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63-592: The Cataracts of the Nile are shallow lengths (or whitewater rapids ) of the Nile river, between Khartoum and Aswan , where the surface of the water is broken by many small boulders and stones jutting out of the river bed, as well as many rocky islets . In some places, these stretches are punctuated by whitewater, while at others the water flow is smoother but still shallow. Counted going upstream (from north to south): In Egypt : In Sudan : Geologists indicate that

126-467: A boatsman with passengers having no direct responsibilities. Catarafts can be of all sizes; many are smaller and more maneuverable than a typical raft. Canoes are often made of fiberglass, kevlar, plastic, or a combination of the three for strength and durability. They may have a spraycover , resembling a kayak, or be "open", resembling the typical canoe. This type of canoe is usually referred to simply as an "open boat". Whitewater canoes are paddled in

189-455: A bucket, and because the only way to get water out of them is by bailing with a bucket. Catarafts are constructed from the same materials as rafts. They can either be paddled or rowed with oars. Typical catarafts are constructed from two inflatable pontoons on either side of the craft that are bridged by a frame. Oar-propelled catarafts have the occupants sitting on seats mounted on the frame. Virtually all oar-powered catarafts are operated by

252-413: A canoe. C1s are similar in construction to whitewater kayaks, but they are paddled in a low, kneeling position. They employ the use of a one-blade paddle, usually a little shorter than used in a more traditional canoe. They have a spraycover, essentially the same type used in kayaking. Like kayaks, C1s can be righted after capsizing with an Eskimo roll. McKenzie River dory (or "drift boat" by some)

315-493: A low kneeling position, with a one-bladed paddle. Open whitewater canoes often have large airbags and in some cases foam, usually 2-lb density ethyl foam, firmly attached to the sides, to displace water in the boat when swamped by big waves and holes and to allow water to be spilled from the boat while still in the river by floating it up on its side using the foam and bags. Like kayaks, whitewater canoes can be righted after capsizing with an Eskimo roll, but this requires more skill in

378-424: A lower rated rapid may give a better "ride" to kayakers or rafters, while a Class V may seem relatively tame. However, it is not so much the "ride," but the inherent danger in the rapid. An exiting rapid may have minimal risk, while a seemingly simply rapid may have terminal hydraulics, undercut rocks, etc.) A rapid's grade is not fixed, since it may vary greatly depending on the water depth and speed of flow. Also,

441-535: A precise description of the Cataract-Nile: It has a similar shape to a backwards letter N. It flows northward from Meroë about 2700 stadia, then turns back to the south and the winter sunset for about 3700 stadia, and it almost reaches the same parallel as the Meroë region and makes its way far into Libya. Then it makes another turn, and flows northward 5300 stadia to the great cataract, curving slightly to

504-485: A river is the rate at which it changes elevation along its course. This loss determines the river's slope, and to a large extent its rate of flow (velocity). Shallow gradients produce gentle, slow rivers, while steep gradients are associated with raging torrents. Constrictions can form a rapid when a river's flow is forced into a narrower channel. This pressure causes the water to flow more rapidly and to react to riverbed events (rocks, drops, etc.). A boulder or ledge in

567-743: A selected few. There are several 'sub-categories' in whitewater canoeing: River running can be thought of as a tour down a river, to enjoy the scenery as well as experiencing challenging whitewater. River running includes short day trips as well as longer multi-day trips. Multi-day canoe trips often entail the use of gear-toting rafts to allow a more comfortable experience without a heavily laden canoe although many people also carry their own gear in their canoes, especially on remote or wilderness sections of rivers. Canoes with gear typically are not commonly used above class IV whitewater without portages. Sometimes, open touring canoes with gear used on multi-day trips are fitted with fabric spraycovers . Whitewater racing

630-612: A steep canyon, the side walls of the canyon can also be undercut. A particularly notorious undercut rock is Dimple Rock, in Dimple Rapid on the Lower Youghiogheny River , a very popular rafting and kayaking river in Pennsylvania. Of about nine people who have died at or near Dimple Rock, including three in 2000, several of the deaths were the result of people becoming entrapped after they were swept under

693-418: A strong sideways or diagonal (also called a "lateral") wave can throw the craft off if the craft hits sideways or at an angle. The safest move for a whitewater boater approaching a lateral is to "square up" or turn the boat such that it hits the wave along the boat's longest axis, reducing the chance of the boat flipping or capsizing. This is often counterintuitive because it requires turning the boat such that it

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756-486: A surfer slipping out the end of the pipeline, where the wave no longer breaks. Low-head dams are insidiously dangerous because their danger cannot be easily recognized by people who have not studied swift water. (Even 'experts' have died in them.) Floating debris (trees, kayaks, etc.) is often trapped in these retroflow 'grinders' for weeks at a time. Waves are formed in a similar manner to hydraulics and are sometimes also considered hydraulics, as well. Waves are noted by

819-683: A wooden framework that was covered with animal skins. Mules hauled the precious skins back to Armenia. The Scot , John MacGregor published in 1866 the book A Thousand Miles in the Roy Rob Canoe . The timing was right and the book became a resounding success. With the Industrial Revolution leading to more leisure time in the middle of the 19th century, people in Europe started to enjoy floating down rivers in all kinds of contraptions taking in nature previously only available to

882-438: Is a more traditional "hard sided" boat. The design is characterized by a wide, flat bottom, flared sides, a narrow, flat bow, a pointed stern, and extreme rocker in the bow and stern to allow the boat to spin about its center for ease in maneuvering in rapids. River bugs are small, single-person, inflatable craft where a person's feet stick out of one end. River bugging is done feet first with no paddle. Creature Craft are

945-513: Is a short list of them: Whitewater kayaks differ from sea kayaks and recreational kayaks in that they are better specialized to deal with moving water. They are often shorter and more maneuverable than sea kayaks and are specially designed to deal with water flowing up onto their decks. Most whitewater kayaks are made of plastics now, although some paddlers (especially racers and "squirt boaters") use kayaks made of fiberglass composites. Whitewater kayaks are fairly stable in turbulent water, once

1008-482: Is as old as the Stone Age . The raft , the catamaran , the canoe and the kayak evolved depending on the needs and environment of the indigenous peoples in different parts of the world. The modern day canoe most likely originated about 8,000 years ago. The Greek , Herodotus , 484-425 BC, wrote in his travel diaries about boats with which merchandise was brought from Armenia to Babylon . The boats were made of

1071-450: Is dependent upon both seasonal variation in precipitation and snowmelt and upon release rates of upstream dams. Streambed topography is the primary factor in creating rapids, and is generally consistent over time. Increased flow, as during a flood or high-rainfall season, can make permanent changes to the streambed by displacing rocks and boulders, by deposition of alluvium , or by creating new channels for flowing water. The gradient of

1134-531: Is likely to include running ledges, slides, and waterfalls on relatively small and tight rivers, though some will allow for very large and big volume rivers in their definition. Canoes used for creeking usually have higher volume (more gallons or liters of displacement) and more rounded bow and stern , as these features provide an extra margin of safety' against the likelihood of pinning, and will resurface more quickly and controllably when coming off larger drops. Creek boats usually have increased "rocker," or rise, on

1197-402: Is no longer parallel to the current. In fluid mechanics, waves are classified as laminar, but the whitewater world has also included waves with turbulence ("breaking waves") under the general heading of waves. Pillows are formed when a large flow of water runs into a large obstruction, causing water to "pile up" or "boil" against the face of the obstruction. Pillows normally signal that a rock

1260-581: Is not undercut. Pillows are also known as "pressure waves". Eddies are formed, like hydraulics, on the downstream face of an obstruction. Unlike hydraulics, which swirl vertically in the water column, eddies revolve on the horizontal surface of the water. Typically, they are calm spots where the downward movement of water is partially or fully arrested—a place to rest or to make one's way upstream. However, in very powerful water, eddies can have powerful, swirling currents that trap or even can flip boats and from which escape can be very difficult. Located between

1323-491: Is the International Scale of River Difficulty , where whitewater (either an individual rapid, or the entire river) is classed in six categories from class I (the easiest and safest) to class VI (the most difficult and most dangerous). The grade reflects both the technical difficulty and the danger associated with a rapid, with grade I referring to flat or slow-moving water with few hazards, and grade VI referring to

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1386-481: Is the competitive aspect of this sub-category, racing canoes down a river as fast as possible. Creeking is perhaps best thought of as a subcategory of river running, involving very technical and difficult rapids, typically in the Grade/Class IV to VI range. While people will differ on the definition, creeking generally involves higher gradient, approaching or in excess of 100 ft per mi (19 m per km), and

1449-608: Is used than on flat water. Running whitewater rivers is a popular recreational sport, but is not without danger. Fast-moving water always has the potential for injury or death by drowning or hitting objects. Fatalities do occur; some 50 people die in whitewater accidents in the United States each year. The dangers can be mitigated (but not eliminated) by training, experience, scouting, the use of safety equipment (such as personal flotation devices , helmets, throw ropes), and using other persons as "spotters". Scouting or examining

1512-568: The American version of the International Scale of River Difficulty). On any given rapid, a multitude of different features can arise from the interplay between the shape of the riverbed and the velocity of the water in the stream. Strainers are formed when an object blocks the passage of larger objects, but allows the flow of water to continue – like a big food strainer or colander . These objects can be very dangerous, because

1575-576: The Kushite invasion, for most of Egyptian history, the Nile's cataracts, particularly the First Cataract, primarily served as a natural border to prevent most crossings from the south, as those in said region would rely on river travel to venture north and south. This allowed Egypt's southern border to be relatively protected from invasions, and besides brief Kushite rule, it remained a natural border for most of Egyptian history. Eratosthenes gave

1638-523: The US, but more frequently just referred to as freestyle events in UK and Europe. Boofing, in whitewater canoeing, refers to the raising of the canoe's bow during freefall, while descending a ledge, ducking behind a boulder, or running a waterfall . This technique is used to avoid submerging the bow of the canoe by ensuring it lands flat when it hits the base of the waterfall. The term is an onomatopoeia which mimics

1701-809: The area between the first and second cataracts (known as Lower Nubia ), and its monuments moved as part of the International Campaign to Save the Monuments of Nubia . Whitewater The term "whitewater" also has a broader meaning, applying to any river or creek that has a significant number of rapids. The term is also used as an adjective describing boating on such rivers, such as whitewater canoeing or whitewater kayaking . Four factors, separately or in combination, can create rapids: gradient, constriction, obstruction, and flow rate. Gradient, constriction, and obstruction are streambed topography factors and are relatively consistent. Flow rate

1764-459: The bedrock was previously eroded to be several thousand feet deep. This created a vast canyon that is now filled with sediment. Despite these characteristics, some of the cataracts which are normally impassable by boat because of the shallow water have become navigable during the flood season. The word "cataract" comes from the Greek word καταρρέω ("to flow down"), although the original Greek term

1827-432: The boat on all possible axis of rotation. More recently, aerial moves have become accessible, where paddlers perform tricks having gained air from using the speed and bounce of the wave. Canoes used for playboating generally have relatively low volume in the bow and stern, allowing the paddler to submerge the ends of the canoe with relative ease. Competitions for playboating or freestyle are sometimes called whitewater rodeo in

1890-415: The boats, which will be made out of kevlar/fiberglass/ carbon fiber composites to be lightweight and have faster hull speed. Plastic whitewater canoes can be used in citizen-level races. In the United States and Canada there are separate slalom organizations and races for decked canoes and open canoes. Playboating, also known as Playboating or Rodeo, is a more gymnastic and artistic kind of canoeing. While

1953-425: The bottom (boat bellyflopping into the water). Another technique used to prevent the bow of the canoe from submerging. The bowsman uses his paddle like an outrigger held horizontal to the rivers surface. Used mostly to limit the amount of water the canoe takes in during running rapids. Some rapids and rock gardens are navigatable when no-one is in the canoe. A line is attached to the canoe, it must be centre lined to

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2016-434: The bow to go up and over obstacles and obstructions within the river, it is a continuous rocker which means that the curvature of the bottom of the boat is a constant curve so there is less water contact. Extreme racing is a competitive form of this aspect of whitewater canoeing, in which canoers race down steep sections and or generally dangerous sections of whitewater. Slalom is a technical competitive form of canoeing, and

2079-803: The difficulty, danger or severity of the rapid. Whitewater grades (or classes) range from I or 1 (the easiest) to VI or 6 (the most difficult/dangerous). Grade/Class I can be described as slightly moving water with ripples. Grade/Class VI can be described as severe or almost unrunnable whitewater, such as Niagara Falls . The canoe (or just 'boat') used in casual whitewater canoeing is different from those used in whitewater racing . Traditionally, canoes were made of tree bark , sewn with tree roots and sealed with resin . Early whitewater boats were made of wood followed by aluminium and later fiberglass or kevlar , followed by more exotic composite materials including spectra , vectran and carbon fiber . The various composite materials are still preferred for racing due to

2142-598: The east; then 1200 stadia to the smaller cataract at Syene (i.e. Aswan ), and then 5300 more to the sea. The six cataracts of the Nile are depicted extensively by European visitors, notably by Winston Churchill in The River War (1899), where he recounts the exploits of the British trying to return to the Sudan between 1896 and 1898 , after they were forced to leave in 1885 . Today, Lake Nasser has filled most of

2205-576: The eddy and the main current, the eddy line is a swirling seam of green and sometimes white water. Eddy lines vary in size based on the size of the water column, the gradient of the section, and the obstacle creating the eddy. Often containing boils and whirlpools, eddy lines can spin and grab your watercraft in unexpected ways, but if used correctly, they can be a really playful spot. Full slice and half slice boaters are able to perform tricks like stern squirts and cartwheels, but nobody uses eddy lines as well as squirt boaters(link to squirt boating wiki), who use

2268-402: The flow rate. In large rivers with high flow rates next to an obstruction, "eddy walls" can occur. An eddy wall is formed when the height of the river is substantially higher than the level of the water in the eddy behind the obstruction. This can make it difficult for a boater, who has stopped in that particular eddy, to re-enter the river due to a wall of water that can be several feet high at

2331-406: The force of the water will pin an object or body against the strainer and then pile up, pushing it down under water. For a person caught in this position, getting to safety will be difficult or impossible, often leading to a fatal outcome. Strainers are formed by many natural or man-made objects, such as storm grates over tunnels, trees that have fallen into a river ("log jam"), bushes by the side of

2394-407: The hardest rapids, which are very dangerous even for expert paddlers, and are rarely run. Grade-VI rapids are sometimes downgraded to grade-V or V+ if they have been run successfully. Harder rapids (for example a grade-V rapid on a mainly grade-III river) are often portaged , a French term for carrying. A portaged rapid is where the boater lands and carries the boat around the hazard. (In many cases,

2457-443: The large, smooth face on the water rushing down. Sometimes, a particularly large wave also is followed by a "wave train", a long series of waves. These standing waves can be smooth, or particularly the larger ones, can be breaking waves (also called "whitecaps" or "haystacks"). Because of the rough and random pattern of a riverbed, waves are often not perpendicular to the river's current. This makes them challenging for boaters, since

2520-516: The level of development in rafting/kayaking technology plays a role. Rapids that would have meant almost certain death a hundred years ago may now be considered only a Class IV or V rapid, due to the development of certain safety features. Although some rapids may be easier at high flows because features are covered or "washed-out", high water usually makes rapids more difficult and dangerous. At flood stage, even rapids that are usually easy can contain lethal and unpredictable hazards (briefly adapted from

2583-584: The lightweight, but most modern recreational whitewater boats are typically rotomoulded from a tough plastic or molded from a plastic laminate called Royalex which is an ABS plastic that is slightly flexible and very durable, is easily scratched but repairable using either plastic welding or a variety of patch bonding techniques. Boats can range in size from barely long enough to hold the paddler (around 6 ft (1.8 m) long), up to 12 ft (3.7 m) or longer for solo boats and typically 14–16 ft for tandem boats. Paddling on rivers, lakes and oceans

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2646-481: The middle of a river or near the side can obstruct the flow of the river, and can also create a "pillow"; when water flows backwards upstream of the obstruction, or a "pour over" (over the boulder); and "hydraulics" or "holes" where the river flows back on itself—perhaps back under the drop—often with fearful results for those caught in its grasp. (Holes, or hydraulics, are so-called because their foamy, aerated water provides less buoyancy and can feel like an actual hole in

2709-472: The most dangerous types of holes are formed by low-head dams ( weirs ), and similar types of obstructions. In a low-head dam, the 'hole' has a very wide, uniform structure with no escape point, and the sides of the hydraulic (ends of the dam) are often blocked by a man-made wall, making paddling around, or slipping off, the side of the hydraulic, where the bypass water flow would become normal (laminar), difficult. By (upside-down) analogy, this would be much like

2772-435: The object under the water. In a river, swimming aggressively away from the strainer and into the main channel is recommended. If avoiding the strainer is not possible, one should swim hard towards it and try to get as much of one's body up and over it as possible. Sweepers are trees fallen in or heavily leaning over the river, still rooted on the shore and not fully submerged. Their trunks and branches may form an obstruction in

2835-402: The object. Holes can be particularly dangerous—a boater or watercraft may become stuck under the surface in the recirculating water—or entertaining play-spots, where paddlers use the holes' features to perform various playboating moves. In high-volume water flows, holes can subtly aerate the water, enough to allow craft to fall through the aerated water to the bottom of a deep 'hole'. Some of

2898-594: The only whitewater event to appear in the Olympic Games . Racers attempt to make their way from the top to the bottom of a designated section of river as fast as possible, while correctly negotiating gates (a series of double-poles suspended vertically over the river). There are usually 18-25 gates in a race which must be navigated in sequential order. Green gates must be negotiated in a downstream direction, red gates in an upstream direction. The events are typically conducted on Grade/Class II to Grade/Class IV water, but

2961-415: The other varieties of canoeing generally involve going from Point A to Point B, playboaters often stay in one spot in the river (usually in a hole, pourover or on a wave) where they work with and against the dynamic forces of the river to perform a variety of maneuvers. These can include surfing, spinning, and various vertical moves (cartwheels, loops, blunts, pistol and donkey flips, and many others), spinning

3024-705: The paddler is skillful with them; if flipped upside-down, the skilled paddler can easily roll them back upright. This essential skill of whitewater kayaking is called the " Eskimo roll ", or simply "roll". Kayaks are paddled in a low sitting position (legs extended forward), with a two-bladed paddle. See Whitewater kayaking . Rafts are also often used as a whitewater craft; more stable than typical kayaks, they are less maneuverable. Rafts can carry large loads, so they are often used for expeditions. Typical whitewater rafts are inflatable craft, made from high-strength fabric coated with PVC, urethane, neoprene or Hypalon; see rafting . While most rafts are large multipassenger craft,

3087-438: The placement of the gates, and precision necessary to paddle them fast and "clean" (without touching a pole and adding 2 seconds to the total time), makes the moves much harder than the water's difficulty suggests. (Slalom has been described as performing class V moves with class III consequences.) Pro level slalom competitions have specific length (350 cm (140 in) for kayaks - new rules), width, and weight requirements for

3150-433: The point at which the eddy meets the river flow. A marked increase or decrease in flow can create a rapid, "wash out" a rapid (decreasing the hazard), or make safe passage through previously navigable rapids more difficult or impossible. Flow rate is measured in volume per unit of time. The stream flow rate may be faster for different parts of a river, such as if there's an undercurrent. The most widely used grading system

3213-555: The rapids before running them is crucial to familiarize oneself with the stream and anticipate the challenges. This is especially important during flood conditions when the highly increased flows have altered the normal conditions drastically. Whitewater canoeing Whitewater canoeing is the sport of paddling a canoe on a moving body of water, typically a whitewater river. Whitewater canoeing can range from simple, carefree gently moving water, to demanding, dangerous whitewater. River rapids are graded like ski runs according to

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3276-414: The region of northern Sudan is tectonically active and this activity has caused the river to take on "youthful" characteristics. The Nubian Swell has diverted the river's course to the west, while keeping its depth shallow and causing the formation of the cataracts. Even as the river bed is worn down by erosion , the landmass is lifted, keeping parts of the river bed exposed. These distinctive features of

3339-472: The river between Aswan and Khartoum have led to the stretch being often referred to as the Cataract Nile , while the downstream portion is occasionally referred to as the "Egyptian" Nile. The geological distinction between these two portions of the river is considerable. North of Aswan, the river bed is not rocky, but is instead composed of sediment, and far from being a shallow river. It is believed that

3402-440: The river like strainers. Since it is an obstruction from above, it often does not contribute to whitewater features, but may create turbulence. In fast water, sweepers can pose a serious hazard to paddlers. Holes, or " hydraulics ", (also known as "stoppers" or "souse-holes" (see also Pillows ) are formed when water pours over the top of a submerged object, or underwater ledges, causing the surface water to flow back upstream toward

3465-411: The river surface.) If the flow passes next to the obstruction, an eddy may form behind the obstruction; although eddies are typically sheltered areas where boaters can stop to rest, scout, or leave the main current, they may be swirling and whirlpool-like. As with hydraulics (which pull downward rather than to the side and are essentially eddies turned at a 90° angle), the power of eddies increases with

3528-417: The river that are flooded during high water, wire fence, rebar from broken concrete structures in the water, or other debris. Strainers occur naturally most often on the outside curves of rivers where the current undermines the shore, exposing the roots of trees and causing them to fall into the river and form strainers. In an emergency, climbing on top of a strainer may be better so as not to be pinned against

3591-413: The rock. Another major whitewater feature is a sieve, which is a narrow, empty space through which water flows between two obstructions, usually rocks. Similar to strainers, water is forced through the sieve, resulting in higher velocity flow, which forces water up and creates turbulence. People use many types of whitewater craft to make their way down a rapid, preferably with finesse and control. Here

3654-489: The smallest rafts are single-person whitewater craft, see packraft . Rafts sometimes have inflatable floors, with holes around the edges, that allow water that splashes into the boat to easily flow to the side and out the bottom (these are typically called "self-bailers" because the occupants do not have to "bail" water out with a bucket). Others have simple fabric floors, without anyway for water to escape, these are called "bucket boats", both for their tendency to hold water like

3717-411: The sound that is usually created when the hull of the canoe makes contact with water at the base of the waterfall. Another type of boof is the "rock boof" which is a move that uses a glancing impact with a boulder at the top of a ledge to bounce the boater over a downstream feature, often finished with a mid-air eddy turn. Rock boofs result in sounds both at the top of the drop (boat impacting rock) and

3780-412: The swirling water and crossing currents to dance below the surface of the river. Undercut rocks have been worn down underneath the surface by the river, or are loose boulders which cantilever out beyond their resting spots on the riverbed. They can be extremely dangerous features of a rapid because a person can get trapped underneath them under water. This is especially true of rocks that are undercut on

3843-579: The ultimate whitewater craft, with a roll cage design that protects the occupants if they are to flip in any manner. You can see these creatures drifting down rivers like the Gauley, waiting to be capsized and righted by other enthusiastic river users. Whitewater SUP (Stand Up Paddle Boarding) , similar to traditional flat water stand up paddle boarding, whitewater SUPing involves the use of a stand up paddle board to run whitewater. The boards are typically specially designed for whitewater use, and more safety gear

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3906-433: The upstream side. Here, a boater may become pinned against the rock under water. Many whitewater deaths have occurred in this fashion. Undercuts sometimes have pillows, but other times the water just flows smoothly under them, which can indicate that the rock is undercut. Undercuts are most common in rivers where the riverbed cuts through sedimentary rocks such as limestone rather than igneous rock such as granite . In

3969-532: Was the plural-only Κατάδουποι . However, contrary to this, none of the Nile 's six primary cataracts could be accurately described as waterfalls, and given a broader definition, this is the same with many of the minor cataracts. In ancient times, Upper Egypt extended from south of the Nile Delta to the first cataract, while further upstream, the land was controlled by the ancient Kingdom of Kush that would later take over Egypt from 760 to 656 BC. Besides

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