'Generous' cash boost for SA flood victims

South Australia has unveiled a $51.6 million assistance package for property owners and businesses hit by flooding along the Murray River.

And the state government has vowed to "err on the side of generosity" with its financial help.

The money will fund levee construction and repairs, support tourism and other businesses, and provide assistance to homeowners.

It includes $9.3 million for levee works, $4.8 million for sandbags and other defences, rental assistance for families, up to $20,000 grants for businesses forced to close, and grants to buy generators for properties set to lose power.

The government has also set aside $1 million for mental health support, $3 million for vouchers to encourage tourists to continue to visit the region, and $10 million for infrastructure repairs, including roads.

Individuals will be able to apply for $400 personal hardships grants, with families to receive $1000.

Premier Peter Malinauskas, who took his cabinet to the Riverland on Tuesday to meet local officials, said the government and the people of SA were ready to respond to the challenge.

"We see this as a very substantial package that may end up being the first," he said.

"We need to be flexible as a government to respond to the needs as they change over the weeks and months ahead.

"We face the real possibility of a protracted event where we have high river flows going right into the early months of next year, potentially even into autumn."

Treasurer Stephen Mullighan said the government was not concerned about the impact on the state budget.

"We're trying to give the Riverland communities what they need," he said.

"We are trying to err on the side of generosity. We've carefully tailored this package to ensure money gets to where it is most needed, and fast."

Local Liberal MP Tim Whetstone welcomed the government's help with the floods, something not witnessed in SA for half a century.

"The Riverland is a tough, strong and united community. We are all working together to weather this storm," he said.

"It is a slow-moving beast and it's coming our way."

Business SA chief executive Andrew Kay said the scope of the government's response reflected the urgency of the situation.

"When emergency situations like this happen, the business community needs support that is simple to obtain and readily accessible for a broad range of operators," he said.

The floods have been declared a major emergency, with forecasts of two distinct peaks in water flows.

The latest information suggests flows will rise to about 175 gigalitres a day by early December and could go higher towards the end of the month and into January.

The second peak has been influenced by the most recent rains interstate in critical catchment areas and the release of water from the Hume Dam.

Flow forecasts for the second peak should be available on Thursday.

The declaration of a major emergency gives Police Commissioner Grant Stevens wider powers to respond and better co-ordinate relief efforts.

He can direct resources and infrastructure, evacuate locations and direct what utilities are cut off.

It also ensures all the economic, social and environmental impacts are properly considered.

Meanwhile, former senior police officer Alex Zimmerman has been appointed the community response and recovery co-ordinator to pull together the recovery efforts.

The flooding is set to impact thousands of shacks, homes and businesses, with at least 4000 properties likely to be inundated.

Renmark is considered the town most at risk. Work has been under way for several weeks to shore up the town's levees, which were designed to withstand river flows of 210GL a day.

However, concerns are rising for Mannum, east of Adelaide, where work will be done to strengthen levees amid fears parts of the town could be flooded.