Flooding in the Blacktown local government area

1964 Flood at Windsor

Blacktown City has experienced several large floods in the past. The largest flood on record occurred in 1867 and was the equivalent of a 1 in 500 year event.

During heavy rainfall flooding can occur in 2 ways:

  • Mainstream flooding where creeks can overflow, break their banks and flood nearby low-lying areas and properties

  • Local overland flooding where the capacity of stormwater pipes is exceeded and stormwater then flows aboveground following the low areas of the landscape.

The Blacktown local government area is divided into 5 distinct catchments:

  1. South Creek

  2. Eastern Creek

  3. Cattai Creek

  4. Parramatta River

  5. Prospect Reservoir.

As each catchment has different characteristics, the type and scale of flooding that occurs can vary.

South Creek, Eastern Creek and Cattai Creek also make up part of the greater Hawkesbury Nepean floodplain.

Due to the specific characteristics of the Hawkesbury Nepean floodplain, flooding can also occur due to floodwaters ‘backing up’ from a narrowing of the Hawkesbury Nepean river between the Sackville Gorge and the Brooklyn Bridge.

The extent, depth and rate of rise of floodwaters within the Hawkesbury Nepean makes flooding a significant risk to the residents living in the floodplain.

For further information on the Hawkesbury Nepean floodplain, please see the State Emergency Services (SES) – Know your flood risk website https://www.ses.nsw.gov.au/flood-resources/before-a-flood/know-your-risk/.

What is your risk of flooding?

If you live close to a river, creek, major drainage system or in a low-lying area you may be at risk of flooding.

Floods can impact peoples lives in many ways; from being cut off/unable to evacuate for a period of time, to losing access to vital infrastructure (electricity, communications, water and sewer), damage to property and even loss of life.

If you live in a flood prone area it is crucial that you know the potential risks of flooding to prepare your family and property prior to a flood occurring, this includes having plans in place.

Areas such as Riverstone, Schofields, Marsden Park and Shanes Park are in low-lying parts of the catchment and have a high risk of flooding from the Hawkesbury Nepean backwater.

This makes it critically important that we work with the community and other authorities, such as the State Emergency Service (SES) to become better informed and prepared so we know what to do when future floods occur.

How is Council reducing flood risk?

We are an active member of Floodplain Management Australia (FMA) and the Local Government Advisory Group for the Hawkesbury Nepean Valley Flood Risk Management Directorate.

We work closely with the SES to prepare and update flood plans for the Blacktown local government area.

We are regularly reviewing and updating our flood information, studies and risk management plans to have up-to-date information available to our residents and members of the public.

We enforce development controls that include setting minimum floor levels, prescribing flood compatible materials, ensuring new buildings are structurally sound, assessing flood impacts to others from development, and evaluating potential flood evacuation routes.  

Where possible we are upgrading old and undersized drainage networks to increase capacity in larger storm events and reduce local overland flooding.

Our Development Control Plan (DCP) Part J requires all new developments (except low density housing) to provide on-site detention to temporarily store water during storm events and in turn reduce flooding to downstream communities. This is particularly important in older areas where little to no open space is available to retrofit detention basins and other drainage infrastructure.

In addition, we and/or developers construct regional facilities such as detention basins and Water Sensitive Urban Design (WSUD) infrastructure to store and treat stormwater thus reducing flooding downstream and improving the quality of water discharged to our natural creek systems.

Where to find flood information?

To view flooding information, you need to: 

  1. click on the link Maps Online

  2. read and agree to the disclaimer

  3. begin typing in an address in the search bar (top left of screen) and select the correct address from the drop-down menu

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  4.  click the ‘layers’ button (top left of screen) beside the search bar 

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  5. select ‘Flooding Precincts’. Note: If there is no change visible to the flooding extents, then: flooding doesn’t extend into your area of interest or there may be no Flood Planning Controls or there is no flooding information available.  You can obtain additional flood information for a specific property from Council for a fee. Requests can be sent by email to floodadvice@blacktown.nsw.gov.au or  contact us on 9839 6000 for more information 

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 You can view details about your site by selecting the various icons on the right-hand side of your screen:

6. the object icon Object-icon.jpg will give you an overview of the information available for the selected property

7.  the legend icon Legend-icon.jpgwill help you interpret the mapping.  Click the bullet point next to ‘flooding precincts’ heading to see what flooding (if any) applies to your site.

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The flood maps are based on the results of engineering studies commissioned by government authorities and Blacktown City Council.  The maps are currently being reviewed and will be updated upon adoption by Council.

You can also obtain additional flood information for a specific property from Council for a fee. Requests can be sent to floodadvice@blacktown.nsw.gov.au or contact us on 9839 6000 for more information.

Useful Links

State Emergency Services (SES) – Know your flood risk

https://www.ses.nsw.gov.au/flood-resources/before-a-flood/know-your-risk/

Hawkesbury-Nepean Valley Flood Risk Management Strategy

http://www.infrastructure.nsw.gov.au/expert-advice/hawkesbury-nepean-flood-risk-management-strategy/

Floodplain Management Australia (FMA)     

http://www.floods.org.au/