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56-486: The fjord narrows to a strait at Svelvik on the west side and Verket in Asker on the east side. The strait is crossed by an automobile ferry . This narrowing, some 200 metres (660 ft) broad and 10 metres (33 ft) deep, combined with the large freshwater inflow from the river Drammenselva (one of Norway's largest rivers) and from the river Lierelva, results in the water north of the strait being brackish water . On

112-547: 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

168-510: A drainage divide atop a ridge , generally requiring an external water source above the highest elevation . The best-known example of such a canal is the Panama Canal . Many canals have been built at elevations, above valleys and other waterways. 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. The term

224-415: A "cistern", or depressed area just downstream from the fall, to "cushion" the water by providing a deep pool for its kinetic energy to be diffused in. Vertical falls work for drops of up to 1.5 m in height, and for discharge of up to 15 cubic meters per second. The transport capacity of pack animals and carts is limited. A mule can carry an eighth-ton [250 pounds (113 kg)] maximum load over

280-496: A canal has 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 can be called a navigation canal when it parallels a natural river and shares part of the latter's discharges 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 . A canal can cut across

336-413: A combination of the three, depending on available water and available path: 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 ). At their simplest, canals consist of a trench filled with water. Depending on

392-549: A journey measured in days and weeks, though much more for shorter distances and periods with appropriate rest. Besides, carts need roads. Transport over water is much more efficient and cost-effective for large cargoes. The oldest known canals were irrigation canals, built in Mesopotamia c.  4000 BC , in what is now Iraq . The Indus Valley civilization of ancient India ( c.  3000 BC ) had sophisticated irrigation and storage systems developed, including

448-714: A number of decades the Drammensfjord was heavily polluted . The sewage and industrial discharges by industries in the city of Drammen have been corrected so that the water is now much cleaner. Salmon and sea trout are again found in both the fjord and the Drammenselva river. In historic times the Drammensfjord was known by the Old Norse name Dramn or Drofn , meaning hazy waters. In the Norse sagas Snorre Sturlason tells that Saint Olav hid himself from Canute

504-581: A rather low gradient for its time. The canal is still in use after renovation. 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, it also needed teamsters to tend it and one man could only tend perhaps five mules, meaning overland bulk transport

560-459: 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 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

616-422: Is a channel that cuts across a drainage divide , making a navigable channel connecting two different drainage basins . Both navigations and canals use engineered structures to improve navigation: 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

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672-701: 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. In

728-599: Is rarely less than 30 metres (98 ft) wide. In the 5th century BC, Achaemenid king Xerxes I of Persia ordered the construction of the Xerxes Canal through the base of Mount Athos peninsula, Chalkidiki , northern Greece. It was constructed as part of his preparations for the Second Persian invasion of Greece , a part of the Greco-Persian Wars . It is one of the few monuments left by

784-418: Is steeper than the desired canal gradient. They are constructed so the falling water's kinetic energy is dissipated in order to prevent it from scouring the bed and sides of the canal. A canal fall is constructed by cut and fill . It may be combined with a regulator, bridge, or other structure to save costs. There are various types of canal falls, based on their shape. One type is the ogee fall, where

840-452: 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 and later in Europe in

896-401: Is typically reserved for much larger, wider features of the marine environment. There are exceptions, with straits being called canals; Pearse Canal , for example. Straits are the converse of isthmuses . That is, while a strait lies between two land masses and connects two large areas of ocean, an isthmus lies between two areas of ocean and connects two large land masses. Some straits have

952-658: 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. The oldest canal in the European settlements of North America, technically a mill race built for industrial purposes, is Mother Brook between the Boston, Massachusetts neighbourhoods of Dedham and Hyde Park connecting

1008-543: The Naviglio Grande built between 1127 and 1257 to connect Milan with the river Ticino . The Naviglio Grande is the most important of the lombard " navigli " 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

1064-545: The Phoenix metropolitan area was the most complex in ancient North America. A portion of the ancient canals has been renovated for the Salt River Project and now helps to supply the city's water. The Sinhalese constructed the 87 km (54 mi) Yodha Ela in 459 A.D. as a part of their extensive irrigation network which functioned in a way of a moving reservoir due to its single banking aspect to manage

1120-528: The River Brue at Northover with Glastonbury Abbey , a distance of about 1.75 kilometres (1,900 yd). 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. More lasting and of more economic impact were canals like

1176-527: The Selvikstrømmen (the Svelvik current). Large ships can only sail in daylight and the largest only when assisted by tugboats . The strait has been made wider and deeper to accommodate traffic. Dead coral reefs are also found at depths of about 10–20 metres (33–66 ft) below sea level in the fjord. The maximum depth of the fjord northwards of the strait, reaching 117 metres (384 ft). For

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1232-614: The Songhai Empire of West Africa, several canals were constructed under Sunni Ali and Askia Muhammad I between Kabara and Timbuktu in the 15th century. These were used primarily for irrigation and transport. Sunni Ali also attempted to construct a canal from the Niger River to Walata to facilitate conquest of the city but his progress was halted when he went to war with the Mossi Kingdoms . Around 1500–1800

1288-468: The Suez Canal . Although rivers and canals often provide passage between two large lakes, and these seem to suit the formal definition of strait, they are not usually referred to as such. Rivers and often canals, generally have a directional flow tied to changes in elevation, whereas straits often are free flowing in either direction or switch direction, maintaining the same elevation. The term strait

1344-556: The reservoirs built at Girnar in 3000 BC. This is the first time that such planned civil project had taken place in the ancient world. 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 . In ancient China , large canals for river transport were established as far back as the Spring and Autumn period (8th–5th centuries BC),

1400-404: 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 . 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

1456-471: 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. Another important development was the mitre gate , which was, it

1512-472: 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

1568-470: The Great at a fjord which was called Dramn. At that time the water stood about 4–5 metres (13–16 ft) higher and the fjord reached up to Hokksund . This area is still rebounding from the enormous weight of the glacial ice ( isostatic rebound ), "growing out of the sea" several millimeters a year, especially near the inner part of the long fjords, where the ice cover was thickest. This is a slow process, thus

1624-590: The Persian Empire in Europe . 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. 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

1680-785: The Southwest by 1300 CE. Archaeologists working at a major archaeological dig in the 1990s in the Tucson Basin, along the Santa Cruz River, identified a culture and people that may have been the ancestors of the Hohokam. This prehistoric group occupied southern Arizona as early as 2000 BCE, and in the Early Agricultural period grew corn, lived year-round in sedentary villages, and developed sophisticated irrigation canals. The large-scale Hohokam irrigation network in

1736-436: The canal pressure with the influx of water. It was also designed as an elongated reservoir passing through traps creating 66 mini catchments as it flows from Kala Wewa to Thissa Wawa . The canal was not designed for the quick conveying of water from Kala Wewa to Thissa Wawa but to create a mass of water between the two reservoirs, which would in turn provided for agriculture and the use of humans and animals. They also achieved

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1792-418: 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. A canal fall , or canal drop, is a vertical drop in the canal bed. These are built when the natural ground slope

1848-462: 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

1904-469: The channel. There are two broad types of canal: 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 for over a century ceased operation. The few canals still in operation in our modern age are a fraction of

1960-399: The drop follows an s-shaped curve to create a smooth transition and reduce turbulence . However, this smooth transition does not dissipate the water's kinetic energy, which leads to heavy scouring. As a result, the canal needs to be reinforced with concrete or masonry to protect it from eroding. Another type of canal fall is the vertical fall, which is "simple and economical". These feature

2016-670: The first summit level canal to use pound locks in Europe 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,

2072-550: The flow, the surface water still flows, for the most part, at the same elevation on both sides and through the strait in both directions. In some straits there may be a dominant directional current through the strait. Most commonly, it is a narrowing channel that lies between two land masses . Some straits are not navigable, for example because they are either too narrow or too shallow, or because of an unnavigable reef or archipelago . Straits are also known to be loci for sediment accumulation. Usually, sand-size deposits occur on both

2128-462: The freedom to make deliveries well away from rail lined road beds or ditches in the dirt which could not operate in the winter. The longest extant canal today, the Grand Canal in northern China, still remains in heavy use, especially the portion south of the Yellow River . It stretches from Beijing to Hangzhou at 1,794 kilometres (1,115 miles). Canals are built in one of three ways, or

2184-549: 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 . Hohokam was a society in the North American Southwest in what is now part of Arizona , United States, and Sonora , Mexico. Their irrigation systems supported the largest population in

2240-480: The longest canal in the world today and the oldest extant one. 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

2296-534: 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. 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

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2352-506: 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

2408-472: The potential to generate significant tidal power using tidal stream turbines . Tides are more predictable than wave power or wind power . The Pentland Firth (a strait) may be capable of generating 10  GW . Cook Strait in New Zealand may be capable of generating 5.6 GW even though the total energy available in the flow is 15 GW. Straits used for international navigation through

2464-604: 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

2520-670: The sea covered substantial areas of what is today dry land for thousands of years following the end of the ice age. During the Viking Age, the Drammensfjorden north of the Svelvik Strait was regarded as a lake and the Svelvik Strait was regarded as the mouth of the Drammenselva river. Strait A strait is a water body connecting two seas or two water basins. While the landform generally constricts

2576-480: The standard of living for any industrialized society. Most ship canals today primarily service 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

2632-407: The surface the water is fairly fresh, resulting in bathing areas that are free of jelly fish , while deeper the water has a higher salt concentration, with saltwater fish such as cod , pollock , flounder , and mackerel . The ocean tide going through the strait is one of Norway's strongest currents. The outflow can reach speeds of 5 knots (9.3  km/h ; 5.8  mph ). The strait is known

2688-423: The territorial sea between one part of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone are subject to the legal regime of transit passage ( Strait of Gibraltar , Dover Strait , Strait of Hormuz ). The regime of innocent passage applies in straits used for international navigation (1) that connect a part of high seas or an exclusive economic zone with

2744-935: The territorial sea of a coastal nation ( Straits of Tiran , Strait of Juan de Fuca , Strait of Baltiysk ) and (2) in straits formed by an island of a state bordering the strait and its mainland if there exists seaward of the island a route through the high seas or through an exclusive economic zone of similar convenience with respect to navigational and hydrographical characteristics ( Strait of Messina , Pentland Firth ). There may be no suspension of innocent passage through such straits. [REDACTED] Media related to Straits at Wikimedia Commons Canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation ) or for conveyancing water transport vehicles (e.g. water taxi ). They carry free, calm surface flow under atmospheric pressure , and can be thought of as artificial rivers . In most cases,

2800-574: The two opposite strait exits, forming subaqueous fans or deltas . The terms channel , pass , or passage can be synonymous and used interchangeably with strait , although each is sometimes differentiated with varying senses. In Scotland, firth or Kyle are also sometimes used as synonyms for strait. Many straits are economically important. Straits can be important shipping routes and wars have been fought for control of them. Numerous artificial channels, called canals , have been constructed to connect two oceans or seas over land, such as

2856-573: 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

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2912-466: 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

2968-458: 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

3024-470: 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

3080-424: 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

3136-426: Was once used to describe linear features seen on the surface of Mars , Martian canals , an optical illusion. 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

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