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31-483: The Big/Great Roussel , Big Russel or Grand Ruau is the channel running between Herm on the west, and Brecqhou , and Sark on the east, in the Channel Islands . It has a treacherous current, and the tidal variations in this region are amongst some of the most extreme in the world. It hides a number of sunken rocks. However, it sees a reasonable amount of marine transport, because Sark has no airstrip, forcing

62-409: A 71 percent grade instead of a 100 percent. But in practice the usual way to calculate slope is to measure the distance along the slope and the vertical rise, and calculate the horizontal run from that, in order to calculate the grade (100% × rise/run) or standard slope (rise/run). When the angle of inclination is small, using the slope length rather than the horizontal displacement (i.e., using

93-483: A constant flux. Channel heads associated with hollows in steep terrain frequently migrate up and down hillslopes depending on sediment supply and precipitation. Natural channels are formed by fluvial process and are found across the Earth . These are mostly formed by flowing water from the hydrological cycle , though can also be formed by other fluids such as flowing lava can form lava channels . Channels also describe

124-415: A physical feature, landform or constructed line refers to the tangent of the angle of that surface to the horizontal . It is a special case of the slope , where zero indicates horizontality . A larger number indicates higher or steeper degree of "tilt". Often slope is calculated as a ratio of "rise" to "run", or as a fraction ("rise over run") in which run is the horizontal distance (not the distance along

155-680: A vehicle can ascend while maintaining a particular speed is sometimes termed that vehicle's "gradeability" (or, less often, "grade ability"). The lateral slopes of a highway geometry are sometimes called fills or cuts where these techniques have been used to create them. In the United States, the maximum grade for federally funded highways is specified in a design table based on terrain and design speeds, with up to 6% generally allowed in mountainous areas and hilly urban areas with exceptions for up to 7% grades on mountainous roads with speed limits below 60 mph (95 km/h). The steepest roads in

186-730: Is 23.1% by the 67-Bernal Heights on Alabama Street between Ripley and Esmeralda Streets. Likewise, the Pittsburgh Department of Engineering and Construction recorded a grade of 37% (20°) for Canton Avenue. The street has formed part of a bicycle race since 1983. Grade, pitch, and slope are important components in landscape design , garden design , landscape architecture , and architecture ; for engineering and aesthetic design factors. Drainage, slope stability, circulation of people and vehicles, complying with building codes, and design integration are all aspects of slope considerations in environmental design . Ruling gradients limit

217-420: Is a difference between low gradient streams (less than a couple of percent in gradient or slightly sloped) and high gradient streams (steeply sloped). A wide variety of stream channel types can be distinguished (e.g. braided rivers , wandering rivers, single-thread sinuous rivers etc.). During floods , water flow may exceed the capacity of the channel and flood waters will spill out of the channel and across

248-654: Is expressed as a percentage, the angle can be determined as: If the angle is expressed as a ratio (1 in n) then: For degrees, percentage (%) and per-mille (‰) notations, larger numbers are steeper slopes. For ratios, larger numbers n of 1 in n are shallower, easier slopes. The examples show round numbers in one or more of the notations and some documented and reasonably well known instances. In vehicular engineering , various land -based designs ( automobiles , sport utility vehicles , trucks , trains , etc.) are rated for their ability to ascend terrain . Trains typically rate much lower than automobiles. The highest grade

279-456: Is frequently called a canal , with the Panama Canal providing an example. The term not only includes the deep-dredged   ship-navigable parts of an estuary or river leading to port facilities, but also to lesser channels accessing boat port-facilities such as marinas . When dredged channels traverse bay mud or sandy bottoms, repeated dredging is often necessary because of

310-661: Is the most upslope part of a channel network and is defined by flowing water between defined identifiable banks. A channel head forms as overland flow and/or subsurface flow accumulate to a point where shear stress can overcome erosion resistance of the ground surface. Channel heads are often associated with colluvium , hollows and landslides . Overland flow is a primary factor in channel initiation where saturation overland flow deepens to increase shear stress and begin channel incision. Overland flows converge in topographical depressions where channel initiation begins. Soil composition, vegetation, precipitation, and topography dictate

341-424: The perpendicular cross slope . There are several ways to express slope: Any of these may be used. Grade is usually expressed as a percentage, but this is easily converted to the angle α by taking the inverse tangent of the standard mathematical slope, which is rise / run or the grade / 100. If one looks at red numbers on the chart specifying grade, one can see the quirkiness of using the grade to specify slope;

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372-581: The valley bottom, floodplain or drainage area . Examples of rivers that are trapped in their channels: Grand Canyon and Black Canyon of the Gunnison . In a larger nautical context, as a geographical place name, the term channel is another word for strait , which is defined as a relatively narrow body of water that connects two larger bodies of water. In this nautical context, the terms strait , channel , sound , and passage are synonymous and usually interchangeable. For example, in an archipelago ,

403-459: The Great Western main line, nicknamed Brunel's Billiard Table, because the early locomotives (and their brakes) were feeble. Steep gradients were concentrated in short sections of lines where it was convenient to employ assistant engines or cable haulage , such as the 1.2 kilometres (0.75 miles) section from Euston to Camden Town . Extremely steep gradients require the use of cables (such as

434-618: The Guinness Book. Drawing on the U.S. National Elevation Dataset, 7x7 (magazine) identified ten blocks of public streets in San Francisco open to vehicular traffic in the city with grades over 30 percent. The steepest at 41 percent is the block of Bradford Street above Tompkins Avenue in the Bernal Heights neighborhood. The San Francisco Municipal Railway operates bus service among the city's hills . The steepest grade for bus operations

465-666: The Scenic Railway at Katoomba Scenic World , Australia, with a maximum grade of 122% (52°), claimed to be the world's steepest passenger-carrying funicular ) or some kind of rack railway (such as the Pilatus railway in Switzerland, with a maximum grade of 48% (26°), claimed to be the world's steepest rack railway ) to help the train ascend or descend. Gradients can be expressed as an angle, as feet per mile, feet per chain, 1 in n , x % or y per mille. Since designers like round figures,

496-545: The amount and rate of overland flow. The composition of a soil determines how quickly saturation occurs and cohesive strength retards the entrainment of material from overland flows. Vegetation slows infiltration rates during precipitation events and plant roots anchor soil on hillslopes. Subsurface flow destabilizes soil and resurfaces on hillslopes where channel heads are often formed. This often results in abrupt channel heads and landslides. Hollows form due to concentrated subsurface flows where concentrations of colluvium are in

527-554: The deeper course through a reef , sand bar , bay , or any shallow body of water. An example of a river running through a sand bar is the Columbia Bar —the mouth of the Columbia River . A stream channel is the physical confine of a stream ( river ) consisting of a bed and stream banks . Stream channels exist in a variety of geometries. Stream channel development is controlled by both water and sediment movement. There

558-457: The horizontal run by using the Pythagorean theorem, after which it is trivial to calculate the (standard math) slope or the grade (percentage). In Europe, road gradients are signed as a percentage. Grades are related using the following equations with symbols from the figure at top. The slope expressed as a percentage can similarly be determined from the tangent of the angle: If the tangent

589-539: The load that a locomotive can haul, including the weight of the locomotive itself. On a 1% gradient (1 in 100) a locomotive can pull half (or less) of the load that it can pull on level track. (A heavily loaded train rolling at 20 km/h on heavy rail may require ten times the pull on a 1% upgrade that it does on the level at that speed.) Early railways in the United Kingdom were laid out with very gentle gradients, such as 0.07575% (1 in 1320) and 0.1515% (1 in 660) on

620-747: The method of expression can affect the gradients selected. The steepest railway lines that do not use a rack system include: Gradients on sharp curves are effectively a bit steeper than the same gradient on straight track, so to compensate for this and make the ruling grade uniform throughout, the gradient on those sharp curves should be reduced slightly. In the era before they were provided with continuous brakes , whether air brakes or vacuum brakes , steep gradients made it extremely difficult for trains to stop safely. In those days, for example, an inspector insisted that Rudgwick railway station in West Sussex be regraded. He would not allow it to open until

651-400: The numbers go from 0 for flat, to 100% at 45 degrees, to infinity as it approaches vertical. Slope may still be expressed when the horizontal run is not known: the rise can be divided by the hypotenuse (the slope length). This is not the usual way to specify slope; this nonstandard expression follows the sine function rather than the tangent function, so it calls a 45 degree slope

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682-681: The population to travel to Guernsey by boat. The Little Roussel (aka the Little Russel ), is the channel running between Herm on the east and St Peter Port on the west. This Guernsey location article is a stub . You can help Misplaced Pages by expanding it . Channel (geography) Channels are important for the functionality of ports and other bodies of water used for navigability for shipping . Naturally, channels will change their depth and capacity due to erosion and deposition processes. Humans maintain navigable channels by dredging and other engineering processes. By extension,

713-400: The product of the sediment load and bed Bukhara size is proportional to the product of discharge and channel slope. A term " navigable channel " is used as a nautical term to mean a lane for ship travel, frequently marked (cf. Buoy ) and sometimes dredged . Thoresen distinguishes few categories of channels, from A (suitable for day and night navigation with guaranteed fairway depth ) all

744-736: The sine of the angle rather than the tangent) makes only an insignificant difference and can then be used as an approximation. Railway gradients are often expressed in terms of the rise in relation to the distance along the track as a practical measure. In cases where the difference between sin and tan is significant, the tangent is used. In either case, the following identity holds for all inclinations up to 90 degrees: tan ⁡ α = sin ⁡ α 1 − sin 2 ⁡ α {\displaystyle \tan {\alpha }={\frac {\sin {\alpha }}{\sqrt {1-\sin ^{2}{\alpha }}}}} . Or more simply, one can calculate

775-413: The slope) and rise is the vertical distance. Slopes of existing physical features such as canyons and hillsides, stream and river banks , and beds are often described as grades, but typically the word "grade" is used for human-made surfaces such as roads, landscape grading, roof pitches , railroads , aqueducts , and pedestrian or bicycle routes. The grade may refer to the longitudinal slope or

806-430: The term also applies to fluids other than water, e.g., lava channels . The term is also traditionally used to describe the waterless surface features on Venus . Channel initiation refers to the site on a mountain slope where water begins to flow between identifiable banks. This site is referred to as the channel head and it marks an important boundary between hillslope processes and fluvial processes. The channel head

837-678: The unstable subsequent movement of benthic soils. Responsibility for monitoring navigability conditions of navigation channels to various port facilities varies, and the actual maintenance work is frequently performed by a third party. Storms, sea-states, flooding, and seasonal sedimentation adversely affect navigability . In the U.S., navigation channels are monitored and maintained by the United States Army Corps of Engineers (USACE), although dredging operations are often carried out by private contractors (under USACE supervision). USACE also monitors water quality and some remediation. This

868-512: The water between islands is typically called a channel or passage . The English Channel is the strait between England and France. The channel form is described in terms of geometry (plan, cross-sections, profile) enclosed by the materials of its bed and banks. This form is under influence of two major forces: water discharge and sediment supply. For erodible channels the mutual dependence of its parameters may be qualitatively described by Lane's Principle (also known as Lane's relationship ):

899-400: The way to D with no navigational aids and only estimated depths provided to the shipmaster . With regard to the dredging , channels can be unrestricted (wide enough to accommodate 10-15 widths of a largest ship used in this channel, semi-restricted with limited dredging in shallow waters, and fully restricted , where the entire channel is dredged. The latter, entirely human-made, channel

930-695: The world according to the Guinness Book of World Records are Baldwin Street in Dunedin, New Zealand, Ffordd Pen Llech in Harlech, Wales and Canton Avenue in Pittsburgh, Pennsylvania. The Guinness World Record once again lists Baldwin Street as the steepest street in the world, with a 34.8% grade (1 in 2.87) after a successful appeal against the ruling that handed the title, briefly, to Ffordd Pen Llech . A number of streets elsewhere have steeper grades than those listed in

961-1361: Was first established under the Rivers and Harbors Act of 1899 and modified under acts of 1913, 1935, and 1938. For example, the USACE developed the Intracoastal Waterway , and has the Mississippi Valley Division responsible for the Mississippi River from the Gulf to Cairo, Illinois , the North Atlantic Division for New York Harbor and Port of Boston , and the South Pacific Division for Port of Los Angeles and Port of Long Beach . Waterways policing as well as some emergency spill response falls under United States Coast Guard jurisdiction, including inland channels serving ports like Saint Louis hundreds of miles from any coast. The various state or local governments maintain lesser channels, for example former Erie Canal . Grade (slope) The grade (US) or gradient (UK) (also called stepth , slope , incline , mainfall , pitch or rise ) of

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