![]() The velocity of flow is highest in the region near the free surface and near the outer bank. The flow is deepest near the foot of the eroding outer bank, and it shoals gradually up the point-bar surface. The flow-transverse profile of a meandering river is highly asymmetrical. The bank is eroded by various processes, the most important of which is undercutting low on the bank and collapse of large masses into the channel. On the outer, or concave, side of the meander bend is a steep bank or cliff, often called a cut bank, of consolidated or semiconsolidated sediment that is eroded during strong flows. Sediment is gradually accreted to the point-bar surface, causing the point bar to shift laterally. This sand body, called a point bar, lies everywhere below bank-full stage and is inundated by floods. On the inner, or convex, side of the meander bend is a fairly smooth and largely non-vegetated body of sand, sloping gently downward toward the center of the channel. Elements of the plan-view features of a meandering river The narrow part of the meander bend, between adjacent reaches of the channel above and below the bend, is called the meander neck. One can also think about a radius of curvature in the bend, but that’s likely to vary from point to point in the bend. The meander bends or meander loops are never perfectly regular, but they are often described as if they were (Figure 5-37), in terms of wavelength and amplitude. Figure 5-36 shows most of the elements of a meandering river system. First of all, keep in mind that the tendencies toward meandering and braiding are complementary rather than mutually exclusive, in the sense that many rivers show elements of both at the same time and within the same reach.įirst, some descriptive stuff on the geometry of meandering rivers. The two most characteristic plan patterns assumed by rivers are meandering and braided. In some schemes, "meandering" applies only to rivers with exaggerated circular loops or secondary meanders that is, meanders on meanders.\) ![]() ![]() Unless otherwise defined in a specific scheme "meandering" and "sinuosity" here are synonymous and mean any repetitious pattern of bends, or waveforms. Parameters based on mathematical formulae or numerical data vary as well, depending on the database used by the theorist. There is not yet full consistency or standardization of scientific terminology used to describe watercourses. 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. When a meander gets cut off from the main stream, an oxbow lake is formed. The result is a snaking pattern as the stream meanders back and forth across its down-valley axis. 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. A meander is formed when the 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 what it is carrying. Streams or rivers with a single channel and sinuosities of 1.5 or more are defined as meandering streams or rivers.įreebase Rate this definition: 0.0 / 0 votesĪ meander, in general, is a bend in a sinuous watercourse or river. The sinuosity of a watercourse is the ratio of the length of the channel to the straight line down-valley distance. 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.The degree of meandering of the channel of a river, stream, or other watercourse is measured by its sinuosity. It typically ranges from 15 to 18 times the width of the channel. 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 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. ![]() Wikipedia Rate this definition: 0.0 / 0 votesĪ meander is one of a series of regular sinuous curves in the channel of a river or other watercourse.
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