Why is the Flood Study being updated and what’s changed?
The main purpose of a flood study is to describe flood behaviour and identify areas that are flood prone. We use computer flood models to estimate where it might flood, and by how much. From time to time, the models are updated and predicted flood levels may change. For the Towradgi Creek Flood Study, we’ve considered Council's revised Blockage Policy, which helps us work out how blocked stormwater structures might affect flooding. We have improved information, such as recent data from land surveying. We've included an extended network of drainage pits and pipes and used more improved and detailed modelling techniques. The updated Blockage Policy generally gives us lower flood levels upstream of main culverts. A culvert is a tunnel or drain structure built under a road or railway to allow water to flow underneath. The maps in the report show what the flood levels are in different areas in the catchment. You can view the report in the Document Library, at the drop-in information session or at Corrimal Library.
What about historical floods?
The Towradgi Creek catchment has experienced several
significant floods over the past decades. The1998 event 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 and rare. There is a 1%
chance of a flood of this size or larger occurring at a particular location in
any given year.
Do the maps in the draft report show the flood levels for my property?
There are hundreds of properties in this catchment. The scale of these maps makes it hard to find individual properties and see what the estimated flood levels might be. Sometimes you can get a better look by opening the maps on a computer and zooming in to the area where your property is, however you’re just looking at the estimated levels for broad areas of the catchment rather than specific levels for individual properties. The report is also a draft, which means some information may be updated before the Study is finalised.
Where can I get information about flood levels on my property?
Council has 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 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 four houses that were identified in the Towradgi 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 Voluntary Purchase are knocked down and the land is turned into parks and open space.
We’ve done weed control, maintenance of creek banks and planting at various locations along Council-owned portions of creeks throughout the catchment.
We've installed a debris control structure and completed channel works immediately upstream of the Memorial Drive culverts near Railway St.
We’ve replaced the Colgong Crescent footbridge with a new elevated footbridge.
We’ve done channel realignment, construction of floodwalls and a debris control structure on North Corrimal Creek, Lemrac Ave, Corrimal.
We’ve done flood mitigation works in Bellambi St, Justine Ave and Cheryl Place, Tarrawanna.
How does Council manage flood risk?
Each year, Council spends millions of dollars on stormwater and floodplain management. Our team of flood experts prepare flood studies and floodplain risk management studies that help us understand the flood behaviour for a particular catchment and see if there are any ways of reducing flooding risk in an area.
Floodplain risk management studies include a plan of potential solutions aimed at reducing the existing and future flood risk. Examples of these solutions include:
- 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.
How will my feedback be used?
At the end 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?