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A levee (from the French for "raised") is a natural or artificial embankment , usually earthen, which parallels the course of a river. It functions to prevent flooding of the adjoining countryside. However it also confines the flow of the river resulting in higher and faster water flow.
Levees are usually built by piling earth on a cleared, level surface. Broad at the base, they taper to a level top, where temporary embankments or sandbags can be placed. Because flood discharge intensity increases in in levees on both banks, and because silt deposits raise the level of riverbeds, planning, as well as auxiliary measures are vital.
A natural levee results from the deposit of material by a river during flood stage resulting in the land near a river being raised in elevation. When the river is not in flood state it cuts a channel in the elevated material. Natural levees are especially noted on the Yellow River in China near the sea where ocean going ships appear to sail high above the plain on the elevated river. Natural levees are also present on the Rio Grande River in Colorado's San Luis Valley.
Natural levees are formed as sediment of larger grain size settle out on the banks of channels due to the drop in flow velocity on the edge of the channel.
Prominent levee systems exist along the Mississippi and Sacramento Rivers in the United States, and the Po, Vistula, and Danube in Europe.
In some countries, levees are known by other names, such as floodbanks or stopbanks.
The song "I've been working on the railroad" was, according to Carl Sandburg, originally "I've been working on the levee" before the days of railroads. Other notable mention of levees in music are Led Zeppelin's "When the levee breaks", and Don McLean's mention of driving his "Chevy to the levee" in his song " American PieAmerican Pie is a nearly nine-minute long classic pop song by singer-songwriter Don McLean, about " the day the music died". Background Recorded in 1971 and released that year on the album of the same name, it was a #1 US hit in 1972 (see 1972 in music)."
See also: DikeA dyke (or dike is a stone or earthen wall constructed as a defence or as a boundary. The best known form of dyke is a construction built along the edge of a body of water to prevent it from flooding onto an adjacent lowland. However dykes have also been
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