Warragamba Dam risks overflow as bomb cyclone batters New South Wales, Australia

The Warragamba Dam in New South Wales (NSW) is at risk of overflowing as heavy rainfall associated with a bomb cyclone batters the east coast of Australia, triggering severe flooding.

Parts of NSW had received over 200 mm (8 inches) of rainfall by Wednesday morning, while many locations from Sydney to the south coast experienced destructive winds of 100 km/h (62 mph).

The Bureau of Meteorology (BOM) recorded 224 mm (8.82 inches) of rainfall in Ulladulla, just north of Burrill Lake, in the 24 hours to 09:00 local time (LT) on Wednesday.

According to Water NSW, the Warragamba Dam reached 98 % capacity on Wednesday and is expected to overflow sometime during the night. As Sydney’s primary water source and Australia’s largest urban water supply, an overflow could cause major flooding in surrounding areas, worsening the ongoing floods.

The strong winds and flooding caused widespread damage across New South Wales, downing power lines, trees, and flooding multiple homes and businesses.

Electricity distributor Ausgrid reported that power had been restored to 30 000 customers, while approximately 9 100 customers remained without electricity as of Wednesday morning. Major roads remain closed, and ferry and train services continue to face delays and suspensions.

The BOM expects a “second surge” of low pressure on Wednesday night, bringing additional rain and wind to the south coast of New South Wales and eastern parts of Victoria.

“Another 50–100 mm (2–4 inches) is quite likely today and tonight,” said BoM senior meteorologist Dean Narramore. “That’s on top of the 100–200 mm (4–8 inches) already recorded, particularly in parts of New South Wales.”

While heavy rain warnings have expired for most areas, the NSW State Emergency Service has issued flood warnings for parts of Greater Sydney, with Advice-level alerts currently active for Camden, Penrith, and North Richmond.

Areas near the Victorian border may also be affected today as the intense coastal low moves south, with damaging conditions expected to continue through Wednesday.

The storms have also caused significant travel disruptions, with Qantas Airways and Virgin Australia, Australia’s biggest airlines, having cancelled at least 55 domestic flights in and out of Sydney on Wednesday, the airport’s website showed. Some international flights have also been delayed.

Rishav Kothari

Rishav Kothari is Editor-in-Chief of The Watchers, where he runs the newsroom and covers earthquakes, volcanoes, severe weather and space weather.

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