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How high's the water?

Flood prevention, TIF - The Environment Agency will have to keep a close eye on the Thames Gateway development if its ood management plans are to succeed.

LAST WEEK the Environment Agency completed the second phase of the Thames Estuary 2100 (TE 2100) project. This mammoth undertaking will determine how the Agency will continue to protect London and the entire Thames Estuary beyond 2100.

'It is time to start putting lines on maps, ' says TE 2100 project manager Sarah Lavery.

Her team has identied four options to protect the capital along lines set out in the government's recent Making Space for Water strategy - to let land that can safely be ooded, be ooded.

As such, six areas have been earmarked by TE 2100 for controlled ooding and the Agency is in 'serious discussions' with landowners and local authorities.

The Agency predicts that giving flood water more room will buy 60 to 80 years, after which the possibility of new barriers to work with the existing, and very effective, Thames Barrier becomes a reality.

The Thames Barrier is actually a complete system, working in conjunction with eight smaller barriers along the river's embankments to protect against high surging tides. Adding to these smaller facilities is also a possibility in the long term.

But the more dramatic option of building a new outer barrage has not been ruled out, according to Lavery, although she stresses that these are not either/or options.

'We are starting with the most sustainable solution, ' she says.

'Based on DEFRA's [Department for the Environment Food and Rural Affairs] predictions for sea level rise, changing land use could be enough protection for 60 to 80 years.' However, this type of prediction is a far from precise science.

As a precaution the Agency is devising plans to accommodate sea level rises beyond the 0.94m over the next 100 years predicted by Defra.

A worst-case prediction of up to 4.2m is now on the table and sea level rises and surge levels will be monitored, and predictions constantly revised.

The current system on the River Thames offers protection against a 1:2,000 year storm and this is thought adequate for the next 20 years, when it falls to 1:1,000.

Luckily for London (and the taxpayer) the system had an unexpected freeboard of 500mm built in that allows the barrier to maintain its 1:2,000 year standard, despite rising seas.

Regardless, the TE 2100 team is busily preparing its report on phase two, which will be made public in the spring. This will then be used as part of a targeted consultation throughout the summer with an open consultation beginning in the autumn.

In the meantime the Agency is talking to landowners and local council's about the plans to ensure that planning permission for any hard developments are not approved for the targeted areas. This is essential as there are plans for more than 130,000 homes in the Thames Gateway area by 2016.

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