If you live or work in the Hawkesbury-Nepean Valley you are at risk of flood

Your home, your family and your animals may be vulnerable when it floods.

Understanding risk

The risk in the valley

It’s a fact that floods in the Hawkesbury-Nepean can be some of the most dangerous in Australia.

The flood mapping tool above shows you the flood risk for different suburbs in the valley. If a flood similar to the largest flood on record happened in the valley now, more than 90,000 people would need to be evacuated and more than 12,000 homes would be impacted by floodwaters.

The information below will help you understand why floods are so dangerous here, the impacts of past floods, and importantly how to understand the meaning of risk and likelihood when it comes to flooding.

First you need to understand your flood risk, then take the next steps to prepare for floods now.

Why floods in the valley are so dangerous

View this video to understand why floods are so deep and dangerous in the Hawkesbury-Nepean Valley.

Learn how the ‘bathtub effect’ causes floodwaters to back-up and cause deep and dangerous flooding.

It will flood again

The Hawkesbury-Nepean Valley has a long history of damaging and dangerous floods.

Five of the 10 largest floods since the record flood of 1867 have occurred since Warragamba Dam was completed in 1960. The last major flood was in 1990.

View remarkable footage of the impacts of these significant floods.

Help understanding flood risk

Floods are often described in terms of the chance that floods of a certain size might occur.

It’s helpful to think about the likelihood of flooding as the chance a particular flood will happen in an 80-year lifetime. The graphic below helps explains this concept of a flood’s likelihood and relates it to other common ways of describing floods. 

Image explaining the flood likelihood percentages