Whanganui flooding - as seen from space

Photo / NASA

While the floods that swamped Whanganui last weekend appeared devastating enough from pictures taken from helicopters, the view from space has offered another perspective altogether.

The Nasa and USGS operated Landsat 8 satellite, which orbits Earth once every 98 minutes and repeats the same ground track every 16 days, snapped this image of floodwaters pouring out of Whanganui River and into the sea as it passed over New Zealand on Saturday.

A "before" image shows what the landscape looks like in summer.

Dr Murray Ford, a geomorphologist at Auckland University, checked the satellite's latest images and spotted how it had captured the "massive discharge" of sediment from land.

The flooding - the worst on record Whanganui's - forced the evacuation of hundreds of homes and left dozens of people stranded.

Damage assessments were this week still being carried out across the Manawatu and Taranaki regions as the clean-up continued.

Some people will be able to return to their flood-affected Wanganui homes today, Civil Defence Minister Nikki Kaye says.

But there a some city properties that have yet to be assessed while it could be weeks before roading is cleared in remote areas.

Ms Kaye attended a Civil Defence briefing in the city this morning before heading out to Waitotara in South Taranaki.

"Obviously everyone is working hard to balance getting people into their homes with public safety," she said.

The situation in rural areas was becoming clearer by the day.

Roading around the winder region and in Rangitikei in particular have taken a hammering and Ms Kaye estimated 75 per cent of affected rural roads would be cleared within a month.

"Clearing those roads is going to be a real priority to ensure those people get access. But again there are some parts of these roads that are really damaged." Rangitikei District Council have asked rural property owners not to use affected roads for heavy truck haulage.

Wanganui Mayor Annette Main said authorities were staying in touch with those in isolated communities.

"There's hundreds of people in our area who are completely cut off and today we're out visiting every single one of those that we can find, dropping in in helicopters," she said.

"We're also dropping off supplies to a large number of place who have contacted us and said they're running out. "What they need most of all is to actually know that somebody cares, that somebody knows that they're there, that somebody's there to respond if they need anything in the meantime."

Ms Kaye said while residents and volunteers who had not been able to access certain properties were frustrated, it was important a structural assessment was done first.

"It's really tough because they want to get into their house, but if they go in there and there's real public health issues we've got a very serious situation on our hands."

Ms Kaye estimated half those affected in urban Wanganui would be able to return to homes permanently in the next few days.

"That's a really positive development." Meanwhile Ms Main said volunteers had been used outside the cordon to clear public area. "They've been doing a fantastic job, it's been wonderful to see them out there."

- additional reporting NZME News Service staff