ONE YEAR ON Anniversary warning: City would be flooded again
Thousands are still in the firing line, says water expert
Major flooding would likely again swamp thousands of Auckland homes and businesses should another extreme storm like last year’s Anniversary Weekend floods strike, the council has admitted.
Four people died in the January 27 catastrophe as emergency teams rushed to more than 700 calls for help — and dramatic photos emerged of rescues, landslips and cars floating down streets.
The storm dumped 307mm — more than half a year’s rainfall — on Auckland in four days, forcing more than 600 people into emergency accommodation as up to 10,000 properties flooded.
Council staff placed hazard stickers on 7000 damaged properties, including about 3000 red and yellow placards on the most seriously damaged. More than 2000 slips hit the city’s transport and water networks, while flooding closed major highways and Auckland Airport.
Auckland Council and the Government have now earmarked $2 billion in funding for recovery projects, including plans to buy about 600 flooddamaged homes that pose the greatest risk to life for traumatised owners.
Private insurers have so far paid out $1.5b in 50,000 insurance claims, while government agencies still face criticism over how they responded to the catastrophic storm.
But while most groups say they’ve learnt valuable lessons, the reality is thousands still sit in the firing line should such a deluge happen again, says Nick Vigar, head of planning for Auckland Council’s Healthy Waters department.
Another 1-in-100 year storm could impact about 50,000 city properties lying in overland flow paths and flood plains.
“A hard truth that we have to be honest with people about is that if you got flooded in that event, you should prepare that more-or-less the same thing will happen,” he told the Weekend Herald.
And other experts are warning that Aucklanders still face a long and costly battle with what many expect to be ever more frequent flooding and natural disasters.
Last January 27, Auckland’s wettest day on record, was driven by what experts called a freak combination of weather forces. At its height, the storm dumped 71mm on Auckland Airport in one hour, while 307mm — or almost half the city’s average annual rainfall — fell between that Friday and the end of the month.
Adding to the emergency responders’ troubles was forecaster MetService’s failure to adequately warn about the scale of the approaching storm.
However, even if there had been more warning, the speed of the falls meant there was nowhere for the water to go, says councillor Richard Hills, chair of Auckland’s Planning, Environment and Parks Committee.
“There’s not really [existing] infrastructure that can take a whole summer’s rain in four hours,” he says.
Vigar says “a pretty similar result” should be expected if a weather system like that hits the city again.
“The point is that mostly this is not things that you can solve with more and bigger stormwater pipes.”
Auckland Council and central Government’s most notable response to the storm is an $800 million pledge to get the most at-risk families out of harm’s way by buying out up to 700 flooded and slip-damaged homes no longer considered safe to live in.
It’s part of a $2b storm recovery programme, with affected homes including clusters in the West Auckland suburbs of Ranui, Swanson and Henderson, and coastal the communities of Piha, Karekare and Muriwai. Other clusters are in Milford and Mangere.
The first 100 such homes considered a “risk to life” were identified late last year. Nearly all have so far been deemed “Category 3”, which means nothing can be done to make them safe.
But other homes will be categorised as “2p”. That means they are currently a risk to life unless “property-level” interventions are made within two years, such as by raising the home on piles above flood waters and creating a raised access for safe entry and exit.
A third “2c” category is for homes where there is a risk to life that can only be mitigated if the council completes large infrastructure projects nearby, such as by building culverts or clearing streams for better stormwater run-off.
Auckland Council hopes to identify most of the 2c homes by March.
Yet building the new community infrastructure needed to make them safe could take five to 10 years.
That means the buy-out process could take months, years or even a decade, depending on each individual home. In the meantime, all these homes remain at a high risk from flooding or landslips should another big storm hit.
Council modelling predicts that
50,000 properties could be affected by big flooding events.
It’s left many dreading each sign of rainfall, says Lyall Carter, spokesman for West Auckland is Flooding, a lobby group of flood-affected homeowners.
There is little sign of visible improvements that would reduce flooding in West Auckland and that is causing “simmering frustration”.
The only obvious change seen so far is that done by the community themselves to get “into the streams and clean them out”, he says.
The council insists it has been busy at work since the floods. Almost $400m has been earmarked to help fix roads and bridges. Nearly 3500 have been identified as requiring rebuilding, repairing or for “resilience” projects. Half of the more than
2000 slips that damaged the transport network have been fixed, while
65 per cent of the 11,000 requests for stormwater repairs have also been completed, the council says.
It’s set up new cameras and other tools to monitor the stormwater network for blockages and to give early warning of heavy water flows.
MetService concluded in a report last October that its forecasting model had performed badly in the lead-up. That was in part because January 27 was an “anomaly” of weather circumstances that made it hard to predict.
“All weather models would still struggle to identify them in advance,” MetService spokeswoman Lisa Murray says.
However, its meteorologists had learned valuable lessons and now believe they could “add value where the models cannot” should similar circumstances occur in future.
MetService has also been working closely with councils and emergency services to simplify its severe warnings system. It is launching mobile notifications to send future alerts direct to app users.