Is your home in a most at-risk suburb?

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By Corazon Miller, Ben Hill

Heavy storms, rainwater run-off and low-lying land pose a flood risk to about 16,000 properties in the Auckland region.

A fortnight ago Auckland was hit with not one but three weather bombs which flooded hundreds of properties caused damage in the hundreds and thousands of dollars.

Auckland Council data given to the Herald showed the region has 52,000 properties sitting in a flood plain - of these 8000 faced the risk of buildings flooding above the ground level in the case of an extreme weather event.

Including properties located outside the flood plains the data indicated 3.2 per cent of the region's properties; 16,000 homes, commercial or industrial buildings were exposed to a flood risk - but around half were due to rainwater flows on the ground.

Property analysis site Relab provided the Herald its breakdown of the 1636 homes in Auckland it found to be at a higher risk of flooding - those where water flowed directly through the property or that were sitting well below the neighbourhood's average altitude.

Henderson had the most homes at risk, 157, followed by Remuera, 131, Pakuranga Heights, 125 and Milford 123.

New Lynn, where some of the worst flooding was experienced in this month's stormy weather, had 79 homes at risk.

Residents on Dover Place in Remuera aren't concerned about their properties flooding, despite being included in a list of homes at a higher risk.

Of the 14 properties on Dover Place, five are at risk of flooding, according to Relab's breakdown.

The street slopes down towards the banks of the Orakei Basin, and residents spoken to by the Herald said they weren't worried about flooding.

One resident, who wished to remain anonymous, said he "hadn't had any issues".

"We've lived here about seven years. We get runoff with the long driveway but there's floodgates on the basin, we've never really had a problem."

He said his house was unscathed by the recent foul weather which lashed Auckland, but a friend was staying with him after his house in New Lynn flooded.

"What agitates some residents is that the creek bed has slowly been gathering silt. There's a lot of run off and it all ends up in the creek."

Another resident, who also declined to be named, said he has had "no issues" and is "not worried".

"We had no problems, even with the bad weather the other weekend.

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"We made adjustments and put in more drainage when we were doing some renovations to the driveway, but that was just as a precaution only."

In the aftermath of this month's storm trio residents expressed frustration the city's infrastructure seemed ill-equipped to cope with floods.

Flooding at properties inMalvern Rd, Mt Albert, Auckland.
Flooding at properties inMalvern Rd, Mt Albert, Auckland.

Auckland Council flood planning manager Nick Brown said the weather was an extreme event - on average across the urban area there was 200mm of rainfall - the largest was 366mm - almost a third what it saw annually.

"We wouldn't have expected any pipe network to cope with those intensities."

In case of a repeat scenario Brown said all 16,000 properties classified as being at risk of flooding would not be affected.

"The extreme rainfall intensities were localised so we would expect only a portion of the properties at risk of flooding in the region to flood."

He said the Unitary Plan had measures in place to address flooding issues, including less development in the green zones, and building regulations in urban areas that would minimise the risk of water getting into buildings

Brown said the public could also do their bit by keeping drains clear of litter and debris, check roof gutters were connected and water was flowing into drains, ensure landscaping features don't block the rainwater run-off, maintain streams on or near one's property and build living areas above the flood level.

Brown said it was also important for people to keep an eye on their property and see if water was getting into it numerous times a year.

"Dampness under floors causes dampness through the walls and mould spores grow and that causes respiratory problems."

Massey University professor in construction Robyn Phipps said if a house was exposed to moisture or flooding it was important to get it dry within 48 hours or else mould could develop.

"There is always going to be a lot of nutrients, especially in carpet and Gib board, when there has been a flood."

Waikato University professor of environmental planning Iain White said it was important for local and national governments to anticipate these extreme weather events could become more frequent in the changing climate.

"A warmer climate can hold more water and thus make intense rainfall events more likely, while the predicted 45,000 extra Auckland residents a year will result in an increase in surface runoff and more demands on existing underground infrastructure.

"It's a matter of dealing with rain water differently, not just sending them through small pipes as quickly as possible; treating it as a resource."

For a full detailed breakdown of your property's risk this information is available on the Auckland Council website.

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