The National Academies of Sciences, Engineering, and Medicineĥ00 Fifth Street, NW | Washington, DC 20001 U.S.DOT United States Department of Transportation TCRP Transit Cooperative Research Program NTSB National Transportation Safety Board
NHTSA National Highway Traffic Safety Administration NCTRP National Cooperative Transit Research and Development Program NCHRP National Cooperative Highway Research Program ITE Institute of Transportation Engineers IEEE Institute of Electrical and Electronics Engineers Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.Ībbreviations used without definitions in TRB publications:ĪASHO American Association of State Highway OfficialsĪASHTO American Association of State Highway and Transportation OfficialsĪPTA American Public Transportation AssociationĪSME American Society of Mechanical EngineersĪSTM American Society for Testing and MaterialsĬTAA Community Transportation Association of AmericaĬTBSSP Commercial Truck and Bus Safety Synthesis ProgramįMCSA Federal Motor Carrier Safety Administration Incised meander in the Tarn River, Sant Chely du Tarn, France (Source: Wikipedia).Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book.
They can be due to a fall in sea level or tectonic uplift. They formed as the river cut down its bed into the bedrock. Incised or entrenched meanders: they are found in narrow, steep valleys.
#Meander definition free
Free meanders: they form where the gradient is gentle, in wide river floodplains, which allow for large meander amplitude.įree meander in the Cuckmere River in England (Source: Wikipedia).The abandoned meander creates a body of water known as an oxbow lake. Abandoned meanders can form during a flood or when the river cannot carry excess sediment through the bend, so the river finds a new path to flow. Over time, the ends of the curve formed by the meander become very close together and the meander is cut off and abandoned (abandoned or cutoff meander). Meanders change position by eroding sideways and slightly downstream. In addition, it depends on other variables such as the lithology of the river margins, the discharge, whether there is a floodplain or not, etc.
Meanders move over time through simultaneous processes of erosion and sedimentation. The development of meanders increases the length of the river and thus decreases its slope. They form more easily in floodplains with a low gradient. How are meanders formed?Ī meander is formed when the water flow velocity diminishes in the river, thus forming curves or meanders. When they are above the water level, they can be recognised forming ridges.
As sediments deposit in the inside of a meander, point bars become larger, composed of sediment that is well sorted. Point bars are crescent-shaped deposits of sand and gravel that accumulate on the inside of a river bend. A meander forms as a watercourse erodes the sediments of an outer, concave bank and deposits sediments on an inner, convex bank (point bar), leading to a meandering channel. Meanders are curves in the middle-lower course of a river.
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