Christchurch Earthquake 2011
New flood rules could mean further frustration and upheaval for Christchurch's quake-ravaged suburbs.
Yesterday the Christchurch City Council issued new data on flood risk in the city, which will result in thousands of homes needing to have higher floor levels if they are rebuilt or substantially repaired.
The number of properties at risk from a one-in-50-year flood has risen because of land changes caused by the earthquakes.
The new rules could mean higher premiums for affected properties, more complex rebuilds for quake-damaged homes and will be included as a possible risk on property information.
The home of New Brighton resident Isabell Linton will likely have to be raised when it is rebuilt, while the home of her neighbour Justine Aldous is a repair job, so not subject to the rules.
Linton, who has lived at her Collingwood St property for about 50 years, was stoic about the changes.
"It's the builder's problem, not mine," she said.
"If it has to be done, it has to be done and it is better to do it now than later. You have to work your way through it and that's all there is."
IAG's Canterbury recovery executive general manager Dean MacGregor said raising a property's level would increase rebuild costs and this would be considered when premiums were assessed.
"We review the relevant factors that determine premiums and it is likely that flood will be one of those factors in consideration. We charge the fair amount for the risk that is present. This will mean some additional costs in the rebuild. The policies cover it and it is one of the costs our reinsurers will have to take into account."
Council regulation and democracy services general manager Peter Mitchell said some homeowners could be concerned flood risk was now noted on property information.
"This is modelled on a one-in-every-50-year event, which may not happen for 50 years or could happen in a shorter time frame," he said.
"I think given what we've been through with the earthquakes and in the context of the 160,000 properties Christchurch has, that's a reasonably small number, but for those living in the area I can understand it's not good."
Christchurch East MP Lianne Dalziel said the new rules were another blow for quake-hit suburbs.
"There is only so much news like this that people can take and absorb," she said.
"Not only have they had the news delivered in the worst possible way with a public announcement, they just had the school announcement dumped on them with no prior warning or consultation. Then there is the ongoing impact of aftershocks and digging silt out of their homes four times over."
MORE HOUSES RISK FLOODING SINCE QUAKES
Nearly 2500 Christchurch properties have been exposed to new flood risk because of the city's earthquakes.
A revised flood management area covering more than 10,000 properties in Sumner and the Avon, Heathcote and Styx river catchments was yesterday released by the Christchurch City Council.
Properties in the management area have the potential to flood in a 50-year rainfall event and will be subject to new minimum floor levels if building consent is sought.
Council regulation and democracy services general manager Peter Mitchell said the new standards were based on land information gathered after the December 2011 aftershocks.
Site-specific solutions would be considered when building consents were lodged, but those who had been granted consent for repairs or a rebuild would not need to reapply.
"The data on the website has a margin of error because it's been flown by an aircraft," Mitchell said. "It'll only [be] when the council processes a building consent for what is required for a rebuild or major repairs that a specific floor level will be set.
"[Consent officers] look at the levels of the road outside, [and] are there public drains nearby. A whole lot of factors go into setting the data."
Christchurch was a flat, low-lying city with areas prone to flooding and the council had always set minimum floor levels in certain areas, Mitchell said.
Flooding in the city was often shallow and more of an inconvenience than a serious threat to life and property.
The 12,222 properties in the existing flood management area pre-quake had increased to 13,247 in the new zone.
Of those, 2886 were in the red zone.
Council land drainage operations manager Mike Gillooly said more than 1500 non-red zoned properties were no longer a flood risk because the land was higher post-quake, leaving a net gain of 769.
"What this tells you is that for Christchurch this is very much the same problem that we had prior to the earthquakes," Gillooly said.
Christchurch was generally a low-rainfall environment, averaging about 600 millimetres a year, he said.
About 530mm had fallen this year so far.
The biggest rainfall event since the quakes was about 95mm over a 72-hour period in August.
The intensity and depth was a one-in-three-year event.
There had been no serious consequences and no new areas of risk because of the rainfall, he said.
The flood risk data can be found at ccc.govt.nz/floorlevels.
- © Fairfax NZ News
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