Levees Flashcards
What is a levee
A levee is a build-up of alluvium on the banks of a river. Levees are caused by floods
Is a levee formed by deposition or erosion
Deposition
Example of levees
the lower courses of the rivers
Moy and Liffey.
Formation of a levee
In times of low flow, material is deposited on the river bed, raising the height of the river bed.
• In times of flood, the water leaves the channel and spreads out over the flood plain. As it does so, it loses energy and deposits its load.
• The coarser, heavier material is deposited on the river banks, and the finer material is carried further onto the flood plain.
• After many floods, the river builds a bank on either side. Artificial levees (human-made river banks) can also be used to protect the surrounding land from flooding.