For months, towns along the Murray River in north-west Victoria have prepared for eventual flooding and evacuations.
Unlike the sudden inundations experienced in coastal areas, the Murray River floodwaters have risen slowly over the course of several weeks.
Time is on the side of emergency authorities, who are able to plan evacuations and alter the way the water flows with levees, but those who choose to stay in their homes could be trapped by floodwater into 2023.
Flooding at Mildura is expected to reach its peak by the weekend.
The river height will reach 38.3 metres at the Mildura Weir — 113 millimetres higher than the historical 1974 floods, but much lower than in 1956.
There is no real way of knowing when the water will start to recede from impacted businesses and homes, but emergency authorities are prepared for when it does.
State Emergency Service incident controller for Mildura Mark Cattell said the picture would become clearer once the water arrived.
"The issue we have is we don't know when the water will stop going into [the Murray]," he said.
"There's still water coming in from the Edwards River, so we won't know until all the water arrives."
'Long haul' for stayers
Evacuation orders have been issued for several Murray River towns during the flooding event, but those who decide to stay in their homes could be facing months of isolation.
The town of Moulamein on the New South Wales side of the Murray River is set to evacuate, with floodwater isolating the town and closing major roads. In Northern Victoria, Kerang was trapped by water in September.
"If they decide not to evacuate and their house is going to be inundated, they need to be prepared to be there for the long haul," Mr Cattell said.
"If the water does get up it could push septic back into your toilet or into your house … for three or two months. It's something they really need to consider.
"They need to make sure they have enough medication, water, an ability to keep food and water fresh, they also might need generators but we don't want people running those in houses."
Why does it take so long?
Ron Dudley is a former engineer and an expert in Murray River hydraulics and said the length of the Murray meant it took time for it to move through the system and subside.
"The Murray is [around 2,500 kilometres] long or more and it takes a long time to clear, the grades are flatter and rain that occurs around Albury takes about a month to reach Mildura," Mr Dudley said.
"In the old language the river gradient is three or four inches to the mile [7.5cm or 10cm to 1.6km], and it takes a long time to get away.
"It is very difficult to track peaks because there are so many tributaries that go into the Murray, there’s the best part of half a dozen in Victoria and probably a similar amount in New South Wales.
"It’s totally dependent on rainfall, if there is a heavy downpour on one of the catchment areas then that's going to end up in the Murray, and if a peak has already been through then it is going to result in another peak."
