Why is the Flood Study being updated and what’s changed?
What about historical floods?
The Allans Creek
catchment has experienced several significant floods over the past decades.
The1998 and 1999 events in particular caused significant disruption and damage to public and private property. The 1998 flood in this area was not as big as a 1% Annual Exceedance Probability (AEP) flood, which explains why residents in some areas mapped as flood affected may not have experienced flooding. A 1% AEP flood is extreme. There is a 1% chance of a flood of this size or larger occurring at a particular location in any given year.
What happens next?
After we’ve completed the flood study, we’ll review the Floodplain Risk Management Study to look at what the risks/damages from floods might be and what we could do to mitigate (reduce) those risks. Next, we’ll review the Floodplain Risk Management Plan, to give us a prioritised plan of flood mitigation measures proposed for the catchment. Then we’ll roll out the Plan! Every 5-10 years, we go back to the beginning of this process and start with a review of the flood study to consider new survey data, policy changes, recent major flood events and changes in the catchment such as flood mitigation works or new development.
What flood mitigation work is Council doing in this catchment?
We’ve purchased nine houses that were identified in the Allans Creek Floodplain Risk Management Study and Plan for Voluntary Purchase, as they were at high risk of serious flooding and not safe to live in. Houses we buy as part of the Voluntary Purchase Scheme are knocked down and the land is turned into parks and open space.
Where can I get information about flood levels on my property?
How does Council manage flood risk?
- Emergency response plans based on detailed understanding of flood behaviour
- Building new structures that collect and carry stormwater into drains or creeks, such as detention basins and swales, or improving existing ones to better manage stormwater and floods
- Land zoning that says what can and can’t be built on flood-prone land
- Voluntary purchase of houses built in high flood risk areas
Why doesn’t Council clear out creeks?
Council is responsible for maintaining watercourses (e.g. creeks, overflow paths or drainpipes) on Council-owned land and has a maintenance program for this. Most watercourses in our city are on private property and their maintenance is the responsibility of the land owner. In these cases, Council is unable to perform any work on the watercourse. If you need advice on maintaining watercourses, please contact our Customer Service team on (02) 4227 7111 or email firstname.lastname@example.org.
Why aren’t you using Australian Rainfall and Runoff 2016 guidelines for this Flood Study?
For the last 30 years, councils have used the national guideline Australian Rainfall and Runoff (ARR) 1987 for flood estimation. A new version was released in 2016, but it uses data that isn't relevant to our region, so we get modelling results that don’t match flood events that have already happened. With our region’s history of floods, we have a responsibility to make sure the data we use is relevant to our area, so that we get reasonable results. We're working to resolve the issues, but until then, we'll continue to use ARR1987, which has been improved and fined-tuned to our area over the last 30 years.
How will my feedback be used?
At the conclusion of the engagement period, all feedback is read and considered. A report will be produced and provided to Councillors, and they will consider whether to adopt the Flood Study.
How can I join the conversation?
- Figtree Community Hall, 11 Princes Highway, Figtree
Wednesday 7 August 4pm - 5:30pm
- Berkeley Community Centre, Winnima Way, Berkeley
Saturday 10 August 10:30am - noon