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Inundation (from the Latin inundatio, flood) is both the act of intentionally flooding land that would otherwise remain dry, for military, agricultural, or river-management purposes, and the result of such an act.
The noun "inundation" refers to both the act of inundating; an overflow; a flood; a rising and spreading of water over grounds; and to the state of being inundated; flooding.It should therefore be distinguished from other types of flooding, not caused by man. It should also be recognised that this type of flooding would not take place without the intentional human act. So e.g. tidal flooding of areas that fall dry at ebb tide, and periodical river floods are not inundations in the sense intended here.
The latter condition implies that in most topographies the act usually applies to causing an overflow of a river or stream by damming it. This is also the only method foreseen in the 1888 British military textbook that discusses the technique correctly under "military obstacles".However, in areas that have been reclaimed from the sea, marches or lakes, and are artificially protected from the waters (either accumulated precipitation, or the water source that would flood the reclaimed area, if it were not artificially protected), as in e.g. the artificial hydrological entities, known as Polders, may be inundated by simply giving the water source access again. In the latter perspective inundation may simply be a form of hydraulic engineering.
Before we limit the concept to military uses, it should be recognised that there are at least two other possible uses of inundation as a human act:
Military inundation creates an obstacle in the field that is intended to impede the movement of the enemy. This may be done both for offensive and defensive purposes. Furthermore, in so far as the methods used are a form of hydraulic engineering, it may be useful to differentiate between controlled inundations (as in most historic inundations in the Netherlands under the Dutch Republic and its successor states in that areaand exemplified in the two Hollandic Water Lines, the Stelling van Amsterdam, the Frisian Water Line, the IJssel Line, the Peel-Raam Line, and the Grebbe line in that country) and uncontrolled ones (as in the second Siege of Leiden during the first part of the Eighty Years' War, and the Inundation of Walcheren, and the Inundation of the Wieringermeer during the Second World War). To count as controlled, a military inundation has to take the interests of the civilian population into account, by allowing them a timely evacuation, by making the inundation reversible, and by making an attempt to minimize the adverse ecological impact of the inundation. As Vandenbohed discusses, that impact may also be adverse in a hydrogeological sense if the inundation lasts a long time.
From a legal point of view, a military inundation should therefore be seen as a government "taking" of private property under the constitutional protection of private property in many countries. In the Netherlands, this was the subject of art. 152 of the Dutch constitution of 1887.
A levee, dike, dyke, embankment, floodbank or stopbank is an elongated naturally occurring ridge or artificially constructed fill or wall that regulates water levels. It is usually earthen and often 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 such as with levees, and larger environmental issues such as climate change and sea level rise.
Hydraulic engineering as a sub-discipline of civil engineering is concerned with the flow and conveyance of fluids, principally water and sewage. One feature of these systems is the extensive use of gravity as the motive force to cause the movement of the fluids. This area of civil engineering is intimately related to the design of bridges, dams, channels, canals, and levees, and to both sanitary and environmental engineering.
The Great Flood of 1993 was a flood that occurred in the Midwestern United States, along the Mississippi and Missouri rivers and their tributaries, from April to October 1993. The flood was among the most costly and devastating to ever occur in the United States, with $15 billion in damages. The hydrographic basin affected over around 745 miles (1,199 km) in length and 435 miles (700 km) in width, totaling about 320,000 square miles (830,000 km2). Within this zone, the flooded area totaled around 30,000 square miles (78,000 km2) and was the worst such U.S. disaster since the Great Mississippi Flood of 1927, as measured by duration, area inundated, persons displaced, crop and property damage, and number of record river levels. In some categories, the 1993 flood even surpassed the 1927 flood, at the time the largest flood ever recorded on the Mississippi.
The Dujiangyan is an ancient irrigation system in Dujiangyan City, Sichuan, China. Originally constructed around 256 BC by the State of Qin as an irrigation and flood control project, it is still in use today. The system's infrastructure develops on the Min River (Minjiang), the longest tributary of the Yangtze. The area is in the west part of the Chengdu Plain, between the Sichuan basin and the Tibetan plateau. Originally, the Min would rush down from the Min Mountains and slow down abruptly after reaching the Chengdu Plain, filling the watercourse with silt, thus making the nearby areas extremely prone to floods. King Zhao of Qin commissioned the project, and the construction of the Dujiangyan harnessed the river using a new method of channeling and dividing the water rather than simply damming it. The water management scheme is still in use today to irrigate over 5,300 km2 (2,000 sq mi) of land in the region. The Dujiangyan, the Zhengguo Canal in Shaanxi and the Lingqu Canal in Guangxi are collectively known as the "three great hydraulic engineering projects of the Qin."
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that the water does not overflow and damage or destroy the dam.
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.
The Alamo River flows west and north from the Mexicali Valley across the Imperial Valley (California). The 52-mile-long (84 km) river drains into the Salton Sea.
Bird's Point is an unincorporated community in Mississippi County, Missouri, United States. It lies on an island or former island in the Mississippi River, near the confluence of the Ohio and Mississippi Rivers and is situated directly across from Cairo, Illinois. This is the point where the U.S. Route 60 bridge connects with Cairo.
The 1938 Yellow River flood was a flood created by the Nationalist Government in central China during the early stage of the Second Sino-Japanese War in an attempt to halt the rapid advance of Japanese forces. It has been called the "largest act of environmental warfare in history".
On 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 and landfall in Mississippi. The levee and flood wall failures caused flooding in 80% of New Orleans and all of St. Bernard Parish. Tens of billions of gallons of water spilled into vast areas of New Orleans, flooding over 100,000 homes and businesses. Responsibility for the design and construction of the levee system belongs to the United States Army Corps of Engineers; the responsibility of maintenance belongs to the local levee boards. The Corps hands components of the system over to the local levee boards upon completion. When Katrina struck on August 29, 2005, the project was between 60–90% complete. Four major investigations were conducted by civil engineers and other experts in an attempt to identify the underlying reasons for the failure of the federal flood protection system. All concur that the primary cause of the flooding was inadequate design and construction by the Corps of Engineers.
River engineering is the process of planned human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit. People have intervened in the natural course and behaviour of rivers since before recorded history—to manage the water resources, to protect against flooding, or to make passage along or across rivers easier. From Roman times, rivers have been used as a source of hydropower. From the late 20th century, river engineering has had environmental concerns broader than immediate human benefit and some river engineering projects have been concerned exclusively with the restoration or protection of natural characteristics and habitats.
The Great Dayton Flood of 1913 resulted from flooding by the Great Miami River reaching Dayton, Ohio, and the surrounding area, causing the greatest natural disaster in Ohio history. In response, the General Assembly passed the Vonderheide Act to enable the formation of conservancy districts. The Miami Conservancy District, which included Dayton and the surrounding area, became one of the first major flood control districts in Ohio and the United States.
The Morganza Spillway or Morganza Control Structure is a flood-control structure in the U.S. state of Louisiana 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.
The Morganza to the Gulf Hurricane Protection Project is a flood protection system for Terrebonne Parish and Lafourche Parish in the U.S. state of Louisiana. The targeted area is bounded on the west by Bayou Du Large and LA 311 and on the east by Bayou Lafourche. The U.S. Army Corps of Engineers is the federal sponsor for this project, and the Louisiana Department of Transportation and Development with the Terrebonne Levee and Conservation District jointly serve as the local sponsor. The Terrebonne Levee and Conservation District will provide operations and maintenance once the system is complete.
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.
The Mississippi River floods in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway in the past century, comparable in extent to the major floods of 1927 and 1993. In April 2011, two major storm systems deposited record levels of rainfall on the Mississippi River watershed. When that additional water combined with the springtime snowmelt, the river and many of its tributaries began to swell to record levels by the beginning of May. Areas along the Mississippi itself experiencing flooding included Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
The Mississippi River and its tributaries have flooded on numerous occasions. This is a list of major floods.
The Middle Rio Grande Project manages water in the Albuquerque Basin of New Mexico, United States. It includes major upgrades and extensions to the irrigation facilities built by the Middle Rio Grande Conservancy District and modifications to the channel of the Rio Grande to control sedimentation and flooding. The bulk of the work was done by the United States Bureau of Reclamation and the United States Army Corps of Engineers in the 1950s, but construction continued into the 1970s and maintenance is ongoing. The project is complementary to the San Juan-Chama Project, which transfers water from the San Juan River in the Colorado River Basin to the Rio Grande. Although distribution of water from the two projects is handled through separate allotments and contracts, there is some sharing of facilities including the river itself. The ecological impact on the river and the riparian zone was the subject of extended litigation after a group of environmentalists filed Rio Grande Silvery Minnow v. Bureau of Reclamation in 1999.
The Inundation of Walcheren was the intentional, but uncontrolled military inundation, effected by bombing the sea dikes of the former island of Walcheren in Zeeland by the Allies on and after 3 October 1944 in the context of Operation Infatuate during the Battle of the Scheldt after the Allied Invasion of Normandy during World War II. Though the inundation was justified by military necessity, it is controversial whether it was proportional in view of the predictable devastating effects for the civilian population, and the ecology of the island. The fact that the breaches in the sea dikes of the island remained open for a very long time, subjecting the island to the full impact of the twice-daily tides, caused severe damage to agricultural land and infrastructure, and severe hardship for the civilian population. Leaving the breaches open for such a long time, which was unavoidable due to the war-time lack of resources making closing impossible, subjected them to scouring by the tides, that widened and deepened them to such an extent that closing them eventually became extremely difficult, necessitating the development of new dike-building techniques, such as the use of caissons. The last breach was closed on 23 October 1945 and the draining of the island took until early 1946. Only after that could rebuilding the infrastructure and reconstructing the housing stock and the island's economy start. Walcheren was spared during the North Sea Flood of 1953 that devastated many other parts of Zeeland.