N.Z: Stopbank collapses in 300 year flood

A once in "500-year event" hits The Bay of Plenty New Zealand as 2,000 are evacuated to higher ground after floods

the Big Wobble,

6 April, 2017

The evacuation of the Eastern Bay of Plenty town of Edgecumbe is under way in what the mayor is calling a one in "500-year event".

The exact number of people being told to leave their homes for higher ground isn't clear; it could be as many as 2000.

Water is reported to be coming through the local stopbank.

Mayor Tony Bonne is calling it an extremely serious situation and is appealing for people to get out. He says police are going door-to-door while buses are also at the local fire station to get people out. Red Cross is helping with the evacuation and is saying that the roads out are congested.

Welfare centres are being set up in Kawerau and Whakatane. Rotorua woman Deeana Tubb, who has lived in Edgecumbe for two years, said there were no words to describe the situation.

"The rain was pretty constant last night but this morning it was beautiful sunshine.
In a decision I now deeply regret I went to work.

Photo abcnews.go.com

I was halfway to Papamoa when I heard Edgecumbe residents were being evacuated.

I turned around because my children were at home... I went right through the cordons at Matata - nothing was stopping me getting to my babies.

"When I got home the water was already waist-deep in the streets.

I managed to get some valuable documents out of the house and everyone else and we headed to Awakeri.

"Now it looks like we're about to lose everything."

Tubb said she had never seen anything like this before.

"I'm worried sick.

At 8:55 a.m. EST (1255 UTC) on April 5, NASA's Aqua satellite showed Tropical Cyclone 14P contained storms with cloud top temperatures as cold as minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in red, east of the center of circulation. Credits: NASA/NRL

There's really no words, as the panic subsides the shock is setting in.

"The most important thing is that everyone has got out safe...

Now we just need to put one foot in front of another and get through this."

In Wellington, two dozen families living along Wellington's south coast were evacuated just before midnight as the Owhiro Stream in Happy Valley Rd burst it banks.

Meanwhile, flights in and out of the capital were to resume at 6am after the bad weather disrupted the systems.

Scores of roads around the lower North Island have been affected by flooding and slips.

In Whanganui and Rangitikei, where a state of civil emergency is expected to be lifted by midday, 170 people remain evacuated.

However, the Whanganui River is no longer expected to flood.

Further north, the country is swinging into clean-up mode and Waikato Civil Defence last night downgraded its activation to monitoring mode.

However, police are still searching for a man believed missing in the swollen Waikato River. MetService says the worst of the weather should now be over for the North Island, but not the South Island where wind and gale warnings remain in force.

Extreme weather a taste of climate effects

Radio NZ,

6 April, 2017

This week's extreme weather is just a small taste of things to come as the intensity of storms increases because of climate change, a scientist says.

Waikato slips around State Highway 22. Photo: Waikato District Council

Victoria University climate scientist Professor James Renwick said heavy rain events like cyclone Debbie and last month's 'Tasman tempest', which brought flooding in Auckland, had a clear human footprint.

The risk of seeing such storms was increasing as time went on, he said.

"It's not as though every time there's a storm it's going to be like this, or that there's going to be torrential rain every month, but it's pushing the odds," Professor Renwick said.

When there was a storm, it was more likely to bring heavier rain than it would without climate change, he said.

Professor Renwick compared pumping greenhouse gases like carbon dioxide into the atmosphere to putting on a warm blanket.

"What's underneath the blanket - i.e. us down at the surface of the earth - is warmer than it would be otherwise. More of the heat that is radiating up from the earth's surface gets intercepted [by greenhouse gases] in the atmosphere and is radiated back down again - exactly the way a thicker duvet works on a bed."

This leads to warmer oceans, which means more evaporation, increasing the amount of moisture in the air.

More moisture in the air meant more rainfall. "You can't avoid it really," Professor Renwick said.

With every degree the atmosphere warms, the amount of moisture the air can absorb increases exponentially - by about seven percent. More warmth means exponentially more wet.

NIWA climate data from last month noted that parts of Auckland, Waikato and the Bay of Plenty had rainfall at more than 300 percent higher than normal.

Whangaparaoa, north of Auckland, received March rainfall of 354mm - nearly five times the normal March total rainfall. Most areas of New Zealand have between 600 and 1600mm of rainfall, spread throughout the year, NIWA said.

The heavy rain dubbed the "Tasman Tempest" caused havoc across Auckland, flooding houses and causing slips and power outages.

It is not just intense storms that we are likely to see as a result of climate change.

Rural fire team research leader at Scion Research, Dr Tara Strand, told RNZ [http://www.radionz.co.nz/news/national/324681/climate-increasing-future-risk-of-big-wildfires-rural-fire-expert climate change would contribute to heightened fire risk in the future, similar to the size and scale of Christchurch's Port Hills fires in February.

"The combination of climate, vegetation change and people ... [means] we are likely to see this type of fire behaviour increase throughout the drier parts of New Zealand," Dr Strand said.

New Zealand's maritime environment had "buffered" the country from extreme fire seen in other continents such as Australia and America, Dr Strand said.

Extreme fire would increase here if the climate trend continued.

NIWA said wind changes are also possible with climate change and the frequency of winds of 108 km/h could double by 2080. An increase of westerly winds of about 10 percent by 2040 and 20 percent by 2090 is also possible and in the winter this increase could be greater.

Sea level rise will continue for several centuries even if greenhouse gas emissions are reduced - the prediction for New Zealand is an increase of 18 to 59cm between 1990 and 2100.

The projected increase in westerly wind could also influence the ocean waves. In particular coastal regions exposed to prevailing winds could see an increase in the frequency of heavy swells that would add to effects of higher sea levels.

I
t's predicted that snowlines will rise, the duration of the snow season will decrease and glaciers will continue to melt. Drought risk for areas prone to dryness will likely increase in the next century.

Read more on this topic here.