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Rain, rain go away: Sydney’s flooding emergency explained

Where to avoid, why it's happening, and what to expect in the coming days

Written by
Maxim Boon

It won’t have escaped your notice that Sydney is a little damp at the moment. In fact, it’s literally waterlogged. Due to the influence of a particularly powerful La Niña, Sydney has had one of its wettest summers in a decade, but the torrential deluges that have drenched the city in recent days have been described by experts as a “once-in-50-year emergency”. Major flooding has hit many low-lying regions and in particular the northwest of Sydney, which last experienced such significant flooding back in 1961.

What’s the current situation?

Floodwaters are expected to reach record levels in Windsor, Pitt Town, North Richmond, Freemans Reach and Colo. Evacuation orders are now in place in Penrith, parts of Jamisontown and Mulgoa, and along the Nepean River, and more communities along the Hawkesbury are also likely to be evacuated, as floodwaters are expected to peak at a record-setting 15 metres, disrupting power and utilities to certain areas of North West Sydney. Torrential rain is set to continue until at least Wednesday 24 March, and while the forecast is set to improve later in the week, floodwaters may remain high for several more days after the rains subside.

At the time of publishing this story, 38 areas of NSW had been officially declared natural disaster areas by the state government, meaning people living in those areas will be eligible for financial support. In her media briefing on March 22, premier Gladys Berejiklian acknowledged that many of the worst affected communities were also on the frontline of the 2019 bushfire disaster, which was followed in short order by the national shutdown orders of 2020. "When you have been through three or four incidents that are life-changing on top of each other, it can make you feel like you are a breaking point," she said. 

Where should I avoid?

Areas around the Nepean River, including Penrith, Parramatta and the lower Blue Mountains, and the Hawkesbury River, including Richmond, Windsor and parts of the Hunter, are currently the most at risk. Travel to these areas and the Central Coast should be avoided until further notice. Authorities are urging Sydneysiders not to underestimate the risks. NSW emergency services minister David Elliott said on March 21, “Motorists in the state need to know that we are statistically moving closer and closer to an inevitable fatality. We cannot say it enough: do not put yourself in danger. Do not endanger the agencies that are there to assist you… This is the wrong time of year to be taking any risks.” This is still a developing situation, so other areas may be named as evacuation zones in the coming days.

Why is Sydney flooding?

While you might picture Sydney as a place of sun, sand and sparkling harbour waters, the city’s geography makes it extremely susceptible to flooding when there’s excessive rain. The nation’s largest metropolis occupies a natural basin, surrounded by three major rivers: the Georges, Nepean and Hawkesbury. This trio of rivers, which all interconnect, funnel water towards the Harbour and the ocean beyond it, but when such colossal volumes of rain inundate Sydney’s waterways for such a sustained amount of time, the flood plains around these rivers and the Harbour estuaries act like bathtubs, funneling water from chokepoints in places like Windsor, Emu Plains and Wallacia. Once the rain subsides, it takes time for the backed-up water to flow into the Harbour, so even after the rains stop, areas can remain saturated for several days. With the La Niña set to deliver yet more wet weather for many more months (the last major La Niña in 2010 lasted more than two years), flooding could become far more common in Sydney.

Confused about our wild weather? Read our deep dive into why Australia has had such a soggy summer.

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