page_title: River Thames
section_title: Physical and natural aspects
hierarchical_section_title: River Thames / Physical and natural aspects
caption_attribution_description: The Thames Barrier prevents the floodplain of most of Greater London from being flooded by exceptionally high tides and storm surges moving up from the North Sea. It has been operational since 1984. When needed, it is closed (raised) during high tide; at low tide it can be opened to restore the river's flow towards the sea. Built approximately 3 km due east of the Isle of Dogs, its northern bank is in Silvertown in the London Borough of Newham and its southern bank is in the New Charlton area of the Royal Borough of Greenwich.
context_page_description: The River Thames, known alternatively in parts as the Isis, is a river that flows through southern England including London. At 215 miles, it is the longest river entirely in England and the second-longest in the United Kingdom, after the River Severn.
  It flows through Oxford, Reading, Henley-on-Thames and Windsor. The lower reaches of the river are called the Tideway, derived from its long tidal reach up to Teddington Lock. It rises at Thames Head in Gloucestershire, and flows into the North Sea via the Thames Estuary. The Thames drains the whole of Greater London.
  Its tidal section, reaching up to Teddington Lock, includes most of its London stretch and has a rise and fall of 23 feet. Running through some of the driest parts of mainland Britain and heavily abstracted for drinking water, the Thames' discharge is low considering its length and breadth: 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.
context_section_description: The usually quoted source of the Thames is at Thames Head (at grid reference ST980994). This is about ³⁄₄ mile (1.2 km) north of Kemble parish church in southern Gloucestershire, near the town of Cirencester, in the Cotswolds.
  However, Seven Springs near Cheltenham, where the Churn (which feeds into the Thames near Cricklade) rises, is also sometimes quoted as the Thames' source, as this location is furthest from the mouth, and adds some 14 miles (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 the year, while those at Thames Head are only seasonal (a winterbourne). 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 miles (23 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 229 miles (369 km), is greater than the Severn's length of 220 miles (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 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, 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 was subject to minor redefining and widening of the main channel around Oxford, Abingdon and Marlow before 1850, since when further cuts to ease navigation have 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, 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 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.
caption: The Thames Barrier provides protection against floods
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