Introduction
There is cause for concern over the Severn Estuary in S.W. England. The Estuary experiences a particularly high tidal range, with Spring Tides of 14/15m. This results in a large expanse of intertidal mudflats, which provide feeding grounds for, particularly, migrating wading birds. The waters in the Estuary are a turbulent mix of seawater and freshwater entering from the many rivers that drain into its upper reaches, so there is a dynamic salinity gradient, together with complex patterns of erosion, deposition and sedimentation. The Estuary is also used by commercial shipping, notably to and from Avonmouth and Newport Docks, and continual dredging is needed to maintain shipping channels.
The high tidal range, and consequent fast flowing waters of the Estuary have attracted a variety of tidal barrage schemes, all eager to turn this tidal energy into electrical energy. Unfortunately, tidal barrages, although good physics, are exceedingly poor biology and ecology: if implemented, they would seriously, and permanently, damage the unique Estuarine ecosystem, not to mention ruining the beaches and foreshores of many of the resorts along its borders. Tidal barrages, then, should be - and so far have been – a ''no-no" for the Severn Estuary–
Then there is the issue of storm-tides and storm surges. Back in 1607 a Storm Tide swept up the Bristol Channel and through the Severn Estuary, drowning some 2,000 people, devastating the towns, villages and churches, innundating farmland, as far up as Chepstow in Monmouthshire and as far inland as the fabled Glastonbury Tor of Athurian legend. Experts believe that the disastrous storm-tide was caused by a movement southward by the jet stream, coupled with a severe depression and persistent storm-force winds blowing up the Channel and the Estuary. Whatever the cause, storm tides appear to be an existential threat to the Severn Estuary. And, with global warming come rising sea levels and temperatures, more severe depressions, more intense rainstorms, etc., increasing the probability and intensity of future storm-tides, inundation and flooding...
So what? So, I have undertaken a concept study to show how these twin problems of conserving and future-proofing the Severn Estuary ecosystem, and generating eco-friendly lunar power; may be accomplished at one and the same time. It is my hope that this concept study will trigger government action to implement a Severn Estuary Eco-barrier broadly along the lines suggested. While we still (appear to) have time...
Derek Hitchins...January 2016
Eco-Barrier Concept Study
There are two complementary ways to become informed over this particular slow-burning issue:
- You can read the Eco-Barrier Brief.
- For a more comprehensive introduction, watch the presentation Severn Estuary Eco-Barrier: it takes some 38 minutes to run, which is a tad long, but it includes a number of simulation model clips, which bring the issues to life. Recommended.
Intrigued? You will be...and there is more, much more, about historic storm surges, including the infamous Bristol Channel Floods of 1607 and the damaging North Sea Floods of 1953: which may give pause for serious thought; the North Sea Floods led directly to the construction of the Thames Barrier, to protect central London from future storm tides surging up the Thames Estuary and threatening the seat of government...
But, curiously, there is no corresponding protection for the Severn Estuary, which is both an area and ecosystem, and is equally vulnerable to the existential threat of storm tides surging up the Bristol Channel.
Conclusions from the Concept Study?A Clarion Call for Government Action!
- Government has an irrevocable duty of care to preserve, conserve and protect the vulnerable Severn Estuary, its ecosystems, population of some 1.04 million, habitats, archaeological sites, unique intertidal mudflats, RAMSAR sites, Somerset Levels, nuclear power stations, etc., etc...
- .. against the threat of increasingly severe depressions & storms, inundations, rising tides and temperatures exacerbated by global warming, already threatening our coastlines (National Trust, 2015) making storm tides and storm surges ever more probable with each passing year
- It is conceptually-feasible & affordable to construct a Severn Estuary Eco-Barrier against storm-tides, corresponding to the existing Thames Barrier, also built to combat storm tides...
- It would be a major civil engineering project, phased-in over many years, needs government backing, careful planning, research, design, development, technology, project & financial management..
- .. and it would bring protection, conservation, employment, income and energy to a largely deprived area of the UK
- The project would be/could be, self-funding, harnessing tidal stream renewable/predictable lunar energy that will not damage, but help to conserve the unique & precious estuarine ecosystem/environment - and people!
- So, very definitely nothing to do with ecologically-destructive tidal barrage schemes, then!
- Time is pressing, with global warming already knocking on our respective doors. Government initiative is recommended soonest.