River Thames

River Thames The River Thames (pronounced /ˈtɛmz/ ( listen) temz) is a major river flowing through southern England. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford, Reading, Henley-on-Thames, Windsor, Kingston Upon Thames and Richmond. The river gives its name to several geographical and political entities including the Thames Valley, a region of England centred around the river between Oxford and west London, the Thames Gateway, the area centred around the tidal Thames, and the Thames Estuary to the east of London. Summary The Thames is the second longest river in the United Kingdom and the longest river entirely in England. It rises at Thames Head in Gloucestershire, and flows into the North Sea at the Thames Estuary. It has a special significance in flowing through London, the capital of the United Kingdom, although London only includes a short part of its course. The river is tidal in London with a rise and fall of 7 metres (23 ft); tides reaching up to Teddington Lock. The catchment area covers a large part of South Eastern and Western England and the river is fed by over 20 tributaries. The river contains over 80 islands, and having both seawater and freshwater stretches, it supports a variety of wildlife. The river has supported human activity from its source to its mouth for thousands of years providing habitation, water power, food and drink. It has also acted as a major highway through the Port of London for international trade, internally along its length and by its connection to the British canal system. The river’s strategic position has seen it at the centre of many events and fashions in British history, earning it a description by John Burns as “Liquid History”. It has been a physical and political boundary over the centuries and generated a range of river crossings. More recently, the river has become a major leisure area supporting tourism and pleasure outings as well as the sports of rowing, sailing, skiffing, kayaking, and punting. The river has had a special appeal to writers, artists, musicians and film-makers and is well-represented in the arts. It is still the subject of various debates about its course, nomenclature and history. Physical and natural aspects The Thames is 215 miles (346 km) long. Its usually quoted source is at Thames Head (at grid reference ST980994), about a mile north of the village of Kemble and near the town of Cirencester, in the Cotswolds.[1] Seven Springs near Cheltenham, where the river Churn rises, is also sometimes quoted as the Thames' source,[2] as this location is furthest from the mouth, and adds some 14 miles (22 km) to the length. The springs at Seven Springs also flow throughout the year, while those at Thames Head are only seasonal. The Thames is the longest river entirely in England, but the River Severn, which is partly in Wales, is the longest river in the United Kingdom. The Thames flows through or alongside Ashton Keynes, Cricklade, Lechlade, Oxford, Abingdon, Wallingford, Goring-on-Thames, Reading, Henley-on-Thames, Marlow, Maidenhead, Windsor, Eton, Staines, Sunbury, Weybridge and Thames Ditton before entering the Greater London area. The present course is the result of several minor redirections of the main channel around Oxford, Abingdon and Maidenhead and more recently the creation of specific cuts to ease navigation. From the outskirts of Greater London, the river passes Hampton Court, Surbiton, Kingston, Teddington, Twickenham, Richmond (with a famous view of the Thames from Richmond Hill), Syon House and Kew before flowing through central London. In central London, the river forms one of the principal axes of the city, from the Palace of Westminster to the Tower of London and was the southern boundary of the medieval city, with Southwark on the opposite bank. Past central London, the river passes between Greenwich and the Isle of Dogs, before flowing through the Thames Barrier, which protects central London from flooding by storm surges. Below the barrier, the river passes Dartford, Tilbury and Gravesend before entering the Thames Estuary near Southend-on-Sea. Catchment area and discharge The river drains a catchment area of 4,995 sq mi (12935.77 km2) or 5,924 sq mi (15,343 km2) if the River Medway is included as a tributary. The non-tidal section Brooks, canals and rivers, within an area of 3,841 square miles (9,948 km2), combine to form 38 main tributaries feeding the Thames between its source and Teddington Lock, the tidal limit. Before Teddington Lock was built in 1810-12, the river was tidal as far as Staines. The tributaries of the River Thames include the rivers Churn, Leach, Cole, Ray, Coln, Windrush, Evenlode, Cherwell, Ock, Thame, Pang, Kennet, Loddon, Colne, Wey and Mole. In addition there are many backwaters and distributaries and some man-made channels such as the Longford River. More recently, the Jubilee River, an artificial secondary channel to the Thames, was built between Maidenhead and Windsor for flood relief. It was completed in 2002. More than half the rain that falls on this catchment is lost to evaporation and plant transpiration. The remainder provides a water resource that has to be shared between river flows, to support the natural environment and navigation, and the population's needs for water supplies to homes, industry and agriculture. The non-tidal section of the river is managed by the Environment Agency which is responsible for both managing the flow of water to control flooding, and providing for navigation. The volume and speed of water down the river is managed by adjusting the gates at each of the weirs and at high water levels are usually dissipated over flood plains adjacent to the river. Occasionally flooding is unavoidable, and the Agency issues Flood Warnings. During heavy rainfall the Thames occasionally receives raw sewage discharge due to sanitary sewer overflow. The tidal section Below Teddington Lock (about 55 miles / 89 kilometres upstream of 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 miles (26 km) upstream.[4] 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.[5] 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 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 broadcast on Twitter. The principal tributaries of the River Thames on the Tideway include the rivers Brent, Wandle, Effra, Westbourne, Fleet, Ravensbourne (the final part of which is called Deptford Creek), Lea, Roding, Darent and Ingrebourne. At 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 the North Sea, and the Thames Barrier was built in the 1980s to protect London from this risk. Islands The River Thames contains over 80 islands ranging from the large estuarial marshlands of the Isle of Sheppey, Isle of Grain and Canvey Island to small tree-covered islets like Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. 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 familiar landmark on the Boat Race course, while Glover's Island forms the centrepiece of the spectacular view from Richmond Hill. Islands with a historical interest are 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 MTBs 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 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. Geological history The River Thames can first be identified as a discrete drainage line as early as 58 million years ago, in the Thanetian stage of the late Palaeocene epoch.[6] Until around half a million 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 Ipswich. At this time the river system headwaters lay in the English West Midlands and may, at times, have received drainage from the North Wales Berwyn Mountains. Arrival of an ice sheet in the Quaternary Ice Age, about 450,000 years ago, dammed the river in Hertfordshire and caused it to be diverted onto its present course through London.

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