What is a Levee? August 2011 www.fema.gov/plan/prevent/fhm/rm_main.shtm · 1–877–FEMA MAP RiskMap type 31 percent LEVEE COMPONENTS: Levee Crown: The flat surface at the top of a levee that is equal to or narrower than the base Embankment: A mound of earth raised to retain or divert water Freeboard: The height of a levee above the flood level it was designed to protect against, used as a safety measure to compensate for design uncertainty and unanticipated factors that could increase the size of a flood Levee Toe: The edge of the levee where the base meets the natural ground Levees and Levee Systems FEMA has identified thousands of miles of levees impacting millions of people Nationwide. Living with levees is a shared responsibility, and it is important for levee owners, communities, and homeowners to understand what levees are and the risks associated with living and working near levee areas. Levees can and do fail, often with catastrophic results. Even the best flood protection system or structure cannot completely eliminate all risk of flooding. The Federal Emergency Management Agency (FEMA) 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 in order to reduce the risk from temporary flooding.” Levees reduce the risk of f looding, but do not eliminate the risk. Aerial2 Levees and floodwalls are constructed from the earth , compacted soil or artificial materials, such as concrete or steel . To protect against erosion and scouring, earthen levees can be covered with grass and gravel or hard surfaces like stone, asphalt, or concrete. Levee systems consist of levees , floodwalls, and associated structures, such as closure and drainage devices, which are constructed and operated in accordance w ith sound engineering practices. All of these elements work together to form a system for reducing flood risk. Levees often have “interior drainage” systems that work in conjunction with the levees to take water from the landward side to the water side. A n interior drainage system may includes culverts, canals, ditches, storm sewers, and/or pumps. Anatomy of a Levee L evee s and floodwalls are typically built parallel to a waterway, most often a river, in order to reduce the risk of flooding to the area behind it . Floodwalls, which are typically made of concrete or steel, are often constructed on a levee crown to increase the height of the levee , without increasing the base of the embankment . The diagram below shows the components of a typical levee. August 2011 www.fema.gov/plan/prevent/fhm/rm_main.shtm · 1–877–FEMA MAP RiskMap type 31 percent USmap_2colors American Society of Civil Engineers Who Owns and Maintains the Nation’s Levees? While a small percentage of levees are built and /or maintained by the U.S. Army Corps of Engineers (USACE) , the majority of levees are not owned or maintained by any F ederal agency. Some levees are designed and built by the USACE, but with a local authority assuming ownership and maintenance responsibiliti es once the construction is complete. States, communities, and private levee owners maintain and operate the levees they own according to their specific design criteria. Where are Levees Located? Levees are located across the Nation, but certain states re ly more extensively on them than others. FEMA estimates levees are located in nearly one - quarter of the Nation’s counties, and 43 percent of the U.S. population lives in counties with levees. Home and business owners living and working in near levees areas are strongly encouraged to learn about the risk associated with them, and know the steps to take now to protect families, businesses, and communities from impacts associated with levee - related flooding . The green on the map below indicates areas across the U.S. where levees are located. Be Prepared for a Flood If you live in an area near a levee, it is essential to put the dangers of flooding into perspective. On average, over the last 30 years, flooding has resulted in more fatalities in the U.S. than any other weather - related incident. Living in a designated f loodplain, an area with at least a one - percent chance of being flooded each year, the risk of damage to a home or business from flooding is two and a half times greater than damage from a fire. Those living or working behind a levee can take simple steps t oday to prepare for a flood, including evacuation, and protect their home or business. Home and business owners can take the following actions to help prevent loss of life and property during a flood: . Purchase flood insurance through the National Flood In surance Program . Determine if there is a flood warning system in their community . Know evacuation routes . Prepare an emergency kit . Make a list of items to take in case of an evacuation . E levat e items (e.g. electrical items) susceptible to flooding Additional Information You can c ontact your local government agenc ies , such as the public works department or flood control district , to stay informed about the status of levees and their location s in your community . . For more information on levee systems and links to levee - related fact sheets, please visit: www.fema.gov/plan/prevent/fhm/lv_intro.shtm or http:// www.fema.gov/levees . . To see how levees work and how they can fail, visit http://www.floodsmart.gov/floodsmart/pages/flooding_ flood_risks/levee_simulator.jsp . . For more information on flood insurance for your home or business or to find an insurance agent, please visit the Floo dSmart website at: www.FloodSmart.gov . . For more information about what to do before, during, and after a flood, visit: www.fema.gov/hazard/flood/index.shtm . . For more information on flood hazard mapping, please visit: www.fema.gov/plan/prevent/fhm/hm_main.shtm .