

If you believe the mapping does not accurately show how water behaves on your property during heavy rain, we would like to hear from you. To allow us to investigate, submissions should include photographs or video showing the flooding, or lack of flooding, at the location in question. Where possible, please include the date the photos were taken and mark the location on a map or describe it clearly.

Submissions will be reviewed, and the mapping will be corrected where the evidence shows it is needed.

After exhibition closes, all submissions will be reviewed and reported back to Council with any proposed changes before the study is adopted. A separate amendment to the Development Control Plan will then be made to remove the doubled freeboard and refer to the new study. The new mapping will only be applied to section 10.7 planning certificates after adoption.