Floodplain management

Floodplain management

Managing floods in the local area

Floodplain management plans for the City of Sydney local area have been developed and adopted by Council. The plans include flood mitigation measures and what can be done to help affected areas.

Under the NSW Government's flood prone land policy the City is required to manage flooding issues and put plans into place to safeguard flood-prone areas.

The local area has been divided into 8 catchments covering 2,666ha.

You can also click an area of the map below to show further information for each catchment.

Due to high urbanisation since the 19th century across the local area there are not many natural creeks or open surface water bodies in the catchment areas to accommodate stormwater.

Generally, stormwater from frequent minor storm events is managed by conventional pits and pipe systems. In less frequent, but major rainfall events, stormwater in excess of the conventional systems travels along low gradients of the catchments, ultimately draining into Sydney Harbour and Botany Bay.

The combination of steep and flat terrain, high density residential, commercial and industrial areas has made areas susceptible to flash flooding. Being aware of the potential for flooding and knowing how to respond will make flood events more manageable.

We are progressively introducing the floodplain management plans, in the final stage of the floodplain risk management process, as outlined in the NSW Government's flood prone land policy.

Floodplain risk management measures

There are 35 structural and 14 non-structural flood mitigation measures across the local area that were recommended in the relevant floodplain management plans. The priority ranges from low to high for implementing the mitigation measures over the short to long-term period.

In 2016, the total estimated cost to undertake the recommended mitigation works in the local area is $363m. The works will require collaboration between the City and state government agencies such as Sydney Water and NSW State Emergency Services.

We are now undertaking the following works with Sydney Water:

Interim floodplain management policy

Council endorsed its interim floodplain management policy in May 2014.

The policy is a responsible and forward-thinking approach to manage flooding issues, which will ensure development in the city is not at undue risk of flood and that proposals do not increase flood risk for existing properties.

Flood models

We have an extensive suite of flood models that were developed to prepare the flood studies.

You can make a formal request to access the flood models for a small fee and subject to a data sharing agreement.

Links

NSW Government: Floodplain Development ManualNSW State Emergency Service FloodSafeBureau of Meteorology: NSW weather and warnings summary

Local flooding history

Since 1910, the City of Sydney's local area has experienced 35 floods classified as serious, severe or minor. In 13 cases, high rainfall resulted in localised flooding. During this period 4 floods were classified extreme in November 1984, March 1975, January 1973 and August 1971.

Floods can occur at any time and in the future could be bigger than any previously recorded event.

Past flood events

DateAverage time between floods of this size
January 193810–20 years
September 194320 years
June 19495 years
January 19555–10 years
November 196110–20 years
August 197120–50 years
January 197320–50 years
February 197310 years
March 1975Greater than 1 in 100 years
November 1984Greater than 1 in 200 years
January 19915–20 years
April 199810 years
February 20011 year

High rainfall storm events

Note: Rainfall levels recorded at Centennial Park, Randwick Bowling Club and Randwick Racecourse since 1888, which caused minor flooding throughout the city.

DateRainfall (mm)
January 1933189
February 1956192
February 1958185
February 1959265
November 1961270
May 1962258
March 1975261
August 1975221
October 1975205
March 1978237
November 1984240
April 1988193
February 1992294

Last updated: Friday, 21 February 2020