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Rapid Transit Lines In Brazil
Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a '' cascade''. Rapids are characterized by the river becoming shallower with some rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white color, forming what is called "whitewater". Rapids occur where the bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length. Rapids cause water aeration of the stream or river, resulting in better water quality. Rapids are categorized in classes, generally running from I to VI. A Class 5 rapid may be categorized as Class 5.1-5.9. While Class I rapids are e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stream Gradient
Stream gradient (or stream slope) is the grade (slope), grade (or slope) of a stream measured by the ratio of drop in elevation per unit horizontal distance, usually expressed as metre, meters per kilometre, kilometer or Foot (length), feet per mile. Hydrology and geology A high gradient indicates a steep slope and rapid volumetric flow rate, flow of water (i.e. more ability to erode); where as a low gradient indicates a more nearly level stream bed and sluggishly moving water, that may be able to carry only small amounts of very fine sediment. High gradient streams tend to have steep, narrow V-shaped valleys, and are referred to as young streams. Low gradient streams have wider and less rugged valleys, with a tendency for the stream to meander. Many rivers involve, to some extent, a flattening of the river gradient as approach the terminus at sea level. Fluvial erosion A stream that flows upon a uniformly erosion, erodible substrate will tend to have a steep gradient near its sour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maumee River
The Maumee River (pronounced ) ( sjw, Hotaawathiipi; mia, Taawaawa siipiiwi) is a river running in the United States Midwest from northeastern Indiana into northwestern Ohio and Lake Erie. It is formed at the confluence of the St. Joseph and St. Marys rivers, where Fort Wayne, Indiana has developed, and meanders northeastwardly for U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed May 19, 2011 through an agricultural region of glacial moraines before flowing into the Maumee Bay of Lake Erie. The city of Toledo is located at the mouth of the Maumee. The Maumee was designated an Ohio State Scenic River on July 18, 1974. The Maumee watershed is Ohio’s breadbasket; it is two-thirds farmland, mostly corn and soybeans. It is the largest watershed of any of the rivers feeding the Great Lakes, and supplies five percent of Lake Erie’s water. History Historically the river was also known as the ''Miami'' in U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limnology
Limnology ( ; from Greek λίμνη, ''limne'', "lake" and λόγος, ''logos'', "knowledge") is the study of inland aquatic ecosystems. The study of limnology includes aspects of the biological, chemical, physical, and geological characteristics of fresh and saline, natural and man-made bodies of water. This includes the study of lakes, reservoirs, ponds, rivers, springs, streams, wetlands, and groundwater.Wetzel, R.G. 2001. Limnology: Lake and River Ecosystems, 3rd ed. Academic Press () Water systems are often categorized as either running (lotic) or standing (lentic). Limnology includes the study of the drainage basin, movement of water through the basin and biogeochemical changes that occur en route. A more recent sub-discipline of limnology, termed landscape limnology, studies, manages, and seeks to conserve these ecosystems using a landscape perspective, by explicitly examining connections between an aquatic ecosystem and its drainage basin. Recently, the need to u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial Landforms
In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes Fluvial processes include the motion of sediment and erosion or deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. In addition, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed ( abrasion). At the same time the fragments themselves are ground down, becoming smaller and more rounded (attrition). Sediment in rivers is transported as either bedload (the coarse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapids
Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. Rapids are characterized by the river becoming shallower with some rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white color, forming what is called "whitewater". Rapids occur where the bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length. Rapids cause water aeration of the stream or river, resulting in better water quality. Rapids are categorized in classes, generally running from I to VI. A Class 5 rapid may be categorized as Class 5.1-5.9. While Class I rapids are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Geographic
''National Geographic'' (formerly the ''National Geographic Magazine'', sometimes branded as NAT GEO) is a popular American monthly magazine published by National Geographic Partners. Known for its photojournalism, it is one of the most widely read magazines of all time. The magazine was founded in 1888 as a scholarly journal, nine months after the establishment of the society, but is now a popular magazine. In 1905, it began including pictures, a style for which it became well-known. Its first color photos appeared in the 1910s. During the Cold War, the magazine committed itself to present a balanced view of the physical and human geography of countries beyond the Iron Curtain. Later, the magazine became outspoken on environmental issues. Since 2019, controlling interest has been held by The Walt Disney Company. Topics of features generally concern geography, history, nature, science, and world culture. The magazine is well known for its distinctive appearance: a thick s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Whitewater
American Whitewater is a not-for-profit 501(c)3 membership organization with the declared mission "to conserve and restore America's whitewater resources and to enhance opportunities to enjoy them safely". The organization can broadly be classified as an advocacy group that engages in a variety of tactics to ensure rivers are accessible to those who wish to use them. This includes working on lobbying efforts at local and national levels as well as maintaining and publishing information about river conservation, statistics on river use, accident reports, and river sports safety. History The organization was founded in 1954 as the American White Water Affiliation incorporated in 1961. Upon its founding, the organizational members set to advance four principal objectives. (1) Encourage the exploration, enjoyment, and preservation of America's recreational waterways for human-powered craft. (2) Protect the wilderness character of waterways through conservation of water, forests, pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River Rapids Ride
A river rapids ride (or river rafting ride) is an amusement ride that simulates whitewater rafting. History The river rapids ride concept was proposed by Bill Crandall (general manager of AstroWorld in Houston) and developed by Intamin. AstroWorld introduced the world's first river rapids ride, Thunder River, in 1980 and popularized a concept which can now be found at most major amusement parks. Despite being an incredibly popular attraction, AstroWorld's Thunder River (being a prototype) was initially plagued by issues that were corrected in the first few seasons of operation. The boat bumpers were re-designed, portions of the wide river channel were narrowed or barricaded to prevent boats from bottle-necking or getting caught in a backflow, and a planned whirlpool effect was scrapped. Construction Many modern river rapids rides feature a much narrower river channel as well as smaller boats (6 seats as opposed to 12 seats). Some are heavily themed, while others may present a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riffle
A riffle is a shallow landform in a flowing channel. Colloquially, it is a shallow place in a river where water flows quickly past rocks. However, in geology a riffle has specific characteristics. Topographic, sedimentary and hydraulic indicators Riffles are almost always found to have a very low discharge compared to the flow that fills the channel (approximately 10–20%), and as a result the water moving over a riffle appears shallow and fast, with a wavy, disturbed water surface. The water's surface over a riffle at low flow also has a much steeper slope than that over other in-channel landforms. Channel sections with a mean water surface slope of roughly 0.1 to 0.5% exhibit riffles, though they can occur in steeper or gentler sloping channels with coarser or finer bed materials, respectively. Except in the period after a flood (when fresh material is deposited on a riffle), the sediment on the riverbed in a riffle is usually much coarser than on that in any other in-chan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rheophile
A rheophile is an animal that prefers to live in fast-moving water. Examples of rheophilic animals Insects *Many aquatic insects living in riffles require current to survive. *'' Epeorus sylvicola'', a rheophilic mayfly species ( Ephemeroptera) *Some African (''Elattoneura'') and Asian threadtail (''Prodasineura'') species Birds * Dippers (''Cinclus'') * Grey wagtail (''Motacilla cinerea'') and mountain wagtail (''Motacilla clara'') *A few swifts often nest behind waterfalls, including American black swift The American black swift, or more simply black swift (''Cypseloides niger''), is a species of bird that is found from northern British Columbia in Canada through the United States and Mexico to Costa Rica and Brazil. They are also found in the C ... (''Cypseloides niger''), giant swiftlet (''Hydrochous gigas''), great dusky swift (''Cypseloides senex'') and white-collared swift (''Streptoprocne zonaris'') *Some waterfowl, including African black duck (''Anas sparsa'') ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
