Dikes, levees and dams are all part of different types of flood protection systems. The terms are sometimes used interchangeably, but dikes, dams and levees have different purposes.

Here is a quick explanation of the terms. Dikes normally run parallel to a body of water such as a river or a sea. They usually only have water on one side. They are embankments constructed to prevent flooding. Dikes protect land that would naturally be underwater most of the time. Dikes were first built to reclaim land from the sea. Today, the most famous system of dikes is in the Netherlands. The word Netherlands means “lowlands”: more than a quarter of the country’s land is below sea level.

Levees are man-made embankment built to keep a river from overflowing its banks or to prevent ocean waves from washing into undesired areas. Therefore, they usually have water only on one side and protect land that is normally dry but that may be flooded when rain or melting snow raises the water level in a body of water. In cities like New Orleans, levees are designed to provide some protection against hurricanes. The National Flood Insurance Program (NFIP) defines a levee as “a man-made structure, usually an earthen embankment, designed and constructed in accordance with sound engineering practices to contain, control, or divert the flow of water so as to reduce risk from temporary flooding.”