Formation of a Levée
Definition: Levées are natural embankments of silt along the banks of a
river, often several metres higher than the floodplain.
The river is on its floodplain with a very low gradient.
The river is mainly depositing (silt and sand).
When the river floods a lot of silt is deposited on the riverbanks and
much less on the floodplain.
Frequent flooding continues this build-up.
When the river is flowing, normally it deposits in the riverbed.
This raises the river above the floodplain.
But usually, the built-up levées protect the plain from flooding.