What is the formation of a levee?

Answer 1

A natural levee is formed when a river floods over the bank and deposits sediment and this causes the banks to be higher than the flood plain.

A manmade levee is formed by piling dirt and rocks, wider at the base and tapering to the top.

Answer 2

When a river carrying sediment overflows it's banks the coarsest sediment is dropped first as the river no longer has the energy to carry it. The coarse material forms a small natural embankment (levee) along the edge of the river channel. The finer material is carried further away from the river channel across the floodplain and is deposited here. Over time if flooding occurs regularly the levees will become naturally higher. In times of low discharge (very dry weather/droughts) within the river channel deposition will occur causing the river bed level to rise making the river more likely to flood. Levees can be artificially strengthend and heightened to help prevent the flooding of the floodplain. The deposition of the sediment from the river means the land of the floodplain is very fertile and so many try to reclaim it for farming etc which is why the levees may be strengthened and heightened. Hope this helps anyone looking for a more simple explaination for the formation of levees (: