naturally raised river banks found on one or both sides of a river channel that is prone to flooding
where are levees found?
in the middle and lower courses, eg minsterworth near gloucester on the river severn
characteristics of a levee
raised river banks (about 2 - 8 metres in the uk)
composed of gravel, stones and alluvium
grading of sediments with biggest ones close to the river bank and smaller ones are furthest away
steep sided, steeper on the channel side than on the land side
fairly flat top, naturally covered by grass which is often used as a footpath
stage 1
during times of high rainfall, the river floods and the sediment the river is carrying is deposited closest to the river as it is more difficult to transport, whereas the finest particles of sediment are carried further onto the flood plain
stage 2
with every flood the river banks are built a little bit higher and the river bed builds up bed load over time, which raises the level of the river and increases the probability of flooding
