Levee

A levee is an embankment, raised either naturally by repeated flood deposits or artificially built up by people, that runs along a riverbank or coastline to hold back floodwater and keep a waterway confined to its channel. Artificial levees are among the oldest known civil engineering works, with evidence of levee construction along the Nile and the Tigris and Euphrates rivers in ancient Egypt and Mesopotamia and along the Yellow River in ancient China, built to protect farmland and settlements from seasonal flooding. Levees remain a primary flood-control structure on major rivers worldwide today, most extensively along the lower Mississippi River in the United States, where an interconnected levee system stretches for thousands of kilometers, though a levee that is overtopped or breached can fail catastrophically, a risk that has driven the parallel development of floodwalls, spillways and levee-setback engineering.