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130-609: Unlike on the upper rivers, there are no locks or dams on the Lower Mississippi. The river is, however, constrained by levees and dikes to control flooding and secure a navigation channel for barges . The Old River Control Structure , the Bonnet Carré Spillway , the Mississippi River – Gulf Outlet Canal and other man-made structures on the lower reaches of the river seek to manipulate

260-740: A flash lock . Pound locks were first used in China during the Song dynasty (960–1279 CE), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. They replaced earlier double slipways that had caused trouble and are mentioned by the Chinese polymath Shen Kuo (1031–1095) in his book Dream Pool Essays (published in 1088), and fully described in the Chinese historical text Song Shi (compiled in 1345): The distance between

390-404: 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. A pound lock is most commonly used on canals and rivers today. A pound lock has a chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as

520-528: A broad canal for more than one boat to be in a staircase at the same time, but managing this without waste of water requires expertise. On English canals, a staircase of more than two chambers is usually staffed: the lockkeepers at Bingley (looking after both the "5-rise" and the "3-rise") ensure that there are no untoward events and that boats are moved through as speedily and efficiently as possible. Such expertise permits miracles of boat balletics: boats travelling in opposite directions can pass each other halfway up

650-468: A competitor but as an economic feeder into the greater Suzhou market. Therefore, the Grand Canal served to make or break the economic fortunes of certain cities along its route and served as the economic lifeline of indigenous trade within China. The scholar Gu Yanwu of the early Qing dynasty (1644–1912) estimated that the previous Ming dynasty had to employ 47,004 full-time laborers recruited by

780-426: A flight of locks is simply a series of locks in close-enough proximity to be identified as a single group. For many reasons, a flight of locks is preferable to the same number of locks spread more widely: crews are put ashore and picked up once, rather than multiple times; transition involves a concentrated burst of effort, rather than a continually interrupted journey; a lock keeper may be stationed to help crews through

910-660: A further canal on the Tonghui River connected Tongzhou with a wharf called the Houhai or "rear sea" in central Beijing. In the Ming and Qing dynasties, however, the water level in the Tonghui River dropped and ships could not travel from Tongzhou to Beijing. Tongzhou then became the northern shipping terminus of the canal. Cargo was unloaded at Tongzhou and transported to Beijing by land. The Tonghui river still exists as

1040-469: A gated space while the water could be drained to appropriate levels; the Chinese also built roofed hangars over the space to add further protection for the ships. Much of the Grand Canal was ruined for several years after 1128 when Kaifeng's governor Du Chong ( 杜 充 , Dù Chōng , d.   1141) decided to break the dykes and dams holding back the waters of the Yellow River in order to decimate

1170-480: A lock is simple. For instance, if a boat travelling downstream finds the lock already full of water: If the lock were empty, the boat would have had to wait 5 to 10 minutes while the lock was filled. For a boat travelling upstream, the process is reversed; the boat enters the empty lock, and then the chamber is filled by opening a valve that allows water to enter the chamber from the upper level. The whole operation will usually take between 10 and 20 minutes, depending on

1300-537: A lock, and the position of the forward edge of the cill is usually marked on the lock side by a white line. The edge of the cill is usually curved, protruding less in the center than at the edges. In some locks, there is a piece of oak about 9 in (23 cm) thick which protects the solid part of the lock cill. On the Oxford Canal it is called a babbie; on the Grand Union Canal it is referred to as

1430-572: A man named Li Hualong created the Jia Canal. Named after the Jia River whose course it followed, it ran 140 kilometers (87 mi) from Xiazhen (modern Weishan) on the shore of Shandong's Weishan Lake to Suqian in Jiangsu. The construction of the Jia Canal left only 100 kilometers (62 mi) of Yellow River navigation on the Grand Canal, from Suqian to Huai'an, which by 1688 had been removed by

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1560-559: A rapid courier system. Enormous lines of trees were also planted along parts of the canal as windbreaks. Although the Tang dynasty (618–907) capital at Chang'an was the most thriving metropolis of China in its day, it was the city of Yangzhou —in proximity to the Grand Canal—that was the economic hub of the Tang era. Besides being the headquarters for the government salt monopoly and

1690-512: A renovated stone channel, it reaches the city of Linqing on the Shandong – Hebei border. Liangshan County is the northern terminus of the canal for barge traffic. The fifth section of the canal extends for a distance of 524 kilometers (326 mi) from Linqing to Tianjin along the course of the canalized Wei River . Though one of the northernmost sections, its name derives from its position relative to Tianjin. The Wei River at this point

1820-419: A series of lakes—Zhaoyang, Dushan, and Nanyang—which nominally form a continuous body of water. At present, diversions of water mean that the lakes are often largely dry land. North of the northernmost Nanyang Lake is the city of Jining . Further on, about 30 km (19 mi) north of Jining, the highest elevation of the canal (38.5 m or 126 ft above sea level) is reached at the town of Nanwang . In

1950-445: A smooth and efficient canal system. The city of Kaifeng grew to be a major hub, later becoming the capital of the Song dynasty (960–1279). Although the Tang and Song dynasty international seaports—the greatest being Guangzhou and Quanzhou , respectively—and maritime foreign trade brought merchants great fortune, it was the Grand Canal within China that spurred the greatest amount of economic activity and commercial profit. During

2080-480: A staircase lock can be used as an emergency dry dock). To avoid these mishaps, it is usual to have the whole staircase empty before starting to descend, or full before starting to ascend, apart from the initial chamber. One striking difference in using a staircase of either type (compared with a single lock, or a flight) is the best sequence for letting boats through. In a single lock (or a flight with room for boats to pass) boats should ideally alternate in direction. In

2210-404: A staircase, however, it is quicker for a boat to follow a previous one going in the same direction. Partly for this reason staircase locks such as Grindley Brook, Foxton, Watford and Bratch are supervised by lockkeepers, at least during the main cruising season, they normally try to alternate as many boats up, followed by down as there are chambers in the flight. As with a flight, it is possible on

2340-467: A total of 165,000 laborers dredged the canal bed in Shandong and built new channels, embankments, and canal locks . The Yongle Emperor moved the Ming capital from Nanjing to Beijing in 1403. This move deprived Nanjing of its status as chief political center of China. The reopening of the Grand Canal also benefited Suzhou over Nanjing since the former was in a better position on the main artery of

2470-400: A tunnel, which when descending does not become visible until the chamber is nearly empty. A pound is the level stretch of water between two locks (also known as a reach ). The cill , also spelled sill , is a narrow horizontal ledge protruding a short way into the chamber from below the upper gates. Allowing the rear of the boat to "hang" on the cill is the main danger when descending

2600-785: A wide, concrete-lined storm-channel and drain for the suburbs of Beijing. The Eastern Zhejiang Canal runs 239 kilometers (149 mi) across the coastal plain south of Hangzhou Bay in northern Zhejiang. It begins at the Qiantang River in Xixing, Binjiang District , Hangzhou; crosses the Cao'e River in Shaoxing ; and connects to the Yong River and ports on the East China Sea at Ningbo . This Hangzhou–Ningbo canal began as

2730-466: Is heavily polluted while drought and industrial water extraction have left it too low to be navigable. The canal, now in Hebei province, passes through the cities of Dezhou and Cangzhou . Although to spectators, the canal appears to be a deep waterway in these city centers, its depth is maintained by weirs and the canal is all but dry where it passes through the surrounding countryside. At its terminus,

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2860-439: 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

2990-426: Is a normal top gate, and the intermediate gates are all as tall as the bottom gate). As there is no intermediate pound, a chamber can only be filled by emptying the one above, or emptied by filling the one below: thus the whole staircase has to be full of water (except for the bottom chamber) before a boat starts to ascend, or empty (except for the top chamber) before a boat starts to descend. In an "apparent" staircase

3120-620: Is an elevation of 42 m (138 ft) above sea level reached in the foothills of Shandong. Ships in Chinese canals did not have trouble reaching higher elevations after the Song official and engineer Qiao Weiyue invented the pound lock in the 10th century. The canal has been admired by many visitors throughout its history, including the Japanese monk Ennin (794–864), the Persian historian Rashid al-Din Hamadani (1247–1318),

3250-856: Is currently navigable. Its course is today divided into seven sections. From south to north these are the Jiangnan Canal, the Li Canal, the Inner Canal, the Middle Canal, the Lu Canal, the South Canal, the North Canal, and the Tonghui River. Man-Made Lake Lianhu Training Lake "Lianhu" was used to feed water to the Grand Canal section near Jiangnan. Since the canal was man-made there was not enough naturally flowing water to keep

3380-443: Is only a staircase if successive lock chambers share a gate (i.e. do not have separate top and bottom gates with a pound between them). Most flights are not staircases, because each chamber is a separate lock (with its own upper and lower gates), there is a navigable pound (however short) between each pair of locks, and the locks are operated in the conventional way. However, some flights include (or consist entirely of) staircases. On

3510-575: Is the change in water-level in the lock. The two deepest locks on the English canal system are Bath deep lock on the Kennet and Avon Canal and Tuel Lane Lock on the Rochdale Canal , which both have a rise of nearly 20 feet (6.1 m). Both locks are amalgamations of two separate locks, which were combined when the canals were restored to accommodate changes in road crossings. By comparison,

3640-550: Is the remnant of the New Nanyang Canal of 1566 – see below). A southerly course passes close by Xuzhou and enters Weishan Lake near Peixian . This latter course is less used today. Canal is utilized by barge traffic bringing coal and construction materials around northern Jiangsu Province. At Weishan Lake, both courses enter Shandong province. From here to Linqing , the canal is called the Lu or 'Shandong' Canal. It crosses

3770-881: The Bollène lock on the River Rhône has a fall of at least 23 m (75 ft), the Leerstetten, Eckersmühlen and Hilpoltstein locks on the Rhine–Main–Danube Canal have a fall of 24.67 m (80.9 ft), each and the Oskemen Lock on the Irtysh River in Kazakhstan has a drop of 42 m (138 ft). The natural extension of the flash lock , or staunch, was to provide an upper gate (or pair of gates) to form an intermediate "pound" which

3900-476: The Grand Union . Operation of a staircase is more involved than a flight. Inexperienced boaters may find operating staircase locks difficult. The key worries (apart from simply being paralysed with indecision) are either sending down more water than the lower chambers can cope with (flooding the towpath, or sending a wave along the canal) or completely emptying an intermediate chamber (although this shows that

4030-718: The Huai River just west of Lake Hongze . With the recorded labor of five million people under the supervision of Ma Shumou, the first major section of the Grand Canal was completed in the year 605 and was called the Bian Qu. The Grand Canal was fully completed from the years 604 to 609 under Emperor Yang , first by linking his southern capital Yangzhou northwest to Luoyang by the Tongji Canal ( t 通 濟 渠 , s 通 济 渠 , Tōngjì Qú ). He then proceeded to connect Yangzhou southeast to Suzhou and Hangzhou by

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4160-577: The Huai River , and then transferred back onto deep barges once the shipment of grain reached the Yellow River . Chinese engineers built a dam to divert the Wen River to the southwest in order to feed 60% of its water north into the Grand Canal, with the remainder going south. They dug four large reservoirs in Shandong to regulate water levels, which allowed them to avoid pumping water from local sources and water tables. Between 1411 and 1415

4290-541: The Jiangnan Canal and to connect Luoyang northeast to his wars with Korea by the Yongji Canal ( t 永 濟 渠 , s 永 济 渠 , Yǒngjì Qú ). After this network's completion in 609, Emperor Yang was said to have led a flotilla of boats 105 km (65 mi) long from the north down to his southern capital at Yangzhou. This process again involved massive levies of conscripted labor and

4420-463: The Kennet and Avon Canal . Grand Canal (China) The Grand Canal ( Chinese : 大运河 ; pinyin : Dà yùnhé ) is a system of interconnected canals linking various major rivers in North and East China , serving as an important waterborne transport infrastructure between the north and the south during Medieval and premodern China . It is the longest artificial waterway in

4550-615: The Korean official Choe Bu (1454–1504), and the Italian missionary Matteo Ricci (1552–1610). In the late Spring and Autumn period , King Fuchai of Wu (whose capital was in present-day Suzhou ), ventured north to attack the State of Qi . He ordered a canal to be constructed for trading purposes, as well as a means to ship ample supplies north in case his forces should engage the northern states of Song and Lu . This became known as

4680-613: The Milan canal system sponsored by Francesco Sforza ) between 1452 and 1458. In Ancient Egypt, the river-locks was probably part of the Canal of the Pharaohs : Ptolemy II is credited by some for being the first to solve the problem of keeping the Nile free of salt water when his engineers invented the lock around 274/273 BC. All pound locks have three elements: The principle of operating

4810-516: The Mongols invaded in the 13th century and began necessary repairs. During the Mongol Yuan dynasty (1271–1368) the capital of China was moved to Beijing, eliminating the need for the canal arm flowing west to Kaifeng or Luoyang. A summit section was dug across the foothills of the Shandong massif during the 1280s, shortening the overall length by as much as 700 km (430 mi), making

4940-598: The Song dynasty (960–1279 CE). The Songshi or History of the Song Dynasty, volume 307, biography 66, records how Qiao Weiyue, a high-ranking tax administrator, was frustrated at the frequent losses incurred when his grain barges were wrecked on the West River near Huai'an in Jiangsu . The soldiers at one double slipway, he discovered, had plotted with bandits to wreck heavy imperial barges so that they could steal

5070-680: The Taiping Rebellion 's Northern Expedition . Because of various factors—the difficulty of crossing the Yellow River, the increased development of an alternative sea route for grain-ships, and the opening of the Tianjin-Pukou Railway and the Beijing-Hankou Railway —the canal languished and for decades the northern and southern parts remained separate. Many of the canal sections fell into disrepair, and some parts were returned to flat fields. Even today,

5200-688: The Yangtze Delta to northern China . Minor additions to the canal were made after the Sui period to cut down on travel time, but overall no fundamental differences existed between the Sui Grand Canal and the Tang Grand Canal. By the year 735, it was recorded that about 149,685,400 kilograms (165,000 short tons) of grain were shipped annually along the canal. The Tang government oversaw canal lock efficiency and built granaries along

5330-553: The hypoxic zone in the Gulf of Mexico . Agricultural runoff has resulted in increased turbidity , siltation , pollution from pesticides , toxicity to aquatic organisms, oxygen depletion and eutrophication . Channel depth of 9 feet is maintained by the Corps of Engineers from St. Louis, Missouri to Baton Rouge, Louisiana . On the lower Mississippi, from Baton Rouge to the Gulf,

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5460-529: The lijia corvée system in order to maintain the entire canal system. It is known that 121,500 soldiers and officers were needed simply to operate the 11,775 government grain barges in the mid-15th century. Besides its function as a grain shipment route and major vein of river-borne indigenous trade in China, the Grand Canal had long been a government-operated courier route as well. In the Ming dynasty, official courier stations were placed at intervals of 35 to 45 km (22 to 28 mi). Each courier station

5590-482: The provinces and municipalities of Zhejiang , Jiangsu , Shandong , Hebei , Tianjin, and Beijing. In 2014, the Chinese government and UNESCO recognized the Eastern Zhejiang Canal from Hangzhou to Ningbo along the former Tongji and Yongji Canals as official components of the Grand Canal. The oldest sections of what is now the Grand Canal were completed in the early 5th century BC during

5720-498: The 1950s a new canal was dug to the south of the old summit section. The old summit section is now dry, while the new canal holds too little water to be navigable. About 50 km (31 mi) further north, passing close by Dongping Lake , the canal reaches the Yellow River. By this point waterless, it no longer connects to the river. It reappears again in Liaocheng City on the north bank where, intermittently flowing through

5850-601: The 1990s, canal barge crews could tell when they neared Hangzhou by the stench of the visibly black water they passed through. Similarly, fishermen on Dongping Lake in Shandong objected to the introduction of water from the Yangtze as part of the South-North Water Diversion Project when they saw it noticeably killing fish and affecting their catch. During the 21st century, increasing efforts have been made to improve environmental conditions along

5980-599: The Beijing–Hangzhou and Sui and Tang canals as part of UNESCO's listing for the Grand Canal. The Grand Canal World Heritage site is composed of 31 sections and a number of accessory heritage sites. Though the canal nominally crosses the watersheds of five river systems, in reality, the variation between these is so low that it has only a single summit section. The elevation of the canal bed varies from 1 m below sea level at Hangzhou to 38.5 m above at its summit. At Beijing, it reaches 27 m, fed by streams flowing downhill from

6110-689: The Carrapatelo and Valeira locks on the Douro river in Portugal, which are 279 feet (85 m) long and 39 feet (12 m) wide, have maximum lifts of 115 and 108 feet (35 and 33 m) respectively. The two Ardnacrusha locks near Limerick on the Shannon navigation in Ireland have a rise of 100 feet (30 m). The upper chamber rises 60 feet (18 m) and is connected to the lower chamber by

6240-466: The Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. A swell was caused by opening suddenly the paddle valves in the lock gates, or when emptying a lock. To help boats traveling downstream exit a lock, the locksman would sometimes open the paddles to create a swell, which would help "flush" the boat out of

6370-495: The Chinese architecture. Many saw the canal as an economic advantage that could bring economic prosperity, like the canal and its benefits. Matteo Ricci 's Journals describes the canal in great detail documenting the economic prosperity. The pound lock is one of the more notable features of the Erie canal that is directly connected to the infrastructure of the Grand Canal as it is used in other similar bodies of water. The Grand Canal

6500-765: The Grand Canal from the low-lying and flood-prone land west of Weishan Lake onto the marginally higher land to its east. It was fed by rivers flowing from east to west from the borders of the Shandong massif. North of the Jizhou Canal summit section, the Huitong Canal ran downhill, fed principally by the River Wen, to join the Wei River in the city of Linqing. In 1289, a geological survey preceded its one-year construction. The Huitong Canal, built by an engineer called Ma Zhizhen, ran across sharply sloping ground and

6630-576: The Grand Canal has not fully recovered its importance prior to the floods of the mid-19th century. After the founding of the People's Republic of China in 1949, the need for economic development led the authorities to order heavy reconstruction work. The Grand Canal played a major role during Mao Zedong 's Great Leap Forward as it provided an efficient way to transport grain. It was further refurbished following Deng Xiaoping 's Reform and Opening Up , with improving economic conditions leading to greater infrastructure investment. The economic importance of

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6760-409: The Grand Canal with a number of historical sections. Some of these have disappeared, others are still partially extant, and others form the basis for the modern canal. The following are the most important but do not form an exhaustive list. In 12 BC, in order to solve the problem of the Grand Canal having to use 160 kilometers (100 mi) of the perilous course of the Yellow River in Northern Jiangsu,

6890-409: The Grand Canal, and so it became Ming China's greatest economic center. The only other viable contender with Suzhou in the Jiangnan region was Hangzhou, but it was located 200 km (120 mi) further down the Grand Canal and away from the main delta. Even the shipwrecked Korean Choe Bu (1454–1504)—while traveling for five months throughout China in 1488—acknowledged that Hangzhou served not as

7020-399: The Grand Union (Leicester) Canal, the Watford flight consists of a four-chamber staircase and three separate locks; and the Foxton flight consists entirely of two adjacent 5-chamber staircases. Where a very steep gradient has to be climbed, a lock staircase is used. There are two types of staircase, "real" and "apparent". A "real" staircase can be thought of as a "compressed" flight, where

7150-468: The Han or Hangou Canal ( t 邗溝 , s 邗沟 , Hángōu ). Work began in 486 BC, from south of Yangzhou to north of Huai'an in Jiangsu, and within three years the Han Canal had connected the Yangtze with the Huai River utilizing existing waterways , lakes , and marshes . The Han Canal is known as the second oldest section of the later Grand Canal since the Hong Canal ( t   鴻溝 , s   鸿沟 , Hónggōu , "Canal of

7280-514: The Jiangnan Canal, the Inner Canal is heavily utilized by barge traffic bringing coal, construction materials and increasingly shipping containers around Jiangsu Province. This 'Middle Canal' section runs from Huai'an to Weishan Lake , passing through Luoma Lake and following more than one course, the result of the impact of centuries of Yellow River flooding. After Pizhou , a northerly course passes through Tai'erzhuang to enter Weishan Lake at Hanzhuang bound for Nanyang and Jining (this course

7410-405: The Jizhou Canal. The Shanyang Canal originally opened onto the Yangtze a short distance south of Yangzhou . As the north shore of the Yangtze gradually silted up to create the sandbank island of Guazhou, it became necessary for boats crossing to and from the Jiangnan Canal to sail the long way around the eastern edge of that island. After a particularly rough crossing of the Yangtze from Zhenjiang,

7540-405: The Shanyin Canal excavated in Shaoxing by the Yue official Fan Li in the early 5th century BC during China's Spring and Autumn period . Despite the difficulty of connecting the route's various watersheds, the present route was completed with the construction of the Xixing Canal by the Jin official He Xun in the late 3rd century AD. The canal was an important artery of transport and supply for

7670-435: The Song and earlier periods, barge ships occasionally crashed and wrecked along the Shanyang Yundao section of the Grand Canal while passing the double slipways, and more often than not those were then robbed of the tax grain by local bandits. This prompted Qiao Weiyue, an Assistant Commissioner of Transport for Huainan , to invent a double-gate system known as the pound lock in the year 984. This allowed ships to wait within

7800-425: The Sui canals was the need to tap into the expanding economic and agricultural resources of the Jiangnan region in the southeast to enrich the main Sui capital at Luoyang to the west and to supply the expeditionary Sui armies in the Goguryeo-Sui Wars to the northeast. The institution of the Grand Canal also obviated the need for army garrisons to become self-sufficient part-time militia-farmers while guarding

7930-473: The Wild Geese" or "Far-Flung Canal") most likely preceded it. It linked the Yellow River near Kaifeng to the Si and Bian rivers and became the model for the shape of the Grand Canal in the north. The exact date of the Hong Canal's construction is uncertain; it is first mentioned by the diplomat Su Qin in 330 BC when discussing state boundaries. The historian Sima Qian (145–90 BC) knew of no historical date for it, placing his discussion of it just after

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8060-428: The Yellow River flooded and changed its course , severing the course of the canal in Shandong. This was foreseen by a Chinese official in 1447, who remarked that the flood-prone Yellow River made the Grand Canal like a throat that could be easily strangled (leading some officials to request restarting the grain shipments through the East China Sea ). In 1855 the dikes of the canal were opened to flood advancing troops of

8190-405: The Yellow River remains in heavy use by barges carrying bulk cargo . Increasing concern over pollution in China and particularly the use of the Grand Canal as the eastern path of the South-North Water Diversion Project —intended to provide clean potable water to the north—has led to regulations and several projects to improve water quality along the waterway. The greatest height on the canal

8320-415: The Yellow River. Such a case occurred in the year 858 when an enormous flood along the Grand Canal inundated thousands of acres of farmland and killed tens of thousands of people in the North China Plain . Such an unfortunate event could reduce the legitimacy of a ruling dynasty by causing others to perceive it as having lost the Mandate of Heaven ; this was a good reason for dynastic authorities to maintain

8450-420: The advent of canals in Britain. The sides of the turf-lock are sloping so, when full, the lock is quite wide. Consequently, this type of lock needs more water to operate than vertical-sided brick- or stone-walled locks. On British canals and waterways most turf-sided locks have been subsequently rebuilt in brick or stone, and so only a few good examples survive, such as at Garston Lock , and Monkey Marsh Lock , on

8580-426: The boat entered the lock. Pulling on the rope slowed the boat, due to the friction of the rope against the post. A rope 2 + 1 ⁄ 2 inches (6.4 cm) in diameter and about 60 feet (18 meters) long was typically used on the Erie Canal to snub a boat in a lock. One incident, which took place in June 1873 on the Chesapeake and Ohio Canal, involved the boat the Henry C. Flagg and its drunk captain. That boat

8710-405: The bottom cill at all but the higher tides – the new bottom chamber rises just far enough to get the boat over the original lock cill. In China, the recently completed Three Gorges Dam includes a double five-step staircase for large ships, and a ship lift for vessels of less than 3000 metric tons. Examples of "apparent" staircases are Foxton Locks and Watford Locks on the Leicester Branch of

8840-406: The bottom of the Hong Canal, obstructing river barges whose drafts were too deep for its waters. The chief engineer of the Sui dynasty, Yuwen Kai, advised the digging of a new canal that would run parallel to the existing canal, diverging from it at Chenliu ( Yanzhou ). The new canal was to pass not Xuzhou but Suzhou , to avoid connecting with the Si River and instead make a direct connection with

8970-493: The canal at proper depth so that boats could travel through it. So a man-made lake was used to feed water to the Jiangnan section of the Grand Canal. It was protected by the Government from reclamation and any use of the lake water without proper taxation was deemed illegal. It was supposed to be protected from profitable exploitation, but because the government changed over the years, lake Lianhu had been reclaimed many times and it started to become more shallow. The government changed

9100-416: The canal joins the Hai River in the center of Tianjin City before turning north-west. In Tianjin, the canal heads northwest, for a short time following the course of the Yongding, a tributary of the Hai River , before branching off toward Tongzhou on the edge of the municipality of Beijing. It is here that the modern canal stops and that a Grand Canal Cultural Park has been built. During the Yuan dynasty,

9230-427: The canal were among the chief factors in the rapid fall of the Sui, but the connection of China's major watersheds and population centers proved enormously beneficial. Additional canals supplied Chang'an (now Xi'an ) even further west under the Tang dynasty while stopover towns along the main course became the economic hubs of the empire. Periodic flooding of the Yellow River threatened the safety and functioning of

9360-505: The canal while, during wartime, the rivers' high dikes were sometimes deliberately broken to delay or sweep away advancing enemy troops. Even so, restoration and improvement of the canal and its associated flood control works was assumed as a duty by each successive dynasty. The canal played a major role in periodically reuniting northern and southern China, and officials in charge of the canal and nearby salt works grew enormously wealthy. Despite damage from floods , rebellions , and wars ,

9490-636: The canal will likely continue. The provincial governments of Shandong , Jiangsu , and Zhejiang undertook dredging intended to increase shipping capacity by 40 percent by 2012. The central government has also made the main route of the Grand Canal the eastern path of the South-North Water Diversion Project , using enormous pumping stations to redirect water from the Yangtze Delta to the drier north. The canal became greatly polluted during China's industrialization. By

9620-641: The canal would cause frequent interruptions of the heavy road traffic. It can be emptied by pumping – but as this uses a lot of electricity the method used when water supplies are adequate is to drain the lock to a nearby burn . In 2016 the Kieldrecht Lock in the Port of Antwerp in Belgium took over the title of the world's largest lock from the Berendrecht Lock in the same port and still has

9750-704: The canal's importance only grew with the removal of the capital to Khanbaliq under the Mongol Yuan and to Beijing under Yongle Emperor of the Ming dynasty and the Manchu Qing dynasty . Despite the importance of railways and roads in modern China, the People's Republic of China has worked to improve the navigability of the canal since the end of the Chinese Civil War and the portion south of

9880-422: The canal. Around Hangzhou, for instance, a $ 250 million restoration project begun in 2001 improved water quality to the point where it no longer produces a noticeable odor and is once again capable of supporting some fauna. On 22 June 2014, UNESCO 's Conference on World Heritage listed the Grand Canal as a World Heritage Site . As well as its present-day course, fourteen centuries of canal-building have left

10010-544: The chambers so that some water from the emptying chamber helps to fill the other. This facility has long been withdrawn on the English canals, although the disused paddle gear can sometimes be seen, as at Hillmorton on the Oxford Canal . Elsewhere they are still in use; a pair of twinned locks was opened in 2014 on the Dortmund–Ems Canal near Münster , Germany. The once-famous staircase at Lockport, New York ,

10140-631: The chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting. Examples of famous "real" staircases in England are Bingley and Grindley Brook . Two-rise staircases are more common: Snakeholme Lock and Struncheon Hill Lock on the Driffield Navigation were converted to staircase locks after low water levels hindered navigation over

10270-404: The chance of a boat finding a lock set in its favour. There can also be water savings: the locks may be of different sizes, so that a small boat does not need to empty a large lock; or each lock may be able to act as a side pond (water-saving basin) for the other. In this latter case, the word used is usually "twinned": here indicating the possibility of saving water by synchronising the operation of

10400-559: The cill bumper. Some canal operation authorities, primarily in the United States and Canada, call the ledge a miter sill (mitre sill in Canada). Gates are the watertight doors which seal off the chamber from the upper and lower pounds. Each end of the chamber is equipped with a gate, or pair of half-gates, traditionally made of oak or elm but now usually made of steel ). The most common arrangement, usually called miter gates ,

10530-578: The cities of Huai'an and Yangzhou . Here the land lying to the west of the canal is higher than its bed while the land to the east is lower. Historically the Shanghe region west of the canal has been prone to frequent flooding, while the Xiahe region to its east has been hit by less frequent but immensely damaging inundations caused by the failure of the Grand Canal levees. Recent works have allowed floodwaters from Shanghe to be diverted safely out to sea. Like

10660-523: The concept has been suggested in a number of cases, the only example in the world of a drop lock that has actually been constructed is at Dalmuir on the Forth and Clyde Canal in Scotland. This lock, of the single-chamber type, was incorporated during the restoration of the canal, to allow the replacement of a swing bridge (on a busy A road) by a fixed bridge, and so answer criticisms that the restoration of

10790-531: The conflicts of China's Spring and Autumn period to provide supplies and transport routes for the states of Wu and Yue . The network was completed by Emperor Yang of the Sui dynasty in AD 609, linking the fertile Jiangnan region in the south to his capital at Luoyang in the west and to his armies in the far north. His unsuccessful and unpopular wars and the massive amounts of conscripted labor involved in creating

10920-591: The construction of the Middle Canal by Jin Fu. In 1566, to escape the problems caused by flooding of the Yellow River around Yutai (now on the western shore of Weishan Lake), the Nanyang New Canal was opened. It ran for 75 kilometers (47 mi) from Nanyang (now Nanyang Town, located in the center of Weishan Lake) to the small settlement of Liucheng (in the vicinity of modern Gaolou Village, Weishan County, Shandong) north of Xuzhou City. This change in effect moved

11050-485: The dry frontiers between China, Goguryeo and Göktürk . A dike -building project in 587 along the Yellow River—overseen by engineer Liang Rui—established canal lock gates to regulate water levels for the canal. Double slipways were installed to haul boats over when the difference in water levels was too great for the flash lock to operate. Similarly, by the year 600, there were major buildups of silt on

11180-425: The flight quickly; and where water is in short supply, a single pump can recycle water to the top of the whole flight. The need for a flight may be determined purely by the lie of the land, but it is possible to group locks purposely into flights by using cuttings or embankments to "postpone" the height change. Examples: Caen Hill locks, Devizes . "Flight" is not synonymous with "Staircase" (see below). A set of locks

11310-482: The flow of water in the vicinity of New Orleans . The political and engineering focus in the 20th century was to separate the Lower Mississippi River from its floodplain . Levees and channelization —along with substantial loss of bottomland forests to agriculture in the alluvial valley —have resulted in a loss of wildlife and fish habitat, decreased water quality, and an expansion of

11440-518: The form of the now-disused Écluse des Lorraines , connecting the Canal latéral à la Loire with the River Allier . A drop lock can consist of two conventional lock chambers leading to a sump pound, or a single long chamber incorporating the sump – although the term properly applies only to the second case. As the pounds at either end of the structure are at the same height, the lock can only be emptied either by allowing water to run to waste from

11570-463: The high concentration of locks gave it the nicknames chahe or zhahe , i.e. 'the river of locks'. Its great number of feeder springs (between two and four hundred, depending on the counting method and season of the year) also led to it being called the quanhe or 'river of springs'. This, the Grand Canal's first true summit section, was engineered by the Mongol Oqruqči in 1238 to connect Jining to

11700-414: The intermediate pounds have disappeared, and the upper gate of one lock is also the lower gate of the one above it. However, it is incorrect to use the terms staircase and flight interchangeably: because of the absence of intermediate pounds, operating a staircase is very different from operating a flight. It can be more useful to think of a staircase as a single lock with intermediate levels (the top gate

11830-467: The lake to become more profitable farmland which led to reclamations and agricultural irrigation using the lake. This began to lead to Lake Lianhu not being able to properly feed water to the Grand Canal. Loss of depth due to reclamation and maintenance costs became too high for the lake to become practical to use. Even though it was a man made lake it was still a beautiful sight. Many different people praised its beauty and various poems have been written about

11960-540: The lake. In recent years recreational uses for the lake have become more popular and may lead to the lake being restored. This southernmost section of the canal runs from Hangzhou in Zhejiang, where the canal connects with the Qiantang River, to Zhenjiang in Jiangsu, where it meets the Yangtze. After leaving Hangzhou heading north toward Beijing, the canal passes around the eastern border of Lake Tai , through

12090-401: The largest pre-modern industrial production center of the empire, Yangzhou was also the geographical midpoint along the north–south trade axis, and so became the major center for southern goods shipped north. One of the greatest benefits of the canal system in the Tang dynasty—and subsequent dynasties—was that it reduced the cost of shipping grain that had been collected in taxes (caoyun) from

12220-603: The legendary works of Yu the Great ; modern scholars now consider it to belong to the 6th century BC. The reunification of China under the Sui dynasty (581–618) ended three centuries of chaos since the Upheaval of the Five Barbarians , and the renewed political stability allowed both the thorough repair of existing canals and flood control systems as well as the construction of new canals. The primary consideration of

12350-414: The local prefect realized that a canal dug directly across Guazhou would reduce the journey time and thus make the crossing safer. The Yilou Canal was opened in 738 and still exists, though not as part of the modern Grand Canal route. The Grand Canal nominally runs between Beijing and Hangzhou over a total length of 1,794 km (1,115 mi); however, only the section from Hangzhou to Liangshan County

12480-403: The lock gates could be replaced and the boat removed from the lock. To economise, especially where good stone would be prohibitively expensive or difficult to obtain, composite locks were made, i.e. they were constructed using rubble or inferior stone, dressing the inside walls of the lock with wood, so as not to abrade the boats. This was done, for instance, on the Chesapeake and Ohio Canal with

12610-403: The lock. A boatsman might ask for a back swell, that is, to open and shut the paddles a few times to create some waves, to help him get off the bank where he was stuck. If boats ran aground (from being overloaded) they sometimes asked passing crews to tell the upstream lock to give them an extra heavy swell, which consisted of opening all the paddles on the lock gate, creating a surge that affected

12740-757: The locks near the Paw Paw Tunnel . and also the Chenango Canal On large modern canals, especially very large ones such as ship canals , the gates and paddles are too large to be hand operated, and are operated by hydraulic or electrical equipment. On the Caledonian Canal the lock gates were operated by man-powered capstans , one connected by chains to open the gate and another to draw it closed. By 1968 these had been replaced by hydraulic power acting through steel rams. The construction of locks (or weirs and dams) on rivers obstructs

12870-463: The major cities of Jiaxing , Suzhou , Wuxi , and Changzhou before reaching Zhenjiang . The Jiangnan (or 'South of the Yangtze') Canal is heavily utilized by barge traffic bringing coal, containers and construction materials to the booming delta. It is generally a minimum of 100 meters wide in the congested city centers, and often two or three times this width in the neighboring countryside. In recent years, broad bypass canals have been dug around

13000-498: The major cities to reduce 'traffic jams'. The Suzhou section of the Jiangnan Canal flows through the western part of the city. It includes ten city gates and over 20 stone bridges of traditional design and historic areas that have been well preserved as well as temples and pavilions. The Inner Canal runs between the Yangtze and Huai rivers, skirting the Shaobo , Gaoyou , and Hongze lakes of central Jiangsu. This section connects

13130-612: The navigation depth is 45 feet, allowing for container ships and cruise ships to dock at the Port of New Orleans and bulk cargo ships shorter than 150 foot air draft to fit under the Huey P. Long Bridge and traverse the Mississippi to Baton Rouge. There is a feasibility study to dredge this portion of the river to 50 feet to allow New Panamax ship depths. 33°45′N 89°45′W  /  33.750°N 89.750°W  / 33.750; -89.750 Navigation lock A lock

13260-688: The new canal was low. This resulted in a sequential pair of locks, with gates pointing in opposite directions: one example was at Hall Green near Kidsgrove , where the southern terminus of the Macclesfield Canal joined the Hall Green Branch of the earlier Trent and Mersey Canal . The four gate stop lock near Kings Norton Junction, between the Stratford-upon-Avon Canal and the Worcester and Birmingham Canal

13390-504: The oncoming Jurchen invaders during the Jin–Song wars . Over a series of floods, this entirely shifted the river south of Shandong , capturing the course of the Si River and emptying the Yellow River into Hongze Lake and the East China Sea for centuries. The Jurchen Jin dynasty continually battled with the Song in this region. The warfare led to the dilapidation of the canal until

13520-528: The passage of fish. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as a fish ladder are often taken to counteract this. Navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. Locks can be built side by side on the same waterway. This is variously called doubling , pairing , or twinning . The Panama Canal has three sets of double locks. Doubling gives advantages in speed, avoiding hold-ups at busy times and increasing

13650-547: The region during periods of disunity in medieval China and was particularly prosperous and vital during the Southern Song , who established their capital at Lin'an within present-day Hangzhou. During the Yuan , Ming , and Qing , the canal diminished in importance but was kept navigable until the development of railways and roads in the 19th and 20th century. Renovation of the canal for use by modern barges began in 2002,

13780-496: The route in case a flood or other disaster impeded the path of shipment. To ensure smooth travel of grain shipments, Transport Commissioner Liu Yan (in office from 763 to 779) had special river barge ships designed and constructed to fit the depths of each section of the entire canal. After the An Lushan rebellion (755–763), the economy of North China was greatly damaged and never recovered due to wars and to constant flooding of

13910-469: The size of the lock and whether the water in the lock was originally set at the boat's level. Boaters approaching a lock are usually pleased to meet another boat coming towards them, because this boat will have just exited the lock on their level and therefore set the lock in their favour – saving about 5 to 10 minutes. However, this is not true for staircase locks, where it is quicker for boats to go through in convoy, and it also uses less water. The rise

14040-416: The southern end of the Huitong Canal. It rose to a height of 42 meters (138 ft) above the Yangtze, but environmental and technical factors left it with chronic water shortages until it was re-engineered in 1411 by Song Li of the Ming . Song Li's improvements, recommended by a local man named Bai Ying, included damming the rivers Wen and Guang and drawing lateral canals from them to feed reservoir lakes at

14170-407: The spilled grain. In 984 Qiao installed a pair of sluice-gates two hundred and fifty feet apart, the entire structure roofed over like a building. By siting two staunch gates so close to one another, Qiao had created a short stretch of canal, effectively a pound-lock, filled from the canal above by raising individual wooden baulks in the top gate and emptied into the canal below by lowering baulks in

14300-411: The staircase by moving sideways around each other; or at peak times, one can have all the chambers full simultaneously with boats travelling in the same direction. When variable conditions meant that a higher water level in the new canal could not be guaranteed, then the older company would also build a stop lock (under its own control, with gates pointing towards its own canal) which could be closed when

14430-413: The sump to a lower stream or drain, or (less wastefully) by pumping water back up to the canal. Particularly in the two-chamber type, there would be a need for a bypass culvert, to allow water to move along the interrupted pound and so supply locks further down the canal. In the case of the single-chamber type, this can be achieved by keeping the lock full and leaving the gates open while not in use. While

14560-493: The title for largest volume. In 2022 the IJmuiden sea lock serving the Port of Amsterdam became the world's largest lock by surface area. The lock is 500 m (1,600 ft) long, 70 m (230 ft) wide and has sliding lock gates creating a usable depth of 18 m (59 ft). The size of locks cannot be compared without considering the difference in water level that they are designed to operate under. For example,

14690-400: The top gate and raising ones in the lower. A turf-sided lock is an early form of canal lock design that uses earth banks to form the lock chamber, subsequently attracting grasses and other vegetation, instead of the now more familiar and widespread brick, stone, or concrete lock wall constructions. This early lock design was most often used on river navigations in the early 18th century before

14820-531: The total length about 1,800 km (1,100 mi) and linking Hangzhou and Beijing with a direct north–south waterway for the first time. As in the Song and Jin era, the canal fell into disuse and dilapidation during the Yuan dynasty's decline. The Grand Canal as infrastructure has had influence on other architectural works in the west. The Erie Canal in North America is designed and draws inspiration from

14950-462: The two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. The gates were 'hanging gates'; when they were closed the water accumulated like a tide until the required level was reached, and then when the time came it was allowed to flow out. The water level could differ by 4 or 5 feet (1.2 or 1.5 m) at each lock and in the Grand Canal the level

15080-668: The very summit, at a small town called Nanwang . In AD 369, General Huan Wen of the Eastern Jin dynasty connected the shallow river valleys of the Huai and the Yellow. He achieved this by joining two of these rivers' tributaries, the Si and the Ji respectively, at their closest point, across a low watershed of the Shandong massif. Huan Wen's primitive summit canal became a model for the engineers of

15210-416: The water on the pound above sometimes causing boats to run aground. In addition, it raised the water level on the pound below, causing some boats to strike bridges or get stuck. On horse-drawn and mule-drawn canals, snubbing posts were used to slow or stop a boat in the lock. A 200-ton boat moving at a few miles an hour could destroy the lock gate. To prevent this, a rope was wound around the snubbing post as

15340-512: The whole pound below. On the Erie Canal, some loaded boats needed a swell to get out of the lock. Particularly lumber boats, being top heavy, would list to one side and get stuck in the lock, and needed a swell to get them out. Some lockkeepers would give a swell to anyone to help them on the way, but some would ask for money for the swell. The Erie Canal management did not like swelling for two reasons. First, it used too much water lowering

15470-610: The world and a UNESCO World Heritage Site . The Grand Canal's main stem , known to the Chinese as the Jing – Hang Grand Canal , is thought to extend for 1,776 km (1,104 mi) and is divided into 6 main subsections. The Jiangnan Canal runs from the Qiantang River at Hangzhou to the Yangtze River at Zhenjiang ; the Inner Canal from the Yangtze at Yangzhou to the Huai River at Huai'an , which for centuries

15600-463: Was all that need be emptied when a boat passed through. This type of lock, called a pound lock was known in Imperial China and ancient Europe and was used by Greek engineers in the Canal of the Pharaohs under Ptolemy II (284 to 246 BC), when engineers solved the problem of overcoming the difference in height through canal locks . Pound locks were first used in medieval China during

15730-422: Was already leaking; the crew, having partially pumped the water out, entered Lock 74, moving in front of another boat. Because they failed to snub the boat, it crashed into and knocked out the downstream gates. The outrush of water from the lock caused the upstream gates to slam shut, breaking them also, and sending a cascade of water over the boat, sinking it. This suspended navigation on the canal for 48 hours until

15860-416: Was also a doubled set of locks. Five twinned locks allowed east- and west-bound boats to climb or descend the 60 feet (18 m) Niagara Escarpment , a considerable engineering feat in the nineteenth century. While Lockport today has two large steel locks, half of the old twin stair acts as an emergency spillway and can still be seen, with the original lock gates having been restored in early 2016. Loosely,

15990-828: Was also its junction with the former course of the Yellow River ; the Middle Canal from Huai'an to the Nansi Lakes ; the Lu Canal from the lakes past Jining and the present course of the Yellow River to the Wei River at Linqing ; the Southern Canal from Linqing to the Hai River at Tianjin ; and the Northern Canal from Tianjin to Tongzhou on the outskirts of Beijing. As such, it passes through

16120-510: Was assigned a different name, all of which were popularized in travel songs of the period. The Manchus invaded China in the mid-17th century, allowed through the northern passes by the Chinese general Wu Sangui once the Ming capital at Beijing had fallen into the hands of a rebel army. The Manchus established the Qing dynasty (1644–1912), and under their leadership, the Grand Canal was overseen and maintained just as in earlier times. In 1855,

16250-603: Was completed except for areas around Ningbo by 2009, and was fully completed in late 2013. In November 2008, the Eastern Zhejiang Canal was added to the Grand Canal's UNESCO nomination and, in May 2013, was officially included as part of the Grand Canal and listed among the 7th group of Major Historical and Cultural Sites Protected at the National Level by the Chinese government. In 2014, it was included with

16380-622: Was detailed at length in the Record of the Opening of the Canal ( t 《 開 河 記 》 , s 《 开 河 记 》 , Kāihéjì ). At this point, the Grand Canal continued to use noncontiguous artificial channels and both canalized and natural waterways rather than presenting a single continuous manmade canal. However, running alongside and parallel to the course of the canals was an imperial roadway with stables maintained at regular intervals to support

16510-412: Was invented by Leonardo da Vinci sometime around the late 15th century. On the old Erie Canal , there was a danger of injury when operating the paddles: water, on reaching a certain position, would push the paddles with a force which could tear the windlass (or handle) out of one's hands, or if one was standing in the wrong place, could knock one into the canal, leading to injuries and drownings. On

16640-456: Was raised in this way by 138 feet (42 m). In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk , Netherlands. This pound lock serviced many ships at once in a large basin . Yet the first true pound lock was built in 1396 at Damme near Bruges , Belgium. The Italian Bertola da Novate (c. 1410–1475) constructed 18 pound locks on the Naviglio di Bereguardo (part of

16770-485: Was renovated almost in its entirety between 1411 and 1415 during the Ming dynasty (1368–1644). A magistrate of Jining, Shandong sent a memorandum to the throne of the Yongle Emperor protesting the current inefficient means of transporting 4,000,000 dan (428,000,000 liters ) of grain a year by means of transferring it along several different rivers and canals in barge types that went from deep to shallow after

16900-606: Was replaced in 1914 by a pair of guillotine lock gates which stopped the water flow regardless of which canal was higher. These gates have been permanently open since nationalisation. The best known example of a round lock is the Agde Round Lock on the Canal du Midi in France. This serves as a lock on the main line of the canal and allows access to the Hérault River . A second French round lock can be found in

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