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The Severn Estuary
Estuary
(Welsh: Môr Hafren) is the estuary of the River Severn, the longest river in Great Britain. It is the confluence of four major rivers, being the Severn, Wye, Usk and Avon, and other smaller rivers.[1][2] Its high tidal range, approximately 50 feet (15 m), means that it has been at the centre of discussions in the UK regarding renewable energy.

Contents

1 Geography 2 Conservation and SSSI status 3 Tidal power 4 Severn Estuary
Estuary
Partnership 5 Archaeology 6 See also 7 References 8 External links

Geography[edit] Definitions of the limits of the Severn Estuary
Estuary
vary. A narrower definition adopted by some maps is that the river becomes the Severn Estuary
Estuary
after the Second Severn Crossing
Second Severn Crossing
near Severn Beach, South Gloucestershire, and stretches to a line from Lavernock Point
Lavernock Point
(south of Cardiff) to Sand Point near Weston-super-Mare.[3] The definition used on Admiralty Chart SC1179 and the Bristol Channel
Bristol Channel
and Severn Cruising Guide is that the estuary extends upstream to Aust, the site of the old Severn Bridge. The estuary is about 2 miles (3.2 km) wide at Aust, and about 9 miles (14 km) wide between Cardiff
Cardiff
and Weston-super-Mare. The Estuary
Estuary
forms the boundary between Wales
Wales
and England
England
in this stretch. On the northern side of the estuary are the Caldicot and Wentloog Levels which are on either side of the city of Newport; and, to the west, the city of Cardiff
Cardiff
together with the resort of Penarth. On the southern, English, side, are Avonmouth, Portishead, Clevedon, and Weston-super-Mare. Denny Island
Denny Island
is a small rocky island of 0.24 hectares (0.6 acres), with scrub vegetation, approximately three miles north of Portishead. Its rocky southern foreshore marks the boundary between England
England
and Wales, but the island itself is reckoned administratively to Monmouthshire, Wales. The estuary has one of the highest tidal ranges in the world — about 50 feet (15 m).[4][5] The estuary's funnel shape, its tidal range and the underlying geology of rock, gravel and sand, produce strong tidal streams and high turbidity, giving the water a notably brown coloration. West of the line between Lavernock Point
Lavernock Point
and Sand Point is the Bristol Channel, which in turn discharges into the Celtic Sea
Celtic Sea
and the wider Atlantic Ocean. The islands of Steep Holm
Steep Holm
and Flat Holm
Flat Holm
are located close to that line, in the middle of the estuary. Sometimes the term Severn Estuary
Estuary
is used to include the tidal upstream stretch between Gloucester
Gloucester
and Aust.[6] During the highest tides on the upper reaches of this stretch, the rising water is funnelled up the estuary into the Severn bore, a self-reinforcing solitary wave that travels rapidly upstream against the river current.[7] Conservation and SSSI status[edit]

Severn Estuary

Site of Special
Special
Scientific Interest

Location near Somerset

Area of Search Gloucestershire

Grid reference ST480830

Coordinates 51°27′42″N 2°59′47″W / 51.4617°N 2.9965°W / 51.4617; -2.9965Coordinates: 51°27′42″N 2°59′47″W / 51.4617°N 2.9965°W / 51.4617; -2.9965

Interest Biological/Geological

Area 15950 hectare

Notification 1976 ( Brean Down
Brean Down
and Uphill Cliff
Uphill Cliff
1952)

Natural England
England
website

Upper Severn Estuary

Site of Special
Special
Scientific Interest

Area of Search Gloucestershire

Grid reference SO720060

Interest Biological/Geological

Area 1436.8 hectare

Notification 1954

Natural England
England
website

The tidal range results in the estuary having one of the most extensive intertidal wildlife habitats in the UK, comprising mudflats, sandflats, rocky platforms and islands. These form a basis for plant and animal communities typical of extreme physical conditions of liquid mud and tide-swept sand and rock. The estuary is recognised as a wetland area of international importance and is designated as a Ramsar site.[8][9] The estuary is recognised as a Special
Special
Protection Area (SPA) under the EC Directive on the conservation of Wild Birds.[10][11] The estuary is recognised as a Special
Special
Area of Conservation (SAC) under the EU Habitats Directive.[12][13] Parts of the estuary have also been designated a Site of Special Scientific Interest. The SSSI includes most of the foreshore upstream from Cardiff
Cardiff
and Brean Down
Brean Down
and most of the upper estuary as far as Sharpness.[1] The Upper Severn Estuary
Estuary
SSSI covers the tidal river between Purton and Frampton on Severn.[14] The Severn Estuary
Estuary
SSSI original designation involves the then counties of Somerset, Avon and Gloucestershire
Gloucestershire
in England, and Gwent and South Glamorgan in Wales. The Severn Estuary
Estuary
SSSI designation overlaps individual site designations for separate sites in Avon (Spring Cove Cliffs, Middle Hope, Portishead Pier to Black Nore, Aust Cliff), Gloucestershire
Gloucestershire
(Purton Passage) and South Glamorgan (Penarth Coast). The 1976 designation includes two sites previously notified in 1952 ( Brean Down
Brean Down
and Uphill Cliff). The SSSI forms the major part of a larger area which includes the Taf/Ely Estuary
Estuary
and Bridgwater Bay
Bridgwater Bay
(as well as the Upper Severn Estuary)[1] The Upper Severn Estuary
Estuary
SSSI designation involves the English county of Gloucestershire.[14] The site (Severn Estuary
Estuary
and Upper Severn Estuary) is listed in the 'Forest of Dean Local Plan Review' as a Key Wildlife Site (KWS).[15] Both SSSI citations provide detail of the geological and biological interest and of particular note is the international importance for wintering and wading birds of passage,[1] and of estuarine habits of outstanding ornithological significance.[14] It is stated that the estuary supports over 10% of the British wintering population and is the single most important wintering ground for dunlin,[1] and for significant numbers of Bewick's swans, European white-fronted geese and wigeon.[14] Nationally important wintering populations are supported such as gadwall, shoveller and pochard.[14] There are notably seven species of migratory fish which pass through the estuary in both directions. These include significant numbers of Atlantic salmon
Atlantic salmon
and common eel.[1] Tidal power[edit] Main article: Severn Barrage

Diagram of a plan to harness tidal power on the Severn River
River
circa 1921. Caption from Popular Mechanics
Popular Mechanics
Magazine 1921

Barrage locations considered over the years

A huge tidal range and high level of surrounding industry and population have long made the Severn Estuary
Estuary
and Bristol Channel
Bristol Channel
a focus for tidal energy schemes and ideas. Plans for a Severn Barrage — running 16 km (9.9 mi) across the Bristol Channel
Bristol Channel
from Lavernock Point
Lavernock Point
near to and south west of Cardiff
Cardiff
to Brean Down
Brean Down
near and just south west of Weston-super-Mare
Weston-super-Mare
in Somerset
Somerset
— would generate a massive 8640 MW when the tide flows, and have been discussed for several decades now. The power generated would come from a lake of 185 square miles (479 km2) with a potential energy depth of 14 metres (46 ft). Tidal power
Tidal power
only runs for around ten hours a day, but by using the enclosed lake as a reservoir of potential energy more hours of operation could be achieved. Other energy sources, such as wind and solar power, also create electricity at times that do not always match when it is needed. Excess power could be stored by pumping water uphill, as is already done at a variety of other installations in the UK. The UK Government shelved the plans in the late 1980s due largely to cost issues and local environmental concerns. However, this was before recent huge rises in the price of energy, and before global warming had started to be taken seriously. In April 2006 the Welsh Assembly approved the idea of utilising the tidal power, but the RSPB has raised serious concerns about the effect on the mud flats, that have European Environmental protection status, and the UK government Energy Review published later in the year did not endorse the scheme.[16] Opinion is still divided on the benefits of a proposed barrage. John Hutton, Secretary of State for Business, Enterprise and Regulatory Reform, announced a further feasibility study on 25 September 2007. The Severn Tidal Power Feasibility Study was launched in January 2008 to assess all tidal range technologies (including barrages, lagoons and others). The study will look at the costs, benefits and impacts of a Severn tidal power scheme and will help Government decide whether it could or could not support such a scheme. The Severn Estuary
Estuary
has the potential to generate more renewable electricity than all other UK estuaries. If harnessed, it could create up to 5% of the UK’s electricity, contributing significantly to UK climate change goals as well as European Union renewable energy targets.[17] The proposal for a hydro-electric barrier to generate 8.6 GW and meet five percent of Britain's power needs, is being opposed by some environmental groups.[18][19] Severn Estuary
Estuary
Partnership[edit] The Severn Estuary
Estuary
Partnership (SEP) was set up in 1995 as an independent initiative to focus the activities of local government, statutory authorities and interested parties such as farmers and fisherman. Its stated aim is To bring together all those involved in the development, management and use of the Estuary
Estuary
within a framework which encourages the integration of their interests and responsibilities to achieve common objectives.[20] In 2001 SEP published the Strategy for the Severn Estuary, which sets out a plan for the management of the estuary.[20] SEP uses a geographically extended definition of the Severn Estuary, beginning at the tidal limit of the River Severn
River Severn
in Gloucester
Gloucester
and ending at a line drawn between Hurlestone Point near Minehead
Minehead
and Nash Point in the Vale of Glamorgan. Archaeology[edit] The archaeology of the Severn Estuary
Estuary
is richly varied and of considerable importance, reflecting both the varied nature of the topography and the importance of the river for both fishing and as a maritime waterway. The archaeological resource within the estuary is under threat from natural processes such as coastal erosion, exacerbated by the high tidal range and strong tidal currents, and from threats such as ongoing development pressure along the shoreline, marine aggregates extraction and new coastal defensive and realignment measures as well as proposed major infrastructure projects.[21] An archaeological aerial survey report of the aerchaeology on the English side is available to view and download from the reference link.[22]

View of Severn Estuary
Estuary
from Newport Wetlands

See also[edit]

Severnside Severn Barrage Severn Tidal Power Feasibility Study

References[edit]

^ a b c d e f Natural England
England
Severn Estuary
Estuary
SSSI information on the citation, map and unit details ^ "Severn Estuary". Retrieved 7 June 2014. 51.4617° N, 2.9965° W Severn Estuary, Coordinates  ^ Severn Boating website ^ "Severn Estuary
Estuary
Barrage". UK Environment Agency. 31 May 2006. Archived from the original (PDF) on 30 September 2007. Retrieved 3 September 2007.  ^ "Coast: Bristol Channel". BBC. Retrieved 27 August 2007.  ^ For example by the Severn Estuary
Estuary
Partnership Archived 5 January 2009 at the Wayback Machine. and VisitEngland ^ "Severn Bore and Trent Aegir". Environment Agency. Archived from the original on 30 December 2007. Retrieved 13 January 2008.  ^ Information on Severn Estuary
Estuary
Ramsar site
Ramsar site
designation ^ Joint Nature Conservation Committee Listing of Ramsars ^ Information on Severn Estuary
Estuary
Special Protection Area designation ^ Joint Nature Conservation Committee Listing of Special
Special
Protection Areas ^ Information on Severn Estuary
Estuary
Special
Special
Area of Conservation designation ^ Joint Nature Conservation Committee Listing of Special
Special
Areas of Conservation ^ a b c d e Natural England
England
Upper Severn Estuary
Estuary
SSSI information on citation, map and unit details ^ Forest of Dean District Local Plan Review, adopted November 2005, Appendix D 'Nature Conservation Site Designations Within the Forest of Dean District', Key Wildlife Sites Archived 29 October 2013 at the Wayback Machine. ^ BBC News
BBC News
(21 April 2006). "Backing for Severn barrage power". Retrieved 9 December 2006.  ^ "Severn Tidal Power". Welsh Assembly
Welsh Assembly
Government. Retrieved 11 November 2010.  ^ Naugthon, Philippe (25 September 2007). " Severn Barrage
Severn Barrage
study alarms campaigners". Times Online. London. Retrieved 26 September 2007.  ^ "New study for Severn energy plan". BBC News. 25 September 2007. Retrieved 26 September 2007.  ^ a b "Strategy for the Severn Estuary
Estuary
(English language summary)" (PDF). The Severn Estuary
Estuary
Partnership. Retrieved 24 December 2007.  ^ "Rapid Coastal Zone Assessment Survey Gloucestershire
Gloucestershire
County Council". Retrieved 25 June 2009.  ^ "Crowther, S. & Dickson, A., 2008. Severn Estuary
Estuary
Rapid Coastal Zone Assessment Survey NMP, Swindon: Gloucestershire
Gloucestershire
County Council and English Heritage". 

External links[edit]

Wikimedia Commons has media related to Severn Estuary.

The Severn Estuary
Estuary
Partnership Natural England
England
(SSSI information)

v t e

Ceremonial county of Somerset

Somerset
Somerset
Portal

Unitary authorities

Bath and North East Somerset North Somerset

Boroughs or districts

Mendip Sedgemoor South Somerset Taunton
Taunton
Deane West Somerset

Major settlements

Axbridge Bath Bridgwater Bruton Burnham-on-Sea Castle Cary Chard Clevedon Crewkerne Dulverton Frome Glastonbury Highbridge Ilminster Keynsham Langport Midsomer Norton Minehead Nailsea North Petherton Portishead Radstock Shepton Mallet Somerton Taunton Watchet Wellington Wells Weston-super-Mare Wincanton Wiveliscombe Yeovil See also: List of civil parishes in Somerset

Rivers

Alham Aller Avill Avon Axe (Bristol Channel) Axe (Lyme Bay) Badgworthy Water Banwell Barle Brue Cam Brook Cary Chew East Lyn Exe Fivehead Frome Haddeo Hoar Oak Water Holford Horner Huntspill Isle Land Yeo Mells Midford Brook Oare Water Parret Severn Estuary Sheppey Somer Sowy Tone Washford Wellow Brook West Lyn Whitelake Yeo (Congresbury) Yeo (South Somerset)

Topics

Country houses County Council Culture of Somerset Economy of Somerset Flag Geography of Somerset Geology of Somerset Grade I listed buildings Grade II* listed buildings High Sheriff of Somerset History of Somerset Local nature reserves Lord Lieutenant of Somerset Museums National nature reserves Parliamentary constituencies Places Population of major settlements Scheduled monuments Schools SSSIs Transport in Somerset Geographic areas: Blackdown Hills Brendon Hills Chew Valley Exmoor Mendip
Mendip
Hills Polden Hills Quantock Hills Somerset
Somerset
Levels South West Coast Path West Somerset
Somerset
Coast Path

v t e

Biological Sites of Special Scientific Interest
Biological Sites of Special Scientific Interest
in Gloucestershire

Summarised data for all sites (biological and geological)

Ashleworth Ham Astridge Wood Badgeworth Barnsley Warren Barton Bushes Bigsweir Woods Blaisdon Hall Bourton Down Box Farm Meadows Boxwell Brassey Brooks Head Grove Buckshraft Mine & Bradley Railway Tunnel Bull Cross, The Frith and Juniper Hill Bushley Muzzard, Brimpsfield Caerwood and Ashberry Goose House Chaceley Meadow Clarke's Pool Meadow Cleeve Common Cockleford Marsh Collinpark Wood Coombe Hill Canal Coombe Hill Cotswold Commons and Beechwoods Cotswold Water Park Crickley Hill and Barrow Wake Daneway Banks Dean Hall Coach House & Cellar Devil's Chapel Scowles Dingle Wood Dixton Wood Dymock Woods Edge Common Elmlea Meadows Frampton Pools Highbury Wood Hobbs Quarry Hornsleasow Roughs Hucclecote Meadows Innsworth Meadow Juniper Hill, Edgeworth Kempley Daffodil Meadow Kingscote and Horsley Woods Lark Wood Leckhampton Hill and Charlton Kings Common Lineover Wood Lower Woods Lower Wye Gorge May Hill Midger Minchinhampton Common Nagshead Old Bow and Old Ham Mines Old River
River
Severn, Upper Lode Pennsylvania Fields, Sedbury Poor's Allotment Puckham Woods Range Farm Fields River
River
Wye Rodborough Common Rough Bank, Miserden Salmonsbury Meadows Selsley
Selsley
Common Severn Estuary Severn Ham, Tewkesbury Shorn Cliff and Caswell Woods Slade Brook Soudley Ponds Speech House Oaks Stenders Quarry Stinchcombe
Stinchcombe
Hill Strawberry Banks Swanpool Wood and Furnace Grove Swift's Hill Sylvan House Barn The Hudnalls The Malvern Hills Tudor Farm Bank Turvey's Piece Upper Severn Estuary Upham Meadow and Summer Leasow Upper Wye Gorge Walmore Common Westbury Brook Ironstone Mine Whelford Meadow Wigpool Ironstone Mine Wildmoorway Meadows Winson Meadows Woodchester Park Workman's Wood Wotton Hill Yarley Meadows

Neighbouring areas Avon Hereford and Worcester Oxfordshire Wiltshire

v t e

Geological Sites of Special Scientific Interest
Geological Sites of Special Scientific Interest
in Gloucestershire

Summarised data for all sites (biological and geological)

Alderton Hill Quarry Bull Cross, The Frith and Juniper Hill Campden Tunnel Gravel Pit Cleeve Common Coaley Wood Quarries Crickley Hill and Barrow Wake Easter Park Farm Quarry Edgehills Quarry Foss Cross Quarry Garden Cliff Hampen Railway Cutting Haresfield Beacon Harford Railway Cutting Hobbs Quarry Hornsleasow Quarry Huntsman's Quarry Jackdaw Quarry Kemble Railway Cuttings Knap House Quarry, Birdlip Land Grove Quarry, Mitcheldean Leckhampton Hill and Charlton Kings Common Longhope Hill Lower Woods Lower Wye Gorge Lydney Cliff May Hill Meezy Hurst Minchinhampton Common New Park Quarry Nibley Knoll Notgrove Railway Cutting Oakenhill Railway Cutting Puddlebrook Quarry River
River
Wye Robin's Wood Hill Quarry Rodborough Common Salmonsbury Meadows Scully Grove Quarry Severn Estuary Slade Brook Stenders Quarry Stony Furlong Railway Cutting Swift's Hill Upper Severn Estuary The Malvern Hills Purton Passage Selsley
Selsley
Common Upper Wye Gorge Veizey's Quarry Wainlode Cliff Wellacre Quarry Wood Green Quarry & Railway Cutting Wotton Hill

Neighbouring areas Avon Hereford and Worcester Oxf

.