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Flood control methods are used to reduce or prevent the detrimental effects of
flood A flood is an overflow of water ( or rarely other fluids) 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 hydrol ...
waters."Flood Control",
MSN Encarta ''Microsoft Encarta'' is a discontinued digital multimedia encyclopedia published by Microsoft from 1993 to 2009. Originally sold on CD-ROM or DVD, it was also available on the World Wide Web via an annual subscription, although later article ...
, 2008 (see below: Further reading).
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 Extreme weather or extreme climate events includes unexpected, unusual, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Often, extreme events are based on a locat ...
upstream, and human changes to waterbodies and runoff. Though building hard infrastructure to prevent flooding, such as flood walls, can be effective at managing flooding, increased
best practice A best practice is a method or technique that has been generally accepted as superior to other known alternatives because it often produces results that are superior to those achieved by other means or because it has become a standard way of doing ...
within landscape engineering is to rely more on soft infrastructure and natural systems, such as
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...
es and
flood plains A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
, for handling the increase in water. For flooding on coasts,
coastal management Coastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands. Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates due to climate change. Changes ...
practices have to not only handle changes water flow, but also natural processes like tides. Flood control and relief is a particularly important part of climate change adaptation and
climate resilience Climate resilience is defined as the "capacity of social, economic and ecosystems to cope with a hazardous event or trend or disturbance".IPCC, 2022Summary for Policymakers .-O. Pörtner, D.C. Roberts, E.S. Poloczanska, K. Mintenbeck, M. Tignor, ...
, both
sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cr ...
and changes in the weather (climate change causes more intense and quicker rainfall), means that flooding of human infrastructure is particularly important the world over.


Causes of flooding

Floods are caused by many factors or a combination of any of these generally prolonged heavy rainfall (locally concentrated or throughout a catchment area), highly accelerated
snowmelt In hydrology, snowmelt is surface runoff produced from melting snow. It can also be used to describe the period or season during which such runoff is produced. Water produced by snowmelt is an important part of the annual water cycle in many p ...
, severe winds over water, unusual high tides, tsunamis, or failure of dams, levees, retention ponds, or other structures that retained the water. Flooding can be exacerbated by increased amounts of impervious surface or by other natural hazards such as wildfires, which reduce the supply of vegetation that can absorb rainfall. Periodic floods occur on many rivers, forming a surrounding region known as the flood plain. During times of rain, some of the water is retained in ponds or soil, some is absorbed by grass and vegetation, some evaporates, and the rest travels over the land as surface runoff. Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannot absorb all the water. This has been exacerbated by human activities such as draining wetlands that naturally store large amounts of water and building paved surfaces that do not absorb any water. Water then runs off the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes, and man-made
reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contr ...
s. About 30 percent of all precipitation becomes runoff and that amount might be increased by water from melting snow. River flooding is often caused by heavy rain, sometimes increased by melting snow. A flood that rises rapidly, with little or no warning, is called a flash flood. Flash floods usually result from intense rainfall over a relatively small area, or if the area was already saturated from previous precipitation.


Severe winds over water

Even when rainfall is relatively light, the shorelines of lakes and bays can be flooded by severe winds—such as during hurricanes—that blow water into the shore areas.


Unusually high tides

Coastal areas are sometimes flooded by unusually high tides, such as
spring tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tabl ...
s, especially when compounded by high winds and
storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the ...
s. This was the cause of the
North Sea flood of 1953 The 1953 North Sea flood was a major flood caused by a heavy storm surge that struck the Netherlands, north-west Belgium, England and Scotland. Most sea defences facing the surge were overwhelmed, causing extensive flooding. The storm and flo ...
which flooded large swathes of the Netherlands and the East coast of England and which remains the greatest recorded natural disaster in England.


Effects of floods

Flooding has many impacts. It damages property and endangers the lives of humans and other species. Rapid water runoff causes soil erosion and concomitant sediment deposition elsewhere (such as further downstream or down a coast). The spawning grounds for fish and other wildlife habitats can become polluted or completely destroyed. Some prolonged high floods can delay traffic in areas which lack elevated roadways. Floods can interfere with drainage and economical use of lands, such as interfering with farming. Structural damage can occur in bridge abutments, bank lines, sewer lines, and other structures within floodways. Waterway navigation and hydroelectric power are often impaired. Financial losses due to floods are typically millions of dollars each year, with the worst floods in recent U.S. history having cost billions of dollars.


Benefits of flooding

There are many disruptive effects of flooding on human settlements and economic activities. However, flooding can bring benefits, such as making the soil more fertile and providing it with more nutrients. Periodic flooding was essential to the well-being of ancient communities along the Tigris-Euphrates Rivers, the
Nile The Nile, , Bohairic , lg, Kiira , Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the longest riv ...
River, the
Indus The Indus ( ) is a transboundary river of Asia and a trans-Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in Western Tibet, flows northwest through the disputed region of Kashmir, ...
River, the
Ganges The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...
and the
Yellow River The Yellow River or Huang He (Chinese: , Mandarin: ''Huáng hé'' ) is the second-longest river in China, after the Yangtze River, and the sixth-longest river system in the world at the estimated length of . Originating in the Bayan Ha ...
, among others. The viability for hydrologically based renewable sources of energy is higher in flood-prone regions.


Methods of flood management

Some methods of flood control have been practiced since ancient times. These methods include planting vegetation to retain extra water, terracing hillsides to slow flow downhill, and the construction of floodways (man-made channels to divert floodwater). Other techniques include the construction of levees, lakes, dams, reservoirs, retention ponds to hold extra water during times of flooding.


Coastal management


Dams

Many dams and their associated reservoirs are designed completely or partially to aid in flood protection and control. Many large dams have flood-control reservations in which the level of a reservoir must be kept below a certain elevation before the onset of the rainy/summer melt season to allow a certain amount of space in which floodwaters can fill. Other beneficial uses of dam created reservoirs include hydroelectric power generation, water conservation, and recreation. Reservoir and dam construction and design is based upon standards, typically set out by the government. In the United States, dam and reservoir design is regulated by the US Army Corps of Engineers (USACE). Design of a dam and reservoir follows guidelines set by the USACE and covers topics such as design flow rates in consideration to meteorological, topographic, streamflow, and soil data for the watershed above the structure. The term dry dam refers to a dam that serves purely for flood control without any conservation storage (e.g.
Mount Morris Dam The Mount Morris Dam is a concrete dam on the Genesee River. It is located south of Rochester, New York in the towns of Leicester and Mount Morris in Livingston County, New York, next to Letchworth State Park. History The Mt. Morris Dam was b ...
,
Seven Oaks Dam Seven Oaks Dam is a high earth and rock fill embankment dam across the Santa Ana River in the San Bernardino Mountains, about northeast of Redlands in San Bernardino County, southern California. It impounds Seven Oaks Reservoir in the San Ber ...
).


Diversion canals


Floodplains and groundwater replenishment

Excess water can be used for
groundwater replenishment Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in ...
by diversion onto land that can absorb the water. This technique can reduce the impact of later droughts by using the ground as a natural reservoir. It is being used in California, where orchards and vineyards can be flooded without damaging crops, or in other places wilderness areas have been re-engineered to act as floodplains.


River defenses

In many countries, rivers are prone to floods and are often carefully managed. Defenses such as levees, bunds, reservoirs, and weirs are used to prevent rivers from bursting their banks. A
weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...
, also known as a lowhead dam, is most often used to create millponds, but on the Humber River in Toronto, a weir was built near Raymore Drive to prevent a recurrence of the flood damage caused by
Hurricane Hazel Hurricane Hazel was the deadliest, second costliest, and most intense hurricane of the 1954 Atlantic hurricane season. The storm killed at least 469 people in Haiti before striking the United States near the border between North and Sout ...
in October 1954. The Leeds flood alleviation scheme uses movable weirs which are lowered during periods of high water to reduce the chances of flooding upstream. Two such weirs, the first in the UK, were installed on the
River Aire The River Aire is a major river in Yorkshire, England, in length. The ''Handbook for Leeds and Airedale'' (1890) notes that the distance from Malham to Howden is direct, but the river's meanderings extend that to . Between Malham Tarn and Ai ...
in October 2017 at Crown Point, Leeds city centre and Knostrop. The Knostrop weir was operated during the
2019 England floods Nineteen or 19 may refer to: * 19 (number), the natural number following 18 and preceding 20 * one of the years 19 BC, AD 19, 1919, 2019 Films * ''19'' (film), a 2001 Japanese film * ''Nineteen'' (film), a 1987 science fiction film Music ...
. They are designed to reduce potential flood levels by up to one metre.


Coastal defenses

Coastal flooding has been addressed with coastal defenses, such as
sea wall A seawall (or sea wall) is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation ...
s,
beach nourishment Beach nourishment (also referred to as beach renourishment, beach replenishment, or sand replenishment) describes a process by which sediment, usually sand, lost through longshore drift or erosion is replaced from other sources. A wider beach ...
, and
barrier island Barrier islands are coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from a ...
s.
Tide gates Flood control methods are used to reduce or prevent the detrimental effects of flood waters."Flood Control", MSN Encarta, 2008 (see below: Further reading). Flood relief methods are used to reduce the effects of flood waters or high water leve ...
are used in conjunction with dykes and culverts. They can be placed at the mouth of streams or small rivers, where an
estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
begins or where tributary streams, or drainage ditches connect to sloughs. Tide gates close during incoming tides to prevent tidal waters from moving upland, and open during outgoing tides to allow waters to drain out via the culvert and into the estuary side of the dike. The opening and closing of the gates is driven by a difference in water level on either side of the gate. Living Breakwaters Case Study The Living Breakwaters initiative is the result of an Obama-era competition for innovative designs to prevent further flooding in coastal communities during harsh weather conditions. In October 2012,
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
hit the east coast of the United States causing more than $65 billion in damages and economic loss. One of the areas that got hit hardest was Staten Island's South Shore where the beach community of Tottenville saw sixteen-foot waves that destroyed homes and killed two residents (Dejean). In response to the devastation, the Department of Housing and Urban Development created the Hurricane Sandy Rebuilding Task Force to develop “implementable solutions to the region's most complex needs (Hurricane Sandy Design Competition).” Shortly after its formation, the task force introduced Rebuild by Design, a competition that promised a total of $920 million from the Community Block Disaster Recovery program for the winners to implement their plans (Tottenville Shoreline Protection Project). Ten teams submitted designs and six of them were eventually awarded funding for their respective projects. One winning design was the Living Breakwaters initiative proposed by landscape architect Kate Orff. Her firm, SCAPE, envisioned what Orff describes as a “living piece of infrastructure” including a barrier that protrudes from the water and houses an oyster reef (Dejean). SCAPE's green infrastructure solution will be implemented in three stages beginning in Tottenville, subsequently expanding to the surrounding areas, and to be completed in 2021 (Melcher). The plan aims to protect the South Shore of Staten Island from future storm damage, employing oysters to purify the water and restore the coastline. They claim that the breakwaters will protect the coastline from the intense storm conditions caused by
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
and the wave protection will reduce
erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...
which has greatly contributed to
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
in the area (Dejean). The living breakwaters, however, are not going to exist in an isolated system. SCAPE's design is a part of a layered approach that includes partnerships with the Billion Oyster Project and the Tottenville Shoreline Protection Project, a separately funded project to build similar shoreline protection structures. In addition, part of the Living Breakwaters project's funding is allocated for establishing a “learning hub” to inform local communities about the benefits of oysters and protecting the shoreline ecosystem (Hurricane Sandy Design Competition). This information hopes to encourage residents of Tottenville the surrounding areas to practice sustainable habits, prevent pollution, and continue to engage with the project in the future.


Self-closing flood barrier

The self-closing flood barrier (SCFB) is a flood defense system designed to protect people and property from inland waterway floods caused by heavy rainfall, gales, or rapid melting snow. The SCFB can be built to protect residential properties and whole communities, as well as industrial or other strategic areas. The barrier system is constantly ready to deploy in a flood situation, it can be installed in any length and uses the rising flood water to deploy.


Temporary perimeter barriers

When permanent defenses fail, emergency measures such as
sandbag A sandbag or dirtbag is a bag or sack made of hessian (burlap), polypropylene or other sturdy materials that is filled with sand or soil and used for such purposes as flood control, military fortification in trenches and bunkers, shielding gl ...
s or inflatable impermeable sacks are used. In 1988, a method of using water to control flooding was discovered. This was accomplished by containing 2 parallel tubes within a third outer tube. When filled, this structure formed a non-rolling wall of water that can control 80 percent of its height in external water depth, with dry ground behind it. Eight foot tall water filled barriers were used to surround
Fort Calhoun Nuclear Generating Station The Fort Calhoun Nuclear Generating Station is a shut-down nuclear power plant located on between Fort Calhoun, and Blair, Nebraska adjacent to the Missouri River between mile markers 645.6 and 646.0. The utility has an easement for another wh ...
during the 2011 Missouri River Flooding. Instead of trucking in sandbag material for a flood, stacking it, then trucking it out to a hazmat disposal site, flood control can be accomplished by using the on site water. However, these are not fool proof. A high long water filled rubber flood berm that surrounded portions of the plant was punctured by a skid-steer loader and it collapsed flooding a portion of the facility. In 1999, a group of Norwegian engineers patented a transportable, removable, and reusable flood barrier which uses the water's weight against itself. This removable flood panels protect cities and public utilities. Other solutions, such as
HydroSack A HydroSack or a HydroSnake is a brand name for a flood control sandbag alternative made by Gravitas International of Cheshire, North West England. They are very lightweight and thin until they come into contact with water, then they begin to r ...
, are polypropylene exteriors with wood pulp within, though they are one-time use.


Hazard reduction


Strategic retreat

One way of reducing the damage caused by flooding is to remove buildings from flood-prone areas, leaving them as parks or returning them to wilderness. Floodplain buyout programs have been operated in places like New Jersey (both before and after
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
),
Charlotte, North Carolina Charlotte ( ) is the most populous city in the U.S. state of North Carolina. Located in the Piedmont region, it is the county seat of Mecklenburg County. The population was 874,579 at the 2020 census, making Charlotte the 16th-most popu ...
, and
Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...
. In the United States, FEMA produces flood insurance rate maps that identify areas of future risk, enabling local governments to apply
zoning Zoning is a method of urban planning in which a municipality or other tier of government divides land into areas called zones, each of which has a set of regulations for new development that differs from other zones. Zones may be defined for a si ...
regulations to prevent or minimize property damage.


Resilience

Buildings and other urban infrastructure can be designed so that even if a flood does happen, the city can recover quickly and costs are minimized. For example, homes can be put on stilts, electrical and HVAC equipment can be put on the roof instead of in the basement, and subway entrances and tunnels can have built-in movable water barriers. New York City began a substantial effort to plan and build for flood resilience after
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
.


Flood control by continent


North America

An elaborate system of flood way defenses can be found in the
Canadian province Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under the jurisdiction of the Canadian Constitution. In the 1867 Canadian Confederation, three provinces of British Nor ...
of
Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...
. The Red River flows northward from the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, passing through the city of
Winnipeg Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749 ...
(where it meets the
Assiniboine River The Assiniboine River (''; french: Rivière Assiniboine'') is a river that runs through the prairies of Western Canada in Saskatchewan and Manitoba. It is a tributary of the Red River. The Assiniboine is a typical meandering river with a sin ...
) and into
Lake Winnipeg Lake Winnipeg (french: Lac Winnipeg, oj, ᐑᓂᐸᑲᒥᐠᓴᑯ˙ᑯᐣ, italics=no, Weenipagamiksaguygun) is a very large, relatively shallow lake in North America, in the province of Manitoba, Canada. Its southern end is about north of ...
. As is the case with all north-flowing rivers in the temperate zone of the Northern Hemisphere, snow melt in southern sections may cause river levels to rise before northern sections have had a chance to completely thaw. This can lead to devastating flooding, as occurred in Winnipeg during the spring of 1950. To protect the city from future floods, the Manitoba government undertook the construction of a massive system of diversions, dikes, and flood ways (including the Red River Floodway and the Portage Diversion). The system kept Winnipeg safe during the 1997 flood which devastated many communities upriver from Winnipeg, including
Grand Forks Grand Forks is the third-largest city in the state of North Dakota (after Fargo and Bismarck) and the county seat of Grand Forks County. According to the 2020 census, the city's population was 59,166. Grand Forks, along with its twin city ...
,
North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, ...
and Ste. Agathe, Manitoba. In the United States, the
U.S. Army Corps of Engineers , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...
is the lead flood control agency. After
Hurricane Sandy Hurricane Sandy (unofficially referred to as ''Superstorm Sandy'') was an extremely destructive and strong Atlantic hurricane, as well as the largest Atlantic hurricane on record as measured by diameter, with tropical-storm-force winds spann ...
,
New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
's
Metropolitan Transportation Authority The Metropolitan Transportation Authority (MTA) is a public benefit corporation responsible for public transportation in the New York City metropolitan area of the U.S. state of New York. The MTA is the largest public transit authority in th ...
(MTA) initiated multiple flood barrier projects to protect the transit assets in Manhattan. In one case, the MTA's
New York City Transit Authority The New York City Transit Authority (also known as NYCTA, the TA, or simply Transit, and branded as MTA New York City Transit) is a New York state public-benefit corporations, public-benefit corporation in the U.S. state of New York (state), New ...
(NYCT) sealed subway entrances in
lower Manhattan Lower Manhattan (also known as Downtown Manhattan or Downtown New York) is the southernmost part of Manhattan, the central borough for business, culture, and government in New York City, which is the most populated city in the United States with ...
using a deployable fabric cover system called Flex-Gate, a system that protects the subway entrances against of water. Extreme storm flood protection levels have been revised based on new
Federal Emergency Management Agency The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Ex ...
guidelines for 100-year and 500-year design flood elevations. In the
New Orleans Metropolitan Area The New Orleans metropolitan area, designated the New Orleans–Metairie metropolitan statistical area by the U.S. Office of Management and Budget, or simply Greater New Orleans (french: Grande Nouvelle-Orléans, es, Gran Nueva Orleans), is a me ...
, 35 percent of which sits below sea level, is protected by hundreds of miles of levees and flood gates. This system failed catastrophically, with numerous breaks, during
Hurricane Katrina Hurricane Katrina was a destructive Category 5 Atlantic hurricane that caused over 1,800 fatalities and $125 billion in damage in late August 2005, especially in the city of New Orleans and the surrounding areas. It was at the time the cost ...
(2005) in the city proper and in eastern sections of the Metro Area, resulting in the inundation of approximately 50 percent of the metropolitan area, ranging from a few inches to twenty feet in coastal communities. The Morganza Spillway provides a method of diverting water from the
Mississippi River The Mississippi River is the List of longest rivers of the United States (by main stem), second-longest river and chief river of the second-largest Drainage system (geomorphology), drainage system in North America, second only to the Hudson B ...
when a river flood threatens
New Orleans New Orleans ( , ,New Orleans
,
Baton Rouge Baton Rouge ( ; ) is a city in and the capital of the U.S. state of Louisiana. Located the eastern bank of the Mississippi River, it is the parish seat of East Baton Rouge Parish, Louisiana's most populous parish—the equivalent of counti ...
and other major cities on the lower Mississippi. It is the largest of a system of spillways and floodways along the Mississippi. Completed in 1954, the spillway has been opened twice, in 1973 and in 2011. In an act of successful flood prevention, the
federal government A federation (also known as a federal state) is a political entity characterized by a union of partially self-governing provinces, states, or other regions under a central federal government ( federalism). In a federation, the self-gover ...
offered to buy out flood-prone properties in the United States in order to prevent repeated disasters after the 1993 flood across the Midwest. Several communities accepted and the government, in partnership with the state, bought 25,000 properties which they converted into
wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...
. These wetlands act as a sponge in storms and in 1995, when the floods returned, the government did not have to expend resources in those areas.Ripley, Amanda (2006-08-28)
"Floods, Tornadoes, Hurricanes, Wildfires, Earthquakes... Why We Don't Prepare."
''Time.''


Asia

In
Kyoto Kyoto (; Japanese: , ''Kyōto'' ), officially , is the capital city of Kyoto Prefecture in Japan. Located in the Kansai region on the island of Honshu, Kyoto forms a part of the Keihanshin metropolitan area along with Osaka and Kobe. , the c ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
, the Hata clan successfully controlled floods on the Katsura River in around 500 A.D and also constructed a sluice on the Kazuno River. In
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
flood diversion areas are rural areas that are deliberately flooded in emergencies in order to protect cities. The consequences of
deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
and changing land use on the risk and severity of flooding are subjects of discussion. In assessing the impacts of Himalayan deforestation on the Ganges-Brahmaputra Lowlands, it was found that forests would not have prevented or significantly reduced flooding in the case of an extreme weather event. However, more general or overview studies agree on the negative impacts that deforestation has on flood safety - and the positive effects of wise land use and reforestation. Many have proposed that loss of vegetation (deforestation) will lead to an increased risk of flooding. With natural forest cover the flood duration should decrease. Reducing the rate of deforestation should improve the incidents and severity of floods.


Africa

In
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...
, both the Aswan Low Dam (1902) and the
Aswan High Dam The Aswan Dam, or more specifically since the 1960s, the Aswan High Dam, is one of the world's largest embankment dams, which was built across the Nile in Aswan, Egypt, between 1960 and 1970. Its significance largely eclipsed the previous Aswan Lo ...
(1976) have controlled various amounts of flooding along the
Nile The Nile, , Bohairic , lg, Kiira , Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered the longest riv ...
River.


Europe

Following the misery and destruction caused by the
1910 Great Flood of Paris The 1910 Great Flood of Paris (french: Crue de la Seine de 1910) was a catastrophe in which the Seine River, carrying winter rains from its tributaries, flooded the Paris conurbation, France. The Seine water level rose eight metres above the or ...
, the French government built a series of reservoirs called (or Great Lakes) which helps remove pressure from the
Seine ) , mouth_location = Le Havre/ Honfleur , mouth_coordinates = , mouth_elevation = , progression = , river_system = Seine basin , basin_size = , tributaries_left = Yonne, Loing, Eure, Risle , tributa ...
during floods, especially the regular winter flooding.
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
is protected from flooding by Thames Barrier, a huge mechanical barrier across the
River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, se ...
, which is raised when the water level reaches a certain point.
Project MOSE Mose, Mosè, or Mosé is a given name which may refer to: People In religion * Mose Durst, former president of the Unification Church of the United States * Mosé Higuera, Colombian Catholic bishop * Mosè Tovini, Italian Roman Catholic priest ...
in
Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400  ...
has a similar arrangement, although it is already unable to cope with very high tides. The defenses of both London and Venice will be rendered inadequate if sea levels continue to rise. The largest and most elaborate flood defenses can be found in the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
, where they are referred to as Delta Works with the
Oosterschelde The Eastern Scheldt ( nl, Oosterschelde) is a former estuary in the province of Zeeland, Netherlands, between Schouwen-Duiveland and Tholen on the north and Noord-Beveland and Zuid-Beveland on the south. It also features the largest nati ...
dam as its crowning achievement. These works were built in response to the
North Sea flood of 1953 The 1953 North Sea flood was a major flood caused by a heavy storm surge that struck the Netherlands, north-west Belgium, England and Scotland. Most sea defences facing the surge were overwhelmed, causing extensive flooding. The storm and flo ...
, in the southwestern part of the Netherlands. The Dutch had already built one of the world's largest dams in the north of the country. The Afsluitdijk closing occurred in 1932. The
Saint Petersburg Dam The Saint Petersburg Flood Prevention Facility Complex ( rus, Ко́мплекс защи́тных сооруже́ний Санкт-Петербу́рга от наводне́ний, kómpleks zashchítnykh sooruzhéniy Sankt-Peterbúrga ot ...
was completed in 2008 to protect
Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
from
storm surge A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the ...
s. It also has a main traffic function, as it completes a
ring road A ring road (also known as circular road, beltline, beltway, circumferential (high)way, loop, bypass or orbital) is a road or a series of connected roads encircling a town, city, or country. The most common purpose of a ring road is to assist i ...
around Saint Petersburg. Eleven dams extend for and stand above
water level Water level, also known as gauge height or stage, is the elevation of the free surface of a sea, stream, lake or reservoir relative to a specified vertical datum.ISO 772: 1996. Hydrometric determinations – Vocabulary and symbols. See also * ...
.


Climate change adaptation


Flood clean-up safety

Clean-up activities following floods often pose hazards to workers and volunteers involved in the effort. Potential dangers include electrical hazards,
carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...
exposure, musculoskeletal hazards,
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
or cold stress,
motor vehicle A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on rails (such as trains or trams) and is used for the transportation of people or cargo. The ...
-related dangers,
fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames ...
,
drowning Drowning is a type of suffocation induced by the submersion of the mouth and nose in a liquid. Most instances of fatal drowning occur alone or in situations where others present are either unaware of the victim's situation or unable to offer as ...
, and exposure to
hazardous materials Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabi ...
. Because flooded disaster sites are unstable, clean-up workers might encounter sharp jagged debris, biological hazards in the flood water, exposed electrical lines, blood or other body fluids, and animal and human remains. In planning for and reacting to flood disasters, managers provide workers with hard hats, goggles, heavy work gloves, life jackets, and watertight boots with steel toes and insoles.


Development of technology

Europe is at the forefront of the flood control technology, with low-lying countries such as the Netherlands and Belgium developing techniques that can serve as examples to other countries facing similar problems and other countries which may soon face these problems. After
Hurricane Katrina Hurricane Katrina was a destructive Category 5 Atlantic hurricane that caused over 1,800 fatalities and $125 billion in damage in late August 2005, especially in the city of New Orleans and the surrounding areas. It was at the time the cost ...
, the US state of
Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is bord ...
sent politicians to the Netherlands to take a tour of the complex and highly developed flood control system in place in the Netherlands. With a BBC article quoting experts as saying 70 percent more people will live in delta cities by 2050, the number of people impacted by a rise in sea level will greatly increase. The Netherlands has one of the best flood control systems in the world and new ways to deal with water are constantly being developed and tested, such as the underground storage of water, storing water in reservoirs in large parking garages or on playgrounds, Rotterdam started a project to construct a floating housing development of to deal with rising sea levels. Several approaches, from
high-tech High technology (high tech), also known as advanced technology (advanced tech) or exotechnology, is technology that is at the cutting edge: the highest form of technology available. It can be defined as either the most complex or the newest te ...
sensors detecting imminent
levee A levee (), dike (American English), dyke (Commonwealth English), 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 coastli ...
failure to movable semi-circular structures closing an entire river, are being developed or used around the world. Regular maintenance of hydraulic structures, however, is another crucial part of flood control.


See also

*
Amphibious vehicle An amphibious vehicle (or simply amphibian), is a vehicle that is a means of transport viable on land as well as on or under water. Amphibious vehicles include amphibious Amphibious cycle, bicycles, Amphibious ATV, ATVs, Amphibious automobile, ca ...
*
Disaster risk reduction Disaster risk reduction (DRR) sometimes called disaster risk management (DRM) is a systematic approach to identifying, assessing and reducing the risks of disaster. It aims to reduce socio-economic vulnerabilities to disaster as well as dealing w ...
* Flash flood *
Flood barrier 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 ...
*
Flood wall A flood wall (or floodwall) is a primarily vertical artificial barrier designed to temporarily contain the waters of a river or other waterway which may rise to unusual levels during seasonal or extreme weather events. Flood walls are mainly u ...
* Flood Control Act of 1934 (in the US) *
Hydrological Ensemble Prediction Experiment HEPEX is an international initiative bringing together hydrologists, meteorologists, researchers and endusers to develop advanced probabilistic hydrological forecast techniques for improved flood, drought and water management. HEPEX was launched in ...
*
Hydrosacks A HydroSack or a HydroSnake is a brand name for a flood control sandbag alternative made by Gravitas International of Cheshire, North West England. They are very lightweight and thin until they come into contact with water, then they begin to ret ...
*
Maeslantkering The Maeslantkering ("Maeslant barrier" in Dutch) is a storm surge barrier on the Nieuwe Waterweg, in South Holland, Netherlands. It was constructed from 1991 to 1997. As part of the Delta Works the barrier responds to water level predictions ...
– Netherlands * MOSE project – Venice *
Northern Stormwater Interceptor, Bristol The Northern Storm Water Interceptor (NSWI), is a large storm drain, stormwater tunnel that acts as a flood prevention measure for Bristol, England. Building of the storm drain started in 1951 to relieve flooding over many parts of Bristol, and ...
(in the UK) * Thames Barrier – London *
Tidal barrage A tidal barrage is a dam-like structure used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces. Instead of damming water on one side like a conventional dam, a tidal barrage allows water to flow ...
*
Weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...


References


Notes


Further reading

* * CNN Newsource. “Cleaning New York's Filthy Harbor with One Billion Oysters.” WTVF, January 17, 2019. https://www.newschannel5.com/news/national/cleaning-new-yorks-filthy-harbor-with-one-billion-oysters. * Dejean, Ashley. “Five Years after Sandy, One New York Town's Flood Prevention Plans Are so Crazy They Just Might Work.” Mother Jones, October 27, 2017. https://www.motherjones.com/politics/2017/10/five-years-after-sandy-one-new-york-towns-flood-prevention-plans-are-so-crazy-they-just-might-work/. * “Hurricane Sandy Design Competition.” Rebuild by Design. Accessed November 16, 2019. http://www.rebuildbydesign.org/our-work/sandy-projects. * “Living Breakwaters.” REGENERATING TOTTENVILLE. Accessed November 18, 2019. https://www.regeneratingtottenville.org/living-breakwaters-project. * “Living Breakwaters Design and Implementation.” SCAPE. Accessed November 18, 2019. https://www.scapestudio.com/projects/living-breakwaters-design-implementation/. * Melcher, Henry. “Rebuild By Design> SCAPE's Living Breakwaters Transform Staten Island's South Shore.” Archpaper.com, April 9, 2014. https://archpaper.com/2014/04/rebuild-by-design-scapes-living-breakwaters-transform-staten-islands-south-shore/. * “Tottenville Shoreline Protection Project.” Tottenville Shoreline Protection Project , Governor's Office of Storm Recovery (GOSR). Accessed November 18, 2019. https://stormrecovery.ny.gov/tottenville-shoreline-protection-project. * “Visualizing The Living Breakwaters at Conference House Park.” Rebuild by Design. Accessed November 19, 2019. http://www.rebuildbydesign.org/news-and-events/press/visualizing-the-living-breakwaters-at-conference-house-park.


External links


Integrated Flood Management
– Associated Programme on Flood Management, Geneva
Flood articles
– BBC News
Flood defence works in Wiltshire
– BBC
Flood defence works in Carlisle
– BBC
Flood management and restoration of habitats
– BBC {{Authority control
Control Control may refer to: Basic meanings Economics and business * Control (management), an element of management * Control, an element of management accounting * Comptroller (or controller), a senior financial officer in an organization * Controlli ...
Water management