Tag Archives: Alexander Portch

Environmental History of Tidal Power in the Severn Estuary

Plan for Severn Barrage

Thomas Fulljames’ watercolour of his plan for the Severn Barrage, 1849.
Source: Wikimedia Commons

In recent decades the interest in renewable energy from sources such as wind, solar and tidal power has steadily increased. However, this interest in harnessing “mother nature’s” energy is not new. Over the past 160 years the Severn estuary has been the focus of numerous proposals to provide a transport route over the estuary, improve navigation and to exploit its large tidal range to generate electricity. As a potential source of predictable, renewable and carbon-free power with the potential to supply up to 5 per cent of current UK electricity needs, such interest is understandable. Despite its potential, the latest proposals, like all its predecessors in the past century and a half, have failed to secure government and public support to build a barrage in the Severn estuary.

How is it that a barrage still has not gone beyond the drawing board? And why are companies, scientists and politicians still willing to invest time, effort and money in further proposals?  Alexander Portch, a PhD candidate in the Department of History at Bristol University, investigates these two questions. Although the past 150 years is the main focus, Alexander also investigates earlier efforts to harness tidal power of the Severn and how the activities of people whose lives were bound up with the estuary’s daily tides have shaped the estuary and lands bordering it. This episode of the podcast features an interview with Alexander Portch and his work on the history of the Severn Estuary.

 

Further reading and resources

Blog posts by Alexander Portch on the Power and the Water website.

Severn Barrage Tidal Power”, The Renewable Energy Website

The Severn Bore website

Charlier, R.H., Menanteau, L., ‘The Saga of Tide Mills,’ Renewable and Sustainable Energy Reviews, 1:3 (1997), 171 – 207.

Godbold, S., Turner, R.C., Hillam, J., Johnson, S., O’Sullivan, A., ‘Medieval Fishtraps in the Severn Estuary,’ Medieval Archaeology, 38:1 (1994), 19 – 54.

Video showing example of tidal mill: Craftsmen: The Tide Miller, 1951 Woodbridge, Suffolk.

 

Music Credits

Stockholm” by timberman, available from ccMixter

Begin (small theme)” by _ghost, available from ccMixter

Easy Killer (DGDGBD)” by Aussens@iter, available from ccMixter

Exploring environmental History podcast

 

This podcast was simultaneously published on the Environmental History Resources website as part of the Exploring Environmental History podcast series.

Engineering a “natural” river: Finding parallels in the Pacific Northwest

Impressions from an ASEH 2016 field trip

By Alexander Porch

More than four years ago a remarkable thing happened along the course of the Elwha, a river on the northern edge of the Olympic National Park in Washington State, USA. In a nation renowned for the number of watercourses that have been heavily modified by the construction of dams – for irrigation, hydroelectricity and water supply – a complex operation began to remove the obstructions that had controlled and exploited the river’s flow since the early decades of the 20th century.[i] As the title of a recent publication by the Seattle Times journalist Lynda V. Mapes attests, the Elwha has now become “a river reborn;” although for better or worse is still the subject of some debate.[ii] For the Lower Elwha Klallam Tribe, whose claim to the river, its fisheries and surrounding lands, extends back thousands of years, the return to their ownership of sections of the river and the reappearance of the fish that had for so long been prevented from migrating to their natural spawning grounds is undoubtedly a reason to rejoice. Likewise, local recreational fishermen (and women), kayakers, and those appreciative of an apparently unspoilt, pristine riverscape are equally positive about the outcome. But for users of the former reservoir and visitors to camping grounds recently washed out by flooding, the benefits are perhaps less obvious.[iii]

site Elwha Dam

The site of the Elwha Dam following its removal. The embankment in the middle distance is all that remains of the original structure. Photo: Alexander Portch.

I first became aware of the Elwha and its rich and complex history through the discovery of Mapes’ book while researching possible comparative studies to consider alongside the saga of the Severn Barrage. Although the dams may not have made use of the tides as their source of energy, I found the subject fascinating as an example of what can happen to a river when a dam is built and, more interesting still, what the implications are of its subsequent removal many years later. The question arose: if a Severn Barrage were to have been built, would there have ever come a time when a case would be made for its removal and, if successful, what would the outcome be of the river’s “rebirth?

To then have the opportunity to visit the Elwha and the site of one of its former dams (there were originally two – the Glines Canyon Dam in its upper reaches, and the Elwha Dam closer to its mouth) as part of the 2016 American Society for Environmental Historians (ASEH) conference in Seattle was an unexpected, but very welcome, pleasure. The conference – at which I presented a poster on my research – was an enjoyable, productive and intellectually stimulating event, with panels ranging from the application of GIS to the study of industrial London and its overseas trade in the 18th and 19th centuries, to “twentieth-century energy frontiers” and the challenges of doing premodern environmental history. However, the visit to the Olympic Peninsula, the Elwha, and particularly the point at which the river meets the Strait of Juan de Fuca within the bounds of the Lower Elwha Klallam Tribe’s reservation, was especially memorable.

The view of the Seattle skyline from the ferry crossing Puget Sound on the return journey from the Olympic National Park. Just visible in the far distance is Mount Rainier, an active volcano. Photo: Alexander Portch.

The view of the Seattle skyline from the ferry crossing Puget Sound on the return journey from the Olympic National Park. Just visible in the far distance is Mount Rainier, an active volcano. Photo: Alexander Portch.

Since the removal of the dams a vast quantity of sediment, previously trapped many miles up-river, has been allowed to flow unobstructed to the sea, being deposited at its mouth. Local tribal members can now walk hundreds of metres out along this accumulated material; with Bald-Headed Eagles gliding majestically overhead, drawn by the return of salmon and other marine species. For me this sight was particularly striking as the Severn is also a river characterised by high volumes of sediment which, it has been suggested, would be trapped behind a barrage, potential blocking and damaging the turbines and requiring regular dredging to keep in check. I wonder what would happen following the removal of a barrage, and the release of all that aggregate?

Newly formed beach

The newly formed beach at the mouth of the Elwha River within the bounds of the Lower Elwha Klallam tribal reservation. Most of this material has been deposited within the past couple of years. Photo: Alexander Portch.

Equally interesting were the insights provided during a stop at the Elwha Dam removal site by one of the archaeologists from the National Park Service who was closely involved in the restoration project. As part of that process archaeological surveys were required, including excavations of prehistoric sites encountered in the vicinity of the dams themselves, and features that were revealed as the lake waters fell and the river resumed a more natural course. Alongside the remnants of early human activity, the dams too were recognised for their historical and archaeological significance. Having been constructed at such an early point in the development of hydroelectricity, and still retaining much of their original machinery, they had been placed on the National Register of Historic Places, necessitating detailed historic building surveys prior to their removal. A Severn Barrage has frequently been cited as having an expected lifespan of up to 120 years. After that period had elapsed would it too be considered as an important part of the nation’s heritage; something requiring thorough recording and analysis before finally being retired from service? Or, conversely, would it be preserved as a monument and museum to 21st century innovation and ingenuity? One thing is for sure, at 18 kilometres (11 miles) in length it would keep archaeologists and historic building surveyors busy for a very long time!

N.B. Attendance at the ASEH conference was made possible by a travel grant from the University of Bristol’s Alumni Foundation.

Bald eagle

Bald-headed eagles wait patiently at the mouth of the Elwha, perhaps for salmon returning to their spawning grounds in the now-accessible upper reaches. Photo: Alexander Portch.

[i] https://www.nps.gov/olym/learn/nature/elwha-ecosystem-restoration.htm

[ii] L.V. Mapes, Elwha: A River Reborn (Seattle, 2013); see also http://projects.seattletimes.com/2016/elwha/

[iii] http://www.seattletimes.com/life/travel/elwha-valley-access-limited-after-undammed-river-wrecks-campgrounds-road/

Tidal Power: A Question of Scale?

By Alexander Portch

Whilst the remarkably well preserved site of Nendrum Monastery on the western shores of Strangford Lough in Northern Ireland may feature the earliest known example of a tidal mill in the world – and, by extension, effectively the starting point for the process of technological evolution that has resulted in today’s tidal energy devices like barrages, lagoons and tidal stream turbines[1] – it suffers from an issue encountered frequently in archaeology: namely that of incomplete evidence and the need to interpret what survives, with the likelihood that any interpretation will be fraught with inaccuracy and conjecture.

This may be familiar to viewers of Channel Four’s Time Team (now sadly also confined to the depths of the past) where, almost on a weekly basis it seemed, entire settlements were reconstructed in astounding detail seemingly on the basis of little more than a handful of pottery shards, the occasional pit, and perhaps the odd wall or two. Admittedly it is in fact possible to say a great deal about a site even if the items listed above comprise the sum total of all features and objects uncovered; not least the fact that a structure existed, its likely whereabouts and possible form and function, and – using the pottery – a likely date for its occupation. The pottery could even hint at possible trade links with faraway places. In order to present this assemblage and any resulting interpretations to a lay audience, however, some form of visual reconstruction is usually necessary and this is where imaginations begin to play a more prominent role, as demonstrated by the often spectacular 3D (re)creations of roundhouses, Roman villas and other assorted ancient monuments, through which Tony and the team could stroll at their leisure.

It is quite likely that many of these efforts are reasonably close to the truth, and even if they fall short of the mark, they do at least succeed in providing entertainment for some, and even inspiration for others (myself for one). Thus, the numerous reconstruction illustrations encountered in the museum at Nendrum Monastery, including a rather impressive physical model of the whole site, served to provide valuable insights into what the location may have been like throughout the duration of its occupation. This included the tide mill, which, despite its sophistication was also a wonderfully simple way of extracting usable energy from the regular rise and fall of the water in the Lough. Such mills may well also have existed around the shores of the Severn Estuary throughout the latter half of the 1st millennium AD; although, as yet, no examples have been identified.

What did exist in more recent times, however, were far larger and more complex structures, such as those at Berkeley and Westbury-on-Severn, both in Gloucestershire. These were certainly in operation from the 18th century, and possibly earlier. Whilst the basic mode of operation differed little from the early medieval tide mills of Northern Ireland, including Nendrum, involving the impounding of water at high tide within a pond, and its subsequent release through waterwheels as the tide ebbed, they also made full use of more modern forms of milling technology, such as vertical wheels, and gearing mechanisms. The latter could enable multiple millstones to be operated by only one or two wheels, whilst simultaneously providing the necessary power to hoist sacks of grain into the upper storeys of the building.

In the case of the example at Berkeley much of the machinery remains in situ within the building (so I have been informed), now derelict following the demise of the last commercial enterprise there in 2004. This may, however, have little to do with tidal power as the mill was converted during the 20th century, first to steam power and then to electricity, whilst the millpond and tailrace have since silted up. In order to fully understand how such facilities operated, therefore, and, in turn, their significance within the context of local communities for whom the tidal cycle of the Severn may have functioned as a focus of livelihood and identity, it seemed necessary to see a tide mill as it might have existed a century or more ago.

There are presently only five restored tidal mills in the British Isles. This may seem like a good number for those who are unfamiliar with such features, as I was only two years ago; however, considering that more than 700 mills were once in existence around the Atlantic coasts of Europe, including many in the British Isles,[2] the remaining examples can hardly be seen as representative. Nonetheless, those that do survive have been restored with care and attention to detail, enabling at least two of them to function once again as they may have done during their working lives. The closest mill to Bristol, where I am currently based, is that at Eling near Southampton which, until it closed for refurbishment earlier this year, produced its own flour on an almost daily basis. Beyond that, the other options were either an expedition to the coast of Suffolk and the working mill at Woodbridge or the slightly more accessible example at Carew Castle in Pembrokeshire. From an archaeologist’s perspective the choice wasn’t difficult to make, and without further delay I headed west.

Carew Cross

The 11th century Carew Cross stands, tall and imposing, facing the eastern entrance to the castle (with the well-positioned Carew Inn visible behind). Photo: Alexander Portch.

The castle at Carew has stood on its promontory overlooking the nearby Carew River, a tidal arm of the Cleddau Ddu, since the beginning of the 12th century when the Norman rulers of England sought to extend their influence into Wales; however, a defensive settlement has been shown to have existed there from the Iron Age. The nearby Celtic cross, one of the finest in Wales, may even hint at the location’s status as a royal centre for the Welsh Kingdom of Deheubarth prior to the arrival of the invaders from the east. It is also likely that a mill existed nearby to supply the castle during the medieval period; however, documentary records for a tide mill date from the 16th century with the present structure being of 19th century construction.[3]

Carew Castle

The West Range of Carew Castle, with its two 13th century drum towers, occupies a commanding position overlooking the still waters of the impounded mill pond. Photo: Alexander Portch.

The building comprises four floors, in addition to the under storey which houses the two vertical waterwheels, and functioned primarily as a corn mill, grinding grain into flour. After a relatively long period of use (longer than most modern power stations at least), the mill ceased operation in 1937 until its restoration in the 1970s. Initially the machinery was put back to use for demonstration purposes; however, now it stands dormant – clean, tidy, well-organised, but too fragile to resume operation. Recent feasibility studies have investigated the potential for breathing new life back into the now arthritic cogs, wheels and gears, in addition to the possibility of installing a modern turbine for generating electricity but, much like the great majority of tidal energy proposals, it remains little more than a report rather than any determined action.

Carew Mill

Carew tidal mill, visible in the distance from a vantage point high up in the nearby castle. Now largely abandoned (with the exception of the occasional wedding party and the regular stream of visitors and re-enactment groups) the castle now provides the ideal habitat for a diverse range of flora and fauna, including more than half of the species of bat found in Britain. Photo: Alexander Portch.

Perhaps the most striking thing about the mill at Carew is the causeway linking the mill building on one side of the river channel with the far bank and housing both the wheels beneath the building, and the sluice gates which allow water to enter during the flood tide. In effect this is a barrage. A very small barrage, at least in contrast to those proposed for the Severn, but a barrage nonetheless, and probably not much smaller than the Annapolis Royal tidal barrage in Nova Scotia.[4] It comprises a solid wall built laterally across the width of a river, thereby effectively cutting off an arm of the waterway from the “natural” operation of the tides. The tides do still affect the millpond created by this structure, but they now rise and fall at the whim of the mill owner or operator (presently the Pembrokeshire Coast National Park Authority). Essentially this could be seen as merely a small-scale version of what might have come to pass on the Severn if a barrage had ever been built. And on that basis, would it have been such a bad thing? At Carew during my visit it was the mill pond that provided the most conspicuous habitat for wading birds, including shell duck and heron, sustained no doubt by the schools of fish that could be seen swimming in the relatively clear waters. The flow of the incoming tide was also discernible, whilst the scent of the salty waters still pervaded the air.

Causeway

The causeway at Carew Castle Tidal Mill: an early tidal barrage? Source: Alexander Portch

But then, the Carew River has no tidal bore, which would be entirely eradicated by a Severn Barrage, and its populations of fish are almost certainly less substantial and diverse than the much larger and more complex Severn. Five hundred years ago the mill pond causeway may have been relatively expensive and could have taken months to build, but that contrasts starkly with the billions of pounds and close to a decade required for the Cardiff-Weston barrage proposals of recent years. In many respects the issue of tidal power is very much a question of scale. Small-scale developments, in terms of size of the buildings and structures, the geographic space they occupy and influence, and the time they take to build have generally been more popular and successful; as demonstrated by the many hundreds of tide mills, the few successful examples of tidal barrages and the current trend towards investment in small-scale tidal turbines and tidal lagoons. Meanwhile, despite the unwavering faith of some its advocates, the comparatively massive Severn barrage continues to flounder. A large-scale fish in a relatively small sea.

 

Notes

[1] http://powerwaterproject.net/?p=562

[2] W.E. Minchinton, ‘Early Tide Mills: Some Problems,’ Technology and Culture, 20:4 (1979), 777 – 786.

[3] For more on the cross, tide mill and castle see: J.R. Kenyon, ‘Carew Cross, Castle and Mill,’ Archaeological Journal, 167 (2010), 29 – 33.

[4] http://www.nspower.ca/en/home/about-us/how-we-make-electricity/renewable-electricity/annapolis-tidal-station.aspx

Brief Encounters of the urban “Wild” Kind

By Alexander Portch

An otter in Bristol. A mere glimpse; a surge of water, a stream of bubbles and the hint of a tail and two rear paws disappearing into the murky depths of the harbour’s impounded waters. Then gone.

Otter

Otter (Source: Wikimedia Commons)

This now represents my first and only siting of a “wild” otter. Hitherto my experience of these elusive and once endangered creatures had been solely through the medium of the screen, usually to the accompaniment of David Attenborough’s familiar narration and, almost by definition, comprising depictions of windswept Scottish lochs or broad North American rivers, hemmed in by miles of forest and mountains, seemingly devoid of human presence. For my first “real-life” encounter with an otter (Lutra lutra) to take place in the very heart of one of Britain’s busiest cities seems incongruous, and utterly unexpected. I had heard rumours of such sightings before but, much like reports of seals in the Severn or Great White Sharks off the coast of North Cornwall,[1] I had assumed they were uncommon – almost “freak” incidents – not something that would be witnessed by someone such as myself, and certainly not whilst casually strolling along the quayside a Friday morning on my way to the train station.

Surely otters, like Eagle Owls (Bubo bubo) and Beaver (Castor fiber), are the preserve of veteran naturalists; wind-swept, weather-beaten individuals whose hours spent ensconced in hides perched high on rugged hills are rewarded with observations of the sort of (non-human) nature everyday office (or library)-dwelling folk will rarely, if ever, have a chance to emulate. The same might once have been said for other seemingly exotic creatures, particularly in urban environments long characterised by low biodiversity and high levels of air, soil and water pollution. Creatures like the Peregrine Falcon (Falco peregrinus), a pair of which had been gazing placidly down at me all the while as I stared wide- (or should that be wild-) eyed down at the otter.

Clearly, however, times have changed. A century ago the area of the city docks where I was fortunate enough to see my first otter was a centre of sugar refining and iron working. During the second world war it bore witness to some of the most intense and destructive air raids by the Luftwaffe (nearby castle park is now a green space in large part due to the damage wrought during the Bristol Blitz).[2] Until relatively recently the cleanliness and clarity of the harbour’s water was also less than ideal. Prior to the construction and opening of the floating harbour in May 1809, the River Avon could at least benefit from the twice daily flushing provided by the flooding and ebbing tides. Once sealed, however, the harbour rapidly became stagnant, and polluted by the regular discharge of sewage from the city and the many ships that made Bristol such a prosperous and (in)famous international port. Whilst this issue was addressed in part through the development by Brunel of a dredging system using a number of sluices emptying into the “New Cut”, it wasn’t until the decline in commercial shipping towards the latter half of the twentieth century and the emergence, more recently, of an interest in the need to create a clean, healthy and pleasant urban environment, that conditions have improved sufficiently to support a wide array of floral and faunal populations.[3]

In many respects, therefore, the return of the otter is perhaps no great surprise; although “return” isn’t perhaps the most appropriate term in this instance. It is almost certain that otters existed along the Avon (and its tributaries the Frome and Malago) in the area that is now central Bristol long before the settlement developed into a wealthy port and cosmopolitan modern city. The intervening centuries, however, have borne witness to the complete transformation of the region’s waterscape, such that the Avon at this point is now a predominantly anthropogenic river. Where once the tides surged upstream from the Severn, the water now flows slowly and placidly within the confines of the harbour; its levels changing almost imperceptibly in conjunction with the opening and closing of locks and sluices. At present that massive tidal range is diverted along the New Cut, a channel carved out through human labour, which two hundred years ago didn’t exist at all. The otters have thus colonised a new human-made space and can, in many respects be considered an entirely urban population. Alongside the Peregrines, roosting high up on the ledges of a former electricity power station, these creatures are a clear example that every so often human activity can in fact have positive benefits for other elements of nature. Given the frequency with which reports concerning the interactions between humans and the rest of “nature” highlight negative impacts and impending threats, such as anthropogenic-enhanced climate change, I think this is something to celebrate.

And it’s not confined to cities. Even within the context of my own focus of research – the history of efforts to harness the power of the tides in the Severn Estuary, and the wider subject of tidal power throughout the British Isles and beyond – the potential for a more positive, almost symbiotic relationship between people and other plants and creatures is increasingly apparent. Research into the environmental implications of wave and tidal energy devices, in addition to offshore wind turbines, now concentrates as much on their ability to function as new habitats for marine creature as the possibility that they may exert a harmful effect.[4] Whether such technology will ever prove to be wholly benign and largely beneficial remains to be seen, but as the 21st century thirst for electricity shows little sign of abating it would surely be a good thing for the sources of that energy to give back to the world as much as they take away.

A brief internet search reveals that my otters aren’t newcomers. In 2011 the BBC reported that otter scat had been found in the harbour area, whilst remote cameras caught the creatures responsible during their night time forays.[5] The Bristol Naturalists Society now operates an otter recording programme, and the City Council lists otters amongst the various species that now call the city home.[6] I may not have made a unique discovery or an original contribution to science, but I have at least been given a new insight, however brief, into a city I thought I knew; much like the river Severn, which I still feel as though I’m discovering for the first time, despite having lived within sight of it for much of my life. Now when I wander along the concrete pavements, holding my nose against the traffic fumes, diverting my attention from the clatter of police helicopters overhead, or ambulance sirens nearby, I can at least rest assured that somewhere, not too far, away the principle sounds and smells are the gentle splash of an otter as it slips gracefully through the harbour waters, and the odour of its fresh fish dinner.

 

Notes

[1] At least I had assumed sitings of seals in the Severn were uncommon until I found this: https://www.facebook.com/keiththeworcestershireseal. For the shark: http://www.independent.co.uk/news/great-white-shark-is-spotted-off-cornwall-1115302.html.

[2] See the Know Your Place website to view various historical maps of the city, in addition to information regarding past activities in the city derived from the Historic Environment Record (HER): http://maps.bristol.gov.uk/knowyourplace/

[3] A brief history of the development of the harbourside is provided in a “Character Appraisal & Management Proposals” document produced by the Bristol City Council: http://www.bristol.gov.uk/sites/default/files/documents/planning_and_building_regulations/conservation/conservation_area_character_appraisals/City%20Docks%20Conservation%20Area%20Appraisal.pdf

[4] J.C. Wilson & M. Elliott, ‘The habitat-creation potential of offshore wind farms,’ Wind Energy, 12:2 (2009), 203 – 212; R. Inger, M.J. Atrrill, S. Bearhop, A.C. Broderick, J. Grecian, D.J. Hodgson, C. Mills, E. Sheehan, S.C. Votier, M.J. Witt and B.J. Godley, ‘Marine renewable energy: potential benefits to biodiversity? An urgent call for research,’ Journal of Applied Ecology, 46:6 (2009), 1145 – 1153; C. Frid, E. Andonegi, J. Depestele, A. Judd, D. Rihan, S.I. Rogers and E. Kenchington, ‘The environmental interactions of tidal and wave energy generation devices,’ Environmental Impact Assessment Review, 32:1 (2012), 133 – 139.

[5] http://www.bbc.co.uk/news/uk-england-bristol-14298095/

[6] http://bns.myspecies.info/content/bristol-otter-survey-group; https://www.bristol.gov.uk/sites/default/files/assets/documents/otter.pdf

Saints and Sea Power in the Tidal Waters of the Irish Sea

By Alexander Portch

In 2008 the Bristol-based renewable energy developer, Marine Current Turbines[1] (MTC), installed the world’s first grid-connected tidal stream turbine in the waters of Strangford Lough on the eastern coast of Northern Ireland. Known as SeaGen S and capable of generating up to 1.2 GW of electricity from the kinetic energy of the Lough’s fast-flowing tidal currents, the device represented a significant step forward in the development of commercially-viable tidal power technologies. The recent near-collapse of MCT following the decision of Siemens, their owners, to sever their connection with the wave and tidal energy industry, served, however, as a reminder of just how much still needs to be achieved before tidal stream and tidal range devices start to receive the same level of investment and support as that enjoyed by other, more prolific renewable energy initiatives like wind and solar[2].

Nonetheless, SeaGen remains in situ, its blades rotating in unison with the twice daily rise and fall of the tide and, thanks to a 24 hour monitoring system, continuing to generate power with minimal adverse impacts on nearby marine fauna[3]. Furthermore, with the recent announcement that Atlantis, another wave and tidal energy company, is to throw MCT a lifeline, the future of tidal power in the Lough would appear to be secure[4]. A rare tale of success, which stands in stark contrast to the on-going saga of failed enterprises in the Severn Estuary.

Interest in the potential inherent in the tidal cycle of Strangford, and other similar environments around the coast of the British Isles, is, however, nothing new, with the achievements of the SeaGen device reflecting similar trends dating back more than a thousand years. In 1999 excavations at the site of Nendrum Monastery on Magee Island, the largest such landmass in Strangford Lough, resulted in the re-interpretation of linear wall structures in the waters to the east of the monastic complex as mill dams, rather than fish weirs as had hitherto been believed. Over subsequent seasons of fieldwork, the well-preserved remains of three successive phases of milling activity were revealed, with dendrochronological dating providing confirmation that this was the site of the earliest example of a tide mill in the world[5].

The first mill was shown to have been constructed between AD 619 and AD 621 and comprised a large dam, 110m in length, which served to impound water within a triangular millpond, 6,500 m2. The pond would fill at high tide and be retained as the tide receded outside the embankment, thereby providing a source of motive power to drive a horizontal waterwheel as it was released back into the Lough. This wheel would have been located in a wheelhouse positioned at the southern corner of the millpond. In the late 7th or early 8th century the first mill fell out of use and was replaced by a second complex of features on the same spot. The most marked change was a reduction in the size of the mill pond, with a new dam forming a smaller, rectangular area of impounded water adjacent to the shore. This was then largely destroyed by the final imposition of a third mill, again in the same location and dating to the end of the 8th century AD. Alongside a wealth of stone and waterlogged wooden artefacts, including a variety of stone slabs marked with crosses, the excavations yielded the almost intact upper millstone from this later development.

Remains Tidal Mill Pond

The surviving remnants of the mill pond embankments now lie largely submerged beneath seaweed and vegetation spreading from the shoreline. In the centre is the long, straight wall associated with the second and third mills, demarcating the boundary of a narrow millpond adjacent to the shore, whilst in the distance to the left is the embankment for the first millpond. Photo: Alexander Portch

Within the remarkably extensive literature on the history and archaeology of tide mills and early water mills, Nendrum has since become an icon of this site-type. Further fieldwork in Ireland is increasingly revealing just how commonplace such structures were in the early medieval period but, at present at least, Nendrum would appear to be where it all began. With my own interest in the recent and much deeper history of the interactions between humans and the non-human process of the tidal cycle, Nendrum has long been a source of some fascination and it was thus with great anticipation that I finally arrived there on a bleak and blustery day in late April. Despite the unseasonal weather conditions and the overcast leaden skies, the atmosphere of the place was tangible and it was a thrill to see the still imposing remnants of the mill pond walls in person. Thankfully a respite from the cold was provided by a superb, if somewhat modest, visitor centre which included a balanced array of written information, artefacts excavated from the site itself, interpretative reconstruction illustrations, a model of the site and an engaging, if rather dated, television documentary (great for someone nostalgic for the 90s, but otherwise in need of updating!).

Model medieval monastery

The fascinating and highly detailed interpretative model of Nendrum located in the centre of the monastery’s visitor centre. It pre-dates the discovery of the tide mills but provides a good insight into what the site may have been like a millennium and a half ago. Photo: Alexander Portch

In many respects this is the real antecedent of the ill-fated Severn Barrage. Whilst recent proponents of tidal range technology frequently tout it as an advanced technology of the future, a means by which to harness an apparently un-tapped source of endless and predictable energy, and an alternative to “old-fashioned” or “out-dated” forms of electricity generation like coal and nuclear, in reality it is nothing of the sorts. Its origins lie in the ingenuity and hard work of people living centuries earlier driven both by their need to extract power from whatever sources were available and their devotion to a power somewhat more intangible. Their lives seem almost impossible to comprehend in the fast-paced, digital age in which we now live, being bound up with cycles of day and night, ebb and flood that have long since been rendered obsolete through modern innovations. Nonetheless, with the recent proposals for a tidal lagoon near Swansea Bay only one step away from receiving government consent[6], it may soon come to pass that the tidal cycle regains some of its former importance as a source of power and sustenance at the heart of our own society.

N.B. For those interested in reading in far greater detail about the excavations at the Nendrum tide mills, a comprehensive archaeological monograph is available: T. McErlean, T. & N. Crothers, Harnessing the Tides: The Early Medieval Tide Mills at Nendrum Monastery, Strangford Lough (London: The Stationery Office, 2007).

 

Notes

[1] http://www.marineturbines.com/

[2] http://www.theengineer.co.uk/news/-siemens-hunts-for-buyer-to-take-on-marine-current-turbines/1019559.article

[3] Keenan, G., et al. “SeaGen Environmental Monitoring Programme Final Report.” Royal Haskoning: Edinburgh, UK, January (2011).

[4] http://www.imeche.org/news/engineering/atlantis-buys-marine-current-turbines-29041502

[5] McErlean, T.C. et al, ‘The Sequence of Early Christian Period Horizontal Tide Mills at Nendrum Monastery: An Interim Statement,’ Historical Archaeology, 41:3 (2007), 63 – 75.

[6] http://www.tidallagoonswanseabay.com/

 

Environmental History in the Making in Portugal and the Severn Sea

By Alexander Portch

Guimaraes

After a week of continuous conference sessions, some fresh air and open space was greatly needed. Thankfully, the UNESCO world heritage city of Guimaraes is situated amongst a truly spectacular landscape; one that could be easily enjoyed thanks to a cable car running direct from the urban centre to the summit of the nearby Montahna da Penha. Photo: Alexander Portch

And so the conference season continues. Whilst a new experience for me personally, the extensive programme of talks and panels circulated in advance of the 2nd World Congress of Environmental History at the University of Minho in Guimaraes, Portugal, which took place between the 8th and 12th of July, provided an insight into what to expect from the one of the year’s most prestigious gatherings of environmental historians, and the subsequent event didn’t disappoint. With presentations and discussions covering a multitude of subject areas, geographic locations and sub-disciplines – from marine cultural environments to the intersections between environmental histories and visual culture; encompassing the Americas, Australasia, India, Africa, and even the comparatively humble Tyne valley in northern England; and drawing upon the work of historians, geographers, zoologists and artists – WCEH 2014 demonstrated quite clearly just how far the practice of environmental history has advanced since the early days of the mid-late 20th century. Nonetheless, despite being daily immersed in a wealth of world-class scholarship disseminated by some remarkably knowledgeable, outgoing and enthusiastic individuals, I still could not help but be distracted by further developments back home in my own area of interest: the Severn Estuary.

Alongside the excitement of meeting and engaging with students, academics and scholars from around the world; listening attentively to discussions on topics as relevant to my interests as the remaking of North American rivers through the construction of hydroelectric dams and as fascinating as the emergence of Earth Art in the 1960s; sampling the many delights of Portugese café culture; and witnessing the tidal wave of destruction that was Germany’s assault on an unsuspecting Brazil in their 7-1 semi-final victory earlier in the week; the news that the Crown Estate have recently agreed seabed rights for a host of new wave and tidal energy demonstration zones, in addition to five new wave and tidal current sites, at various locations around the British coast, couldn’t fail to attract my attention. This includes three sites to be operated by Cornwall-based company WaveHub, encompassing wave testing zones in North Cornwall and South Pembrokeshire and a tidal stream array off the north coast of Devon near Lynmouth. The latter has been announced as the test site for Pulse Tidal’s Pulse-Stream system, which employs an alternative approach to harnessing the power of tidal stream currents to that employed by the majority of developers. Rather than creating the equivalent of an undersea wind turbine, as has been the case for MCT Siemens with their SeaGen design and Open Hydro with their Open Centre technology, the pulse-system exhibits a vertical up-and-down motion akin to the flaps on an aircraft which enables it to be deployed in relatively shallow water.

Equally distracting was the news that, despite the apparent finality of the UK government’s decision last year to reject proposals by Hafren Power for a tidal barrage along the Cardiff-Weston route (from Lavernock Point on the Welsh side of the Severn Estuary to Brean Down on the English side), the newly formed Severn Tidal Energy have recently succeeded in negotiating up to £200m of investment for a renewed attempt at securing support for an identical scheme. The investor, who is reported to be experienced in funding global infrastructure projects, has yet to be formally identified; however, it seems evident that STE are intent on pursuing a similar strategy to that of Hafren Power who made it clear that their project would be dependent on significant financial support from a private investor.

Cardiff-Weston Line

The “Cardiff-Weston Line” with Weston to the left and the islands of Steep Holm and Flat Holm marking the route to Lavernock Point on the Welsh coast near Cardiff. What will this view be like by the middle of the 21st Century? Very different if the newly-formed Severn Tidal Energy succeeds in its renewed attempt at securing permission for a Severn Estuary tidal barrage. Photo: Alexander Portch

As part of my work into the history of tidal energy and the exploitation and harnessing of the tides in the Severn Estuary and Inner Bristol Channel, it is my intention to employ the insights gained from my study of the past to enable the development of informed predictions and imaginings of future scenarios for such activity in the region. Could for example, the now derelict tide mill at Berkeley be resurrected as a small-scale hydro-electricity power station capable of servicing the local community? However, the activities of companies like WaveHub and organisations such as RegenSW serve as a reminder that such a future is already in the process of being envisioned. Perhaps, in place of older technologies such as tide mills or barrages, electricity will be generated through the widespread establishment of vast undersea tidal stream farms, supplemented in places by tidal lagoons such as that proposed for Swansea Bay. Alternatively, the recent establishment of Severn Tidal Energy and the renewed effort by its supporters to realise the potential for generating 5% of the UK’s electricity supply through construction of a single large-scale piece of infrastructure could still result in the designs from the past being made manifest in the future. Only time will tell, but whatever comes to pass, regardless of where I am in the world, at which conference I am presenting or which major sporting event is taking place, I will be sure to remain abreast of developments in the Severn Sea.

 

Sources/Relevant Website Links (all accessed on 14/07/14):

http://pulsetidal.com/pulse-tidal-plans-commercial-demonstration-at-lynmouth.html

http://www.bbc.co.uk/news/uk-wales-28204423

http://www.openhydro.com/technology.html

http://www.pulsetidal.com/our-technology.html

http://www.tidallagoonswanseabay.com/

http://www.walesonline.co.uk/business/business-news/company-behind-tidal-barrage-project-7373290

http://www.wavehub.co.uk/news/crown-estate-unlocks-further-uk-wave-and-tidal-current-opportunities/#more-1185

From the Bristol Channel to the Outer Hebrides: The politics, economics, social consequences and environmental effects of harnessing the power of the seas in the 21st Century

A report from the 6th Bristol Tidal Forum and the 2nd Environmental Impacts of Marine Renewables (EIMR) Conference in Stornoway, Isle of Lewis, Scotland.

By: Alexander Portch

The sun is shining, the grass is green, blossom adorns the cherry and the hawthorn, and the mornings are filled with a cacophony of birdsong: the conference season has clearly arrived. Whilst the much anticipated 2nd World Congress of Environmental History in Guimaraes, Portugal, is still several weeks away, the interdisciplinary nature of my research into tidal power in the Severn Estuary is such that it seemed appropriate to attend the 6th session of the Bristol Tidal Forum on 24 April at the University of Bristol, before packing my bags and embarking on a more extended expedition to the farthest reaches of the British Isles to join the 2nd Environmental Impact of Marine Renewables (EIMR) Conference in Stornoway.

sailing away from Ullapool

The soaring peaks of the Scottish Highlands near Ullapool fade into the distance as the Caledonian MacBrayne ferry MV Isle of Lewis departs for Stornoway (Photo: Alexander Portch).

Whilst my research mainly adopts an historical perspective to study the various ways in which people have harnessed the power of the tidal cycle in the past, it is also my intention to consider how that practice may continue into the future, particularly if a barrage is never constructed. With the UK still faced with the need to massively reduce its reliance on fossil fuels by the end of the decade, thereby meeting targets imposed by the EU, and the likelihood that without further investment in new facilities for electricity generation the population, even in developed areas, could suffer from energy shortages, interest in the potential offered by wave and tidal power remains high.

This is particularly so in some of the more remote parts of the British Isles, where strong tidal currents and energetic wave environments are commonplace, such as the Orkney Islands and the Outer Hebrides. In the latter’s case, the scattered villages and isolated crofts are subject to the highest levels of fuel poverty in the UK and, being so far removed from the coal-fired power stations and nuclear power plants that provide the greater part of the mainland’s power, are in a precarious position with regards to their present and future electricity supply. In more recent times, small arrays of wind turbines have been built across much of Lewis; but wind is widely known for its fickle and unreliable nature, even in one of the most windswept places in Europe. It is in response, therefore, to the increasing demand for alternative sources of renewable and reliable energy in places like the northern and western isles of Scotland, and their possession of an unparalleled wave and tidal resource, that an embryonic industry has sprung up in the region and is rapidly increasing in scale and sophistication. In the southwest, too, the combination of a high tidal range in the Severn estuary, powerful tidal currents around the north Devon coast and Cornish peninsula and the high energy waves rolling in from the Atlantic, in addition to the strong winds that drive them, has been recognised through the creation of the South West Marine Energy Park. This is an initiative which seeks to foster collaboration and engagement amongst a variety of companies and organisations, including consultancies, think-tanks and tidal turbine developers.

All such developments have implications for the future of the Severn estuary. Will a barrage be constructed after all? Or will the estuary be divided up into a series of tidal lagoons, as may already be taking place with the recent plans for a lagoon in Swansea Bay? Alternatively, will the estuary be left unmodified to facilitate the widespread exploitation of the waves, winds and tidal currents further out to sea in the Bristol Channel? These are all options to be considered, particularly as each has significant implications for both humans and the non-human environment. With these thoughts and questions in mind, I took my first tentative steps into this year’s conference season.

The Bristol Tidal Forum is a relatively small-scale affair. Taking place over the course of a single day, the event was composed of a linear sequence of talks given by key individuals involved in the south west’s burgeoning tidal energy industry. As quickly became clear, these were mostly people working in the development and financing aspects of the sector, including the directors of engineering firms responsible for designing and building the devices themselves, representatives of organisations tasked with providing the financial support necessary to make such technology economically viable, and policymakers whose remit it is to ensure that the industry continues to develop in line with relevant guidance and government priorities. The environmental aspects of the technology were thus rarely touched upon, whilst the barrage was evidently far from most people’s minds. In fact, one speaker even went as far as to express frustration with the obstacles that have arisen in response to the deployment by their company of turbines in Puget Sound, in the Pacific Northwest of the USA, resulting from the need to monitor the resident orca (killer whale) populations. In many respects, the tone was set from the very beginning by Andrew Garrad of DNV-GL. In his opening address he laid the blame for any delays and difficulties in developing the industry on a combination of political and economic factors, rather than environmental concerns. Perhaps there is some truth in this assertion, and it is something I will be testing through my own historical study of the Severn barrage.

In marked contrast to the Bristol Tidal Forum, the EIMR 2014 conference, as the title implies, was very much focussed on the real and predicted impacts that tidal and wave energy generation may exert on “the environment”. With delegates arriving from as far afield as Oregon, Washington state, France and Spain, and bringing with them expertise in disciplines as diverse as social science, underwater noise propagation, monitoring of marine mammals and diving seabirds, maritime archaeology – and, in my case, environmental history – the resulting presentations, posters and coffee-break discussions proved to be enjoyably eclectic and adopted an open-minded perception of “the environment” as encapsulating human and non-human elements, as well as sentient and inanimate agents. Of particular interest were talks on community engagement as part of the development of tidal power in Nova Scotia, an area now favoured for tidal stream turbines, but also recognised for possessing one of the few operational tidal barrages in the world; a monitoring project centred on salmon around the coasts of Scotland which employed a combination of contemporary and historical tagging data, including some dating back to the mid-19th century; an overview by representatives of Historic Scotland of recently published historic environment guidance for wave and tidal energy developers[i]; and a poster which sought to demonstrate that construction of barrages around the UK, including one in the Bristol Channel, would significantly alter the tidal range as far afield as the Bay of Fundy and the coast of Maine.

What was perhaps most apparent, however, was just how substantial the impact of these new wave and tidal energy devices is likely to be for the marine and coastal environments; for both people and the rest of nature. Despite their relatively modest size in comparison to more substantial structures such as tidal barrages and lagoons, they may still pose a threat to marine mammals such as seals, basking sharks and whales, and seabirds, in addition to modifying tidal range and tidal current velocity, whilst also affecting rates of sedimentation and wave propagation. They could also pose a hazard for shipping, influence the size and frequency of waves currently enjoyed by surfers and other water users (although a talk on this subject with regards to the north Cornish coast suggested that the modifications imposed by the new WaveHub testing site near St Ives are unlikely to be particularly noticeable), and function as an eyesore for tourists and local inhabitants of coastal areas. What is also clear, however, is just how much people care about such issues and how enthusiastic they are about finding ways through which to overcome any problems inherent in the technology in order to facilitate the successful deployment of what could prove to be one of the “cleanest” and most “sustainable” forms of electric energy generation.

Delegates EIMR 2014

Delegates at the EIMR 2014 Conference in Stornoway pose for the final end-of-conference. Reused with kind permission of the organisers of EIMR 2014.

The excitement that currently surrounds the wave and tidal energy industry was perhaps most clearly demonstrated towards the end of my travels in the Outer Hebrides during a journey around western Lewis organised as part of the conference. In addition to visits to the Callanish Stones (Calanais in gaelic) – the Stonehenge of the north, according to some – the Gearrannan Blackhouse Museum and the Dun Carloway (or Dùn Chàrlabhaigh) Broch (thus satisfying my passion for all things archaeological and ancient), the trip took in the proposed site for the Siadar wave energy testing facility located on the north-west coast of Lewis. Developed by Aquamarine Power and employing their Oyster wave energy machines, this is set to become the largest single array of wave energy devices in the world, providing approx. 40 MW of energy to communities on the island. Whilst the devices will be mostly submerged beneath the water, they will nonetheless become visible at the surface during operation. Concern also surrounded the potential risks they pose for marine mammals, the important seabird population of Lewis, the area’s archaeological and historic environment resource, and any vessels that may pass nearby. Additionally, the visual aesthetics of the region were in danger of being compromised by the large number of metal objects scattered across an extensive swathe of coastline.

Lewis coast

Looking south west along the windswept Atlantic-facing coast of Lewis towards the site of Aquamarine’s proposed Siader wave energy farm. The project was awarded full consent by the Scottish government in May 2013, but as can be seen here development has yet to begin. The photograph was also taken on a particularly calm and flat day but the Isle of Lewis is nonetheless renowned for its frequent high-energy waves (photo: Alexander Portch).

In contrast to many energy generation proposals, however, the Siadar site seems to be remarkable for overcoming all such potential obstacles. Seabird and mammal surveys have indicated that the area is largely devoid of any significant populations, and certainly isn’t used as a breeding ground or for feeding; archaeological remains are few and far between; shipping tends to be located further out at sea, away from such an exposed and rocky coast; whilst the decision to paint the devices in battleship grey with only a small amount of luminous yellow facing out to sea will keep their visual impact to a minimum. Local people are largely in support of the project, which will also make use of nearby insular harbour facilities and fabrication centres, and will benefit directly from the electricity produced at the site.

Beach at Dalmore

Breakers pound the beach at Dalmore, a short distance to the south west of the Siader wave site. This demonstrates that even on a calm day the waves on the west coast of Lewis can be sizable. Many a-surfer in the south west of England would no doubt be envious! (Photo: Alexander Portch)

Indeed, as I flew back to Bristol from Inverness at the end of what had been a most enlightening and enjoyable venture, and gazed down upon the miles of offshore wind turbines sprouting contentiously from the seabed off the Lancashire coast, I couldn’t help but wish that all energy developments could be so straightforward and acceptable. On the other hand, if that were so, my doctoral research would be much less interesting! In reality even the Siadar wave site is a long way from completion, and it will undoubtedly encounter further challenges along the way. But the lessons learned from that development could prove instrumental for subsequent projects elsewhere in Britain, and further afield; including, perhaps, the Bristol Channel and the Severn Estuary. Thus, as I delve deeper into the libraries and archives, I will be sure to keep at least one finger on the pulse of the wave and tidal power industries of the 21st century.

 

[i]Firth, A. Historic Environment Guidance for Wave and Tidal Energy. English Heritage,   2013.

 

Saints, Sailors and Seabirds in the Bristol Channel: The Past, Present and Potential Future of Flat Holm Island

By Alexander Portch

“This year came a great naval armament over hither south from the Lidwiccians… They went then west about, till they entered the mouth of the Severn; and plundered in North-Wales everywhere by the sea, where it then suited them… but the men of Hertford met them; and of Glocester, and of the nighest towns; and fought with them, and put them to flight… And they drove them into a park; and beset them there without, until they gave them hostages, that they would depart from the realm of King Edward. And the King had contrived that a guard should be set against them on the south side of Severnmouth… Nevertheless, they eluded them at night, by stealing up twice; at one time to the east of Watchet, and at another time at Porlock. There was great slaughter each time; so that few of them came away, except those only who swam out to the ships. Then sat they outward on an island, called the Flat-Holms…”

Extract from the The Anglo-Saxon Chronicle for the year AD 918 (source:britannia.com)

 

And so, like the Viking raiders of more than a millennium before, three Bristol-based members of The Power and the Water Project Team set forth from the English mainland, and thence across the expanse of the Bristol Channel in search of the sanctuary and isolation of the island of Flat Holm. Situated approximately five miles out to sea from Cardiff and Barry on the south-eastern coast of Wales, Flat Holm is one of two small islands located along a line between the pronounced headland of Brean Down, near Weston-super-Mare, and Lavernock Point, a short distance along the coast from Cardiff. With the discovery in 1988 of a Bronze Age Axe, dating to c. 900 – 700 BC, indicating the presence of humans on the island more than 2000 years ago; records of regular visits during the late 6th century by the Welsh saint Cadoc; and physical and documentary evidence for continuous occupation throughout the past 800 years; this small (approx.. 500m across) expanse of land in the midst of the Severn Sea is of great historic interest. Combined with its important geological features and rich natural heritage, recognised through its status as a SSSI, Local Nature Reserve, and Geological Conservation Review Site (GCR), the island is more than worthy of a visit by anyone with even a passing interest in the Severn Estuary, wildlife, history or archaeology.

Approach of Flat Holm

The islands of Flat Holm (in the foreground) and Steep Holm (beyond) line up as the cross-estuary ferry “Westward Ho” passes by to the north. Photo: Alexander Portch.

The fact, however, that it also lies along the line of the frequently postulated Cardiff-Weston route for a Severn Barrage, makes it especially significant for this writer. When viewed from afar Flat Holm, with its renowned population of Lesser Black-backed Gulls (Larus fuscus) (approx.. 4000 pairs), a stronghold of the Wild Leek, and historic value as the place where, in May 1897, Guglielmo Marconi first successfully transmitted a message across the open water using his wireless telegraphy system, would appear to be particularly vulnerable to the potential negative impacts associated with the erection nearby of a vast wall of rock, steel and concrete, complete with shipping locks and potentially even a road, railway and series of wind turbines. Despite the obvious presence of humans throughout much of the past 2500 years, demonstrated most tangibly by the remains of defensive fortifications dating to the mid-19th century, further military structures from the Second World war, the ruins of a farmhouse, and a lighthouse; the island still seems, even upon close inspection, like a wild and windswept place, where humans are an invasive species – disturbers of the peace enjoyed by the gulls, rabbits, lizards and sheep. From such a perspective, opposition to a barrage could be seen as wholly understandable and indeed a worthy cause.

Light house

Flat Holm lighthouse, located at the southern end of the island. The light is now fully automated and has been powered by solar panels since 1997. Photo: Alexander Portch.

It was, perhaps, with such views in mind that on Wednesday April 16th 2014 project members Peter Coates, Jill Payne Payne and I arrived on “Coal Beach,” at the north-eastern end of the island having traversed the full width of the Channel between Weston-Super-Mare and Cardiff aboard the bow-loading, Island Class Passenger Vessel “Westward Ho”; a rather small yet accommodating ferry which operates between Cardiff, Weston and Flat Holm throughout much of the Spring and Summer months (http://mwmarine.org/index.php/notable-vessels). This included a brief stop-over in Cardiff Bay; an area of water impounded behind a fixed barrier which, since its construction in 1999, has completely transformed the industrial maritime landscape of disused dockside facilities and intertidal mudflats into the social, cultural and recreational hub of modern Cardiff, replete with an opera house, shopping centre and the iconic copper-plated structure of the Senedd, which houses the National Assembly of Wales (see http://cardiffbay.co.uk/index.php/history). When first postulated the Cardiff Bay Barrage, much like its bigger estuarine cousin, met with fierce objection, including from those who feared the loss of important wetland habitats for birds, flora and other coastal wildlife. In many respects their concerns were well-founded, as such resources have indeed been lost; however, it is difficult to overlook the vibrant atmosphere of the area today, nor the smart-looking yachts and well-tended blocks of flats; their balconies overlooking the comings and goings of vessels navigating their way through the three locks which connect the Bay with the wider tidal estuary. For me at least, the experience of being conveyed through a large shipping lock was a first, and one which proved to be an unexpected, yet most welcome, highlight of the expedition. Whilst the locks that would be incorporated into a Cardiff-Weston barrage would be significantly larger, it was still possible to gain a sense of what entering the Severn Estuary Lake from the tidal Bristol Channel might be like for incoming container ships if a Severn Barrage were ever to be built.

Bristol Locks

Peter Coates watches with interest as one of the three locks connecting the freshwater lagoon of Cardiff Bay with the tidal waters of the Bristol Channel begins to fill with water. Photo: Alexander Portch.

Much as the tide is the key factor motivating the proposals for building a barrage, it is also a conspicuous force influencing the ways in which people, both now and in the past, interact with the island of Flat Holm. Arrival and departure times are wholly subject to the operation of the tides, with boats arriving on the pebble-strewn beaches at high tide, disembarking their cargoes of goods and passengers, then either leaving straight away on the falling tide or, as in the case of our own mode of transport, being left high and dry for up to six hours until the water level once again reaches a height sufficient to float the vessel free. It was perhaps such a characteristic of the two “holms” (a Scandinavian term for a river island) that attracted religious communities during the middle centuries of the 1st millennium AD. On the nearby Steep Holm the ruins of a medieval chapel attest to their presence, whilst on Flat Holm little physical evidence remains for the existence of such a community, with the exception of a cross-inscribed slab found incorporated into the base of the garden wall of the island’s farmhouse. Medieval burials and a curving enclosure ditch, excavated in 1979, may also hint at the whereabouts of some of the island’s earliest structures. With access to the island being governed by the movement of the Channel’s waters and facilitating landings only with great skill and much danger, particularly during inclement weather, the early Christian inhabitants must have found it the ideal place to pray, meditate and practice their distinctive eremitic lifestyle. The workings of the tide may also have played a key role in the island’s infamous history as a haunt for smugglers throughout much of the 17th and 18th centuries. In full view of the local authorities in Cardiff, smugglers were known to convey goods to caves in the cliffs on the eastern side of the island in broad daylight, with little apparent concern about the risk of being caught. Such activity was greatly aided by the fact that the authorities lacked a suitable vessel with which to pursue the smugglers; however, even if such a craft had been within their means, their passage out from the mainland would still have been dependent on the timing of the flood and subsequent ebb tides, with any delay providing the perfect opportunity for those engaged in illicit activities to slip away to safety.

Beached Ferry on Flat Holm

The bow-loading Island Class Passenger Vessel “Westward Ho” sitting high and dry as it awaits the incoming tide to free it from its berth on the pebbly shores of Flat Holm Island. From this point it took little more than 15 – 20 minutes before it was ready to depart – a clear demonstration of the speed with which the tide ebbs and flows around the coastline of the Bristol Channel and Severn Estuary. Photo: Alexander Portch.

It is apparent, therefore, that for as long as humans have interacted with the islands of the Bristol Channel they have, in so doing, interacted with non-human nature. Through knowledge of the tidal cycle people have gained access to Flat Holm, and through exploitation of its mineral resources and agricultural potential they have derived wealth and sustenance. In many respects Flat Holm is an excellent example of how closely human activity can be integrated with the functioning of the “natural” world, as the characteristics that presently justify the island’s status as a SSSI, almost without exception, are the product of anthropogenic influence. The Wild Leeks, for example, are believed to have originally been brought over by the monks who cultivated them on neighbouring Steep Holm, whilst the rabbits were intentionally introduced in the 12th Century. The present plant communities that dominate much of the island’s open landscape, including various grasses, nettles and ground ivy are most likely the result of the rich soils that have built up in response to years of pastoral activity, including manuring by cows, sheep and goats. The Wild Peony was also introduced from Steep Holm, although at a later date, during the Second World War; whilst the thousands of Lesser Black-backed Gulls that call the island their home, and in turn create such a feeling of wildness despite the obvious human presence, only arrived during the 1950s as a result of the abandonment of the military facilities by the 350 soldiers who had been stationed there.

This close ties between human and natural history of the island was further propounded, much to the shock of the project team members, upon conversing with the knowledgeable and welcoming wardens and volunteers of the Flat Holm Project, who have managed and operated the island since 1982 (http://www.flatholmisland.com/). It was initially felt that somehow the gulls of Flat Holm gave the appearance of being somewhat healthier and more “natural” in such a wild and rural setting than their comparatively unkempt urban relatives in towns and cities like Bristol. To be informed, therefore, that the principal food supply for the Flat Holm population comprises the nearby Cardiff City landfill came as quite a surprise. It was also explained that the numerous small bones found scattered across the island were not in fact the remains of predated rabbits, but were predominantly chicken bones; the leftovers from the seagull equivalent of a trip to the local Chinese takeaway. Similarly, pieces of plastic, fragments of children’s toys and plastic balls were also found to represent the colourful trinkets picked up by the birds in their enthusiasm as they scour the dump in search of a chicken drumstick or juicy spare rib. As such, the great majority of litter scattered about the island isn’t the direct result of human carelessness, but is the work of supposedly wild creatures exploiting the products of our own throwaway culture. The fault could thus still be perceived as ours; if perhaps an unexpected and unintentional consequence of our actions. It is also clear, however, that the remarkable number of Black-backed Gulls on Flat Holm are almost wholly reliant on the waste products of human society for their survival and it is believed that their initial arrival and subsequent explosion in numbers could be directly attributable to such a rich and easy source of sustenance. The current population is in fact almost half that which existed earlier in the 20th century, a product of a careful programme of management intended to conserve a maritime grassland habitat across the northern end of the island: yet another example of human involvement in the development and proliferation of nature on this small outcrop of limestone cast adrift in the middle of the Severn Sea.

Lesser Black-backed Gulls

Lesser Black-backed Gulls (Larus fuscus) perched on the cliffs at the southern end of Flat Holm. With approximately 4000 pairs, it is very much their island! Photo: Alexander Portch.

If humans have been so pivotal in the development of wildness on Flat Holm, therefore, could it not be argued that further human involvement in the region, even in the form of a barrage, is a continuation of that activity? A central concept in the discipline of environmental history is the idea that throughout much of their existence humans have exerted a profound influence upon non-human nature and, in turn, non-human nature has been a key factor in shaping human history. Indeed for many scholars, humans and nature are indivisible: humans are a part of nature and thus their activities are wholly natural. It is almost certain that a barrage would lead to significant change on Flat Holm, and could result in the loss of many of the species and habitats for which it is presently renowned. But filling the void left by their demise would be a host of new plants and animals that would greatly benefit from the altered tidal regime, the modified air currents (particularly if wind turbines were also constructed) and the varying levels of pollution, both during and after construction Nonetheless, even if the natural world is seen to benefit, there is no escaping the fact that the visual aesthetics of the estuarine landscape, and the feeling of remoteness which so vividly evokes the isolation that must have been appreciated by the early Christian inhabitants, will be irrevocably transformed and perhaps even lost entirely.

Farewell to Flat Holm

Farewell to Flat Holm. Silhouetted against the clear blue sky can be seen a wind turbine, and the foghorn which remained in operation until 1988. In addition to wind power, the island benefits from solar panel arrays and a biomass boiler. Alongside a large Victorian aquifer for storing collected rainwater, it can boast a remarkably high level of self-sufficiency. Photo: Alexander Portch.

Nonetheless, as the ferry departed Flat Holm, Ynys Echni in Welsh, leaving behind the ghosts of Bronze Age explorers, early Medieval monks, Viking raiders and the scores of mariners shipwrecked around its treacherous shores, it wasn’t the inter-connectedness of humans and their environment, or the comparative benefits of barrages and tidal stream turbines that were foremost in my thoughts. Instead, as the first time I had viewed what had always seemed a familiar land/seascape from such a different perspective, I could do little but gaze upon the holms in wonderment at their beauty as they faded in the half light of the setting sun.