Prime Minister Scott Morrison will visit flood-impacted areas of northern NSW on Wednesday but he's unlikely to get a warm welcome, Barnaby Joyce says.

After finishing a week in COVID-19 isolation, Mr Morrison will travel to Lismore, one of the areas hardest hit by the devastating floods, where thousands of homes and businesses have been destroyed.

The prime minister is expected to announce more funding to help rebuild communities impacted by the floods, with a focus on long-term reconstruction projects.

However, the deputy prime minister said Mr Morrison probably won't receive a warm welcome from locals during his visit.

"People are incredibly vulnerable, and it's understandable that they want to express that and the pain that they're going through," Mr Joyce told Sky News.

"I would be incredibly surprised if people got a happy reception, because they're not in a happy place, and they want to be heard."

Residents in Lismore and surrounding areas have criticised the government's handling of the crisis, calling the response too slow to help deal with the clean-up efforts.

There are 1800 ADF personnel on the ground in northern NSW assisting flood recovery efforts, with that number set to grow to 2500 by the end of the day.

Brigadier Robert Lording, who is on the ground in Lismore on Wednesday, told Sydney radio station 2GB that figure would increase to 4000 by week's end.

"The scale of this incident has been far bigger than anything we've potentially experienced in this area before," he said.

"It's a large logistics effort to get people up here, and importantly, it's a big logistics effort for us to get the money here and to be able to support them."

Mr Joyce said residents in flood-affected areas had not been let down by the government response or ADF rollout.

"It was an incredible circumstance ... we're fully aware, to be quite frank, I wanted to make sure that this is the time where people need to be heard the most, as the floodwaters go down," he said.

"I fully expect people to be incredibly upset and incredibly under pressure, that they would be tormented about what the future holds."

Opposition emergency management spokesman Murray Watt said residents in northern NSW had felt abandoned.

"If ... community members hadn't stepped up, then we would have been seeing a death toll in the hundreds of people," Senator Watt told ABC Radio.

"While people are grateful for the assistance they've had from the army, there's just nowhere near enough of it."

Senator Watt has urged the government to declare a national emergency for the flooding event, which would allow for the Commonwealth to deploy more resources and ADF support to impacted regions.

Agriculture Minister David Littleproud said the response to the natural disaster could always be better.

"No disaster is the same, as I found from the bushfires and then into floods and into cyclones, but there's long-established protocols in whereby the states lead the process," he said.

"We stand ready, the defence force is there, and we need to make sure they're utilised the proper way and they don't get in the road."

There have been issues with physically getting ADF personnel into areas where access was limited or non-existent due to floodwaters and intense weather conditions.

As of Tuesday morning, more than $282 million in disaster payments to flood victims have been paid to 242,000 people.

Of that, $157 million has been paid to victims in NSW and $125 million in Queensland.

© AAP 2022