levee

Levees are formed on the banks of meandering rivers when the river floods over its flood plain. The flow of the flood water is slower over the levees than it is in the river bed and so silt is deposited there.

Naturally formed raised bank along the side of a river channel. When a river overflows its banks, the rate of flow is less than that in the channel, and silt is deposited on the banks. With each successive flood the levee increases in height so that eventually the river may be above the surface of the surrounding flood plain. Notable levees are found on the lower reaches of the Mississippi in the USA, and along the Po in Italy. The Hwang Ho in China also has well-developed levees.