Tideway

For the software company acquired by BMC Software, see Tideway Systems.
Teddington Weir marks the start of the Tideway.

The Tideway is a name given to the part of the River Thames in England that is subject to tides. This stretch of water is downstream from Teddington Lock and is in its widest definition just under 160 kilometres (99 mi) long.[1] The Tideway includes the Thames Estuary, the Thames Gateway and the Pool of London.

Tidal activity

Depending on the time of year, the river tide rises and falls twice a day by up to 7 m (24 ft) and due to the need to overcome the outflow of fresh water from a significant part of England takes longer to subside (ebb) (6–9 hours) than it does to flow in (4–5 hours).

London Bridge is used as the basis for published tide tables giving the times of high tide. High tide reaches Putney about 30 minutes later, similarly Teddington/Ham.

Low-lying banks of London have been defended against natural vulnerability to flooding by storm surges. The threat has increased due to a slow but continuous rise in high water level, caused by the extremely slow 'tilting' of Britain (up in the north and down in the south) due to post-glacial rebound and the gradual rise in sea levels due to climate change.[2] The Thames Barrier was constructed across the Thames at Woolwich to deal with this threat.

Responsibilities

A Fast Response Targa 31 boat of the Marine Support Unit of the Metropolitan Police

The Tideway is managed by the Port of London Authority (PLA) and is often referred to as the Port of London. The upstream limit of its authority is marked by an obelisk just short of Teddington Lock. The PLA is responsible for one lock on the Thames: Richmond Lock.

In London, the Thames is policed by the Thames Division, the river police arm of London’s Metropolitan Police. Essex Police and Kent Police have responsibilities for the rest of the Tideway. 21st century criminal investigations have included the Roberto Calvi and Torso in the Thames cases. The London Fire Brigade has a fire boat on the river.

RNLI E class lifeboat based at Chiswick Pier performing a rescue

As a result of the Marchioness disaster in 1989 when 51 people died, the Government asked the Maritime and Coastguard Agency, the Port of London Authority and the Royal National Lifeboat Institution (RNLI) to work together to set up a dedicated Search and Rescue service for the tidal River Thames. As a result, there are four lifeboat stations on the Thames, at: Teddington, Chiswick Pier, Tower Pier and Gravesend.[3]

Navigation

Main article: Port of London
River traffic around Waterloo Pier in 2008
The Thames Lock on the Grand Union Canal at Brentford

The river is navigable to large ocean-going ships as far as the Pool of London at London Bridge and is the United Kingdom's second largest port by tonnage.[4] Today little commercial traffic passes above the Thames Barrier and central London sees only the occasional visiting cruise ship or warship, moored alongside HMS Belfast and a few smaller aggregate or refuse vessels, operating from wharves in the west of London. Most trade is handled by Tilbury docks, ro-ro ferry terminals at Dagenham and Dartford, and petroleum products handling facilities at Purfleet, Coryton and Canvey Island.

There is a speed limit of 8 knots (15 km/h) west of Wandsworth Bridge and in tributary creeks, and 12 knots (22 km/h) between Wandsworth Bridge and Margaretness.[5]

The tidal river is used for leisure navigation. In London sections there are many sightseeing tours in tourist boats, past the more famous riverside attractions such as the Houses of Parliament and the Tower of London as well as regular riverboat services provided by London River Services. This section is not suitable for sporting activity because of the strong stream through the bridges.

Rowing has a significant presence upstream of Putney Bridge, while sailing takes place in the same area and also along the coasts of the Estuary. The annual Great River Race for traditional rowed craft takes place over the stretch from Greenwich to Ham. Thames meander challenges along the length of the Thames from Lechlade often pass through the London sections and finish well downstream, for example at Gravesend Pier.

The Grand Union Canal joins the river at Brentford, with a branch – the Regent's Canal – joining at Limehouse Basin. The other part of the canal network still connecting on the Tideway is the River Lea Navigation.

Thames Reaches east of Westminster
Reach 1 Upper Pool, Lower Pool and Limehouse Reach
Reach 2 Limehouse, Greenwich and Blackwall Reach
Reach 3 Bugsby’s and Woolwich Reach
Reach 4 Gallions and Barking Reach
Reach 5 Halfway and Erith Reach
Reach 6 Erith Reach, Erith Rands and Long Reach
Reach 7 Long Reach and Fiddler’s Reach
Reach 8 Northfleet Hope
Reach 9 Gravesend Reach
Reach 10 The Lower Hope
Reach 11 Sea Reach

Environment

The River Thames flooding at Chiswick Lane South

Narrow low-lying belts beside the tidal section of the Thames regularly flood at spring tides, supporting brackish plants. However flooding has increased. One such example exists at Chiswick Lane South, where the river, as pictured, overflows this road a few times per year.

Although water quality has improved over the last 40 years and efforts to clean up the Tideway have led to the reintroduction of marine life and birds, the environment of the Tideway is still poor. Heavier rainfall in London causes overflows from pipes on the river banks from the standard type of sewer in the capital, the combined sewer. Around 39,000,000 m3 (3.9×1010 l) or 39 million tonnes of untreated sewage mixed with rainwater are released into the Tideway each year from sewage treatment works and combined sewer overflows (CSOs), averaging 106,849 m3 (106,849,000 l) per day or 106,849 tonnes per day (or 86.56 acre-feet per day).[6][7] These CSOs can cause the deaths of marine life and health hazards for river users.

Thames Estuary

Main article: Thames Estuary

The Thames Estuary applies to the coast and the low-lying lands upstream between the mouth of the River Stour on the Essex/Suffolk border and The Swale in north Kent. It is now usually designated the Greater Thames Estuary and is one of the largest inlets on the coast of Great Britain. It has the world's second largest tidal movement, where the water can rise by 4 metres moving at a speed of 8 miles per hour.

The estuary extends into London near Tower Bridge, divided into the Outer Estuary up to the Swale at the west end of the Isle of Sheppey, and the Inner Estuary, designated the Thames Gateway above this point. The shore of the Outer estuary consists of saltmarshes and mudflats, but there are man-made embankments along much of the route where the land behind is cultivated or used for grazing. Parts of the Outer estuary constitute a major shipping route.

Thames Gateway

Main article: Thames Gateway
The Grain Tower, Isle of Grain 1855, and causeway seen at low tide 2008
The Queen Elizabeth II Bridge

The Gateway is some 70 kilometres (43 mi) long,[1] stretching from the Isle of Sheppey to Westferry in Tower Hamlets. Its boundary was drawn to capture the riverside strip that formerly hosted many land extensive industries, serving London and the South East. The decline of these industries has left a legacy of large scale dereliction and contaminated land, but an opportunity for major redevelopment. The area includes the London Docklands, Millennium Dome, London Riverside and Thames Barrier.

Major crossings

Tributaries

Islands

Pool of London

Main article: Pool of London
Bridge open to admit HMS Northumberland

The Pool of London is divided into two parts, the Lower Pool and Upper Pool. The Lower Pool traditionally runs from the Cherry Garden Pier in Rotherhithe to Tower Bridge. The Upper Pool consists of the section between Tower Bridge and London Bridge. In the 18th and 19th centuries the river was lined with nearly continuous walls of wharves running for miles along both banks, and hundreds of ships moored in the river or alongside the quays. The lack of capacity in the Pool of London prompted landowners to build London's Docklands with enclosed docks with better security and facilities. The abrupt collapse of commercial traffic in the Thames due to the introduction of shipping containers and coastal deep-water ports in the 1960s emptied the Pool and led to all of the wharves being closed down. The Lower Pool area was extensively redeveloped in the 1980s and 1990s to create new residential and commercial neighbourhoods, often using converted warehouses. In the Upper Pool this provided scope for office development in the City of London and Southwark.

Major crossings

Inner London

London Bridge with the Gherkin in the background
Blackfriars Bridge with St Paul's Cathedral behind
Lambeth Palace, photographed looking east across the River Thames.
Battersea Power Station viewed from the north bank of the River Thames at Pimlico.

Between London Bridge and Putney Bridge, the river passes through Central London and some of the most famous landmarks.

North Bank South Bank
Monument
St Paul's Cathedral
Inner Temple
Somerset House
Victoria Embankment
HMS President
HMS Wellington
Cleopatra's Needle
Charing Cross railway station
Norman Shaw Buildings
Houses of Parliament
Tate Britain
Thames Embankment		 Southwark Cathedral
St Saviour's Dock
Globe Theatre
Tate Modern
Royal National Theatre
Royal Festival Hall
London Eye
Albert Embankment
County Hall, London
St Thomas' Hospital
Lambeth Palace
SIS Building
Battersea Power Station

Riverboats carry tourists up down and across the river, and also provide regular commuter service.

Major crossings

Tributaries

(culverted tributaries largely converted to sewers are marked ‡)

Outer London

Putney Bridge
Historic riverside pub, Strand-on-the-Green, Chiswick
View from Richmond Hill, Richmond.

From Putney Bridge to Teddington Lock, the river passes through inner and outer suburbs such as Hammersmith, Chiswick, Barnes, Richmond on Thames and Ham. This part of the Tideway is home to most of London's rowing clubs, and is the venue for training and racing throughout the year. The Championship Course over which The Boat Race and many other events are run, stretches from Putney to Mortlake.

Major crossings

Tributaries

Islands

See also

References

External links

Coordinates: 51°25′47″N 0°19′12″W / 51.4298°N 0.3200°W / 51.4298; -0.3200

This article is issued from Wikipedia - version of the Tuesday, April 19, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.