Working to reduce flood risk in the Hawkesbury-Nepean Valley
The NSW Government has been working to reduce flood risk in the Hawkesbury-Nepean Valley for many years. The NSW Reconstruction Authority (RA) has delivered a flood focused draft foundation Hawkesbury-Nepean Valley Disaster Adaptation Plan (HNV DAP) to the government. Once this important plan is endorsed it will be released for comment.
DAPs are a recommendation of the State Disaster Mitigation Plan and support action and investment ahead of disasters to reduce the costs and impacts of natural hazards. They align with DAP Guidelines that provide a framework for this locally shaped, regionally coordinated and State facilitated approach to disaster adaptation planning.
The foundation HNV DAP will be shared with community and key stakeholders for feedback in late 2025. Learn more about the HNV DAP.
Stay up to date with progress on the HNV DAP Have Your Say page.
Previous work in the Hawkesbury-Nepean Valley
The HNV DAP builds on previous work in the region. Up to date technical information is critical for community safety, evacuation and emergency management, as well as land use planning and infrastructure investment prioritisation for a diverse and growing population.
The RA’s 2024 Hawkesbury-Nepean River Flood Study (the Flood Study) is a key HNV DAP input. It is one of the most comprehensive flood studies undertaken in Australia and a leading example of best-practice scientific analysis. You can download the Flood Study, including all technical volumes and map books, through the NSW SES Flood Portal. You can also read an overview (PDF 23.91MB) of its development and key findings and find information about flood risk in your suburb on the Hawkesbury-Nepean Valley SES Mapping Tool.
The 2024 Flood Study contemporised the Hawkesbury-Nepean Valley Regional Flood Study 2019.
The Resilient Valley, Resilient Communities – Hawkesbury-Nepean Valley Flood Risk Management Strategy (PDF 5.37MB) (PDF 5.37MB) (Flood Strategy) provided a multi-faceted approach to flood risk reduction including an extensive and award-winning Community Resilience Program. The Flood Strategy was the result of years of investigation into the best ways to reduce impacts of flooding and recommended a regional approach to risk reduction. Learn more about the outcomes of the Flood Strategy.
Understanding risk and supporting preparedness
The NSW Government has conducted flood risk awareness research in the HNV since 2014. This research is used to shape valuable community risk awareness and preparedness campaigns and programs. The most recent round of research was undertaken from November 2024 to February 2025 to contemporise data collected in 2022. It included an in depth phone survey of 800 residents in high-risk areas of the region.
Despite experiencing 8 floods since 2020, research tells us in the past 2 years, the HNV community has become less prepared for damaging floods, less likely to follow official advice, and less aware of risk awareness and preparedness campaigns.
It also tells us many believe recent floods were 1 in 100 chance per year events, when they were around the much lower 1 in 20 chance per year flood height. Floods can be much bigger in the HNV, and the HNV DAP will help communities understand the risk and be better prepared. You can watch this video to learn more about flood chance and the terminology used.
Long history of flooding
History is a vital tool to understand place, as past events help us assess and define present and future risk.
As part of the HNV DAP’s focus on understanding flood risk, the RA is working with the University of Wollongong on a palaeoflood project to find evidence of ancient floods in the catchment.
The Hawkesbury-Nepean River is known to the Dharug Traditional Custodians as Dyarubbin and has been home to Aboriginal people for at least 50,000 years.
The HNV has a long history of flooding interspersed with cycles of drought. Aboriginal oral accounts describe a flood at what is now known as Windsor, in around 1780 that may have exceeded 22.3m above sea level – more than 2 metres higher than the flood of record in 1867. This flood reached 19.7 metres at Windsor, nearly 6 metres higher than the July 2022 flood. In Penrith in 1867, floodwater almost reached the corner of High and Woodriff streets, and much of Emu Plains was under water.
There have been more than 130 moderate to major floods in the HNV since records began in 1790. The March 2021 event was the first major flood since 1990.