A levee, floodbank or stopbank is a natural or artificial embankment or dike, usually earthen, which parallels the course of a river.
The main purpose of an artificial levee is to prevent flooding of the adjoining countryside; however, they also confine the flow of the river resulting in higher and faster water flow.
Levees are usually built by piling earth on a cleared, level surface.
Broad at the base, they taper to a level top, where temporary embankments or sandbags can be placed.
Because flood discharge intensity increases in levees on both river banks, and because silt deposits raise the level of riverbeds, planning and auxiliary measures are vital.
Sections are often set back from the river to form a wider channel, and flood valley basins are divided by multiple levees to prevent a single breach from flooding a large area.