Costs of floods in Mairehau $2.2m

04:52, Mar 20 2014
Tony Doyle carries Andy Kimber
HELPING HAND: Tony Doyle carries Andy Kimber across Warrington St, Mairehau, after helping flood-affected neighbours in nearby Flockton St.

Scientists predict the cost of this month's flooding for Mairehau alone will be more than $2 million.

National Institute of Water and Atmospheric Research (Niwa) scientists have sifted through more than 500 photos of the March 5 flooding in Christchurch.

For each photograph, the exact location was established and the water level calculated. Anywhere a recognisable landmark was visible, like a doorstep or fence; a survey team will visit to measure a precise water level.

Other data was also being collected from areas that emergency services were called out to and where technicians were needed.

Flood water depths will be used in conjunction with RiskScape, a scientific model used to calculate the human and economic impacts of flooding.

As an example, Niwa has released provisional calculations on the effect of Mairehau, one of the worst-hit Christchurch suburbs.

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Calculations predict 47 Mairehau houses were affected by this month's flood, with an estimated $1.28 million of repair costs and $900,000 worth of content damage.

With the clean-up cost added, Niwa predicts the cost of house flooding in Mairehau will total about $2.2 million.

The model indicates that if floor levels had been raised by 10cm, the total cost in Mairehau would have been halved. If the floor levels had been raised by 45cm, there would have been no flood-related house damage.

The Press