Sydney March 21: The Australian government has declared a natural disaster in New South Wales after heavy rains caused flooding in rivers and a dam and thousands had to evacuate. The NSW and the federal government have signed 16 natural disaster declarations in areas spanning the central and mid-north coast, from Hunter Valley near Sydney to Coff's Harbour, said NSW Emergency Services Minister David Elliott in a news conference on Sunday, as reported by CNN.

Areas evacuated include Pitt Town North, Pitt Town Bottoms, low-lying parts of North Richmond, Freemans Reach lowlands, the northern end of Agnes Bank, Gronos Point, and Cornwallis. Residents of Cornwallis and Pitt Town North bordering Hawkesbury River found themselves at risk of being cut off and were urged to evacuate as soon as possible.

"If floodwaters reach 8.19m on the Windsor gauge, escape routes will be cut and as floodwaters rise, the area will flood. If you remain in the area, you may become trapped without power, water, and other essential services and it may be too dangerous for NSW SES to rescue you," SES said in an evacuation warning issued on their website," as reported by Sputnik. Australia's Most Populous State Hit by Severe Rains, Floods.

An evacuation centre has been set up at the Richmond Club for those who are unable to stay with friends and family. A number of roads and bridges have already been closed due to flooding. Over 100mm of rain fell overnight and more is expected to come throughout this day.

The Bureau of Meteorology (BOM) issued a flood warning for Gloucester and Manning Rivers, which are further up north from Sydney. This flood is one of the biggest since 1964, BOM says.

"It is one of the biggest floods we are likely to see for a very long time," National Flood Service Manager at BOM Justin Robinson told CNN. Millions across the state are urged to stay at home as BOM warns the weather situation will stay "volatile, dangerous and dynamic". According to SES Deputy Commissioner Daniel Austin, the emergency service saw 1,940 calls for help since last night.