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Will a channel be the answer to flooding? + Video
UNFORTUNATELY forecasters predict climate change will cause more rain and more flooding in the future.
With two severe floods within two years, Oxfordshire is bearing the brunt of that reality.
Flooding earlier this month claimed two lives, destroyed homes and businesses, and shut two of Oxford’s main roads for several days.
In its wake, experts are asking again: how do you solve the problem of flooding in Oxford?
More than 3,600 homes and businesses in Oxford lie in floodplains.
And just 12 miles away from the city lies the headquarters of a global research and testing company which counts flood defence within its specialisms.
HR Wallingford was initially a government organisation, but now claims the Government and the Environment Agency (EA) as its clients.
The head of flood management for HR Wallingford, David Ramsbottom, is convinced a £125m scheme could be the answer.
He worked with the EA in 2009 creating an Oxfordshire strategy for flooding.
They came up with plans for a flood diversion channel running west of Oxford starting north of Botley Road and ending at Sandford Lock in Kennington.
The 2m deep by 30m wide earth and gravel channel was christened the Western Conveyance Channel.
But although in a public consultation of 2009, the EA stated, “work could start by 2013”, the scheme was shelved because of the estimated £160m cost.
Mr Ramsbottom said: “The Thames at Oxford divides into lots of channels so there are lots of routes into which the water could flow.
“But we created a computerised model of the complicated system in Oxford to try and predict where the water would go and it looked like it would work.
“My personal view is the new river channel would be the best thing to have, but it is expensive.”
He explained building a flood wall to try to defend parts of the city would simply not work because the ground under Oxford is very permeable and so water would just seep beneath.
- Flooding at Bullstake Close in the Botley Road area of Oxford on January 10
The EA also looked into lowering the floodplains by removing one metre of top soil, but that plan was ruled out.
Since 2009 the EA has reworked the project so it would cost £125m, rather than £160m, but the funds are still out of reach.
Environment Agency spokeswoman Cheryl Walmsley said: “We would expect to be able to bid for £40m from the Government under the partnership funding approach, once the rest has been secured from third party contributions.
However, this next phase does not yet meet the economic criteria needed for work to start.
“We have already delivered the first phases of the Oxford strategy and we have spent £2.5m on a range of measures, such as the temporary defences, to reduce the risk to properties from lower level flooding.”
Defences including putting up temporary barriers at Osney Island proved a success in the floods.
It is the smaller flood defence systems which the head of HR Wallingford’s flood group Andy Tagg backs as the solution to the problem.
He said: “Clearly we need to think very clearly about just allowing rivers to flood in their natural floodplains. Building big defences to channel the water down really isn’t the answer because it just passes the problem on.
“We need to let the river flood naturally along its whole length.
“Smaller flood defence systems for houses is the best way forward.”
Included in this are barriers for doors, toilet bungs to stop flooded water coming up through the sewerage system, and new floodproof UPVC doors.
Mr Tagg has also advised the Government on how to build new homes to better standards of flood resistance.
This included using waterproof insulation, waterproof paints, and moving electrics a metre higher.
He added: “These kinds of devices have become a lot more popular.
“The estimates are about 300,000 homes in the UK will need these kinds of devices in 25 years, and it costs about £30,000 to put right a flooded house.”
A PLACE WHERE THE EXPERTS STUDY WATER MANAGEMENT
HR Wallingford was originally a government organisation formed in 1947 called the Hydraulic Research Station.
It moved from London in 1951 to set up base in Howbery Business Park at Crowmarsh Gifford, Wallingford.
In 1982 it was the second organisation to be privatised by Margaret Thatcher. It was renamed HR Wallingford in 1991.
In 2003 it built the biggest test centre in the UK for flood testing and research.
HR Wallingford is an international hydraulics organisation which acts as a consultancy and research company. It has offices in Houston, New York, Dubai, Mumbai, Shanghai, Kuala Lumpur, Perth, and Brisbane, but its headquarters are in Wallingford.
It deals with coasts, shipping, climate change, drought, energy and flooding.
Flood and water management is one of its five departments.
- A mocked-up living room with flood defences at the research station
Its biggest clients include the Government and the Environment Agency.
The company employs about 290 people, with 25 people working specifically in the “flood group”.
The floods group covers extreme flooding, flood defences, forecasting, the environment and risk analysis.
It has tested about 20 flood defence systems since 2010.
The tests are done either through a computerised model, or in its 11,200m test centre called the Froude Modelling Hall.
CASE STUDY - JUBILEE RIVER FLOOD ALLEVIATION SCHEME, WINDSOR
- The Jubilee River was built in the 1990s at a cost of approximately £110million as a flood alleviation scheme similar to what was planned for Oxford.
- It opened in 2002 to reduce the risk of flooding to more than 3,000 homes in Cookham, Maidenhead, Windsor and Eton.
- It is 7 and 1/4 miles long and 50-metres wide.
- It diverts river water from the Thames upstream of Maidenhead, and runs parallel and to the north of the river before rejoining the Thames downstream of Windsor at Datchet.
- During flooding, water is diverted from the Thames into the Jubilee River, reducing water levels through Maidenhead, Windsor and Eton.
- The Jubilee River flood alleviation scheme just north of the Thames carries flood water past the towns of Windsor and Eton close to the M4 at Slough
- More than 1,000 homes in the Maidenhead and Windsor area were protected from flooding by the scheme in 2003. But communities downstream of the scheme, in Datchet and Old Windsor complained the scheme worsened the flooding.
- In 2004 an independent review concluded it did not. Also during the 2003 floods the channel was damaged and needed expensive repair work.
- Technical director for flood management of HR Wallingford, David Ramsbottom, said: “The concept worked, but at the first major flood there was some bad damage done to the actual river which cost about £2.5m to repair. So it is a proven concept, it will work.”
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