A levee, dike, dyke, embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastlines.
A flood is an overflow of water that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding, for example land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees, and larger environmental issues such as climate change and sea level rise. In particular climate change's increased rainfall and extreme weather events increases the severity of other causes for flooding, resulting in more intense floods and increased flood risk.
A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. The soils usually consist of clays, silts, sands, and gravels deposited during floods.
The Mississippi River–Gulf Outlet Canal is a 76 mi (122 km) channel constructed by the United States Army Corps of Engineers at the direction of Congress in the mid-20th century that provided a shorter route between the Gulf of Mexico and New Orleans' inner harbor Industrial Canal via the Intracoastal Waterway. In 2005, the MRGO channeled Hurricane Katrina's storm surge into the heart of Greater New Orleans, contributing significantly to the subsequent multiple engineering failures experienced by the region's hurricane protection network. In the aftermath the channel was closed. A permanent storm surge barrier was constructed in the MRGO in 2009, and the channel has been closed to maritime shipping.
A revetment in stream restoration, river engineering or coastal engineering is a facing of impact-resistant material applied to a bank or wall in order to absorb the energy of incoming water and protect it from erosion. River or coastal revetments are usually built to preserve the existing uses of the shoreline and to protect the slope.
Hurricane preparedness in New Orleans has been an issue since the city's early settlement because of its location.
A levee breach or levee failure is a situation where a levee fails or is intentionally breached, causing the previously contained water to flood the land behind the levee.
Though Hurricane Katrina did not deal the city of New Orleans a direct hit on August 29, 2005, the associated storm surge precipitated catastrophic failures of the levees and flood walls. The Mississippi River Gulf Outlet ("MR-GO") breached its levees in approximately 15 places. The major levee breaches in the city include the 17th Street Canal levee, the London Avenue Canal, and the wide, navigable Industrial Canal, which left approximately 80% of the city flooded.
A coupure is a means of closing an opening in a wall, floodwall or levee (dike). The word comes from the French verb couper which means to cut. In historic times a coupure was a location where a breach in the city walls or the walls of a fortress was closed. In more modern times a coupure is a way of allowing traffic to pass a flood protection structure.
On Monday, August 29, 2005, there were over 50 failures of the levees and flood walls protecting New Orleans, Louisiana, and its suburbs following passage of Hurricane Katrina. The failures caused flooding in 80% of New Orleans and all of St. Bernard Parish. In New Orleans alone, 134,000 housing units — 70% of all occupied units — suffered damage from Hurricane Katrina and the subsequent flooding.
A flood barrier, surge barrier or storm surge barrier is a specific type of floodgate, designed to prevent a storm surge or spring tide from flooding the protected area behind the barrier. A surge barrier is almost always part of a larger flood protection system consisting of floodwalls, levees, and other constructions and natural geographical features.
Drainage in New Orleans, Louisiana, has been a major concern since the founding of the city in the early 18th century, remaining an important factor in the history of New Orleans today. The central portion of metropolitan New Orleans is fairly unusual in that it is almost completely surrounded by water: Lake Pontchartrain to the north, Lake Borgne to the east, wetlands to the east and west, and the Mississippi River to the south. Half of the land area between these bodies of water is at or below sea level, and no longer has a natural outlet for flowing surface water. As such, virtually all rainfall occurring within this area must be removed through either evapotranspiration or pumping. Thus, flood threats to metropolitan New Orleans include the Mississippi River, Lake Pontchartrain, canals throughout the city, and natural rainfall. Artificial levees have been built to keep out rising river and lake waters but have had the negative effect of keeping rainfall in, and have failed on numerous occasions.
The Morganza Spillway or Morganza Control Structure is a flood-control structure in the U.S. state of Louisiana. It is located along the western bank of the Lower Mississippi River at river mile 280, near Morganza in Pointe Coupee Parish. The spillway stands between the Mississippi and the Morganza Floodway, which leads to the Atchafalaya Basin and the Atchafalaya River in south-central Louisiana. Its purpose is to divert water from the Mississippi River during major flood events by flooding the Atchafalaya Basin, including the Atchafalaya River and the Atchafalaya Swamp. The spillway and adjacent levees also help prevent the Mississippi from changing its present course through the major port cities of Baton Rouge and New Orleans to a new course down the Atchafalaya River to the Gulf of Mexico. The Morganza Spillway, operated by the U.S. Army Corps of Engineers, was opened during the 1973 and 2011 Mississippi River floods.
Floodplain restoration is the process of fully or partially restoring a river's floodplain to its original conditions before having been affected by the construction of levees (dikes) and the draining of wetlands and marshes.
The Flood Control Act of 1928 authorized the U.S. Army Corps of Engineers to design and construct projects for the control of floods on the Mississippi River and its tributaries as well as the Sacramento River in California. It was sponsored by Sen. Wesley L. Jones (R) of Washington and Rep. Frank R. Reid (R) of Illinois, in response to the Great Mississippi Flood of 1927.
Flood control methods are used to reduce or prevent the detrimental effects of flood waters. Flood relief methods are used to reduce the effects of flood waters or high water levels. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Building hard infrastructure to prevent flooding, such as flood walls, can be effective at managing flooding. However, increased best practice within landscape engineering is to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water. For flooding on coasts, coastal management practices have to not only handle changes water flow, but also natural processes like tides.
The Big Muddy National Fish and Wildlife Refuge was established in 1994, and has grown to over 16,700 acres (68 km2). Like pearls on a string, these acres are spread out as individual units along the Missouri River between Kansas City and St. Louis. These pearls of habitat benefit floodplain-dependent fish and wildlife species. The Big Muddy Refuge is planning to grow to 60,000 acres (240 km2) by buying land from willing sellers who want to see their properties set aside for the benefit of wildlife and the enjoyment of all.
The Gulf Intracoastal Waterway West Closure Complex is a part of the New Orleans Drainage System; it consists of a navigable floodgate, a pumping station, flood walls, sluice gates, foreshore protection, and an earthen levee. The complex was designed to reduce risk for residences and businesses in the project area from a storm surge associated with a tropical event, with an intensity that has a one percent chance of occurring in any given year. This project was operated for the first time on August 29, 2012, in response to Hurricane Isaac.
The greater New Orleans Hurricane & Storm Damage Risk Reduction System (HSDRRS) is an infrastructure systems in southern Louisiana which seeks to provide the greater New Orleans area a 100-year level of risk reduction, meaning reduced risk from a storm surge that has a 1% chance of occurring or being exceeded in any given year. In 2019, the Army Corps of Engineers announced that due to increased rate of sea level rise and continued sinking of soil the levee system would no longer offer original planned levels of protection as early as the year 2023.
The Great Flood of 1913 severely affected Columbus, Ohio. The area most affected was Franklinton, also known as the Bottoms, for its low elevation near the Scioto River. Among many infrastructure projects, a 7.2-mile floodwall was built from 1993 to 2004 to protect most of Franklinton from flooding.
