Meander
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| + | A '''meander''', in general, is a bend in a [[sinuosity|sinuous]] watercourse or river. A meander forms when moving water in a stream erodes the outer banks and widens its valley, and the inner part of the river has less energy and deposits silt. A [[stream]] of any volume may assume a ''meandering'' course, alternately [[erosion|eroding]] [[sediment]]s from the outside of a bend and depositing them on the inside. The result is a ''snaking'' pattern as the stream meanders back and forth across its down-valley axis. When a meander gets cut off from the main stream, an [[oxbow lake]] forms. Over time meanders migrate downstream, sometimes in such a short time as to create civil engineering problems for local municipalities attempting to maintain stable roads and bridges. | ||
| - | '''Patterns in nature''' are visible [[regularities]] of form found in the natural world. These [[patterns]] recur in different contexts and can sometimes be [[modelled mathematically]]. Natural patterns include [[symmetry|symmetries]], [[tree]]s, [[spiral]]s, [[meander]]s, [[wave]]s, [[foam]]s, [[tessellation]]s, [[fracture|cracks]] and [[stripe]]s. Early [[Greek philosophers]] studied pattern, with [[Plato]], [[Pythagoras]] and [[Empedocles]] attempting to explain order in nature. The modern understanding of visible patterns developed gradually over time. | + | There is not yet full consistency or standardization of scientific terminology used to describe watercourses. A variety of symbols and schemes exist. Parameters based on mathematical formulae or numerical data vary as well, depending on the database used by the theorist. Unless otherwise defined in a specific scheme ‘meandering’ and ‘sinuosity’ here are synonymous and mean any repetitious pattern of bends, or waveforms. In some schemes, ‘meandering’ applies only to rivers with exaggerated circular loops or secondary meanders; that is, meanders on meanders. |
| - | In the 19th century, Belgian physicist [[Joseph Plateau]] examined [[soap film]]s, leading him to formulate the concept of a [[minimal surface]]. German biologist and artist [[Ernst Haeckel]] painted hundreds of [[Marine biology|marine organisms]] to emphasise their [[symmetry]]. Scottish biologist [[D'Arcy Thompson]] pioneered the study of growth patterns in both plants and animals, showing that simple equations could explain spiral growth. In the 20th century, British mathematician [[Alan Turing]] predicted mechanisms of [[morphogenesis]] which give rise to patterns of spots and stripes. Hungarian biologist [[Aristid Lindenmayer]] and French American mathematician [[Benoît Mandelbrot]] showed how the mathematics of [[fractals]] could create plant growth patterns. | + | Sinuosity is one of the [[channel types]] that a stream may assume over all or part of its course. All streams are sinuous at some time in their geologic history over some part of their length. The sinuosity of a meandering stream has a tendency to approach a critical state at which the opposing forces which create and cut off meanders interact in such a way that sinuosity fluctuates around a constant mean, regardless of the original conditions. |
| - | [[Mathematics]], [[physics]] and [[chemistry]] can explain patterns in nature at different levels. Patterns in living things are explained by the [[biology|biological]] processes of [[natural selection]] and [[sexual selection]]. Studies of [[pattern formation]] make use of [[computer models]] to simulate a wide range of patterns. | + | ==See also== |
| + | *[[Meander (art)]] | ||
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A meander, in general, is a bend in a sinuous watercourse or river. A meander forms when moving water in a stream erodes the outer banks and widens its valley, and the inner part of the river has less energy and deposits silt. A stream of any volume may assume a meandering course, alternately eroding sediments from the outside of a bend and depositing them on the inside. The result is a snaking pattern as the stream meanders back and forth across its down-valley axis. When a meander gets cut off from the main stream, an oxbow lake forms. Over time meanders migrate downstream, sometimes in such a short time as to create civil engineering problems for local municipalities attempting to maintain stable roads and bridges.
There is not yet full consistency or standardization of scientific terminology used to describe watercourses. A variety of symbols and schemes exist. Parameters based on mathematical formulae or numerical data vary as well, depending on the database used by the theorist. Unless otherwise defined in a specific scheme ‘meandering’ and ‘sinuosity’ here are synonymous and mean any repetitious pattern of bends, or waveforms. In some schemes, ‘meandering’ applies only to rivers with exaggerated circular loops or secondary meanders; that is, meanders on meanders.
Sinuosity is one of the channel types that a stream may assume over all or part of its course. All streams are sinuous at some time in their geologic history over some part of their length. The sinuosity of a meandering stream has a tendency to approach a critical state at which the opposing forces which create and cut off meanders interact in such a way that sinuosity fluctuates around a constant mean, regardless of the original conditions.
See also
