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COUNCILS WARNED OF FLOOD RISK
RICHARD EDMONDSON
chief reporter
Flooding that threatened two of New Zealand's oldest buildings last month could have been prevented, say flood experts.
Kerikeri hydrologist Fred Terry warned authorities in 2004 that boulders and debris in the Kerikeri River increased the chances of the Stone Store and Kemp House flooding in a storm.
Mr Terry - who led flood relief efforts on the East Coast after Cyclone Bola - told the district and regional councils that the historic buildings were at risk of flooding even in a smaller storm than that of 1981, which caused more than a million dollars of damage to the buildings.
The Government should have used $500,000 it spent on a sustainable development plan for the basin to commission a hydraulic survey of the river and catchment management plan, he says.
Measures that may have prevented last month's flood included widening the river where it meets the basin and building a stop bank between the river and Kemp House.
Removing boulders from the river and vegetation from the flood plain would also have reduced the severity of flooding.
"You can't fight water, but you can manage it, spread it out and delay its action," Mr Terry says.
Pulling out the Stone Store Bridge when the Heritage Bypass is completed will not, on its own, prevent flooding in the basin.
A flood in 1829 damaged Kemp House before the bridge was built, he says.
Kerikeri agricultural consultant John Greenfield, who has designed catchment schemes for the World Bank, says a dozen strategically placed earth dams in the 9000ha catchment would reduce the likelihood of flooding in the basin.
Spillways could divert water from the Kerikeri River to the Waipapa River during peak flows, reducing the volume of water entering the basin, he says.
"If you want to prevent flooding, you must control runoff - spread it out, slow it down or contain it."
The Northland Regional Council's 2006-16 community plan requires the council to have an operational management plan for the river by July 2009.
Land operations manager Bob Cathcart says the council plans to invite public comment on a draft plan within the next year.
Measures to reduce basin flooding could include the removal of a willow-infested boulder bank in the river above Kemp House and construction of a stop bank between the river and the house.
"Nothing is ruled out. It's just that all the options need to be analysed on a cost-benefit ratio basis."
The council won't rule out the use of dams to control the flow of water through the catchment, Mr Cathcart says.
However, it is unlikely that a plan would depend entirely on dams to reduce the flood risk.
"Gone are the days when you built lots of dams and stop banks to prevent flooding."
A lobby group fighting to preserve public access to the Kerikeri Basin wants an inquiry into the councils' failure to tackle the basin's flood problems.
"The Kerikeri community, as well as central government, should be investigating this serious omission of public duty," says Guardians of the Basin chairwoman Leslie Solmes.
The Guardians are also concerned that the Far North District Council is developing an infrastructure plan to guide growth in Kerikeri and Waipapa without a catchment plan for the area.
"Proceeding with a structure plan without a Kerikeri River Management Plan is putting the cart before the horse," she says.
The council was invited to comment, but did not respond by edition time. |