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Dozen of houses in Nelson have been damaged by flooding and slips caused by heavy rain the region, with more homes evacuated this afternoon.
Roads and footpaths near the Matai River - which runs through Nelson - have eroded away, with the river breaching its banks in a number of places.
Newstalk ZB reporter Tyler Adams said many houses close to the river in the centre of town had been damaged.
"A lot of people out there, their houses have just been tipped in to the river and as the day goes on we hear more about evacuations. We have an area called The Wood, which is just two minutes out of the CBD, about 40-50 residents have been evacuated out of their houses there. A lot of those houses have just crumbled on the surface that they're on."
Incident commander Steve Caldwell confirmed residents were being evacuated from Grove Street.
"There's all sorts of rumblings going on at the back and we're not taking any chance at all, so people have been asked to leave their houses and they're being very co-operative with us,'' he says.
Mr Adams did not know exactly how many houses had been severely damaged by flooding and slips, but expected it to number at least 50.
"At this stage I've personally seen at least two dozen, just in the CBD. I've seen pictures from Golden Bay, Liger Bay, there are massive slips taking out 10 houses at a time.
"A lot of people in Nelson know someone who has been affected, they know someone who has had part of their house pulled away by slips or damaged by floods. It has damaged a large part of Nelson town, and as far as I know it has damaged a large part of Golden Bay.
"Other rivers around the region, as far as I know, are holding steady. A couple of rivers in Takaka and Golden Bay came close (to breaching their banks), they did start receding and they've just remained steady again.
Mr Adams said despite Civil Defence warnings yesterday, people did not expect the rain to be as bad.
"I don't think anyone expected it to be this severe. I don't think there was a feeling it would be this torrential."
Many who were travelling in Abel Tasman National Park are stranded as the wild weather lashing the top of the south has destroyed many of the access tracks.
Eleven campers had to be evacuated from a camp site in the park last night due to flood waters, and there's currently no access to Totaranui campground.
DOC Nelson Marlborough Communications advisor Trish Grant says they can get people out if they are concerned.
"One thing we have done is we've commissioned an Abel Tasman sea shuttle boat to evacuate people from coastal areas of Abel Tasman National Park so people have been able to leave there today if they wish to,'' she says.
Heavy rain heads north
The heavy rain is expected to ease in the Nelson region this afternoon, but rain is forecast to get heavier for Marlborough and the top half of the North Island.
A state of emergency remains in place for the Nelson region this morning after heavy rain which fell last night and is continuing to swamp the area.
More than 100 people had to be evacuated from their homes overnight, as swollen rivers and landslides cut off roads and towns, and heavy rains flooded homes.
MetService has a severe weather warning in place for Nelson, Marlborough, Taranaki, Northland, Coromandel Peninsula, Bay Of Plenty, Rotorua, Taupo, Taihape, Taumarunui and Auckland.
From 9am to 3pm today, another 50-100mm of rainfall is expected about the Nelson Ranges, with 30-60mm forecast for the rest of the Nelson region.
Significant rain has already fallen in parts of Marlborough, Taranaki and Northland and high amounts are also expected in the north of Auckland, Coromandel Peninsula, Bay of Plenty and Tongariro National Park from this morning through to this evening, and may continue in the east of the Bay of Plenty and Tongariro until the early hours of tomorrow.
Rain has eased in Westland and Buller and the warnings there have been lifted.
Crisis Management Centre activated
Civil Defence said rain has continued overnight in the Tasman region, although at a slower rate.
More than 500mm has fallen near Takaka in the past 48 hours.
The National Crisis Management Centre at Parliament has been activated, according to Civil Defence.
The Nelson and Tasman region had almost two months' worth of rain fall yesterday.
In the 24 hours to 3am, 423mm has fallen at Takaka, 368mm at Anatoki, 329mm at Brook, 205mm at Richmond and 323mm at Roding. The Civil Defence said these totals were "well in excess" of a one in 100 year event.
A fire service spokesman said crews had attended more than 120 call-outs in the Tasman area.
"The nature of incidents we attended ranged from public assistance, evacuations, water pumping, transfer, and reassurance.
"We are currently on our way to a report of people who have become stuck in an apartment building in the Wakefield area due to a landslide."
More than 60 landslides have been reported across the Nelson region. Collingwood is inaccessible, as SH60 is closed past Takaka. Several other roads across the region are also closed, however SH6 remains open.
Last night a dam collapsed above Polari Gully in Golden Bay, stranding 24 people who were rescued by volunteers.
Earlier in the day, two tourists had to climb a tree to evade raging flood waters, a motorist had a lucky escape when a huge rock hit his vehicle, and filming of The Hobbit was moved out of Nelson.
Two tourists - a German man in his 20s and his Canadian companion - were rescued from a tree they climbed to escape the surging Maitai River.
Nelson Search and Rescue volunteer Noah Hosie said the two were uninjured, but "a bit cold".
Their ordeal should be taken as a warning of the dangers of rivers during heavy rain.
"There's no point going in the water, you never know what's underneath," he said.
"There's roots and logs and all sorts of things which can be dangerous."
A motorist narrowly escaped being sent plunging into the sea when his car was hit by a falling rock.
Lawyer Rick Farr watched as a rock "half the size of a car" slammed into the side of the four-wheel-drive metres ahead of him.
Its driver was "extremely lucky" not to have been pushed into the sea or crushed by the debris, Mr Farr said.
"There was an explosion from the side of the hill and suddenly we could see very large boulders heading towards us.
"It was a split second and stuff came right at this guy's truck and slammed into the side of him and then stopped ...he's the luckiest man alive."
The driver appeared unhurt.
The heavy downpour also caused the filming of The Hobbit to be cut short by a couple of days.
Production company 3 Foot 7 publicist Ceris Price said the rain made it impossible to continue.
"We've been really blessed for the last two months because we've had absolutely wonderful weather, but this has just been such a shame," she said.
Ms Price said they had shot almost everything they needed for the film and a decision would be made next year on whether they would would return to film at Canaan Downs.
More rain to come
MetService meteorologist Daniel Corbett said the rain was a one-in-20-year event but it could be upgraded to a once-in-100-years flood overnight.
At Nelson Airport, 123mm of rain fell in 24 hours, but hills and mountains in the area got up to 259mm.
Mr Corbett said the hills could get more than 400mm of rain before the weather system moved north later today.
Up to 10 roads were closed in the Nelson Tasman region because of the floods and the local Civil Defence kept a close eye on bridges in case they too needed to be shut.
"It's just a pipeline of rain coming in from the Tasman," Mr Corbett said. "Instead of the weather going straight through, it's just piling in - almost like somebody with a strong garden hose continuing to spray it on the area."
The weather system was slowly making its way over the North Island late last night and early this morning.
"So it'll be a very wet day for the North Island [today] ... the big band of heavy rain just sits over the North Island and will take most of the day to clear away."
The weekend would be quite wet, but with much less rain than yesterday and today.
Heavy band of rain over much of the North Island. Weather warnings issued.
The rain continues but weather starts to move away from New Zealand.
Showers continue over the North Island.