A second peak in the Murray River runs through South Australia and is now expected to reach 185 gigalitres per day in late December.
The latest modeling has river flows reaching 175 GL per day early next month, ahead of a period when the river stabilizes.
However, the second peak will now reach Christmas after recent interstate rains and the release of water from Hume Dam.
Prime Minister Peter Malinauskas said to put that into perspective, the flows would be close to the total amount of water consumed by all South Australians over a full year.
“We now face the prospect of it crossing the border every day,” he said on Thursday.
“It’s a lot of water. It presents a lot of challenges.”
The Murray’s flood is expected to be the worst since the 1970s, with more than 4,000 properties including cabins, homes and businesses likely to be flooded.
Some of the most at-risk areas include Renmark, near the Victorian border, and Mannum, east Adelaide, where a seawall may be built across the high street, potentially blocking some homes and shops on the wrong side of the barrier .
Earlier this week, the state government unveiled a $51.6 million relief package for homeowners affected by rising waters.
The money will fund the construction and repair of dykes, support tourism and other businesses, and provide assistance to homeowners.
It includes $9.3 million for seawall works, $4.8 million for sandbags and other defenses, rent assistance for families, grants of up to $20,000 for hard-pressed businesses to close and grants to purchase generators for properties that will lose power.
The government has also earmarked $1 million for mental health support, $3 million for vouchers to encourage tourists to continue visiting the area, and $10 million for infrastructure repairs, including roads.
Individuals will be able to apply for personal hardship grants of $400, with families receiving $1,000.
South Australia will take delivery of 4km of flood barriers from Italy on Thursday and expects a further 400,000 sandbags to arrive in the coming days.
State Emergency Services Chief Chris Beattie said it was important for river communities to act now.
He said all people should know their level of risk and, if they are likely to be flooded, plan when to leave.
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