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80-721: Sheepwash Channel connects the River Thames to the west and the Castle Mill Stream next to the Oxford Canal to the east (linked through Isis Lock ), in west Oxford , England . To the north are Cripley Meadow (largely allotments ) and Fiddler's Island . To the south are Osney Island and the Botley Road . The Cherwell Valley Line and Cotswold Line cross the channel just north of Oxford railway station on Sheepwash Channel Railway Bridge . Just to

160-498: A closed drainage basin, or endorheic basin , rather than flowing to the ocean, water converges toward the interior of the basin, known as a sink , which may be a permanent lake, a dry lake , or a point where surface water is lost underground . Drainage basins are similar but not identical to hydrologic units , which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system . Hydrologic units are defined to allow multiple inlets, outlets, or sinks. In

240-444: A drainage basin are catchment area , catchment basin , drainage area , river basin , water basin , and impluvium . In North America, they are commonly called a watershed , though in other English-speaking places, "watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation , a common task in environmental engineering and science. In

320-454: A drainage basin, and there are different ways to interpret that data. In the unlikely event that the gauges are many and evenly distributed over an area of uniform precipitation, using the arithmetic mean method will give good results. In the Thiessen polygon method, the drainage basin is divided into polygons with the rain gauge in the middle of each polygon assumed to be representative for

400-540: A drainage boundary is referred to as watershed delineation . Finding the area and extent of a drainage basin is an important step in many areas of science and engineering. Most of the water that discharges from the basin outlet originated as precipitation falling on the basin. A portion of the water that enters the groundwater system beneath the drainage basin may flow towards the outlet of another drainage basin because groundwater flow directions do not always match those of their overlying drainage network. Measurement of

480-561: A network of creeks. Lying below sea level, it is prone to flooding at exceptional tides, but has nevertheless been inhabited since Roman times. The usually quoted source of the Thames is at Thames Head (at grid reference ST980994 ). This is about 1.5 mi (2.4 km) north of the village of Kemble in southern Gloucestershire , near the town of Cirencester , in the Cotswolds . However, Seven Springs near Cheltenham , where

560-588: A river in England is a stub . You can help Misplaced Pages by expanding it . River Thames The River Thames ( / t ɛ m z / TEMZ ), known alternatively in parts as the River Isis , is a river that flows through southern England including London . At 215 miles (346 km), it is the longest river entirely in England and the second-longest in the United Kingdom , after

640-794: A small part of the Canadian provinces of Alberta and Saskatchewan , eastern Central America , the islands of the Caribbean and the Gulf, and a small part of northern South America. The Mediterranean Sea basin, with the Black Sea , includes much of North Africa , east-central Africa (through the Nile River ), Southern , Central, and Eastern Europe , Turkey , and the coastal areas of Israel , Lebanon , and Syria . The Arctic Ocean drains most of Western Canada and Northern Canada east of

720-826: A strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. About 48.71% of the world's land drains to the Atlantic Ocean . In North America , surface water drains to the Atlantic via the Saint Lawrence River and Great Lakes basins, the Eastern Seaboard of the United States, the Canadian Maritimes , and most of Newfoundland and Labrador . Nearly all of South America east of

800-639: A summer venue for organised swimming, which is prohibited on safety grounds in a stretch centred on Central London . After the river took its present-day course, many of the banks of the Thames Estuary and the Thames Valley in London were partly covered in marshland , as was the adjoining Lower Lea Valley . Streams and rivers like the River Lea , Tyburn Brook and Bollo Brook drained into

880-471: Is a landmark on the Boat Race course, while Glover's Island forms the centre of a view from Richmond Hill . Islands of historical interest include Magna Carta Island at Runnymede , Fry's Island at Reading, and Pharaoh's Island near Shepperton. In more recent times Platts Eyot at Hampton was the place where Motor Torpedo Boats (MTB)s were built, Tagg's Island near Molesey was associated with

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960-402: 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. Brooks, canals and rivers, within an area of 3,842 sq mi (9,951 km ), combine to form 38 main tributaries feeding the Thames between its source and Teddington Lock . This

1040-649: Is believed that Tamesubugus' name was derived from that of the river. Tamese was referred to as a place, not a river in the Ravenna Cosmography ( c.  AD 700 ). The river's name has always been pronounced with a simple t /t/ ; the Middle English spelling was typically Temese and the Brittonic form Tamesis . A similar spelling from 1210, "Tamisiam" (the accusative case of "Tamisia"; see Kingston upon Thames § Early history ),

1120-572: Is derived from the Brittonic name for the river, Tamesas (from * tamēssa ), recorded in Latin as Tamesis and yielding modern Welsh Tafwys "Thames". The name element Tam may have meant "dark" and can be compared to other cognates such as Russian темно ( Proto-Slavic * tĭmĭnŭ ), Lithuanian tamsi "dark", Latvian tumsa "darkness", Sanskrit tamas and Welsh tywyll "darkness" and Middle Irish teimen "dark grey". The origin

1200-511: Is fed by at least 50 named tributaries . The river contains over 80 islands . With its waters varying from freshwater to almost seawater, the Thames supports a variety of wildlife and has a number of adjoining Sites of Special Scientific Interest , with the largest being in the North Kent Marshes and covering 20.4 sq mi (5,289 ha). According to Mallory and Adams, the Thames, from Middle English Temese ,

1280-604: Is formed for much of its length for shipping and supplies: through the Port of London for international trade, internally along its length and by its connection to the British canal system. The river's position has put it at the centre of many events in British history, leading to it being described by John Burns as "liquid history". Two broad canals link the river to other rivers: the Kennet and Avon Canal ( Reading to Bath ) and

1360-697: Is found in Magna Carta . The Thames through Oxford is sometimes called the Isis . Historically, and especially in Victorian times, gazetteers and cartographers insisted that the entire river was correctly named the Isis from its source down to Dorchester on Thames and that only from this point, where the river meets the Thame and becomes the "Thame-isis" (supposedly subsequently abbreviated to Thames) should it be so called. Ordnance Survey maps still label

1440-487: Is referred to as " watershed management ". In Brazil , the National Policy of Water Resources, regulated by Act n° 9.433 of 1997, establishes the drainage basin as the territorial division of Brazilian water management. When a river basin crosses at least one political border, either a border within a nation or an international boundary, it is identified as a transboundary river . Management of such basins becomes

1520-452: 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

1600-948: Is shared by many other river names in Britain, such as the River Tamar at the border of Devon and Cornwall , several rivers named Tame in the Midlands and North Yorkshire , the Tavy on Dartmoor , the Team of the North East, the Teifi and Teme of Wales , the Teviot in the Scottish Borders and a Thames tributary, the Thame . Kenneth H. Jackson proposed that the name of

1680-614: Is the Dead Sea . Drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important. For example, the English crown gave the Hudson's Bay Company a monopoly on the fur trade in the entire Hudson Bay basin, an area called Rupert's Land . Bioregional political organization today includes agreements of states (e.g., international treaties and, within

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1760-404: 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 weir , which is visible from the towpath and bridge beside Hampton Court Palace . Before Teddington Lock was built in 1810–12,

1840-713: The African Great Lakes , the interiors of Australia and the Arabian Peninsula , and parts in Mexico and the Andes . Some of these, such as the Great Basin, are not single drainage basins but collections of separate, adjacent closed basins. In endorheic bodies of water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this

1920-464: The Andes also drains to the Atlantic, as does most of Western and Central Europe and the greatest portion of western Sub-Saharan Africa , as well as Western Sahara and part of Morocco . The two major mediterranean seas of the world also flow to the Atlantic. The Caribbean Sea and Gulf of Mexico basin includes most of the U.S. interior between the Appalachian and Rocky Mountains ,

2000-811: The Berwyn Mountains in North Wales . About 450,000 years ago, in the most extreme Ice Age of the Pleistocene , the Anglian , the furthest southern extent of the ice sheet reached Hornchurch in east London, the Vale of St Albans, and the Finchley Gap . It dammed the river in Hertfordshire , resulting in the formation of large ice lakes, which eventually burst their banks and caused

2080-541: 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. 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 mm per year from 10,000 to 6,000 years ago. The rise of sea level dramatically reduced when

2160-518: The Churn (which feeds into the Thames near Cricklade ) rises, is also sometimes quoted as the Thames' source, as this location is farthest from the mouth and adds some 14 mi (23 km) to the river's length. At Seven Springs above the source is a stone with the Latin hexameter inscription "Hic tuus o Tamesine pater septemgeminus fons", which means "Here, O Father Thames, [is] your sevenfold source". The springs at Seven Springs flow throughout

2240-765: The Continental Divide , northern Alaska and parts of North Dakota , South Dakota , Minnesota , and Montana in the United States, the north shore of the Scandinavian peninsula in Europe, central and northern Russia, and parts of Kazakhstan and Mongolia in Asia , which totals to about 17% of the world's land. Just over 13% of the land in the world drains to the Pacific Ocean . Its basin includes much of China, eastern and southeastern Russia, Japan,

2320-684: The Grand Union Canal (London to the Midlands). The Grand Union effectively bypassed the earlier, narrow and winding Oxford Canal which remains open as a popular scenic recreational route. Three further cross-basin canals are disused but are in various stages of reconstruction: the Thames and Severn Canal (via Stroud ), which operated until 1927 (to the west coast of England), the Wey and Arun Canal to Littlehampton , which operated until 1871 (to

2400-714: The Korean Peninsula , most of Indochina, Indonesia and Malaysia, the Philippines, all of the Pacific Islands , the northeast coast of Australia , and Canada and the United States west of the Continental Divide (including most of Alaska), as well as western Central America and South America west of the Andes. The Indian Ocean 's drainage basin also comprises about 13% of Earth's land. It drains

2480-489: The River Lea can be considered another boundary. Most of the local riverside was also marshland. The land was drained and became farmland; it was built on after the Industrial Revolution . Canvey Island in southern Essex (area 18.45 km , 7.12 sq mi; population 40,000 ) was once marshy, but is now a fully reclaimed island in the Thames estuary, separated from the mainland of south Essex by

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2560-636: The River Severn . The river rises at Thames Head in Gloucestershire and flows into the North Sea near Tilbury , Essex and Gravesend , Kent, via the Thames Estuary . From the west, it flows through Oxford (where it is sometimes called the Isis), Reading , Henley-on-Thames and Windsor . The Thames also drains the whole of Greater London . The lower reaches of the river are called

2640-662: The Royal Academy , London , in 1785. They are now on show at the River and Rowing Museum in Henley). Richard Coates suggests that while the river was as a whole called the Thames, part of it, where it was too wide to ford, was called * (p)lowonida . This gave the name to a settlement on its banks, which became known as Londinium , from the Indo-European roots * pleu- "flow" and * -nedi "river" meaning something like

2720-504: The Thames Barrier , which protects central London from flooding by storm surges . 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 . The sea level in the Thames estuary is rising and the rate of rise is increasing. Sediment cores up to 10 m deep collected by

2800-549: The Thanetian stage of the late Palaeocene epoch. Until around 500,000 years ago, the Thames flowed on its existing course through what is now Oxfordshire , before turning to the north-east through Hertfordshire and East Anglia and reaching the North Sea near present-day Ipswich . At this time the river-system headwaters lay in the English West Midlands and may, at times, have received drainage from

2880-474: The Tideway , derived from its long tidal reach up to Teddington Lock . Its tidal section includes most of its London stretch and has a rise and fall of 23 ft (7 m). From Oxford to the estuary, the Thames drops by 55 metres (180 ft). Running through some of the drier parts of mainland Britain and heavily abstracted for drinking water, the Thames' discharge is low considering its length and breadth:

2960-719: The Castle Mill Stream and the Oxford Canal, allowing access between the Oxford Canal and the River Thames via the channel for boats. At the western end is a footbridge over Sheepwash Channel, forming part of the Thames Path . 51°45′20″N 1°16′15″W  /  51.755586°N 1.270946°W  / 51.755586; -1.270946 This Oxfordshire location article is a stub . You can help Misplaced Pages by expanding it . This article related to

3040-411: 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 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

3120-489: The River Thames on the Tideway include the rivers Crane , Brent , Wandle , Ravensbourne (the final part of which is called Deptford Creek ), Lea (the final part of which is called Bow Creek ), Roding (Barking Creek), Darent and Ingrebourne . In London, the water is slightly brackish with sea salt, being a mix of sea and fresh water. 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

3200-401: The Severn has a discharge almost twice as large on average despite having a smaller drainage basin . In Scotland , the Tay achieves more than double the Thames' average discharge from a drainage basin that is 60% smaller. Along its course are 45 navigation locks with accompanying weirs . Its catchment area covers a large part of south-eastern and a small part of western England; the river

3280-416: The Thames Estuary), the river is subject to tidal activity from the North Sea . Before the lock was installed, the river was tidal as far as Staines, about 16 mi (26 km) upstream. London, capital of Roman Britain , was established on two hills, now known as Cornhill and Ludgate Hill . These provided a firm base for a trading centre at the lowest possible point on the Thames. A river crossing

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3360-470: The Thames as "River Thames or Isis" down to Dorchester. Since the early 20th century this distinction has been lost in common usage outside of Oxford, and some historians suggest the name Isis is nothing more than a truncation of Tamesis , the Latin name for the Thames. Sculptures titled Tamesis and Isis by Anne Seymour Damer are located on the bridge at Henley-on-Thames , Oxfordshire (the original terracotta and plaster models were exhibited at

3440-439: The Thames is not Indo-European (and of unknown meaning), while Peter Kitson suggested that it is Indo-European but originated before the Britons and has a name indicating "muddiness" from a root *tā- , 'melt'. Early variants of the name include: Indirect evidence for the antiquity of the name "Thames" is provided by a Roman potsherd found at Oxford, bearing the inscription Tamesubugus fecit (Tamesubugus made [this]). It

3520-417: The US, interstate compacts ) or other political entities in a particular drainage basin to manage the body or bodies of water into which it drains. Examples of such interstate compacts are the Great Lakes Commission and the Tahoe Regional Planning Agency . In hydrology , the drainage basin is a logical unit of focus for studying the movement of water within the hydrological cycle . The process of finding

3600-406: The basin, it can form tributaries that change the structure of the land. There are three different main types, which are affected by the rocks and ground underneath. Rock that is quick to erode forms dendritic patterns, and these are seen most often. The two other types of patterns that form are trellis patterns and rectangular patterns. Rain gauge data is used to measure total precipitation over

3680-423: The case of the 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. The non-tidal section of the river is managed by the Environment Agency , which

3760-423: The confluence, the overall length of the Thames measured from Seven Springs, at 229 mi (369 km), is greater than the Severn's length of 220 mi (350 km). 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

3840-430: The discharge of water from a basin may be made by a stream gauge located at the basin's outlet. Depending on the conditions of the drainage basin, as rainfall occurs some of it seeps directly into the ground. This water will either remain underground, slowly making its way downhill and eventually reaching the basin, or it will permeate deeper into the soil and consolidate into groundwater aquifers. As water flows through

3920-441: The drainage area is dependent on the soil type. Certain soil types such as sandy soils are very free-draining, and rainfall on sandy soil is likely to be absorbed by the ground. However, soils containing clay can be almost impermeable and therefore rainfall on clay soils will run off and contribute to flood volumes. After prolonged rainfall even free-draining soils can become saturated , meaning that any further rainfall will reach

4000-642: The drainage basin to the mouth, and may accumulate there, disturbing the natural mineral balance. This can cause eutrophication where plant growth is accelerated by the additional material. Because drainage basins are coherent entities in a hydrological sense, it has become common to manage water resources on the basis of individual basins. In the U.S. state of Minnesota , governmental entities that perform this function are called " watershed districts ". In New Zealand, they are called catchment boards. Comparable community groups based in Ontario, Canada, are called conservation authorities . In North America, this function

4080-400: The east, there is Rewley Road Swing Bridge , a swing bridge for the former Buckinghamshire Railway line of London and North Western Railway , that used to serve the Oxford Rewley Road railway station , which was on the site of the Saïd Business School . Rewley Road Bridge also crosses Sheepwash Channel. The Isis Lock just to the north of the eastern end of Sheepwash Channel connects

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4160-432: The eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf , the Indian subcontinent , Burma, and most parts of Australia . The five largest river basins (by area), from largest to smallest, are those of the Amazon (7 million km ), the Congo (4 million km ), the Nile (3.4 million km ), the Mississippi (3.22 million km ), and the Río de la Plata (3.17 million km ). The three rivers that drain

4240-412: The flowing river or the wide flowing unfordable river. The river gives its name to three informal areas: the Thames Valley , a region of England around the river between Oxford and West London; the Thames Gateway ; and the greatly overlapping Thames Estuary around the tidal Thames to the east of London and including the waterway itself. Thames Valley Police is a formal body that takes its name from

4320-435: The ground and along rivers it can pick up nutrients , sediment , and pollutants . With the water, they are transported towards the outlet of the basin, and can affect the ecological processes along the way as well as in the receiving water body . Modern use of artificial fertilizers , containing nitrogen (as nitrates ), phosphorus , and potassium , has affected the mouths of drainage basins. The minerals are carried by

4400-422: The ground at its terminus, the area can go by several names, such playa, salt flat, dry lake , or alkali sink . The largest endorheic basins are in Central Asia , including the Caspian Sea , the Aral Sea , and numerous smaller lakes. Other endorheic regions include the Great Basin in the United States, much of the Sahara Desert , the drainage basin of the Okavango River ( Kalahari Basin ), highlands near

4480-533: The grounds of the National Star College at Ullenwood . The Thames flows through or alongside Ashton Keynes , Cricklade , Lechlade , Oxford , Abingdon-on-Thames , Wallingford , Goring-on-Thames and Streatley (at the Goring Gap ), Pangbourne and Whitchurch-on-Thames , Reading , Wargrave , Henley-on-Thames , Marlow , Maidenhead , Windsor and Eton , Staines-upon-Thames and Egham , Chertsey , Shepperton , Weybridge , Sunbury-on-Thames , Walton-on-Thames , Molesey and Thames Ditton . The river

4560-404: The ice melt nearly concluded over the past 4,000 years. Since the beginning of the 20th century, rates of sea level rise range from 1.22 mm per year to 2.14 mm per year. The Thames River Basin District, including the Medway catchment, covers an area of 6,229 sq mi (16,130 km ). The entire river basin is a mixture of urban and rural, with rural landscape predominating in

4640-416: The impresario Fred Karno and Eel Pie Island at Twickenham was the birthplace of the South East's R&B music scene. Westminster Abbey and the Palace of Westminster (commonly known today as the Houses of Parliament ) were built on Thorney Island , which used to be an eyot . Researchers have identified the River Thames as a discrete drainage line flowing as early as 58 million years ago, in

4720-409: The most water, from most to least, are the Amazon, Ganges , and Congo rivers. Endorheic basin are inland basins that do not drain to an ocean. Endorheic basins cover around 18% of the Earth's land. Some endorheic basins drain to an Endorheic lake or Inland sea . Many of these lakes are ephemeral or vary dramatically in size depending on climate and inflow. If water evaporates or infiltrates into

4800-426: The non-tidal river, which is a drinking water source before treatment, sanitary sewer overflow from the many sewage treatment plants 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 despite claims by Thames Water to the contrary. Below Teddington Lock (about 55 mi or 89 km upstream of

4880-418: The rainfall on the area of land included in its polygon. These polygons are made by drawing lines between gauges, then making perpendicular bisectors of those lines form the polygons. The isohyetal method involves contours of equal precipitation are drawn over the gauges on a map. Calculating the area between these curves and adding up the volume of water is time-consuming. Isochrone maps can be used to show

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4960-572: The responsibility of the countries sharing it. Nile Basin Initiative , OMVS for Senegal River , Mekong River Commission are a few examples of arrangements involving management of shared river basins. Management of shared drainage basins is also seen as a way to build lasting peaceful relationships among countries. The catchment is the most significant factor determining the amount or likelihood of flooding . Catchment factors are: topography , shape, size, soil type, and land use (paved or roofed areas). Catchment topography and shape determine

5040-534: 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 , New Charlton and Silvertown , before flowing through

5120-461: The river rather than being absorbed by the ground. If the surface is impermeable the precipitation will create surface run-off which will lead to higher risk of flooding; if the ground is permeable, the precipitation will infiltrate the soil. Land use can contribute to the volume of water reaching the river, in a similar way to clay soils. For example, rainfall on roofs, pavements , and roads will be collected by rivers with almost no absorption into

5200-404: The river to divert onto its present course through the area of present-day London. The ice lobe which stopped at present-day Finchley deposited about 14 metres of boulder clay there. Its torrent of meltwater gushed through the Finchley Gap and south towards the new course of the Thames, and proceeded to carve out the Brent Valley in the process. Drainage basin Other terms for

5280-439: 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 Churn , Leach , Cole , Ray , Coln , Windrush , Evenlode , Cherwell , Ock , Thame , Pang , Kennet , Loddon , Colne , Wey and Mole . In addition, there are occasional backwaters and artificial cuts that form islands, distributaries (most numerous in

5360-530: The river, covering three counties . In non-administrative use, the river's name is used in those of Thames Valley University , Thames Water , Thames Television , publishing company Thames & Hudson , Thameslink (north–south rail service passing through central London ) and South Thames College . An example of its use in the names of historic entities is the Thames Ironworks and Shipbuilding Company . Marks of human activity, in some cases dating back to Pre-Roman Britain , are visible at various points along

5440-399: The river, while some islands, e.g. Thorney Island , formed over the ages. The northern tip of the ancient parish of Lambeth , for example, was marshland known as Lambeth Marshe , but it was drained in the 18th century; the street names Lower Marsh and Upper Marsh preserve a memory. Until the middle of the Victorian era, malaria was commonplace beside the River Thames, even in London, and

5520-467: The river. These include a variety of structures connected with use of the river, such as navigations, bridges and watermills , as well as prehistoric burial mounds . The lower Thames in the Roman era was a shallow waterway winding through marshes. But centuries of human intervention have transformed it into a deep tidal canal flowing between 200 miles of solid walls; these defend a floodplain where 1.5 million people work and live. A major maritime route

5600-494: The sandbank was a major hazard for shipping coming in and out of London, in 1732 it received the world's first 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. 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

5680-419: The south coast), and the Wilts & Berks Canal . Rowing and sailing clubs are common along the Thames, which is navigable to such vessels. Kayaking and canoeing also take place. Major annual events include the Henley Royal Regatta and the Boat Race , while the Thames has been used during two Summer Olympic Games : 1908 ( rowing ) and 1948 ( rowing and canoeing ). Safe headwaters and reaches are

5760-418: The speed with which the runoff reaches a river. A long thin catchment will take longer to drain than a circular catchment. Size will help determine the amount of water reaching the river, as the larger the catchment the greater the potential for flooding. It is also determined on the basis of length and width of the drainage basin. Soil type will help determine how much water reaches the river. The runoff from

5840-415: The time taken for rain to reach the river, while catchment size, soil type, and development determine the amount of water to reach the river. Generally, topography plays a big part in how fast runoff will reach a river. Rain that falls in steep mountainous areas will reach the primary river in the drainage basin faster than flat or lightly sloping areas (e.g., > 1% gradient). Shape will contribute to

5920-477: The time taken for runoff water within a drainage basin to reach a lake, reservoir or outlet, assuming constant and uniform effective rainfall. Drainage basins are the principal hydrologic unit considered in fluvial geomorphology . A drainage basin is the source for water and sediment that moves from higher elevation through the river system to lower elevations as they reshape the channel forms. Drainage basins are important in ecology . As water flows over

6000-866: 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

6080-412: The western part. The area is among the driest in the United Kingdom. Water resources consist of groundwater from aquifers and water taken from the Thames and its tributaries, much of it stored in large bank-side reservoirs . 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

6160-580: The year, while those at Thames Head are seasonal (a winterbourne ). With a length of 215 mi (346 km), the Thames is the longest river entirely in England. (The longest river in the United Kingdom, the Severn , flows partly in Wales .) However, as the River Churn, sourced at Seven Springs, is 14 mi (23 km) longer than the section of the Thames from its traditional source at Thames Head to

6240-479: Was built at the site of London Bridge . London Bridge is now used as the basis for published tide tables giving the times of high tide . High tide reaches Putney about 30 minutes later than London Bridge, and Teddington about an hour later. The tidal stretch of the river is known as "the Tideway ". Tide tables are published by the Port of London Authority and are available online. Times of high and low tides are also posted on Twitter. The principal tributaries of

6320-463: Was frequently lethal. Some cases continued to occur into the early 20th century. Draining of the marshes helped with its eradication, but the causes are complex and unclear. The East End of London , also known simply as the East End , was the area of London east of the medieval walled City of London and north of the River Thames, although it is not defined by universally accepted formal boundaries;

6400-617: 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 , and in Greater London the Thames passes Hampton Court Palace , Surbiton , Kingston upon Thames , Teddington , Twickenham , Richmond (with a famous view of the Thames from Richmond Hill), Syon House , Kew , Brentford , Chiswick , Barnes , Hammersmith , Fulham , Putney , Wandsworth , Battersea and Chelsea . In central London ,

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