|
Meandering
A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank (cut bank) and deposits sediments on an inner, convex bank which is typically a point bar. The result of this coupled erosion and sedimentation is the formation of a sinuous course as the channel migrates back and forth across the axis of a floodplain. The zone within which a meandering stream periodically shifts its channel is known as a meander belt. It typically ranges from 15 to 18 times the width of the channel. Over time, meanders migrate downstream, sometimes in such a short time as to create civil engineering challenges for local municipalities attempting to maintain stable roads and bridges.Neuendorf, K.K.E., J.P. Mehl Jr., and J.A. Jackson, J.A., eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Charlton, R., 2007. ''Fundamentals o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meander Cutoff
A meander cutoff is a natural form of a cutting or cut in a river occurs when a pronounced meander (hook) in a river is breached by a flow that connects the two closest parts of the hook to form a new channel, a full loop. The steeper drop in gradient (slope) causes the river flow gradually to abandon the meander which will silt up with sediment from deposition. Cutoffs are a natural part of the evolution of a meandering river. Rivers form meanders as they flow laterally downstream, see sinuosity. Meandering rivers flow higher and hence with more total flow, pressure and erosion on the outside of their bends due to forming a vortex as in a stirred coffee cup and consequently the river erodes more the outer bank. On the inside bend of a river, the level is lower, secondary flow moves sand and gravel across the river bed creating shallows and point bars, and friction of air and perturbances of the bed act against a higher proportion of the column of water, being shorter, slowing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Flow
In fluid dynamics, flow can be decomposed into primary plus secondary flow, a relatively weaker flow pattern superimposed on the stronger primary flow pattern. The primary flow is often chosen to be an exact solution to simplified or approximated (for instance, inviscid) governing equations, such as potential flow around a wing or geostrophic current or wind on the rotating Earth. In that case, the secondary flow usefully spotlights the effects of complicated real-world terms neglected in those approximated equations. For instance, the consequences of viscosity are spotlighted by secondary flow in the viscous boundary layer, resolving the tea leaf paradox. As another example, if the primary flow is taken to be a balanced flow approximation with net force equated to zero, then the secondary circulation helps spotlight acceleration due to the mild imbalance of forces. A smallness assumption about secondary flow also facilitates linearization. In engineering secondary flow also id ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point Bar
A point bar is a depositional feature made of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope. Point bars are found in abundance in mature or meandering streams. They are crescent-shaped and located on the inside of a stream bend, being very similar to, though often smaller than, towheads, or river islands. Point bars are composed of sediment that is well sorted and typically reflects the overall capacity of the stream. They also have a very gentle ''slope'' and an elevation very close to water level. Since they are low-lying, they are often overtaken by floods and can accumulate driftwood and other debris during times of high water levels. Due to their near flat topography and the fact that the water speed is slow in the shallows of the point bar they are popular rest stops for boaters and rafters. However, camping on a point bar can be dangerous as a flash flood that raises the stream level by as little as a few inches (centimetre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinuous
Sinuosity, sinuosity index, or sinuosity coefficient of a continuously differentiable curve having at least one inflection point is the ratio of the curvilinear length (along the curve) and the Euclidean distance (straight line) between the end points of the curve. This dimensionless quantity can also be rephrased as the "actual path length" divided by the "shortest path length" of a curve. The value ranges from 1 (case of straight line) to infinity (case of a closed loop, where the shortest path length is zero or for an infinitely-long actual path). Interpretation The curve must be continuous (no jump) between the two ends. The sinuosity value is really significant when the line is continuously differentiable (no angular point). The distance between both ends can also be evaluated by a plurality of segments according to a broken line passing through the successive inflection points (sinuosity of order 2). The calculation of the sinuosity is valid in a 3-dimensional space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as Stream#Creek, creek, Stream#Brook, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to Geographical feature, geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "Burn (landform), burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek, but not always: the language is vague. Rivers are part of the water cycle. Water generally collects in a river from Precipitation (meteorology), precipitation through a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinuosity
Sinuosity, sinuosity index, or sinuosity coefficient of a continuously differentiable curve having at least one inflection point is the ratio of the curvilinear length (along the curve) and the Euclidean distance (straight line) between the end points of the curve. This dimensionless quantity can also be rephrased as the "actual path length" divided by the "shortest path length" of a curve. The value ranges from 1 (case of straight line) to infinity (case of a closed loop, where the shortest path length is zero or for an infinitely-long actual path). Interpretation The curve must be continuous (no jump) between the two ends. The sinuosity value is really significant when the line is continuously differentiable (no angular point). The distance between both ends can also be evaluated by a plurality of segments according to a broken line passing through the successive inflection points (sinuosity of order 2). The calculation of the sinuosity is valid in a 3-dimensional space (e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helicoidal Flow
Helicoidal flow is the cork-screw-like flow of water in a meander. It is one example of a secondary flow. Helicoidal flow is a contributing factor to the formation of slip-off slopes and river cliffs in a meandering section of the river. The helicoidal motion of the flow aids the processes of hydraulic action and corrasion on the outside of the meander, and sweeps sediment across the floor of the meander towards the inside of the meander, forming point bar deposits. See also *Laminar flow *Turbulent flow In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ... * Baer's law * Secondary flow in river bends References Bibliography Journal of Geophysical Research, Volume 107 (2002) Rivers {{Fluiddynamics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miletus
Miletus (; gr, Μῑ́λητος, Mī́lētos; Hittite transcription ''Millawanda'' or ''Milawata'' (exonyms); la, Mīlētus; tr, Milet) was an ancient Greek city on the western coast of Anatolia, near the mouth of the Maeander River in ancient Ionia. Its ruins are located near the modern village of Balat in Aydın Province, Turkey. Before the Persian rule that started in the 6th century BC, Miletus was considered among the greatest and wealthiest of Greek cities. Evidence of first settlement at the site has been made inaccessible by the rise of sea level and deposition of sediments from the Maeander. The first available evidence is of the Neolithic. In the early and middle Bronze Age the settlement came under Minoan influence. Legend has it that an influx of Cretans occurred displacing the indigenous Leleges, and the site was renamed Miletus after a place in Crete. Recorded history at Miletus begins with the records of the Hittite Empire, and the Mycenaean records of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graben
In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic context by Eduard Suess in 1883. The plural form is either ''graben'' or ''grabens''. Formation A graben is a valley with a distinct escarpment on each side caused by the displacement of a block of land downward. Graben often occur side by side with horsts. Horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward, while that of the footwall is upward. The faults typically dip toward the center of the graben from both sides. Horsts are parallel blocks that remain between graben; the bounding faults of a horst typically dip away from the center line of the horst. Single or multiple graben can produce a rift valley. Half-g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bend2
Bend may refer to: Materials * Bend, a curvature in a pipe, tube, or pipeline (see Bend radius) * Bend knot, a knot used to tie two ropes together; see List of bend knots *Bending, the deformation of an object due to an applied load Music Musical techniques * Bend (guitar), a guitar technique * Bending, for blues harp (harmonica) Albums and songs * ''Bend'' (8stops7 album), 2006 * ''Bend'' (The Origin album), 1992 * "Bend" (song), a 2015 song by Chet Faker People * Lin Bend (1922–1978), Canadian ice hockey centre * Robert Bend (1914–1999), Manitoba politician Places * Bend, British Columbia, a railway point in Canada * Bend, California * Bend, Missouri * Bend, Oregon * Bend, South Dakota * Bend, Texas Other uses * Bend (heraldry), a diagonal band used as a heraldic charge * Bend, a meander in a river * Decompression sickness, commonly known as "the bends" * Curl (association football), a playing technique also called "bend" See also * * * Bends (other) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomorphology
Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, to understand landform and terrain history and dynamics and to predict changes through a combination of field observations, physical experiments and numerical modeling. Geomorphologists work within disciplines such as physical geography, geology, geodesy, engineering geology, archaeology, climatology, and geotechnical engineering. This broad base of interests contributes to many research styles and interests within the field. Overview Earth's surface is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence, and shape the coastal geography. Surface processes co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
