Sylvie Claire / Mars 21, 2021

The Australian city of Sydney was bracing Sunday for the worst flooding in decades after record rainfall caused a dam to overflow and led to mass evacuations. Other cities also affected include Taree and Windsor

Emergency services have ordered residents in low-lying areas of parts of the city to take shelter due to a potentially life-threatening situation in New South Wales

The Warragamba Dam, which supplies much of Sydney's drinking water, overflowed Saturday afternoon, and flooding of a level not seen since 1961 is expected in the Hawkesbury River downstream, authorities said.

This is one of the biggest floods we're likely to see in a very long time, said Bureau of Meteorological Services official Justin Robinson.

Evacuations are underway

Numerous evacuations have already taken place as a result of the rising waters and some 4,000 more people may be asked to leave their homes in the coming days.

hose in flood-prone areas must leave immediately, insisted state Deputy Emergency Services Commissioner Dean Storey. Many evacuees began gathering Saturday at centers north of the city as torrential rains pounded the area.

State Premier Gladys Berejiklian was alarmed by a once-in-a-century event and called it a national disaster.

The bad weather is expected to intensify again on Monday north of Sydney before improving later in the week, according to the weather service. Conditions are still going to be dangerous said climate expert Agata Imielska, predicting more record rainfall in the coming days.

Emergency services have received more than 7,000 calls for help and have conducted 650 rescue operations since Thursday. They had to call in reinforcements from other states.

Australia is set to start the first major phase of its flu shot campaign for the public on Monday. Flooding could create delays in the Sydney area.