Editing River Thames (section)

==Course==
[[File:ThamesMarker.JPG|thumb|The marker stone at the official source of the River Thames named [[Thames Head]] near [[Kemble, Gloucestershire|Kemble]]]]
[[File:Thames Panorama, London - June 2009.jpg|thumb|The Thames passes by some of the sights of London, including the [[Houses of Parliament]] and the [[London Eye]].]]
[[File:River Thames.jpg|thumb|River Thames, [[Southend-on-Sea]], 2019]]
The usually quoted [[river source|source]] of the Thames is at [[Thames Head]] (at {{gbmapping|ST980994}}). This is about {{cvt|1.5|mi|km}}<ref>{{cite web |title=Thames Head, the Source of the River Thames |url=https://www.britainexpress.com/counties/glouces/countryside/thames-head.htm |website=Britain Express |language=en}}</ref> north of the village of [[Kemble, Gloucestershire|Kemble]] in southern [[Gloucestershire]], near the town of [[Cirencester]], in the [[Cotswolds]].<ref>{{cite web |title=The Source |url=http://www.thamespathway.com/chapter1/the-source.aspx |publisher=THames Pathway |access-date=27 August 2020 |archive-date=27 August 2020 |archive-url=https://web.archive.org/web/20200827085612/http://www.thamespathway.com/chapter1/the-source.aspx |url-status=live}}</ref> However, [[Seven Springs, Gloucestershire|Seven Springs]] near [[Cheltenham]], where the [[River Churn|Churn]] (which feeds into the Thames near [[Cricklade]]) rises, is also sometimes quoted as the Thames' source,<ref name="BBC">{{cite news |url=https://www.bbc.co.uk/news/uk-england-gloucestershire-17858944 |title=Tracing the source of the Thames |first=David |last=Bailey |date=15 May 2012 |work=BBC News |access-date=12 September 2018 |archive-date=27 August 2020 |archive-url=https://web.archive.org/web/20200827085618/https://www.bbc.com/news/uk-england-gloucestershire-17858944 |url-status=live}}</ref><ref>{{cite web |first=Dorothy |last=Hart |url=http://www.the-river-thames.co.uk/thames.htm |title=Seven Springs and the Churn |publisher=The-river-thames.co.uk |date=9 May 2004 |access-date=17 May 2010 |archive-date=16 May 2010 |archive-url=https://web.archive.org/web/20100516000937/http://www.the-river-thames.co.uk/thames.htm |url-status=dead}}</ref> as this location is farthest from the mouth and adds some {{cvt|14|mi|km}} to the river's length. At Seven Springs above the source is a stone with the Latin [[dactylic hexameter|hexameter]] inscription "Hic tuus o Tamesine pater septemgeminus fons", which means "Here, O Father Thames, [is] your sevenfold source".<ref>{{cite book |url=https://books.google.com/books?id=_VCFu-2LuJgC&q=%22septemgeminus+fons%22&pg=PA11 |title=I Never Knew That about the River Thames |first=Christopher |last=Winn |date=19 April 2018 |publisher=Ebury Publishing |via=Google Books |isbn=9780091933579 |access-date=20 January 2019 |archive-date=27 August 2020 |archive-url=https://web.archive.org/web/20200827085617/https://books.google.com/books?id=_VCFu-2LuJgC&pg=PA11&lpg=PA11&dq=%22septemgeminus+fons%22&hl=en#v=onepage&q=%22septemgeminus+fons%22&f=false |url-status=live}}</ref>

The [[Spring (hydrology)|springs]] at Seven Springs flow throughout the year, while those at Thames Head are seasonal (a [[Winterbourne (stream)|winterbourne]]). With a length of {{cvt|215|mi|km}},<ref>{{cite book |last1=Clayton |first1=Phil |title=Headwaters: Walking to British River Sources |date=2012 |publisher=Frances Lincoln Limited |location=London |isbn=9780711233638 |page=38 |edition=First}}</ref> the Thames is the longest river entirely in England. (The [[List of rivers of the United Kingdom|longest river]] in the United Kingdom, the [[River Severn|Severn]], flows partly in [[Wales]].) However, as the River Churn, sourced at Seven Springs, is {{cvt|14|mi|km}} longer than the section of the Thames from its traditional source at Thames Head to the confluence, the overall length of the Thames measured from Seven Springs, at {{cvt|229|mi|km}}, is greater than the Severn's length of {{cvt|220|mi|km}}.<ref>{{cite web |url=https://www.bbc.co.uk/england/sevenwonders/west/severn-river/ |title=The River Severn Facts |publisher=BBC
|access-date=17 August 2022
|archive-date=11 October 2007
|archive-url=https://web.archive.org/web/20071011115541/http://www.bbc.co.uk/england/sevenwonders/west/severn-river/}}</ref> Thus, the "Churn/Thames" river may be regarded as the longest natural river in the United Kingdom. The stream from Seven Springs is joined at [[Coberley]] by a longer tributary which could further increase the length of the Thames, with its source in the grounds of the [[National Star College]] at [[Ullenwood]].

The Thames flows through or alongside [[Ashton Keynes]], [[Cricklade]], [[Lechlade]], [[Oxford]], [[Abingdon-on-Thames]], [[Wallingford, Oxfordshire|Wallingford]], [[Goring-on-Thames]] and [[Streatley, Berkshire|Streatley]]  (at the [[Goring Gap]]),  [[Pangbourne]] and [[Whitchurch-on-Thames]], [[Reading, Berkshire|Reading]], [[Wargrave]], [[Henley-on-Thames]], [[Marlow, Buckinghamshire|Marlow]], [[Maidenhead]], [[Windsor, Berkshire|Windsor]] and [[Eton, Berkshire|Eton]], [[Staines-upon-Thames]] and [[Egham]], [[Chertsey]], [[Shepperton]], [[Weybridge]], [[Sunbury-on-Thames]], [[Walton-on-Thames]], [[Molesey]] and [[Thames Ditton]]. The river was subject to minor redefining and widening of the main channel around Oxford, Abingdon and Marlow before 1850, when further cuts to ease navigation reduced distances further.

[[Molesey]] faces [[Hampton, London|Hampton]], and in [[Greater London]] the Thames passes [[Hampton Court Palace]], [[Surbiton]], [[Kingston upon Thames]], [[Teddington]], [[Twickenham]], [[Richmond, London|Richmond]] (with a famous view of the Thames from Richmond Hill), [[Syon House]], [[Kew]], [[Brentford]], [[Chiswick]], [[Barnes, London|Barnes]], [[Hammersmith]], [[Fulham]], [[Putney]], [[Wandsworth]], [[Battersea]] and [[Chelsea, London|Chelsea]]. In [[central London]], the river passes [[Pimlico]] and [[Vauxhall]], and then forms one of the principal axes of the city, from the [[Palace of Westminster]] to the [[Tower of London]]. At this point, it historically formed the southern boundary of the medieval city, with [[Southwark]], on the opposite bank, then being part of [[Surrey]].

Beyond central London, the river passes [[Bermondsey]], [[Wapping]], [[Shadwell]], [[Limehouse]], [[Rotherhithe]], [[Millwall]], [[Deptford]], [[Greenwich]], [[Cubitt Town]], [[Blackwall, London|Blackwall]], [[New Charlton]] and [[Silvertown]], before flowing through the [[Thames Barrier]], which protects central London from flooding by [[storm surge]]s. Below the barrier, the river passes [[Woolwich]], [[Thamesmead]], [[Dagenham]], [[Erith]], [[Purfleet]], [[Dartford]], [[West Thurrock]], [[Northfleet]], [[Tilbury]] and [[Gravesend]] before entering the [[Thames Estuary]] near [[Southend-on-Sea]].

===Sea level===
The sea level in the Thames estuary is rising and the rate of rise is increasing.<ref>{{cite web|url=https://www.southampton.ac.uk/news/2021/02/thames-estuary-changes.page|title=Thames Estuary report highlights changes over decade |publisher=Southampton University|access-date=13 August 2023|date=23 February 2021}}</ref><ref>{{cite web|url=https://www.gov.uk/government/news/thames-estuary-2100-time-to-plan-and-time-to-act|title=Thames Estuary 2100: Time to Plan and Time to Act |access-date=13 August 2023|date=17 May 2023|publisher=Environment Agency}}</ref>

Sediment cores up to 10 m deep collected by the [[British Geological Survey]] from the banks of the tidal River Thames contain geochemical information and fossils which provide a 10,000-year record of sea-level change.<ref name=" The application of δ13C, TOC, C/N geochemistry to reconstruct Holocene relative sea levels and paleoenvironments in the Thames Estuary, UK.">{{cite journal |url=http://nora.nerc.ac.uk/id/eprint/511378/1/ThamesGeochem_v10_.pdf |via=ResearchGate |title=The application of δ13C, TOC, C/N geochemistry to reconstruct Holocene relative sea levels and paleoenvironments in the Thames Estuary, UK. |last1=Khan |first1=S. N. |last2=Vane |first2=C. H. |last3=Horton |first3=B. P. |last4=Hillier |first4=C.| last5=Riding |first5=J. B. |last6=Kendrick |first6=C. |date=2015 |journal=Journal of Quaternary Science |doi=10.1002/jqs.2784 |volume=30 |issue=5 |pages=417–433 |bibcode=2015JQS....30..417K |s2cid=12143258 |s2cid-access=free |access-date=20 January 2019 |archive-date= |archive-url= |url-status=}}</ref> Combined, this and other studies suggest that the Thames sea-level has risen more than 30 m during the Holocene at a rate of around 5–6&nbsp;mm per year from 10,000 to 6,000 years ago.<ref name=" The application of δ13C, TOC, C/N geochemistry to reconstruct Holocene relative sea levels and paleoenvironments in the Thames Estuary, UK."/> The rise of sea level dramatically reduced when the ice melt nearly concluded{{clarify|date=August 2023}} over the past 4,000 years. Since the beginning of the 20th century, rates of sea level rise range from 1.22&nbsp;mm per year to 2.14&nbsp;mm per year.<ref name=" The application of δ13C, TOC, C/N geochemistry to reconstruct Holocene relative sea levels and paleoenvironments in the Thames Estuary, UK."/>

===Catchment area and discharge===
{{Main|Tributaries of the River Thames}}
The Thames River Basin<ref name="Map of the river Thames watershed">
Map of the River Thames watershed:
*{{cite web |last1=Barrow |first1=Mandy |title=River Thames Basin |url=https://www.primaryhomeworkhelp.co.uk/riverthames/basin.htm |website=Primary Homework Help |access-date=11 April 2023}}
*{{cite journal |last1=Futter |first1=M. N. |last2=Erlandsson |first2=M. A. |last3=Butterfield |first3=D. |last4=Whitehead |first4=P. G. |last5=Oni |first5=S. K. |last6=Wade |first6=A. J. |title=PERSiST: a flexible rainfall-runoff modelling toolkit for use with the INCA family of models |journal=Hydrology and Earth System Sciences |date=28 February 2014 |volume=18 |issue=2 |pages=855–873 |doi=10.5194/hess-18-855-2014 |bibcode=2014HESS...18..855F |bibcode-access=free |url=https://www.researchgate.net/publication/260598355 |via=ResearchGate |access-date=11 April 2023 |doi-access=free |url-status=live |archive-url= https://web.archive.org/web/20230815180942/https://www.researchgate.net/publication/260598355_PERSiST_A_flexible_rainfall-runoff_modelling_toolkit_for_use_with_the_INCA_family_of_models |archive-date= Aug 15, 2023 }} Map on page 864</ref> District, including the Medway catchment, covers an area of {{cvt|6229|sqmi|km2}}.<ref name="The Environment Agency">{{cite web |url=http://www.environment-agency.gov.uk/research/planning/33130.aspx |title=More about the Thames River Basin District |date=2 September 2011 |publisher=Environment Agency |access-date=6 November 2011 |archive-url=https://web.archive.org/web/20110908011951/http://www.environment-agency.gov.uk/research/planning/33130.aspx |archive-date=8 September 2011 |url-status=dead }}</ref> The entire river basin is a mixture of urban and rural, with rural landscape predominating in the western part. The area is among the driest in the United Kingdom. Water resources consist of [[groundwater]] from [[aquifer]]s and water taken from the Thames and its tributaries, much of it stored in large [[Reservoir#Bank-side|bank-side reservoirs]].<ref name="The Environment Agency"/>

The Thames itself provides two-thirds of London's drinking water, while groundwater supplies about 40 per cent of public water supplies in the overall catchment area. Groundwater is an important water source, especially in the drier months, so maintaining its quality and quantity is extremely important. Groundwater is vulnerable to surface pollution, especially in highly urbanised areas.<ref name="The Environment Agency" />

====Non-tidal section====
{{Main|Locks and weirs on the River Thames}}
[[File:jubilee weir.jpg|thumb|The [[Jubilee River]] at [[Slough Weir]]]]
[[File:St John's Lock and Lechlade in background.JPG|thumb|upright|St John's Lock, near [[Lechlade]]]]
[[File:River thames oxford.jpg|thumb|right|The River Thames in [[Oxford]]]]

Brooks, canals and rivers, within an area of {{cvt|3842|sqmi|km2|0}},<ref name="CEH">{{cite web |url=http://www.ceh.ac.uk/data/nrfa/nhmp/annual_review/feature_articles/Flow_Gauging_on_River_Thames_100_Years.pdf |title=Flow Gauging on the River Thames – The First 100 Years |year=1983|page=33 |publisher=Hydrological Data |access-date=9 November 2011 |archive-date=Dec 2, 2011 |archive-url=https://web.archive.org/web/20111202170904/http://www.ceh.ac.uk/data/nrfa/nhmp/annual_review/feature_articles/Flow_Gauging_on_River_Thames_100_Years.pdf |url-status=dead }}</ref> combine to form 38 main tributaries feeding the Thames between its source and [[Teddington Lock]]. This is the usual [[tidal limit]]; however, high spring tides can raise the head water level in the reach above Teddington and can occasionally reverse the river flow for a short time. In these circumstances, tidal effects can be observed upstream to the next lock beside [[Molesey Lock|Molesey weir]],<ref name="CEH"/> which is visible from the towpath and [[Hampton Court Bridge|bridge]] beside [[Hampton Court Palace]]. Before Teddington Lock was built in 1810–12, the river was tidal at peak spring tides as far as [[Staines upon Thames]].

In descending order, non-related tributaries of the non-tidal Thames, with river status, are the [[River Churn|Churn]], [[River Leach|Leach]], [[River Cole, Wiltshire|Cole]], [[River Ray, Wiltshire|Ray]], [[River Coln|Coln]], [[River Windrush|Windrush]], [[River Evenlode|Evenlode]], [[River Cherwell|Cherwell]], [[River Ock|Ock]], [[River Thame|Thame]], [[River Pang|Pang]], [[River Kennet|Kennet]], [[River Loddon|Loddon]], [[River Colne, Hertfordshire|Colne]], [[River Wey|Wey]] and [[River Mole, Surrey|Mole]]. In addition, there are occasional backwaters and artificial cuts that form islands, [[distributary|distributaries]] (most numerous in the case of the [[River Colne, Hertfordshire|Colne]]), and man-made distributaries such as the [[Longford River]]. Three canals intersect this stretch: the [[Oxford Canal]], [[Kennet and Avon Canal]] and [[Wey Navigation]].

Its longest artificial secondary channel (cut), the [[Jubilee River]], was built between Maidenhead and Windsor for flood relief and completed in 2002.<ref>{{cite web |url=http://www.ukriversguidebook.co.uk/seengland/thamesjubilee.htm |title=UK Rivers Guide Book Guide to the River Thames – Jubilee River |publisher=Ukriversguidebook.co.uk |date=23 January 2011 |access-date=2 April 2012 |archive-date=3 May 2010 |archive-url=https://web.archive.org/web/20100503110907/http://www.ukriversguidebook.co.uk/seengland/thamesjubilee.htm |url-status=dead}}</ref><ref>{{cite web |url=http://www.environment-agency.gov.uk/commondata/acrobat/jubileerivermap_1200567.pdf |archive-url=https://web.archive.org/web/20070930152507/http://www.environment-agency.gov.uk/commondata/acrobat/jubileerivermap_1200567.pdf |archive-date=30 September 2007 |title=Environment Agency – A map indicating the location and route of the Jubilee River |date=30 September 2007 |access-date=2 April 2012}}</ref>

The non-tidal section of the river is managed by the [[Environment Agency]], which is responsible for managing the flow of water to help prevent and mitigate flooding, and providing for navigation: the volume and speed of water downstream is managed by adjusting the sluices at each of the weirs and, at peak high water, levels are generally dissipated over preferred flood plains adjacent to the river. Occasionally, flooding of inhabited areas is unavoidable and the agency issues flood warnings. Due to stiff penalties applicable on the non-tidal river, which is a drinking water source before treatment, [[sanitary sewer overflow]] from the many [[sewage treatment plant]]s covering the upper Thames basin should be rare in the non-tidal Thames. However, storm sewage overflows are still common in almost all the main tributaries of the Thames<ref>{{cite web |url=https://www.theguardian.com/environment/2020/jul/01/water-firms-raw-sewage-england-rivers |title=Exclusive: water firms discharged raw sewage into England's rivers 200,000 times in 2019 |work=The Guardian |access-date=4 August 2020 |date=1 July 2020 |archive-date=27 August 2020 |archive-url=https://web.archive.org/web/20200827085619/https://www.theguardian.com/environment/2020/jul/01/water-firms-raw-sewage-england-rivers |url-status=live}}</ref><ref>{{cite web |url=https://www.arcgis.com/apps/webappviewer/index.html?id=a6dd42e3bc264fc28134c64c00db4a5b&extent=146436.9576%2C27590.8012%2C854242.0922%2C563326.0668%2C27700 |publisher=The Rivers TRust |access-date=4 August 2020 |title=Is my river fit to play in? |archive-date=5 August 2020 |archive-url=https://web.archive.org/web/20200805024256/https://www.arcgis.com/apps/webappviewer/index.html?id=a6dd42e3bc264fc28134c64c00db4a5b&extent=146436.9576%2C27590.8012%2C854242.0922%2C563326.0668%2C27700 |url-status=live}}</ref> despite claims by Thames Water to the contrary.<ref>{{cite web |url=http://www.thameswater.co.uk/tw/common/downloads/about%20us%20-%20corporate%20responsibility/annual-performance-report-2011-12.pdf |title=Report of the designated sewerage company for the entire Thames Basin and major supplier of London's water supply: Thames Water |access-date=20 November 2012 |archive-url=https://web.archive.org/web/20150131021304/http://www.thameswater.co.uk/tw/common/downloads/about%20us%20-%20corporate%20responsibility/annual-performance-report-2011-12.pdf |archive-date=31 January 2015 |url-status=dead}}</ref>

====Tidal section====
{{Main|Tideway}}
[[File:London Stone, Staines 028.jpg|upright|thumb|[[London Stone (riparian)|London Stone]] at Staines, built in 1285 marked the customs limit of the Thames and the [[City of London]]'s jurisdiction.]]
[[File:Thames tide.jpg|thumb|Waterstand of Thames at low tide (left) and high tide (right) in comparison at Blackfriars Bridge in London]]
Below Teddington Lock (about {{cvt|55|mi|km|0|disp=or}} upstream of the Thames Estuary), the river is subject to [[tide|tidal activity]] from the [[North Sea]]. Before the lock was installed, the river was tidal as far as Staines, about {{cvt|16|mi|km}} upstream.<ref>{{cite web |url=http://www.visitthames.co.uk/text/106/free_fishing.html |title=River Thames Free Fishing |publisher=River Thames Alliance |access-date=10 June 2010 |archive-date=29 November 2010 |archive-url=https://web.archive.org/web/20101129220916/http://visitthames.co.uk/text/106/free_fishing.html |url-status=live}}</ref> London, capital of [[Roman Britain]], was established on two hills, now known as [[Cornhill, London|Cornhill]] and [[Ludgate Hill]]. These provided a firm base for a trading centre at the lowest possible point on the Thames.<ref>Peter Ackroyd ''London:The Biography'' Vintage 2001</ref>

A river crossing was built at the site of [[London Bridge]]. London Bridge is now used as the basis for published tide tables giving the times of [[tide|high tide]]. High tide reaches Putney about 30 minutes later than London Bridge, and Teddington about an hour later. The [[tidal reach|tidal stretch]] of the river is known as "the [[Tideway]]". Tide tables are published by the [[Port of London Authority]] and are available online.{{cn|date=March 2025}}

The principal [[tributaries of the River Thames]] on the Tideway include the rivers [[River Crane, London|Crane]], [[River Brent|Brent]], [[River Wandle|Wandle]], [[River Ravensbourne|Ravensbourne]] (the final part of which is called [[Deptford Creek]]), [[River Lea|Lea]] (the final part of which is called [[Bow Creek (London)|Bow Creek]]), [[River Roding|Roding]] (Barking Creek), [[River Darent|Darent]] and [[River Ingrebourne|Ingrebourne]]. In London, the water is slightly [[brackish water|brackish]] with sea salt, being a mix of sea and fresh water.

[[File:06 2023 Thames Barrier IMG 7506.jpg|thumb|The [[Thames Barrier]] provides protection against floods.]]
This part of the river is managed by the [[Port of London Authority]]. The flood threat here comes from high tides and strong winds from the North Sea, and the Thames Barrier was built in the 1980s to protect London from this risk.

[[The Nore]] is the [[sandbank]] that marks the mouth of the [[Thames Estuary]], where the outflow from the Thames meets the [[North Sea]]. It is roughly halfway between [[River Roach#The tidal river|Havengore Creek]] in Essex and Warden Point on the [[Isle of Sheppey]] in Kent. Until 1964 it marked the seaward limit of the Port of London Authority. As the sandbank was a major hazard for shipping coming in and out of London, in 1732 it received the world's first [[lightvessel|lightship]]. This became a major landmark, and was used as an assembly point for shipping. Today it is marked by Sea Reach No. 1 Buoy.<ref name=PortCities>{{Cite web |url=http://www.portcities.org.uk/london/server/show/nav.001008 |archive-url=https://web.archive.org/web/20071229125347/http://www.portcities.org.uk/london/server/show/nav.001008 |url-status=dead |title=PortCities London |archive-date=29 December 2007}}</ref>

===Islands===
{{Main|Islands in the River Thames}}

[[File:Aerial view of London City Airport 2007.jpg|thumb|right|[[London City Airport]] is on the site of a dock.]]

The River Thames contains over 80 islands ranging from the large estuarial marshlands of the [[Isle of Sheppey]] and [[Canvey Island]] to small tree-covered islets like [[Rose Isle]] in Oxfordshire and [[Headpile Eyot]] in Berkshire. They are found all the way from [[Fiddler's Island]] in Oxfordshire to the [[Isle of Sheppey]] in Kent. Some of the largest inland islands, for example [[Formosa Island]] near Cookham and [[Andersey Island]] at Abingdon, were created naturally when the course of the river divided into separate streams.

In the Oxford area the river splits into several streams across the [[floodplain]] ([[Seacourt Stream]], [[Castle Mill Stream]], [[Bulstake Stream]] and others), creating several islands ([[Fiddler's Island]], [[Osney]] and others). [[Desborough Island]], [[Ham Island]] at Old Windsor and [[Penton Hook Island]] were artificially created by lock cuts and navigation channels. [[Chiswick Eyot]] is a landmark on the Boat Race course, while [[Glover's Island]] forms the centre of a view from [[Richmond Hill, London|Richmond Hill]].

Islands of historical interest include [[Magna Carta Island]] at [[Runnymede]], [[Fry's Island]] at Reading, and [[Pharaoh's Island, River Thames|Pharaoh's Island]] near Shepperton. In more recent times [[Platts Eyot]] at [[Hampton, London|Hampton]] was the place where [[Motor Torpedo Boats]] (MTB)s were built, [[Tagg's Island]] near Molesey was associated with the impresario [[Fred Karno]] and [[Eel Pie Island]] at Twickenham was the birthplace of the South East's [[Rhythm and blues|R&B]] music scene.

[[Westminster Abbey]] and the [[Palace of Westminster]] (commonly known today as the [[Houses of Parliament]]) were built on [[Thorney Island (Westminster)|Thorney Island]], which used to be an [[eyot]].