Canal

Canals, or navigations, are human-made channels, or artificial waterways, for water conveyance, or to service water transport vehicles.

In most cases, the engineered works will have a series of dams and locks that create reservoirs of low speed current flow. These reservoirs are referred to as slack water levels, often just called levels.

A canal is also known as a navigation when it parallels a river and shares part of its waters and drainage basin, and leverages its resources by building dams and locks to increase and lengthen its stretches of slack water levels while staying in its valley.

In contrast, a canal cuts across a drainage divide atop a ridge, generally requiring an external water source above the highest elevation.

Many canals have been built at elevations towering over valleys and other water ways crossing far below.

Canals with sources of water at a higher level can deliver water to a destination such as a city where water is needed. The Roman Empire's aqueducts were such water supply canals.

Alter Strom
The Alter Strom, in the sea resort of Warnemünde, Germany.
Basingstoke Canal - Lock
Small boat canals such as the Basingstoke Canal fuelled the industrial revolution in much of Europe and the United States.
Wenecja, kanał wodny (Aw58TF)
Canal in Venice.

Types of artificial waterways

A navigation is a series of channels that run roughly parallel to the valley and stream bed of an unimproved river. A navigation always shares the drainage basin of the river. A vessel uses the calm parts of the river itself as well as improvements, traversing the same changes in height.

A true canal is a channel that cuts across a drainage divide, making a navigable channel connecting two different drainage basins.

Most commercially important canals of the first half of the 19th century were a little of each, using rivers in long stretches, and divide crossing canals in others. This is true for many canals still in use.

Structures used in artificial waterways

Both navigations and canals use engineered structures to improve navigation:

  • weirs and dams to raise river water levels to usable depths;
  • looping descents to create a longer and gentler channel around a stretch of rapids or falls;
  • locks to allow ships and barges to ascend/descend.

Since they cut across drainage divides, canals are more difficult to construct and often need additional improvements, like viaducts and aqueducts to bridge waters over streams and roads, and ways to keep water in the channel.

Types of canals

There are two broad types of canal:

  • Waterways: canals and navigations used for carrying vessels transporting goods and people. These can be subdivided into two kinds:
Chutes Loading the Canal Boats on the Lehigh Canal
Loading Anthracite on the Lehigh Canal to feed the early United States industries in the pioneer-era.
River Levee Cross Section Figure
1. Design High Water Level (HWL) 2. Low water channel 3. Flood channel 4. Riverside slope 5. Riverside banquette 6. Levee crown 7. Landside slope 8. Landside banquette 9. Berm 10. Low water revetment 11. Riverside land 12. Levee 13. Protected lowland 14. River zone

Importance

Canal de Castilla
Canal de Castilla in Castile and León, Spain, has 207 kilometers, crossing 38 municipalities, initially to transport wheat, now it is used for irrigation.

Historically canals were of immense importance to commerce and the development, growth and vitality of a civilization. In 1855 the Lehigh Canal carried over 1.2 million tons of anthracite coal; by the 1930s the company which built and operated it over a century pulled the plug. The few canals still in operation in our modern age are a fraction of the numbers that once fueled and enabled economic growth, indeed were practically a prerequisite to further urbanization and industrialization – for the movement of bulk raw materials such as coal and ores are difficult and marginally affordable without water transport. Such raw materials fueled the industrial developments and new metallurgy resulting of the spiral of increasing mechanization during 17th–20th century, leading to new research disciplines, new industries and economies of scale, raising the standard of living for any industrialized society.

The surviving canals, including most ship canals, today primarily service mostly bulk cargo and large ship transportation industries, whereas the once critical smaller inland waterways conceived and engineered as boat and barge canals have largely been supplanted and filled in, abandoned and left to deteriorate, or kept in service and staffed by state employees, where dams and locks are maintained for flood control or pleasure boating. Their replacement was gradual, beginning first in the United States in the mid-1850s where canal shipping was first augmented by, then began being replaced by using much faster, less geographically constrained & limited, and generally cheaper to maintain railways.

By the early 1880s, canals which had little ability to economically compete with rail transport, were off the map. In the next couple of decades, coal was increasingly diminished as the heating fuel of choice by oil, and growth of coal shipments leveled off. Later, after World War I when motor-trucks came into their own, the last small U.S. barge canals saw a steady decline in cargo ton-miles alongside many railways, the flexibility and steep slope climbing capability of lorries taking over cargo hauling increasingly as road networks were improved, and which also had the freedom to make deliveries well away from rail lined road beds or ditches in the dirt which couldn't operate in the winter.

Construction

Canals are built in one of three ways, or a combination of the three, depending on available water and available path:

Human made streams
  • A canal can be created where no stream presently exists. Either the body of the canal is dug or the sides of the canal are created by making dykes or levees by piling dirt, stone, concrete or other building materials. The finished shape of the canal as seen in cross section is known as the canal prism.[1] The water for the canal must be provided from an external source, like streams or reservoirs. Where the new waterway must change elevation engineering works like locks, lifts or elevators are constructed to raise and lower vessels. Examples include canals that connect valleys over a higher body of land, like Canal du Midi, Canal de Briare and the Panama Canal.
  • A canal can be constructed by dredging a channel in the bottom of an existing lake. When the channel is complete, the lake is drained and the channel becomes a new canal, serving both drainage of the surrounding polder and providing transport there. Examples include the Lage Vaart. One can also build two parallel dikes in an existing lake, forming the new canal in between, and then drain the remaining parts of the lake. The eastern and central parts of the North Sea Canal were constructed in this way. In both cases pumping stations are required to keep the land surrounding the canal dry, either pumping water from the canal into surrounding waters, or pumping it from the land into the canal.
Canalization and navigations
Lateral canals
  • When a stream is too difficult to modify with canalization, a second stream can be created next to or at least near the existing stream. This is called a lateral canal, and may meander in a large horseshoe bend or series of curves some distance from the source waters stream bed lengthening the effective length in order to lower the ratio of rise over run (slope or pitch). The existing stream usually acts as the water source and the landscape around its banks provide a path for the new body. Examples include the Chesapeake and Ohio Canal, Canal latéral à la Loire, Garonne Lateral Canal and Juliana Canal.


Smaller transportation canals can carry barges or narrowboats, while ship canals allow seagoing ships to travel to an inland port (e.g., Manchester Ship Canal), or from one sea or ocean to another (e.g., Caledonian Canal, Panama Canal).

Features

Caen.hill.locks.in.devizes.arp
The flight of 16 consecutive locks at Caen Hill on the Kennet and Avon Canal, Wiltshire.
Pontcysyllte aqueduct arp
A canal boat traverses the longest and highest aqueduct in the UK, at Pontcysyllte in Denbighshire, Wales.

At their simplest, canals consist of a trench filled with water. Depending on the stratum the canal passes through, it may be necessary to line the cut with some form of watertight material such as clay or concrete. When this is done with clay, it is known as puddling.

Canal of korinth greece
The Corinth Canal seen from the air.

Canals need to be level, and while small irregularities in the lie of the land can be dealt with through cuttings and embankments, for larger deviations other approaches have been adopted. The most common is the pound lock, which consists of a chamber within which the water level can be raised or lowered connecting either two pieces of canal at a different level or the canal with a river or the sea. When there is a hill to be climbed, flights of many locks in short succession may be used.

Prior to the development of the pound lock in 984 AD in China by Chhaio Wei-Yo[2] and later in Europe in the 15th century, either flash locks consisting of a single gate were used or ramps, sometimes equipped with rollers, were used to change the level. Flash locks were only practical where there was plenty of water available.

Locks use a lot of water, so builders have adopted other approaches for situations where little water is available. These include boat lifts, such as the Falkirk Wheel, which use a caisson of water in which boats float while being moved between two levels; and inclined planes where a caisson is hauled up a steep railway.

To cross a stream, road or valley (where the delay caused by a flight of locks at either side would be unacceptable) the valley can be spanned by a navigable aqueduct – a famous example in Wales is the Pontcysyllte Aqueduct (now a UNESCO World Heritage Site) across the valley of the River Dee.

Another option for dealing with hills is to tunnel through them. An example of this approach is the Harecastle Tunnel on the Trent and Mersey Canal. Tunnels are only practical for smaller canals.

Some canals attempted to keep changes in level down to a minimum. These canals known as contour canals would take longer, winding routes, along which the land was a uniform altitude. Other, generally later, canals took more direct routes requiring the use of various methods to deal with the change in level.

Canals have various features to tackle the problem of water supply. In cases, like the Suez Canal, the canal is simply open to the sea. Where the canal is not at sea level, a number of approaches have been adopted. Taking water from existing rivers or springs was an option in some cases, sometimes supplemented by other methods to deal with seasonal variations in flow. Where such sources were unavailable, reservoirs – either separate from the canal or built into its course – and back pumping were used to provide the required water. In other cases, water pumped from mines was used to feed the canal. In certain cases, extensive "feeder canals" were built to bring water from sources located far from the canal.

Where large amounts of goods are loaded or unloaded such as at the end of a canal, a canal basin may be built. This would normally be a section of water wider than the general canal. In some cases, the canal basins contain wharfs and cranes to assist with movement of goods.

When a section of the canal needs to be sealed off so it can be drained for maintenance stop planks are frequently used. These consist of planks of wood placed across the canal to form a dam. They are generally placed in pre-existing grooves in the canal bank. On more modern canals, "guard locks" or gates were sometimes placed to allow a section of the canal to be quickly closed off, either for maintenance, or to prevent a major loss of water due to a canal breach.

History

Canal de la Peyrade, Sète, Hérault 01
Canal in Sète, France.

The transport capacity of pack animals and carts is limited. A mule can carry an eighth-ton[3] [250 pounds (113 kg)] maximum load over a journey measured in days and weeks,[3] though much more for shorter distances and periods with appropriate rest.[3] Besides, carts need roads. Transport over water is much more efficient and cost-effective for large cargoes. It goes back to the earliest days of recorded history.

Ancient canals

The oldest known canals were irrigation canals, built in Mesopotamia circa 4000 BC, in what is now Iraq and Iran. The Indus Valley Civilization, Ancient India, (circa 2600 BC) had sophisticated irrigation and storage systems developed, including the reservoirs built at Girnar in 3000 BC.[4] In Egypt, canals date back at least to the time of Pepi I Meryre (reigned 2332–2283 BC), who ordered a canal built to bypass the cataract on the Nile near Aswan.[5]

In ancient China, large canals for river transport were established as far back as the Spring and Autumn Period (8th–5th centuries BC), the longest one of that period being the Hong Gou (Canal of the Wild Geese), which according to the ancient historian Sima Qian connected the old states of Song, Zhang, Chen, Cai, Cao, and Wei.[6] The Caoyun System of canals was essential for imperial taxation, which was largely assessed in kind and involved enormous shipments of rice and other grains. By far the longest canal was the Grand Canal of China, still the longest canal in the world today and the oldest extant one.[7] It is 1,794 kilometres (1,115 mi) long and was built to carry the Emperor Yang Guang between Zhuodu (Beijing) and Yuhang (Hangzhou). The project began in 605 and was completed in 609, although much of the work combined older canals, the oldest section of the canal existing since at least 486 BC. Even in its narrowest urban sections it is rarely less than 30 metres (98 ft) wide.

Greek engineers were also among the first to use canal locks, by which they regulated the water flow in the Ancient Suez Canal as early as the 3rd century BC.[8][9][10]

"There was little experience moving bulk loads by carts, while a pack-horse would [i.e. 'could'] carry only an eighth of a ton. On a soft road a horse might be able to draw 5/8ths of a ton. But if the load were carried by a barge on a waterway, then up to 30 tons could be drawn by the same horse."
— technology historian Ronald W. Clark referring to transport realities before the industrial revolution and the Canal age.[3]

Middle Ages

Thal Canal
Thal Canal, Punjab, Pakistan.

In the Middle Ages, water transport was several times cheaper and faster than transport overland. Overland transport by animal drawn conveyances was used around settled areas, but unimproved roads required pack animal trains, usually of mules to carry any degree of mass, and while a mule could carry an eighth ton,[3] it also needed teamsters to tend it and one man could only tend perhaps five mules,[3] meaning overland bulk transport was also expensive, as men expect compensation in the form of wages, room and board. This was because long-haul roads were unpaved, more often than not too narrow for carts, much less wagons, and in poor condition, wending their way through forests, marshy or muddy quagmires as often as unimproved but dry footing. In that era, as today, greater cargoes, especially bulk goods and raw materials, could be transported by ship far more economically than by land; in the pre-railroad days of the industrial revolution, water transport was the gold standard of fast transportation. The first artificial canal in Western Europe was the Fossa Carolina built at the end of the 8th century under personal supervision of Charlemagne.

In Britain, the Glastonbury Canal  is believed to be the first post-Roman canal and was built in the middle of the 10th century to link the River Brue at Northover[11] with Glastonbury Abbey, a distance of about 1.75 kilometres (1,900 yd).[12] Its initial purpose is believed to be the transport of building stone for the abbey, but later it was used for delivering produce, including grain, wine and fish, from the abbey's outlying properties. It remained in use until at least the 14th century, but possibly as late as the mid-16th century.[13]
More lasting and of more economic impact were canals like the Naviglio Grande built between 1127 and 1257 to connect Milan with the Ticino River. The Naviglio Grande is the most important of the lombard "navigli"[14] and the oldest functioning canal in Europe.
Later, canals were built in the Netherlands and Flanders to drain the polders and assist transportation of goods and people.

Canal building was revived in this age because of commercial expansion from the 12th century. River navigations were improved progressively by the use of single, or flash locks. Taking boats through these used large amounts of water leading to conflicts with watermill owners and to correct this, the pound or chamber lock first appeared, in the 10th century in China and in Europe in 1373 in Vreeswijk, Netherlands.[15] Another important development was the mitre gate, which was, it is presumed, introduced in Italy by Bertola da Novate in the 16th century. This allowed wider gates and also removed the height restriction of guillotine locks.

To break out of the limitations caused by river valleys, the first summit level canals were developed with the Grand Canal of China in 581–617 AD whilst in Europe the first, also using single locks, was the Stecknitz Canal in Germany in 1398.

Early modern period

Negombo canal 2
Dutch canal in Negombo, Sri Lanka.

Around 1500–1800 the first canal to use pound locks was the Briare Canal connecting the Loire and Seine (1642), followed by the more ambitious Canal du Midi (1683) connecting the Atlantic to the Mediterranean. This included a staircase of 8 locks at Béziers, a 157 metres (515 ft) tunnel, and three major aqueducts.

Canal building progressed steadily in Germany in the 17th and 18th centuries with three great rivers, the Elbe, Oder and Weser being linked by canals. In post-Roman Britain, the first early modern period canal built appears to have been the Exeter Canal, which was surveyed in 1563, and open in 1566.[16][17]

The oldest canal in North America, technically a mill race built for industrial purposes, is Mother Brook between the Boston, Massachusetts neighbourhoods of Dedham and Hyde Park connecting the higher waters of the Charles River and the mouth of the Neponset River and the sea. It was constructed in 1639 to provide water power for mills.

In Russia, the Volga–Baltic Waterway, a nationwide canal system connecting the Baltic Sea and Caspian Sea via the Neva and Volga rivers, was opened in 1718.

Industrial Revolution

1975 map of canal system in Lowell, Massachusetts
Lowell's power canal system.

The modern canal system was mainly a product of the 18th century and early 19th century. It came into being because the Industrial Revolution (which began in Britain during the mid-18th century) demanded an economic and reliable way to transport goods and commodities in large quantities.

By the early 18th century, river navigations such as the Aire and Calder Navigation were becoming quite sophisticated, with pound locks and longer and longer "cuts" (some with intermediate locks) to avoid circuitous or difficult stretches of river. Eventually, the experience of building long multi-level cuts with their own locks gave rise to the idea of building a "pure" canal, a waterway designed on the basis of where goods needed to go, not where a river happened to be.

The claim for the first pure canal in Great Britain is debated between "Sankey" and "Bridgewater" supporters.[18] The first true canal in what is now the United Kingdom was the Newry Canal in Northern Ireland constructed by Thomas Steers in 1741.

The Sankey Brook Navigation, which connected St Helens with the River Mersey, is often claimed as the first modern "purely artificial" canal because although originally a scheme to make the Sankey Brook navigable, it included an entirely new artificial channel that was effectively a canal along the Sankey Brook valley.[18][19] However, "Bridgewater" supporters point out that the last quarter-mile of the navigation is indeed a canalized stretch of the Brook, and that it was the Bridgewater Canal (less obviously associated with an existing river) that captured the popular imagination and inspired further canals.[18][19]

In the mid-eighteenth century the 3rd Duke of Bridgewater, who owned a number of coal mines in northern England, wanted a reliable way to transport his coal to the rapidly industrializing city of Manchester. He commissioned the engineer James Brindley to build a canal for that purpose. Brindley's design included an aqueduct carrying the canal over the River Irwell. This was an engineering wonder which immediately attracted tourists.[18][19] The construction of this canal was funded entirely by the Duke and was called the Bridgewater Canal. It opened in 1761 and was the first major British canal.[20]

The new canals proved highly successful. The boats on the canal were horse-drawn with a towpath alongside the canal for the horse to walk along. This horse-drawn system proved to be highly economical and became standard across the British canal network. Commercial horse-drawn canal boats could be seen on the UK's canals until as late as the 1950s, although by then diesel-powered boats, often towing a second unpowered boat, had become standard.

The canal boats could carry thirty tons at a time with only one horse pulling[20] – more than ten times the amount of cargo per horse that was possible with a cart. Because of this huge increase in supply, the Bridgewater canal reduced the price of coal in Manchester by nearly two-thirds within just a year of its opening. The Bridgewater was also a huge financial success, with it earning what had been spent on its construction within just a few years.

This success proved the viability of canal transport, and soon industrialists in many other parts of the country wanted canals. After the Bridgewater canal, early canals were built by groups of private individuals with an interest in improving communications. In Staffordshire the famous potter Josiah Wedgwood saw an opportunity to bring bulky cargoes of clay to his factory doors and to transport his fragile finished goods to market in Manchester, Birmingham or further away, by water, minimizing breakages. Within just a few years of the Bridgewater's opening, an embryonic national canal network came into being, with the construction of canals such as the Oxford Canal and the Trent & Mersey Canal.[21]

The new canal system was both cause and effect of the rapid industrialization of The Midlands and the north. The period between the 1770s and the 1830s is often referred to as the "Golden Age" of British canals.

For each canal, an Act of Parliament was necessary to authorize construction, and as people saw the high incomes achieved from canal tolls, canal proposals came to be put forward by investors interested in profiting from dividends, at least as much as by people whose businesses would profit from cheaper transport of raw materials and finished goods.

In a further development, there was often out-and-out speculation, where people would try to buy shares in a newly floated company simply to sell them on for an immediate profit, regardless of whether the canal was ever profitable, or even built. During this period of "canal mania", huge sums were invested in canal building, and although many schemes came to nothing, the canal system rapidly expanded to nearly 4,000 miles (over 6,400 kilometres) in length.[20]

Many rival canal companies were formed and competition was rampant. Perhaps the best example was Worcester Bar in Birmingham, a point where the Worcester and Birmingham Canal and the Birmingham Canal Navigations Main Line were only seven feet apart. For many years, a dispute about tolls meant that goods travelling through Birmingham had to be portaged from boats in one canal to boats in the other.[22]

NYmohawk-ErieCanalRexford
Aqueduct over the Mohawk River at Rexford, New York, one of 32 navigable aqueducts on the Erie Canal.

Canal companies were initially chartered by individual states in the United States. These early canals were constructed, owned, and operated by private joint-stock companies. Three were completed when the War of 1812 broke out; these were the Santee Canal (opened 1800) in South Carolina, the Middlesex Canal (opened 1802) in Massachusetts and the Dismal Swamp Canal (opened 1805) in Virginia. The Erie Canal (opened 1825) was chartered and owned by the state of New York and financed by bonds bought by private investors. The Erie canal runs about 363 miles (584 km) from Albany, New York, on the Hudson River to Buffalo, New York, at Lake Erie. The Hudson River connects Albany to the Atlantic port of New York City and the Erie Canal completed a navigable water route from the Atlantic Ocean to the Great Lakes. The canal contains 36 locks and encompasses a total elevation differential of around 565 ft. (169 m). The Erie Canal with its easy connections to most of the U.S. mid-west and New York City soon quickly paid back all its invested capital (US$7 million) and started turning a profit. By cutting transportation costs in half or more it became a large profit center for Albany and New York City as it allowed the cheap transportation of many of the agricultural products grown in the mid west of the United States to the rest of the world. From New York City these agricultural products could easily be shipped to other U.S. states or overseas. Assured of a market for their farm products the settlement of the U.S. mid-west was greatly accelerated by the Erie Canal. The profits generated by the Erie Canal project started a canal building boom in the United States that lasted until about 1850 when railroads started becoming seriously competitive in price and convenience. The Blackstone Canal (finished in 1828) in Massachusetts and Rhode Island fulfilled a similar role in the early industrial revolution between 1828 and 1848. The Blackstone Valley was a major contributor of the American Industrial Revolution where Samuel Slater built his first textile mill.

Power canals

Gabčíkovo sluice Slovakia
Sluice in the canal of Gabčíkovo Dam (Slovakia) – the canal is conveying water to a hydroelectric power station.

A power canal refers to a canal used for hydraulic power generation, rather than for transport. Nowadays power canals are built almost exclusively as parts of hydroelectric power stations. Parts of the United States, particularly in the Northeast, had enough fast-flowing rivers that water power was the primary means of powering factories (usually textile mills) until after the American Civil War. For example, Lowell, Massachusetts, considered to be "The Cradle of the American Industrial Revolution," has 6 miles (9.7 km) of canals, built from around 1790 to 1850, that provided water power and a means of transportation for the city. The output of the system is estimated at 10,000 horsepower.[23] Other cities with extensive power canal systems include Lawrence, Massachusetts, Holyoke, Massachusetts, Manchester, New Hampshire, and Augusta, Georgia. The most notable power canal was built in 1862 for the Niagara Falls Hydraulic Power and Manufacturing Company.

19th century

Canals USA 1825
American canals circa 1825.

Competition, from railways from the 1830s and roads in the 20th century, made the smaller canals obsolete for most commercial transport, and many of the British canals fell into decay. Only the Manchester Ship Canal and the Aire and Calder Canal bucked this trend. Yet in other countries canals grew in size as construction techniques improved. During the 19th century in the US, the length of canals grew from 100 miles (161 km) to over 4,000, with a complex network making the Great Lakes navigable, in conjunction with Canada, although some canals were later drained and used as railroad rights-of-way.

In the United States, navigable canals reached into isolated areas and brought them in touch with the world beyond. By 1825 the Erie Canal, 363 miles (584 km) long with 36 locks, opened up a connection from the populated Northeast to the Great Lakes. Settlers flooded into regions serviced by such canals, since access to markets was available. The Erie Canal (as well as other canals) was instrumental in lowering the differences in commodity prices between these various markets across America. The canals caused price convergence between different regions because of their reduction in transportation costs, which allowed Americans to ship and buy goods from farther distances much cheaper. Ohio built many miles of canal, Indiana had working canals for a few decades, and the Illinois and Michigan Canal connected the Great Lakes to the Mississippi River system until replaced by a channelized river waterway.

Amsterdam - Herengracht - 0206
A family rides a boat in one of the canals of Amsterdam.

Three major canals with very different purposes were built in what is now Canada. The first Welland Canal, which opened in 1829 between Lake Ontario and Lake Erie, bypassing Niagara Falls and the Lachine Canal (1825), which allowed ships to skirt the nearly impassable rapids on the St. Lawrence River at Montreal, were built for commerce. The Rideau Canal, completed in 1832, connects Ottawa on the Ottawa River to Kingston, Ontario on Lake Ontario. The Rideau Canal was built as a result of the War of 1812 to provide military transportation between the British colonies of Upper Canada and Lower Canada as an alternative to part of the St. Lawrence River, which was susceptible to blockade by the United States.

1870 Nicaragua Canal Map Restoration
A proposal for the Nicaragua Canal, from around 1870.

In France, a steady linking of all the river systems – Rhine, Rhône, Saône and Seine – and the North Sea was boosted in 1879 by the establishment of the Freycinet gauge, which specified the minimum size of locks. Canal traffic doubled in the first decades of the 20th century.[24]

Many notable sea canals were completed in this period, starting with the Suez Canal (1869) – which carries tonnage many times that of most other canals – and the Kiel Canal (1897), though the Panama Canal was not opened until 1914.

In the 19th century, a number of canals were built in Japan including the Biwako canal and the Tone canal. These canals were partially built with the help of engineers from the Netherlands and other countries.[25]

Modern uses

Viewing man-made canals in the marsh in Louisiana, Barataria Basin
Canals can disrupt water circulation in marsh systems.

Large-scale ship canals such as the Panama Canal and Suez Canal continue to operate for cargo transportation, as do European barge canals. Due to globalization, they are becoming increasingly important, resulting in expansion projects such as the Panama Canal expansion project. The expanded canal began commercial operation on 26 June 2016. The new set of locks allow transit of larger, Post-Panamax and New Panamax ships.[26]

The narrow early industrial canals, however, have ceased to carry significant amounts of trade and many have been abandoned to navigation, but may still be used as a system for transportation of untreated water. In some cases railways have been built along the canal route, an example being the Croydon Canal.

A movement that began in Britain and France to use the early industrial canals for pleasure boats, such as hotel barges, has spurred rehabilitation of stretches of historic canals. In some cases, abandoned canals such as the Kennet and Avon Canal have been restored and are now used by pleasure boaters. In Britain, canalside housing has also proven popular in recent years.

The Seine–Nord Europe Canal is being developed into a major transportation waterway, linking France with Belgium, Germany, and the Netherlands.

Canals have found another use in the 21st century, as easements for the installation of fibre optic telecommunications network cabling, avoiding having them buried in roadways while facilitating access and reducing the hazard of being damaged from digging equipment.

Canals are still used to provide water for agriculture. An extensive canal system exists within the Imperial Valley in the Southern California desert to provide irrigation to agriculture within the area.

Cities on water

Goldcoast Queensland Australia aerial view
Aerial view of the man-made canals of the Gold Coast, Queensland, Australia.
Utrecht Canals - July 2006
Wharfs along the Oudegracht in Utrecht, Netherlands.

Canals are so deeply identified with Venice that many canal cities have been nicknamed "the Venice of…". The city is built on marshy islands, with wooden piles supporting the buildings, so that the land is man-made rather than the waterways. The islands have a long history of settlement; by the 12th century, Venice was a powerful city state.

Amsterdam was built in a similar way, with buildings on wooden piles. It became a city around 1300. Many Amsterdam canals were built as part of fortifications. They became grachten when the city was enlarged and houses were built alongside the water.

Quai Maréchal de Lattre de Tassigny, Sète 02
Canal of La Peyrade in Sète, France.

Other cities with extensive canal networks include: Alkmaar, Amersfoort, Bolsward, Brielle, Delft, Den Bosch, Dokkum, Dordrecht, Enkhuizen, Franeker, Gouda, Haarlem, Harlingen, Leeuwarden, Leiden, Sneek and Utrecht in the Netherlands; Brugge and Gent in Flanders, Belgium; Birmingham in England; Saint Petersburg in Russia; Aveiro in Portugal; Hamburg and Berlin in Germany; Fort Lauderdale and Cape Coral in Florida, United States and Lahore in Pakistan.

Liverpool Maritime Mercantile City is a UNESCO World Heritage Site near the centre of Liverpool, England, where a system of intertwining waterways and docks is now being developed for mainly residential and leisure use.

Canal Estates (commonly known as bayous) are a form of subdivision popular in cities like Miami, Florida, Texas City, Texas and the Gold Coast, Queensland; the Gold Coast has over 700 km of residential canals. Wetlands are difficult areas upon which to build housing estates, so dredging part of the wetland down to a navigable channel provides fill to build up another part of the wetland above the flood level for houses. Land is built up in a finger pattern that provides a suburban street layout of waterfront housing blocks.

Boats

Panama Canal Miraflores Locks
Two Panamax ships in the Miraflores Locks on the Panama Canal, Panama.

Inland canals have often had boats specifically built for them. An example of this is the British narrowboat, which is up to 72 feet (21.95 m) long and 7 feet (2.13 m) wide and was primarily built for British Midland canals. In this case the limiting factor was the size of the locks. This is also the limiting factor on the Panama canal where Panamax ships were limited to a length of 289.56 m (950 ft) and a beam of 32.31 m (106 ft) until 26 June 2016 when the opening of larger locks allowed for the passage of larger New Panamax ships. For the lockless Suez Canal the limiting factor for Suezmax ships is generally draft, which is limited to 16 m (52.5 ft). At the other end of the scale, tub-boat canals such as the Bude Canal were limited to boats of under 10 tons for much of their length due to the capacity of their inclined planes or boat lifts. Most canals have a limit on height imposed either by bridges or by tunnels.

Lists of canals

See also

References

Notes

  1. ^ Thompson, Kristi. "Glossary". www.usbr.gov. US Bureau of Reclamation. Retrieved 15 September 2017.
  2. ^ Hadfield 1986, p. 22.
  3. ^ a b c d e f "Works of Man", Ronald W. Clark, ISBN 0-670-80483-5 (1985) 352 pages, Viking Penguin, Inc, New York,
    quotation p. 87: "There was little experience moving bulk loads by carts, while a packhorse would [sic, meaning 'could' or 'can only'] carry only an eighth of a ton. On a soft road a horse might be able to draw 5/8ths of a ton. But if the load were carried by a barge on a waterway, then up to 30 tons could be drawn by the same horse."
  4. ^ Rodda 2004, p. 161.
  5. ^ Hadfield 1986, p. 16.
  6. ^ Needham 1971, p. 269.
  7. ^ Donald Langmead (2001). Encyclopedia of Architectural and Engineering Feats. ABC-CLIO. p. 37. ISBN 978-1-57607-112-0. Retrieved 15 February 2013. the world's largest artificial waterway and oldest canal still in existence
  8. ^ Moore, Frank Gardner (1950): "Three Canal Projects, Roman and Byzantine", American Journal of Archaeology, Vol. 54, No. 2, pp. 97–111 (99–101)
  9. ^ Froriep, Siegfried (1986): "Ein Wasserweg in Bithynien. Bemühungen der Römer, Byzantiner und Osmanen", Antike Welt, 2nd Special Edition, pp. 39–50 (46)
  10. ^ Schörner, Hadwiga (2000): "Künstliche Schiffahrtskanäle in der Antike. Der sogenannte antike Suez-Kanal", Skyllis, Vol. 3, No. 1, pp. 28–43 (33–35)
  11. ^ specifically from (51°08′18″N 2°44′09″W / 51.1384°N 2.7358°W), Start point at River Brue
  12. ^ Details text and data with cites from Glastonbury Canal (medieval).
  13. ^ Gathercole, Clare (2003). An archaeological assessment of Glastonbury (PDF). English Heritage Extensive Urban Survey. Taunton: Somerset County Council. pp. 19–20. Archived from the original (PDF) on 15 July 2011. Retrieved 2 February 2010.
  14. ^ Calvert 1963, p. .
  15. ^ The International Canal Monuments List (PDF), retrieved 8 October 2008
  16. ^ David Cornforth (February 2012). "Exeter Canal and Quayside – a short history". www.exetermemories.co.uk. Retrieved 14 September 2013.
  17. ^ Exeter history by www.exeter.gov.uk, .pdf file Exeter Ship Canal, The First Four Hundred Years Archived 19 September 2015 at the Wayback Machine, accessdate=13 September 2013
  18. ^ a b c d Burton, (1995). Chapter 3: Building the Canals
  19. ^ a b c Rolt, Inland Waterways
  20. ^ a b c Reader's Digest Library of Modern Knowledge. London: Readers Digest. 1978. p. 990.
  21. ^ Hadfield, Charles (1981). The Canal Age (Second ed.). David & Charles. ISBN 978-0-7153-8079-6.
  22. ^ Hadfield, Charles (1966). The Canals of the West Midlands. David & Charles. ISBN 978-0-7153-4660-0.
  23. ^ Lowell National Historical Park – Lowell History Prologue, retrieved 8 October 2008
  24. ^ Edwards 2002, p. .
  25. ^ Hadfield 1986, p. 191.
  26. ^ The Associated Press (26 June 2016). "Panama Canal Opens $5B Locks, Bullish Despite Shipping Woes". The New York Times. Retrieved 26 June 2016.

Bibliography

  • Burton, Anthony (1995) [1989], The Great Days of the Canals, Twickenham: Tiger Books, ISBN 978-1-85501-695-8
  • Calvert, Roger (1963), Inland Waterways of Europe, George Allen and Unwin
  • Edwards-May, David (2008), European Waterways - map and concise directory, 3rd edition, Euromapping
  • Hadfield, Charles (1986), World Canals: Inland Navigation Past and Present, David and Charles, ISBN 978-0-7153-8555-5
  • Needham, J. (1971), Science and Civilisation in China, C.U.P. Cambridge
  • Rodda, J.C. (2004), The Basis of Civilization - Water Science?, International Association of Hydrological Sciences

External links

Barge

A barge is a flat-bottomed ship, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and must be towed or pushed by towboats, canal barges or towed by draft animals on an adjacent towpath. Barges contended with the railway in the early Industrial Revolution, but were outcompeted in the carriage of high-value items due to the higher speed, falling costs and route flexibility of railways.

Canal

Canals, or navigations, are human-made channels, or artificial waterways, for water conveyance, or to service water transport vehicles.

In most cases, the engineered works will have a series of dams and locks that create reservoirs of low speed current flow. These reservoirs are referred to as slack water levels, often just called levels.

A canal is also known as a navigation when it parallels a river and shares part of its waters and drainage basin, and leverages its resources by building dams and locks to increase and lengthen its stretches of slack water levels while staying in its valley.

In contrast, a canal cuts across a drainage divide atop a ridge, generally requiring an external water source above the highest elevation.

Many canals have been built at elevations towering over valleys and other water ways crossing far below.

Canals with sources of water at a higher level can deliver water to a destination such as a city where water is needed. The Roman Empire's aqueducts were such water supply canals.

Cannes Film Festival

The Cannes Festival (; French: Festival de Cannes), until 2002 called the International Film Festival (Festival international du film) and known in English as the Cannes Film Festival, is an annual film festival held in Cannes, France, which previews new films of all genres, including documentaries from all around the world. Founded in 1946, the invitation-only festival is held annually (usually in May) at the Palais des Festivals et des Congrès. It is one of the "Big Three" alongside the Venice Film Festival and Berlin International Film Festival.

On 1 July 2014, co-founder and former head of French pay-TV operator Canal+, Pierre Lescure, took over as President of the Festival, while Thierry Fremaux became the General Delegate. The board of directors also appointed Gilles Jacob as Honorary President of the Festival.The 2019 Cannes Film Festival took place from 14 and 25 May 2019 and Mexican filmmaker Alejandro González Iñárritu was the jury president. Parasite, directed by South Korean director Bong Joon-ho, won the Palme d'Or.

Cervix

The cervix or cervix uteri (Latin: neck of the uterus) is the lower part of the uterus in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during pregnancy. The narrow, central cervical canal runs along its entire length, connecting the uterine cavity and the lumen of the vagina. The opening into the uterus is called the internal os, and the opening into the vagina is called the external os. The lower part of the cervix, known as the vaginal portion of the cervix (or ectocervix), bulges into the top of the vagina. The cervix has been documented anatomically since at least the time of Hippocrates, over 2,000 years ago.

The cervical canal is a passage through which sperm must travel to fertilize an egg cell after sexual intercourse. Several methods of contraception, including cervical caps and cervical diaphragms, aim to block or prevent the passage of sperm through the cervical canal. Cervical mucus is used in several methods of fertility awareness, such as the Creighton model and Billings method, due to its changes in consistency throughout the menstrual period. During vaginal childbirth, the cervix must flatten and dilate to allow the fetus to progress along the birth canal. Midwives and doctors use the extent of the dilation of the cervix to assist decision-making during childbirth.

The cervical canal is lined with a single layer of column-shaped cells, while the ectocervix is covered with multiple layers of cells topped with flat cells. The two types of epithelia meet the squamocolumnar junction. Infection with the human papillomavirus (HPV) can cause changes in the epithelium, which can lead to cancer of the cervix. Cervical cytology tests can often detect cervical cancer and its precursors, and enable early successful treatment. Ways to avoid HPV include avoiding sex, using condoms, and HPV vaccination. HPV vaccines, developed in the early 21st century, reduce the risk of cervical cancer by preventing infections from the main cancer-causing strains of HPV.

Erie Canal

The Erie Canal is a canal in New York, United States that is part of the east–west, cross-state route of the New York State Canal System (formerly known as the New York State Barge Canal). Originally, it ran 363 miles (584 km) from where Albany meets the Hudson River to where Buffalo meets Lake Erie. It was built to create a navigable water route from New York City and the Atlantic Ocean to the Great Lakes. When completed in 1825, it was the second longest canal in the world (after the Grand Canal in China) and greatly affected the development and economy of New York, New York City, and the United States.The canal was first proposed in the 1780s, then re-proposed in 1807. A survey was authorized, funded, and executed in 1808. Proponents of the project gradually wore down opponents; its construction began in 1817. The canal has 34 numbered locks starting with Black Rock Lock and ending downstream with the Troy Federal Lock. Both are owned by the federal government. It has an elevation difference of about 565 feet (172 m). It opened on October 26, 1825.In a time when bulk goods were limited to pack animals (a 250-pound (113 kg) maximum), and there were no railways, water was the most cost-effective way to ship bulk goods.

The canal was denigrated by its political opponents as "Clinton's Folly" or "Clinton's Big Ditch". It was the first transportation system between the Eastern Seaboard and the western interior of the United States that did not require portage.

It was faster than carts pulled by draft animals and cut transport costs by about 95%. The canal gave New York City's port an incomparable advantage over all other U.S. port cities and ushered in the state's 19th century political and cultural ascendancy. The canal fostered a population surge in western New York and opened regions farther west to settlement. It was enlarged between 1834 and 1862. The canal's peak year was 1855, when 33,000 commercial shipments took place. In 1918, the western part of the canal was enlarged to become part of the New York State Barge Canal, which also extended to the Hudson River running parallel to the eastern half of the Erie Canal.

In 2000, the United States Congress designated the Erie Canalway National Heritage Corridor to recognize the national significance of the canal system as the most successful and influential human-built waterway and one of the most important works of civil engineering and construction in North America. The canal has been mainly used by recreational watercraft since the retirement of the last large commercial ship, Day Peckinpaugh, in 1994. The canal saw a recovery in commercial traffic in 2008.

Gastrointestinal tract

The gastrointestinal tract (digestive tract, digestional tract, GI tract, GIT, gut, or alimentary canal) is an organ system within humans and other animals which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as feces. The mouth, esophagus, stomach and intestines are part of the gastrointestinal tract. Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs.

All bilaterians have a gastrointestinal tract, also called a gut or an alimentary canal. This is a tube that transfers food to the organs of digestion. In large bilaterians, the gastrointestinal tract also has an exit, the anus, by which the animal disposes of feces (solid wastes). Some small bilaterians have no anus and dispose of solid wastes by other means (for example, through the mouth). The human gastrointestinal tract consists of the esophagus, stomach, and intestines, and is divided into the upper and lower gastrointestinal tracts. The GI tract includes all structures between the mouth and the anus, forming a continuous passageway that includes the main organs of digestion, namely, the stomach, small intestine, and large intestine. However, the complete human digestive system is made up of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver and gallbladder). The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment. The whole human GI tract is about nine metres (30 feet) long at autopsy. It is considerably shorter in the living body because the intestines, which are tubes of smooth muscle tissue, maintain constant muscle tone in a halfway-tense state but can relax in spots to allow for local distention and peristalsis.The gastrointestinal tract contains trillions of microbes, with some 4,000 different strains of bacteria having diverse roles in maintenance of immune health and metabolism. Cells of the GI tract release hormones to help regulate the digestive process. These digestive hormones, including gastrin, secretin, cholecystokinin, and ghrelin, are mediated through either intracrine or autocrine mechanisms, indicating that the cells releasing these hormones are conserved structures throughout evolution.

Grand Canal (China)

The Grand Canal, known to the Chinese as the Jing–Hang Grand Canal (Chinese: 京杭大运河; pinyin: Jīng-Háng Dà Yùnhé; literally: 'Beijing–Hangzhou Grand Canal'), a UNESCO World Heritage Site, is the longest as well as the oldest canal or artificial river in the world. Starting at Beijing, it passes through Tianjin and the provinces of Hebei, Shandong, Jiangsu and Zhejiang to the city of Hangzhou, linking the Yellow River and Yangtze River. The oldest parts of the canal date back to the 5th century BC, but the various sections were first connected during the Sui dynasty (581–618 AD). Dynasties in 1271–1633 significantly rebuilt the canal and altered its route to supply their capital Beijing.

The total length of the Grand Canal is 1,776 km (1,104 mi). Its greatest height is reached in the mountains of Shandong, at a summit of 42 m (138 ft). Ships in Chinese canals did not have trouble reaching higher elevations after the pound lock was invented in the 10th century, during the Song dynasty (960–1279), by the government official and engineer Qiao Weiyue. The canal has been admired by many throughout history including Japanese monk Ennin (794–864), Persian historian Rashid al-Din (1247–1318), Korean official Choe Bu (1454–1504), and Italian missionary Matteo Ricci (1552–1610).Historically, periodic flooding of the Yellow River threatened the safety and functioning of the canal. During wartime the high dikes of the Yellow River were sometimes deliberately broken in order to flood advancing enemy troops. This caused disaster and prolonged economic hardships. Despite temporary periods of desolation and disuse, the Grand Canal furthered an indigenous and growing economic market in China's urban centers since the Sui period. It has allowed faster trading and has improved China's economy. The southern portion remains in heavy use to the present day.

Grand Union Canal

The Grand Union Canal in England is part of the British canal system. Its main line starts in London and ends in Birmingham, stretching for 137 miles (220 km) with 166 locks. It has arms to places including Leicester, Slough, Aylesbury, Wendover and Northampton.

The Grand Union Canal was also the original name for part of what is now part of the Leicester Line of the modern Grand Union: this latter is now generally referred to as the Old Grand Union Canal to avoid ambiguity.

Guadalcanal

Guadalcanal (indigenous name: Isatabu) is the principal island in Guadalcanal Province of the nation of Solomon Islands, located in the south-western Pacific, northeast of Australia. The island is mainly covered in dense tropical rainforest and has a mountainous interior.

Guadalcanal's discovery by westerners was under the Spanish expedition of Álvaro de Mendaña in 1568. The name comes from the village of Guadalcanal, in the province of Seville, in Andalusia, Spain, birthplace of Pedro de Ortega Valencia, a member of Mendaña's expedition.

During 1942–43, it was the scene of the Guadalcanal Campaign and saw bitter fighting between Japanese and US troops. The Americans were ultimately victorious. At the end of World War II, Honiara, on the north coast of Guadalcanal, became the new capital of the British Solomon Islands Protectorate.

Lock (water navigation)

A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is the chamber itself (usually then called a caisson) that rises and falls.

Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken.

Since 2016, the largest lock worldwide is the Kieldrecht Lock in the Port of Antwerp, Belgium.

Panama

Panama ( (listen) PAN-ə-mah; Spanish: Panamá [panaˈma]), officially the Republic of Panama (Spanish: República de Panamá), is a country in Central America, bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and the Pacific Ocean to the south. The capital and largest city is Panama City, whose metropolitan area is home to nearly half the country's 4 million people.Panama was inhabited by indigenous tribes before Spanish colonists arrived in the 16th century. It broke away from Spain in 1821 and joined the Republic of Gran Colombia, a union of Nueva Granada, Ecuador, and Venezuela. After Gran Colombia dissolved in 1831, Panama and Nueva Granada eventually became the Republic of Colombia. With the backing of the United States, Panama seceded from Colombia in 1903, allowing the construction of the Panama Canal to be completed by the US Army Corps of Engineers between 1904 and 1914. The 1977 Torrijos–Carter Treaties led to the transfer of the Canal from the United States to Panama on December 31, 1999.Revenue from canal tolls continues to represent a significant portion of Panama's GDP, although commerce, banking, and tourism are major and growing sectors. It is regarded as a high-income country. In 2015 Panama ranked 60th in the world in terms of the Human Development Index. In 2018, Panama was ranked seventh-most competitive economy in Latin America, according to the World Economic Forum's Global Competitiveness Index. Covering around 40 percent of its land area, Panama's jungles are home to an abundance of tropical plants and animals – some of them found nowhere else on the planet. Panama is a founding member of the United Nations and other international organizations such as OAS, LAIA, G77, WHO and NAM.

Panama Canal

The Panama Canal (Spanish: Canal de Panamá) is an artificial 82 km (51 mi) waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean. The canal cuts across the Isthmus of Panama and is a conduit for maritime trade. Canal locks are at each end to lift ships up to Gatun Lake, an artificial lake created to reduce the amount of excavation work required for the canal, 26 m (85 ft) above sea level, and then lower the ships at the other end. The original locks are 34 m (110 ft) wide. A third, wider lane of locks was constructed between September 2007 and May 2016. The expanded canal began commercial operation on June 26, 2016. The new locks allow transit of larger, post-Panamax ships, capable of handling more cargo.France began work on the canal in 1881, but stopped due to engineering problems and a high worker mortality rate. The United States took over the project in 1904 and opened the canal on August 15, 1914. One of the largest and most difficult engineering projects ever undertaken, the Panama Canal shortcut greatly reduced the time for ships to travel between the Atlantic and Pacific oceans, enabling them to avoid the lengthy, hazardous Cape Horn route around the southernmost tip of South America via the Drake Passage or Strait of Magellan.

Colombia, France, and later the United States controlled the territory surrounding the canal during construction. The US continued to control the canal and surrounding Panama Canal Zone until the 1977 Torrijos–Carter Treaties provided for handover to Panama. After a period of joint American–Panamanian control, in 1999, the canal was taken over by the Panamanian government. It is now managed and operated by the government-owned Panama Canal Authority.

Annual traffic has risen from about 1,000 ships in 1914, when the canal opened, to 14,702 vessels in 2008, for a total of 333.7 million Panama Canal/Universal Measurement System (PC/UMS) tons. By 2012, more than 815,000 vessels had passed through the canal. It takes 11.38 hours to pass through the Panama Canal. The American Society of Civil Engineers has ranked the Panama Canal one of the seven wonders of the modern world.

Panama Canal Zone

The Panama Canal Zone (Spanish: Zona del Canal de Panamá) was an unincorporated territory of the United States from 1903 to 1979, centered on the Panama Canal and surrounded by the Republic of Panama. The zone consisted of the canal and an area generally extending five miles (8.0 km) on each side of the centerline, excluding Panama City and Colón, which otherwise would have been partly within the limits of the Zone. Its border spanned three of Panama's provinces. When reservoirs were created to assure a steady supply of water for the locks, those lakes were included within the Zone.

In 1904, the Isthmian Canal Convention was proclaimed. In it, the Republic of Panama granted to the United States in perpetuity the use, occupation, and control of a zone of land and land under water for the construction, maintenance, operation, sanitation, and protection of the canal. From 1903 to 1979, the territory was controlled by the United States, which had purchased the land from the private and public owners, built the canal and financed its construction. The Canal Zone was abolished in 1979, as a term of the Torrijos–Carter Treaties two years earlier; the canal itself was later under joint U.S.–Panamanian control until it was fully turned over to Panama in 1999.

Rideau Canal

The Rideau Canal, also known unofficially as the Rideau Waterway, connects Canada's capital city of Ottawa, Ontario, to Lake Ontario and the Saint Lawrence River at Kingston, Ontario. It is 202 kilometres in length. The name Rideau, French for "curtain", is derived from the curtain-like appearance of the Rideau River's twin waterfalls where they join the Ottawa River. The canal system uses sections of two rivers, the Rideau and the Cataraqui, as well as several lakes. The Rideau Canal is operated by Parks Canada.

The canal was opened in 1832 as a precaution in case of war with the United States. It remains in use today primarily for pleasure boating, with most of its original structures intact, operated by Parks Canada. The locks on the system open for navigation in mid-May and close in mid-October. It is the oldest continuously operated canal system in North America, and in 2007 it was registered as a UNESCO World Heritage Site.

StudioCanal

StudioCanal (formerly known as Le Studio Canal+, Canal Plus, Canal+ Distribution, Canal+ Production, and Canal+ Image) is a French film production and distribution company that owns the third-largest film library in the world. The company is a unit of the Canal+ Group, owned by Vivendi.

Suez Canal

The Suez Canal (Arabic: قناة السويس‎ qanāt as-suwēs) is a sea-level waterway in Egypt, connecting the Mediterranean Sea to the Red Sea through the Isthmus of Suez. Constructed by the Suez Canal Company between 1859 and 1869, it was officially opened on 17 November 1869. The canal offers watercraft a more direct route between the North Atlantic and northern Indian oceans via the Mediterranean and Red seas, thus avoiding the South Atlantic and southern Indian Oceans and thereby reducing the journey distance from the Arabian Sea to, for example, London by approximately 8,900 kilometres (5,500 mi). It extends from the northern terminus of Port Said to the southern terminus of Port Tewfik at the city of Suez. Its length is 193.30 km (120.11 mi), including its northern and southern access channels. In 2012, 17,225 vessels traversed the canal (an average of 47 per day).The original canal was a single-lane waterway with passing locations in the Ballah Bypass and the Great Bitter Lake. It contains no locks system, with seawater flowing freely through it. In general, the canal north of the Bitter Lakes flows north in winter and south in summer. South of the lakes, the current changes with the tide at Suez.The Canal was owned by the United Kingdom and France until 1956 when Gamal Abdel Nasser nationalized it, an event which led to the Suez Crisis. The canal is owned and maintained by the Suez Canal Authority (SCA) of Egypt. Under the Convention of Constantinople, it may be used "in time of war as in time of peace, by every vessel of commerce or of war, without distinction of flag".In August 2014, construction was launched to expand and widen the Ballah Bypass for 35 km (22 mi) to speed the canal's transit time. The expansion was planned to double the capacity of the Suez Canal from 49 to 97 ships a day. At a cost of $8.4 billion, this project was funded with interest-bearing investment certificates issued exclusively to Egyptian entities and individuals. The "New Suez Canal", as the expansion was dubbed, was opened with great fanfare in a ceremony on 6 August 2015.On 24 February 2016, the Suez Canal Authority officially opened the new side channel. This side channel, located at the northern side of the east extension of the Suez Canal, serves the East Terminal for berthing and unberthing vessels from the terminal. As the East Container Terminal is located on the Canal itself, before the construction of the new side channel it was not possible to berth or unberth vessels at the terminal while the convoy was running.

Suez Crisis

The Suez Crisis, or the Second Arab–Israeli War, also named the Tripartite Aggression in the Arab world (Arabic: العدوان الثلاثي‎) and Operation Kadesh or Sinai War in Israel, was an invasion of Egypt in late 1956 by Israel, followed by the United Kingdom and France. The aims were to regain Western control of the Suez Canal and to remove Egyptian President Gamal Abdel Nasser, who had just nationalized the canal. After the fighting had started, political pressure from the United States, the Soviet Union and the United Nations led to a withdrawal by the three invaders. The episode humiliated the United Kingdom and France and strengthened Nasser.On 29 October, Israel invaded the Egyptian Sinai. Britain and France issued a joint ultimatum to cease fire, which was ignored. On 5 November, Britain and France landed paratroopers along the Suez Canal. The Egyptian forces were defeated, but they did block the canal to all shipping. It later became clear that the Israeli invasion and the subsequent Anglo-French attack had been planned beforehand by the three countries.

The three allies had attained a number of their military objectives, but the canal was useless. Heavy political pressure from the United States and the USSR led to a withdrawal. U.S. President Dwight D. Eisenhower had strongly warned Britain not to invade; he threatened serious damage to the British financial system by selling the US government's pound sterling bonds. Historians conclude the crisis "signified the end of Great Britain's role as one of the world's major powers". The Suez Canal was closed from October 1956 until March 1957. Israel fulfilled some of its objectives, such as attaining freedom of navigation through the Straits of Tiran, which Egypt had blocked to Israeli shipping since 1950.As a result of the conflict, the United Nations created the UNEF Peacekeepers to police the Egyptian–Israeli border, British Prime Minister Anthony Eden resigned, Canadian Minister of External Affairs Lester Pearson won the Nobel Peace Prize, and the USSR may have been emboldened to invade Hungary.

Vagina

In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vulva to the cervix. The outer vaginal opening is normally partly covered by a membrane called the hymen. At the deep end, the cervix (neck of the uterus) bulges into the vagina. The vagina allows for sexual intercourse and birth. It also channels menstrual flow (menses), which occurs in humans and closely related primates as part of the monthly menstrual cycle.

Although research on the vagina is especially lacking for different animals, its location, structure and size is documented as varying among species. Female mammals usually have two external openings in the vulva, the urethral opening for the urinary tract and the vaginal opening for the genital tract. This is different from male mammals, who usually have a single urethral opening for both urination and reproduction. The vaginal opening is much larger than the nearby urethral opening, and both are protected by the labia in humans. In amphibians, birds, reptiles and monotremes, the cloaca is the single external opening for the gastrointestinal tract, the urinary, and reproductive tracts.

To accommodate smoother penetration of the vagina during sexual intercourse or other sexual activity, vaginal moisture increases during sexual arousal in human females and other female mammals. This increase in moisture provides vaginal lubrication, which reduces friction. The texture of the vaginal walls creates friction for the penis during sexual intercourse and stimulates it toward ejaculation, enabling fertilization. Along with pleasure and bonding, women's sexual behavior with others (which can include heterosexual or lesbian sexual activity) can result in sexually transmitted infections (STIs), the risk of which can be reduced by recommended safe sex practices. Other health issues may also affect the human vagina.

The vagina and vulva have evoked strong reactions in societies throughout history, including negative perceptions and language, cultural taboos, and their use as symbols for female sexuality, spirituality, or regeneration of life. In common speech, the word vagina is often used to refer to the vulva or to the female genitals in general. By its dictionary and anatomical definitions, however, vagina refers exclusively to the specific internal structure, and understanding the distinction can improve knowledge of the female genitalia and aid in healthcare communication.

Yamuna

The Yamuna (Hindustani: pronounced [jəmʊnaː]), also known as the Jumna or Jamna (not to be mistaken with the Jamuna of Bangladesh), is the second largest tributary river of the Ganges (Ganga) and the longest tributary in India. Originating from the Yamunotri Glacier at a height of 6,387 metres (20,955 ft) on the southwestern slopes of Banderpooch peaks of the Lower Himalaya in Uttarakhand, it travels a total length of 1,376 kilometres (855 mi) and has a drainage system of 366,223 square kilometres (141,399 sq mi), 40.2% of the entire Ganges Basin. It merges with the Ganges at Triveni Sangam, Prayagraj (Prayagraj), which is a site of the Kumbh Mela, a Hindu festival held every 12 years.

It crosses several states: Haryana and Uttar Pradesh, passing by Uttarakhand and later Delhi, and meeting its tributaries on the way, including Tons, its largest tributary, Chambal, its longest tributary which has its own large basin, followed by Sindh, the Betwa, and Ken. From Uttaranchal, the river flows into the state of Himachal Pradesh. After passing Paonta Sahib, Yamuna flows along the boundary of Haryana and Uttar Pradesh and after exiting Haryana it continues to flow till it merges with the river Ganga (Ganges) at Sangam or Prayag in Allahbad (Uttar Pradesh). It helps create the highly fertile alluvial Yamuna-Ganges Doab region between itself and the Ganges in the Indo-Gangetic plain. Nearly 57 million people depend on the Yamuna's waters. With an annual flow of about 10,000 cubic billion metres (cbm; 8.1 billion acre⋅ft) and usage of 4,400 cbm (of which irrigation constitutes 96 per cent), the river accounts for more than 70 per cent of Delhi's water supply. Like the Ganges, the Yamuna is highly venerated in Hinduism and worshipped as the goddess Yamuna. In Hindu mythology she is the daughter of the Sun Deva, Surya, and the sister of Yama, the Deva of Death, hence also known as Yami. According to popular legends, bathing in its sacred waters frees one from the torments of death.At the Hathni Kund Barrage, its waters are diverted into two large canals: the Western Yamuna Canal flowing towards Haryana and the Eastern Yamuna Canal towards Uttar Pradesh. Beyond that point the Yamuna is joined only by the Somb, a seasonal rivulet from Haryana, and by the highly polluted Hindon River near Noida, so that it continues only as a trickling sewage-bearing drain before joining the Chambal at Pachnada in the Etawah District of Uttar Pradesh. The water of Yamuna is of "reasonably good quality" through its length from Yamunotri in the Himalayas to Wazirabad barrage in Delhi, about 375 kilometres (233 mi); below this, the discharge of wastewater through 15 drains between Wazirabad barrage and Okhla barrage renders the river severely polluted.

One official described the river as a "sewage drain" with biochemical oxygen demand (BOD) values ranging from 14 to 28 mg/l and high coliform content. There are three main sources of pollution in the river: household and municipal disposal sites, soil erosion resulting from deforestation occurring to make way for agriculture, and resulting chemical wash-off from fertilizers, herbicides, and pesticides and run-off from commercial activity and industrial sites. The Yamuna from its origin at Yamunotri to Okhla barrage is called the Upper Yamuna.

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