Photo: Bernard Spragg via Flickr

Torrential downpours flood North Island – Expert Reaction

Roads are closed due to flooding and slips overnight, as a deluge battered Auckland and areas of Gisborne and the Bay of Plenty.

The wild weather has caused Auckland to enter its third state of emergency this year.

The SMC asked experts to comment.

Professor James Renwick, Victoria University of Wellington, is available for comment:

“Yet another round of flooding in Auckland and across parts of the North Island. I really feel for those affected, it must be extra-dispiriting to be hit again, so soon after the last event. Why are we having this series of big floods this year?

“Partly, it’s down to climate change. A warmer atmosphere carries more water vapour, so there’s more fuel when a storm comes along and we tend to have heavier rainfalls more often. Even individual thunderstorms are affected, as the release of heat from condensing water is what drives them, so a moister atmosphere literally has more thunderstorm “fuel” in it. We can also point to the long-lived La Niña in the tropical Pacific that has helped keep sea surface temperatures warmer than normal around Aotearoa. That assists evaporation and can add to storm intensity.

“But, we’ve had a warmer moister atmosphere, and warmer seas, for years now. Why all these floods this year, so close together? I think that’s largely down to luck – bad luck in this case. The atmosphere can set itself up to encourage storm development in some regions, such as the Tasman Sea and New Zealand area, for weeks at a time. Then those conditions will ease off and re-form somewhere else. This happens at random, and as far as I can see, this country has just been unlucky so far this year.

“I’ve heard it said that the Tongan volcano must be the cause as it put a lot of water vapour into the atmosphere. There was a lot of water vapour released in the eruption, but that was a year and a half ago. Water vapour lasts in the troposphere (the bottom layer of the atmosphere where we are and where the weather is) for around 10 days, so it will have all rained out many months ago. A large amount of the water vapour went into the stratosphere where it can linger for much longer. That can change the wind circulations above us, but we don’t get rain out of the stratosphere so again it’s not a consideration.

“I don’t see the bad luck continuing for us all year. An El Niño is brewing up in the tropical Pacific and that typically brings stronger westerly winds over New Zealand and quite a change in weather conditions compared to what we’ve experienced lately. Fingers crossed.”

No conflict of interest declared.

Dr Lauren Vinnell, Lecturer of Emergency Management, Joint Centre for Disaster Research, Massey University, comments:

“The state of emergency declared in Auckland shows the severity of flooding, with more rain forecast.

“The most important thing for people in the area to do right now is to keep themselves safe. If possible, get home or somewhere safe and stay there. Avoid going into or driving through floodwaters.

“If there’s nothing you can do right now, have a think about what might help you for next time. We know one of the best ways to cope during an event like this is to focus on actions you can take, even if that’s to help you for future similar events.

“Be patient with yourself and those around you, the stress of emergencies can affect the ability to make decisions, make people feel fatigued, and heighten negative emotions like anger.”

No conflict of interest declared.

Dr Lucy Telfar Barnard, Senior Research Fellow, He Kāinga Oranga Housing and Health Research Programme, University of Otago, Wellington, comments:

“If your rented home is uninhabitable because of flood damage, you can stop paying rent, and give your landlord 48 hours notice (and if you’ve paid rent in advance, you can expect that back).

“If some areas of your rented home are damaged by flooding, but it’s still habitable, you can expect reduced rent. You’ll need to work out with your landlord how much reduction is reasonable, but if you don’t think they’re being fair, you can apply to the Tenancy Tribunal to decide how much the reduction should be.

“When deciding what parts of your home are habitable, it’s safest to treat any areas that have had floodwater in them in the same way as if they’ve had sewer water in them.

“BRANZ has produced a good guide to cleaning up after a flood.”

No conflict of interest declared.

Professor John Tookey, School of Future Environments, AUT, comments:

“The latest set of flooding and accompanying disruptions is a further blow for both communities and the building industry.

“Since the cyclone that came through, extensive works have taken place to stabilise, reinforce and repair infrastructure. Great strides have been made. Certainly in Auckland, much of the necessary immediate works have been completed.

“Further afield, and in outlying districts the picture is less positive since the initial damage was that much worse. Renewed rain and flooding will inevitably undo some repairs and create the demand for more. This in turn is piling up the costs for councils and communities.

“The industry as a whole is struggling to keep on top of these sorts of works. The sector is after all finite in scale and has multiple demands on it for ‘regular’ building – not just emergency repairs.

“It should also be remembered that in many instances the initial claims made against insurance policies during the January floods and the subsequent Cyclone Gabrielle damage are yet to be fully settled. New damage and further compounding effects will inevitably set back final completion dates for claims. The wall of work being generated is very substantial.

“The wider effects would seem similarly clear: multiple building projects will be delayed further, and delay/repair costs will increase. Existing or planned projects will overshoot their intended in service dates. Insurance premiums are going to be further hit. The ‘topping up’ of the saturated ground water means that we are again going to be highly sensitive to any further rainfall over the next few days.”

No conflict of interest declared.