Hawkesbury-Nepean Valley flood management

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Hawkesbury-Nepean Valley flood management

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EARLY STAGE PROPOSAL
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POTENTIAL INVESTMENT OPTIONS
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INVESTMENT READY PROPOSAL
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PROJECT DELIVERY
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POST COMPLETION REVIEW

Hawkesbury-Nepean Valley flood management

A graphic of the Australian continent with NSW state shaded and small dot representing  Katoomba.
LOCATION
Hawkesbury-Nepean Valley, NSW
GEOGRAPHY
Fast-growing cities
SECTOR
Multiple Sectors
OUTCOME CATEGORY
Adaptation and resilience
PROPONENT
NSW Government
PROBLEM TIMEFRAME
Near term (0-5 years)
DATE ADDED
17 February 2016
Problem

There is increasing flood risk in the highly populated and major growth region of the Hawkesbury-Nepean Valley. Over the long term, the annual average cost of flood damage in the Hawkesbury-Nepean Valley is expected to be in the order of $70 million.

Hawkesbury-Nepean Valley flood management represents a long-term infrastructure resilience challenge. Increasingly frequent extreme weather events, combined with the impacts of population growth in new and more densely populated areas, will likely require an increase in the level of resilience of some infrastructure networks. Infrastructure should be able to continue operating through minor disruptions, and recover quickly from major disruptions.

The largest flood on record in the Hawkesbury-Nepean Valley occurred in 1867, when the river level at Windsor reached 19.2 m above mean sea level, compared to the normal river level, which is less than 0.5 m above mean sea level. If the 1867 flood levels were to occur today, it is estimated that the total tangible damages could exceed$3 billion. If a more extreme event were to occur, the total damages could approach $8 billion (for a 1 in 1,000 year event).

Potential investment options

The Hawkesbury-Nepean Valley Integrated Flood Management Strategy presents a series of proposals and investments to reduce flood risk in the valley. Elements of the strategy being investigated and implemented include:

  • flood mitigation infrastructure, including raising Warragamba Dam
  • road infrastructure upgrades to improve flood evacuation capacity, such as culvert upgrades, new bridges, road raising and widening, and intersection upgrades
  • a community engagement strategy
  • improved governance and accountability to reduce flood risk through the integration of emergency, road and land use planning.
Next Steps

Proponent to develop a business case and submit to Infrastructure Australia (Stage 3 of Infrastructure Australia’s Assessment Framework).

The business case for Warragamba Dam Raising is currently being finalised.

 

Refer to Infrastructure Glossary for terms and definitions.