A flood control structure is a system of man-made structures used to reduce the risk of flooding. The three most common types of flood control structures are levees, dams, and dikes. Levees are earthen embankments built along rivers or coasts to prevent flooding. Dams are barriers built across rivers to control the flow of water and create reservoirs. Dikes are similar to levees, but are built on land instead of along rivers or coasts. All three of these structures are used to protect people and property from flooding.