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UK braced for surge in flood prevention as dual purpose Thames Barrier mooted

Plans for a new Thames Barrier could be integrated into the Highways Agency plans for a new Dartford Crossing, the Environment Agency said this week.

The Environment Agency’s Thames Estuary 2100 (TE2100) strategy document suggests a new barrier will be needed from 2070 (see box). It favours a location at Long Reach, close to the Dartford Crossing. An alternative site at Tilbury is also under consideration. Both sites are also being eyed up by the Highways Agency as locations for a new Thames crossing. The Highways Agency wants a new road link to relieve congestion on the existing Dartford Crossing.    

The Environment Agency head of flood risk strategy David Rooke said that he would be interested in discussing options for a dualpurpose crossing.    

“The plan for a new [Dartford] crossing does open up all sorts of possibilities,” he said. More extravagant proposals for a barrage and island airport further out into the Thames Estuary could be considered as an alternative, but one that Rooke played down.    

The Gateway area is afforded one of the highest levels of protection in the UK. Clearly we want to maintain that going forward

David Rooke, Environment Agency  

London mayor Boris Johnson is investigating the feasibility of building an island airport in the Thames Estuary with above or below ground road and rail links to Essex and Kent.    

The Department for Environment Food & Rural Affairs and the Department for Communities & Local Government have viewed proposals by architect Sir Terry Farrell to build a barrage linked to Thames Estuary islands (NCE 5 October 2006).    

Farrell’s proposal is a 9km flood barrage across the mouth of the Thames Estuary from Southend to Sheerness to protect the Thames Gateway development area from a 1:200 year storm surge.    

Rooke was cool on the need for this barrage, claiming that the Thames Gateway is well defended.    

“The Gateway area is aff orded one of the highest levels of protection in the UK. Clearly we want to maintain that going forward.”    

Farrell’s proposal, drawn up in detail by consultant Scott Wilson, would be topped by a cable stayed road and rail bridge to create a transport link between north Kent and the east of England. Three man-made islands behind the barrage would be developed for housing and leisure and the money raised could help pay for the project.     

THAMES FLOOD MANAGEMENT CONSULTATION    

Local government elections in Kent and Essex next month could force the Environment Agency to extend consultation about its plans to manage flood risk in the Thames Estuary.    

The consultation period for the Thames Estuary 2100 (TE2100) plans could be extended by a month to the end of July, the Agency said last week.    

The extension is being considered because some local authorities will be in purdah ahead of the elections and will be unable to make policy announcements.    

The plan follows a two year £275,000 Agency-commissioned study of the impact of climate change on the Thames Estuary.    

The study found that storm surges were not expected to dramatically increase in frequency, but it said that sea level rises and rainfall increases were likely to cause a rise in estuary water levels of between 1m and 2.7m by 2100.   

 “We wanted to ensure the plan was adaptable to change – without having a crystal ball we don’t exactly know exactly so it needed to be adaptable for uncertainty,” said Environment Agency TE 2100 technical strategy manager Rachel Hill.    

The four main estuary-wide options are:

  • Improve the existing defences
  • Create tidal flood storage
  • Build a new barrier at Tilbury or Long Reach
  • Build a barrier with locks at Tilbury or Long Reach or convert the Thames Barrier into a barrier with locks when operational limit of closures per year is reached.

The plan is scheduled to become effective from next year. Over the first 25 years, the focus would be on maintaining and improving existing defences and safeguarding land for flood management in the future. This will cost £1.4bn.    

The plan also anticipates a £3.1bn spend on raising flood walls and reshaping the riverside between 2035 and 2069. There will also need to be a decision about the final 30 years of the century.    

From 2070 onwards an estimated £4.2bn is expected to be spent on the frontrunner options of either maintaining and improving existing flood defences or building a new barrier at Long Reach.

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