Hawkesbury-Nepean Valley Flood Risk Management

A long-term plan to reduce flood risk in the most flood exposed region in New South Wales, the Hawkesbury-Nepean Valley.

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New campaign launched by RA and SES

A 3d render of a simulated flood event around a house

NSW SES and the RA have launched a thought-provoking new campaign to improve understanding of flood risk and increase community preparedness. The Future Flood campaign shares the stories of 4 real Hawkesbury-Nepean Valley residents who chose not to follow evacuation warnings in recent flood events. They are among an alarming 70% of people who think it’s safe to stay at home during a flood. Using flood simulations to show their homes underwater, the residents say they’ll think differently about what they would do in a future flood. See the video

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New information on flood risk in the Valley

The Reconstruction Authority (RA) recently completed the 2024 Hawkesbury-Nepean River Flood Study, one of the most comprehensive flood studies undertaken in Australia.

The Hawkesbury-Nepean Valley (the Valley) is an incredibly complex floodplain with one of the highest flood risks in Australia. Up-to-date technical information is critical for community safety, evacuation and emergency management, as well as land use planning and infrastructure investment prioritisation.

Subject to 2 independent reviews and including 12 technical reports, the Study is a leading example of best-practice scientific analysis. The RA used new technology to model how water moves through the Valley and provide high resolution flood level, depth and velocity data to better understand flood risk. More than 20,000 different scenarios were analysed, and the work was informed by and tested against recent flood events in the Valley.

The Study is considered the most up-to-date and reliable source of flood information for the Hawkesbury-Nepean River and should be used to inform all flood-related decision making from June 2024.

You can download the Study, including all technical volumes and map books, through the NSW SES Flood Portal. You can also read an overview (PDF 4.22MB) of the Flood Study’s development and key findings and find more information about flood risk through the Hawkesbury-Nepean floods SES Mapping Tool.

The new Study will inform the Disaster Adaptation Plan currently being developed by the RA to address flood risk in the Valley.

Prioritised Hawkesbury-Nepean Valley Disaster Adaptation Plan

The RA has already started developing a high-priority regional DAP to address flood risk in the Hawkesbury-Nepean Valley (the Valley).

The Valley is one of the most dangerous floodplains in Australia, flooding 6 times between 2020-2022. Every flood is different – past events can’t predict future events – and floods in the Valley can be more frequent and get much worse.

The Hawkesbury-Nepean Valley DAP is the first of its kind in NSW and builds on many years of work to understand the impact of floods and how to reduce risk to life and property. It is being developed throughout 2024 in partnership with community, councils, government agencies, emergency services and technical specialists.

Some options being investigated for the DAP include mitigation infrastructure, such as levees, improvements to evacuation roads and ways to better prepare the community.

Community input is vital to the success of the DAP. If you live or work in the Valley, visit our Have Your Say page to share your thoughts, ideas and experience with floods to help shape the DAP, and complete a short survey.

Previous work in the Valley

The Hawkesbury-Nepean Valley (the valley) covers from Bents Basin, near Wallacia, to the Brooklyn Bridge. The valley has the highest flood exposure in NSW because of its unique landscape and large existing population. Floods in the valley can be deep and extensive, and can have a significant impact on people’s lives, livelihoods and homes.

In 2017 the Resilient Valley, Resilient Communities – Hawkesbury-Nepean Valley Flood Risk Management Strategy (PDF 5.37MB) (Flood Strategy) was released. The Flood Strategy is the result of years of investigation into the best ways to reduce impacts of flooding in the valley. It uses a regional approach as floods from the river system cover a wide area, with impacts felt in 10 local council areas.

In July 2023, the Hawkesbury-Nepean Flood Risk Management transitioned from INSW to the NSW Reconstruction Authority (RA). The RA will improve how NSW plans for disasters and make sure communities across the state recover from them faster.

The RA is developing a high-priority regional Disaster Adaptation Plan (DAP) to address flood risk in the Hawkesbury-Nepean Valley which builds on the 2017 Flood Strategy. The DAP will be developed throughout 2024 and include a suite of integrated measures to reduce the impact of floods.

Why Hawkesbury-Nepean floods are so dangerous

Key publications

For more information, read publications and frequently asked questions.

Flood Strategy

There is no simple solution to managing or reducing the valley’s high flood risk (PDF 229.09KB). The NSW Government continues to deliver the Flood Strategy program, together with local councils, businesses and the community, while the DAP is being developed.

The program is aligned with the State Emergency Management Plan and the National strategy for disaster resilience (PDF 4.02MB).

These strategies are the state and national standard for managing the risks of natural disasters. Emergency management in Australia is built on the emergency management cycle which has four elements: prevention, preparation, response and recovery (PPRR).

Flood Strategy outcomes	Activities
1. Regional, coordinated flood risk management Lead: NSW Reconstruction Authority	Coordination and oversight of the Flood Strategy program, and coordination of flood risk management responsibilities at a regional level. NSW Reconstruction Authority has a dedicated directorate that includes flood risk and evacuation specialists, GIS mapping analysts, and community engagement and resilience specialists.
2. Infrastructure measures to reduce flood risk Lead: WaterNSW	A range of infrastructure measures have been investigated to reduce flood risk. The Warragamba Dam raising proposal was investigated and is not proceeding. Please visit WaterNSW or the Department of Planning and Environment to find out more.
3. Strategic and integrated land use and road planning Lead: NSW Department of Planning and Environment, Transport for NSW	A Regional Land Use Planning Framework is being developed to establish a new land use and settlement strategy for the valley. This will help to address the significant flood risk in the valley, in alignment with approaches being developed for evacuation road planning. Read some frequently asked questions about land use planning.
4. Contemporary flood risk information Lead: NSW Reconstruction Authority	A new Hawkesbury Nepean Valley Regional Flood Study was completed in 2019 using the latest data and science available and a sound scientific approach. Read the Flood Study Overview (PDF 3.48MB). Further work is underway to increase understanding of flood behaviour using latest information including recent floods from 2020, 2021 and 2022.
5. An aware, prepared and responsive community Lead: NSW Reconstruction Authority, NSW State Emergency Service and Transport for NSW	An extensive Community Resilience Program aims to increase flood awareness and preparedness. This includes programs for: young people in schools with both primary and secondary school teaching and learning resources available. View school resources. broad community awareness campaigns and resources, including a new flood mapping tool, videos and other resources. View flood preparation resources. broad community preparedness campaigns, including content for the CALD community and animal owners. Visit NSW SES Get Ready Animals and receive in language material. a communities of concern program with targeted partnerships addressing the most vulnerable, including those with animals. new flood evacuation signage across the floodplain. Read an overview of the Community Resilience Program (PDF 8.18MB) or watch the Community Resilience Program showcase video.
6. Improved weather and flood predictions Lead: Bureau of Meteorology	The Hawkesbury-Nepean Advanced Flood Forecasting pilot project has developed new rainfall and flood forecasting tools which will provide better information about the timing, behaviour and heights of floods. This will help emergency services to understand and respond to floods which, in turn, helps the community to respond to flood alerts and warnings.
7. Best practice emergency response and recovery Lead: NSW State Emergency Service and NSW Reconstruction Authority	Emergency response and recovery agencies work together to maintain, test and enhance capability in the floodplain. In 2019, a series of exercises was delivered across the emergency management sector to test and improve coordination of response to and recovery from a major flood in the valley. The Hawkesbury-Nepean Flood Plan continues to be updated to take account of contemporary flood risk information including recent flood events in 2020 and 2021.
8. Adequate local roads for evacuation Lead: Transport for NSW	The Flood Strategy identified the need to deliver a resilience roads package to maintain and upgrade local evacuation roads to ensure access to major regional evacuation routes. Local flood modelling and technical assessments were undertaken to identify and prioritise appropriate road upgrades for the package. A strategic-level business case has been developed for NSW Government consideration.
9. Ongoing monitoring and evaluation, reporting and improvement of the Flood Strategy Lead: NSW Reconstruction Authority	A framework has been developed and is being implemented to monitor, evaluate, review and improve the Flood Strategy program over time. Key considerations include potential changes to community profiles and preparedness, urban development, road evacuation capacity, climate change and experience from flood events. View the interim evaluation report (PDF 898.16KB).

Flood Strategy outcomes

Activities

1. Regional, coordinated flood risk management

Lead: NSW Reconstruction Authority

Coordination and oversight of the Flood Strategy program, and coordination of flood risk management responsibilities at a regional level. NSW Reconstruction Authority has a dedicated directorate that includes flood risk and evacuation specialists, GIS mapping analysts, and community engagement and resilience specialists.

2. Infrastructure measures to reduce flood risk

Lead: WaterNSW

A range of infrastructure measures have been investigated to reduce flood risk. The Warragamba Dam raising proposal was investigated and is not proceeding. Please visit WaterNSW or the Department of Planning and Environment to find out more.

3. Strategic and integrated land use and road planning

Lead: NSW Department of Planning and Environment, Transport for NSW

A Regional Land Use Planning Framework is being developed to establish a new land use and settlement strategy for the valley. This will help to address the significant flood risk in the valley, in alignment with approaches being developed for evacuation road planning. Read some frequently asked questions about land use planning.

4. Contemporary flood risk information

Lead: NSW Reconstruction Authority

A new Hawkesbury Nepean Valley Regional Flood Study was completed in 2019 using the latest data and science available and a sound scientific approach. Read the Flood Study Overview (PDF 3.48MB).

Further work is underway to increase understanding of flood behaviour using latest information including recent floods from 2020, 2021 and 2022.

5. An aware, prepared and responsive community

Lead: NSW Reconstruction Authority, NSW State Emergency Service and Transport for NSW

An extensive Community Resilience Program aims to increase flood awareness and preparedness. This includes programs for:

young people in schools with both primary and secondary school teaching and learning resources available. View school resources.
broad community awareness campaigns and resources, including a new flood mapping tool, videos and other resources. View flood preparation resources.
broad community preparedness campaigns, including content for the CALD community and animal owners. Visit NSW SES Get Ready Animals and receive in language material.
a communities of concern program with targeted partnerships addressing the most vulnerable, including those with animals.
new flood evacuation signage across the floodplain.

Read an overview of the Community Resilience Program (PDF 8.18MB) or watch the Community Resilience Program showcase video.

6. Improved weather and flood predictions

Lead: Bureau of Meteorology

The Hawkesbury-Nepean Advanced Flood Forecasting pilot project has developed new rainfall and flood forecasting tools which will provide better information about the timing, behaviour and heights of floods. This will help emergency services to understand and respond to floods which, in turn, helps the community to respond to flood alerts and warnings.

7. Best practice emergency response and recovery

Lead: NSW State Emergency Service and NSW Reconstruction Authority

Emergency response and recovery agencies work together to maintain, test and enhance capability in the floodplain. In 2019, a series of exercises was delivered across the emergency management sector to test and improve coordination of response to and recovery from a major flood in the valley.

The Hawkesbury-Nepean Flood Plan continues to be updated to take account of contemporary flood risk information including recent flood events in 2020 and 2021.

8. Adequate local roads for evacuation

Lead: Transport for NSW

The Flood Strategy identified the need to deliver a resilience roads package to maintain and upgrade local evacuation roads to ensure access to major regional evacuation routes. Local flood modelling and technical assessments were undertaken to identify and prioritise appropriate road upgrades for the package. A strategic-level business case has been developed for NSW Government consideration.

9. Ongoing monitoring and evaluation, reporting and improvement of the Flood Strategy

Lead: NSW Reconstruction Authority

A framework has been developed and is being implemented to monitor, evaluate, review and improve the Flood Strategy program over time. Key considerations include potential changes to community profiles and preparedness, urban development, road evacuation capacity, climate change and experience from flood events. View the interim evaluation report (PDF 898.16KB).

Read the Flood Strategy (PDF 5.37MB) and frequently asked questions (PDF 198.31KB) (FAQs) about the Flood Strategy.