Editing River Thames (section)

===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>