Managed Retreat Case Study Uk Abroad

Case Study - Medmerry, West Sussex

Project Synopsis

Medmerry is the largest managed realignment of the open coast in Europe, on the stretch of coast that was most threatened by coastal flooding in South East England. The Environment Agency (EA) has built 7km of new flood embankment on higher ground and has breached the existing defence, creating intertidal habitat to compensate for Natura 2000 (N2K) loss elsewhere around the Solent. The scheme mitigated for the loss of freshwater SSSI and the impact on important populations of protected species, and created an accessible landscape-scale nature reserve in collaboration with the RSPB and the local community. The Medmerry scheme had 3 key objectives: 

1) Sustainable flood risk management: It will provide a higher standard of protection to 348 properties in Selsey, as well as key infrastructure such as the main road and waste water treatment works. 

2) Creation of compensatory intertidal habitat: Delivering 183ha of intertidal habitat, including mudflat, saltmarsh and transitional grassland. 

3) Involvement of local communities: Creating new access routes and viewpoints for walkers, cyclists and horse riders, and linking Selsey to Bracklesham. 

ASE was commissioned by the Environment Agency to undertake archaeological mitigation works during the Medmerry Managed Realignment, Europe's largest managed realignment scheme.  The works involved the archaeological mitigation of over 40 hectares of relief channel, borrow pit, access road and service trenching across the c. 450 hectare site from August 2011 to November 2013.  Site conditions were challenging and the persistent wet weather from mid 2012 to early 2013 eventually forced a pause in works from January-March 2013.  Further information about the project can be found at Environment Agency website.

Descriptions of Works

ASE managed the archaeological fieldwork and advised the Medmerry Project team on the risks posed to the project by archaeology and how they could be mitigated.  These risks were a result of; the scale of the ground works, the increasing significance and extent of finds being recovered and the inability to fully evaluate areas ahead of mitigation. ASE employed different methodological approaches to reduce the risk of delay to the construction programme as a result of archaeological works.  ASE also offered advice on the management of the archaeological costs of the project and how archaeological mitigation could most effectively be programmed.  ASE contributed to what became a close working relationship between the various contractors, designers and client, that successfully delivered a complex and time constrained programme of works. 

The Results

Extensive Bronze Age remains dating to c. 1,000BC were recorded across the site including houses, wells, industrial sites and funerary remains.  These finds suggest a level of population and structure within the Bronze Age landscape not previously observed in Sussex.  

A c. 200m long medieval timber structure constructed of wattle 'sails' was uncovered, preserved in silts at the base of a wide channel.  The structure has provisionally been interpreted as a fish weir and is the first discovered in Sussex.   

The works also highlighted the role the site played during WWII with pill boxes and plane crash sites dating from 1940-41 and an air to ground attack training ground from 1943, which continued in use until the early 1960s.  

Palaeoenvironmental sampling is proving to be key in relating change observed within the archaeological record with contemporary environmental and climatic conditions.   This work has already identified and dated a number of ancient storm surge events and ongoing post-excavation work is expected  to establish how environmental conditions altered over the last c. 6,000 years.  This work will contribute to our understanding of how climatic and environmental change affects human populations, a pertinent issue relating directly to this site and the local population.  

Page last modified on 14 aug 14 12:39


Before the coast became our national park and playground, we once feared the sea. It was where "beauty, horror and immensity united", as the Romantics might put it. This phrase sprang to mind watching the church tower of Porthleven cowering behind terrifying blasts of spray this week, and seeing a section of Isambard Kingdom Brunel's South Devon railway, the engineering marvel that snakes along the south coast, reduced to something like a rope bridge at Dawlish.

Those whose homes have been wrecked by the storms feel a real sense of loss, but the destruction of much-loved pieces of our coast – from the rock arch at Porthcothan Bay, Cornwall, to the stack on the south of Portland, Dorset – is a small trauma for millions. When I visited my local beach at Wells-next-the-sea in Norfolk after the storm surge in December, I was stunned, not by the smashed-up beach huts, but by the sand dune that had disappeared overnight. There was a void on the horizon and it filled me with desolation. I'd played on that dune as a boy; I'd proposed there. We struggle to accept a new landscape forged by forces utterly beyond our control.

Denial is a natural human reaction, and it is writ large in the government's response to this week's water torture. David Cameron pledged £100m for repairs and maintenance of our battered coastline and the stricken Somerset Levels. Eric Pickles added £30m and criticised Lord Smith, chair of the Environment Agency, for suggesting we would have to choose between "front rooms or farmland". Some political interventions are as surreal as the storm damage. "We have got to force the sea back and keep it out," cried one Tory backbencher, "not retreat from it like we have been for years."

The British Isles are more edge than middle. We are never more than 75 miles from the sea. It protected us from invasion, it gave us an empire and then it became fun. Unlike those flood gurus, the Dutch, whose nation depends on protecting just 451kms of coast, the UK has an indefensible 17,381km (far more than Brazil or India). Despite this, we have fortified it ferociously: 45.6% of England's coast is buttressed with sea walls, groynes or artificial beaches, compared with just 7.6% of Ireland. Most erosion is on a geological timescale (the 10,000-year-old east coast is regarded as recent, and is still adjusting to current sea levels) but scientists believe it is likely to worsen. The Intergovernmental Panel on Climate Change last year increased its projections for sea level rise. Some climate scientists predict a global rise of between 0.7 and 1.2 metres by 2100. Nearly a million homes in England and Wales could be at significant risk of tidal flooding by the 2080s.

Over the past year, I've had the lovely task of visiting our uniquely varied coastline to research a book about the bits owned by the National Trust. Thanks to its hugely successful Neptune campaign to save the coast from development (which celebrates its 50th anniversary next year), the Trust now owns 742 miles of English, Welsh and Northern Irish coast. This is a glorious public park by the sea – and an enormous headache for the Trust.

The government's approach is clear: patch up and protect, or "hold the line" in the jargon of the shoreline management plans in place around our island. But any GCSE geographer can explain that hard defences will never stop erosion.

There is a frightening example of this at Orford Ness, a sinuous shingle spit in Suffolk that was a sinister cold war military site until it was turned into a nature reserve by the Trust. This long peninsula is changing alarmingly quickly. When I stayed there last spring, its lighthouse cast its beam out to sea. Now it is dark and decommissioned because it is about to topple into the water. The sea is threatening to turn the Ness into an island by destroying its tenuous connection with the land – a shingle bank just to the south of Aldeburgh. Here, exactly where decaying sea defences stop, spring storms almost punched through in 2013. Artificially strengthening one piece of coast weakens another. The Environment Agency repaired this breach with shingle last year, but the December storm surge pulled the ridge apart again. Using a bulldozer to create a shingle ridge is not as effective as a naturally formed bank, because it lacks the fine sand that becomes impermeable cement within a natural ridge. Undaunted, the agency repaired it again in January. This week, when I called Grant Lohoar, who has managed the Ness for 21 years, he wasn't sure if he was on an island or not, because the latest storm had washed away the track to the breached area.

"It's going to be a seminal moment in a lot of ways," says Lohoar of the winter storms. "It will be for Orford Ness, and for the Norfolk coast and the south-west. Everywhere is getting it, and there isn't going to be money to do everything."

The Somerset Levels are the source of most immediate concern and, historically, investment in river flood alleviation has dwarfed the funds for coastal protection. The ultimate decision on the future of Orford Ness rests with the Environment Agency. Local people living behind the Ness fear they would be inundated if it became an island, and the official policy is to repair the shingle bank for the next 25 years unless it becomes unsustainable. But who defines sustainability?

"Are we just going to be applying more sticking plasters on things that will pull off again and again?" asks Phil Dyke, the National Trust's coast and marine adviser. "Or are we going to take a proper look at vulnerable places and think about rollback, adaptation and realignment, and allow the undeveloped parts of the coast to function more naturally?"

The Trust once built hard sea defences, but over the past decade it has embraced a radical programme of adapting to coastal change, in consultation with local people. "We think sea defences are permanent structures, but they are not. Even the most ardent coastal defence engineer will say a structure has a lifespan of 50 years," says Dyke. Scientific studies show how hard defences are linked to a dramatic lowering of beaches. Sand dunes will naturally roll landwards and reform unless they are constrained by defences, which cause them to rapidly erode. So do salt marshes, which are brilliant at dissipating wave energy. Once sand or shingle is washed away, it is usually gone for good. Managed realignment will result in increased local erosion, but marine scientists say erosion may benefit other sections of the coast, reducing erosion or even enhancing accretion elsewhere.

Many coastal residents are suspicious of managed realignment because it sounds like a euphemism for doing nothing. But as Malcolm Kerby, founder of National Voice of Coastal Communities, says, seaside settlements must be given a choice other than defend or give up. "I'm delighted to see that at last we've got whole communities beginning to engage with this idea of adaptation rather than that stupid situation – defence or nothing," says Kerby. The government, however, is still unwilling to offer money for any solution other than hard defences.

Kerby has seen the future: his home village of Happisburgh in Norfolk, which was protected by sea defences for half a century until the authorities announced, "We're changing our mind, goodbye," as Kerby puts it. The defenceless village lost more than 40 metres of land between 1998 and 2007, making seaside homes dangerous and worthless. Kerby's campaigning helped create the experimental Pathfinder scheme, in which the government offered £11m for communities to adapt to shifting shores. North Norfolk district council won a £3m grant and the community devised a solution: cliff-edge residents were offered planning rights to build a replacement home on the landward side of Happisburgh, and a small price for their worthless homes. Alternatively, they could sell this planning right to the council and obtain almost 50% of the "no problem" market value of their home. In the end, the nine affected families sold their planning rights to the council. The council can now sell these rights to developers and amass a fund for the next adaptation to the sea. "It's a sustainable model," says Kerby. It also means that Happisburgh will continue to exist, slowly migrating inland, rather than being lost to sea like the drowned villages all along our coast.

The Happisburgh solution is exciting, but Kerby believes the government doesn't like it because it came perilously close to looking like compensation. "Every time we lose more coast, the success of Pathfinder is underlined, but the government doesn't want it because it might cost them a shilling or two," he says. "They simply won't fund adaptation. In some cases, these communities desperately need assistance."

New kinds of coastal adaptation must be judged when the going gets tough. The largest managed realignment scheme on the open coast in Europe was completed late last year at Medmerry, West Sussex. Like most locals, Alan Chamberlain, manager of Medmerry Park holiday village, was horrified when the Environment Agency proposed punching a hole in the sea defences and "letting the sea go". But it protected homes with four miles of new floodbanks inland and turned agricultural land into lakes and marshes. Locals scoffed that £28m was being spent on creating a bird reserve, but when it was hammered by the January storms, it worked. "It's really been tested. We're just amazed at how well we've come out of it," says Chamberlain. "Normally by now we would've had flooding, but we've had none at all."

Sometimes, there is no need to choose between protecting people or countryside: Medmerry's new wetlands have enabled the holiday village to revamp itself as an ecotourism destination. And realignment projects that help wildlife can tap into funding unavailable to conventional coastal defences. Orford Ness coped with the winter storms better than expected because of new ditches, sluices and lagoons created by a €1m wildlife project funded by EU LIFE+. Ironically, this was designed to help rare birds during droughts, but the measures have alleviated the floods.

Governments and their Cobra committees may excel at crisis management, but politicians are hopeless at taking wise decisions over geological time, even when natural erosion is quickened by climate change. All around our coast, scenarios drawn up for 2044 have materialised this winter. "Everybody thought this would hit us in 20 or 30 years time, but it's come now," says Lohoar

Our coast is changing, and it will change us. Even if we don't lose a home, our childhood idylls may never look the same again. Phil Dyke predicts that higher seas and a stormier climate may ultimately strip the sand from many much-loved Cornish coves and turn them, permanently, to stone. Like Icarus with the sun, so it is with us and the sea: we cannot resist living too close, craving its fun and solace from cradle to grave, despite its destructive majesty.

• This article was amended on 11 February 2014 to correct the spelling of groyne.

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