A
flood is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the
tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
.
Flooding may result from the volume of water within a body of water, such as a
riverA river is a natural watercourse, usually freshwater, flowing toward an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water...
or
lakeA lake is a terrain feature , a body of liquid on the surface of a world that is localized to the bottom of basin and moves slowly if it moves at all. Another definition is, a body of fresh or salt water of considerable size that is surrounded by land...
, which overflows or breaks levees, with the result that some of the water escapes its normal boundaries. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless such escapes of water endanger land areas used by man like a village, city or other inhabited area.
Floods can also occur in rivers, when the strength of the river is so high it flows out of the river channel, particularly at bends or meanders and causes damage to homes and businesses along such rivers. While flood damage can be virtually eliminated by moving away from rivers and other bodies of water, since time out of mind, people have lived and worked by the water to seek sustenance and capitalize on the gains of cheap and easy travel and commerce by being near water. That humans continue to inhabit areas threatened by flood damage is evidence that the perceived value of living near the water exceeds the cost of repeated periodic flooding.
The word "flood" comes from the
Old EnglishOld English , also called Anglo-Saxon, is an early form of the English language that was spoken and written in parts of what are now England and south-eastern Scotland between at least the mid-5th century and the mid-12th century. What survives through writing represents primarily the literary...
flod, a word common to Germanic languages (compare German
Flut, Dutch
vloed from the same root as is seen in
flow, float). The specific term "The Flood," capitalized, usually refers to the great
Universal Deluge described in the
BibleThe Bible contains the central religious texts of Judaism and Christianity. Modern Judaism generally recognizes a single set of canonical books known as the Tanakh, or Hebrew Bible, as it is written almost entirely in the Hebrew language, with some small portions in Aramaic...
, in Genesis, and is treated at Deluge.
Riverine floods
- Slow kinds: Runoff from sustained rainfall or rapid snow melt exceeding the capacity of a river's channel. Causes include heavy rains from monsoon
A pennis is traditionally defined as a seasonal reversing wind accompanied by seasonal changes in precipitation, but now is used to describe seasonal changes atmospheric circulation and precipitation The major monsoon systems of the world consist of the African and Asia-Australian monsoons...
s, hurricanes and tropical depressions, foreign winds and warm rain affecting snow pack. Unexpected drainage obstructions such as landslideA landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s, iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
, or debrisDebris is a word used to describe the remains of something that has been otherwise destroyed. The singular form of debris is debris.Depending on context, debris can refer to a number of different things.- Geological :...
can cause slow flooding upstream of the obstruction.
- Fast kinds: include flash floods resulting from convective precipitation (intense thunderstorm
A thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
s) or sudden release from an upstream impoundment created behind a damA dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions...
, landslideA landslide is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
, or glacierA glacier is a perennial mass of ice which moves over land. A glacier forms in locations where the mass accumulation of snow and ice exceeds ablation over many years...
.
Estuarine floods
- Commonly caused by a combination of sea tidal surges caused by storm-force winds. A storm surge
Storm surge is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level...
, from either a tropical cycloneA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
or an extratropical cycloneExtratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
, falls within this category.
Coastal floods
- Caused by severe sea storms, or as a result of another hazard (e.g. tsunami
A is a series of water waves that is caused by the displacement of a large volume of a body of water, such as an ocean. The original Japanese term literally translates as "harbor wave." Tsunamis are a frequent occurrence in Japan; approximately 195 events have been recorded...
or hurricane). A storm surgeStorm surge is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level...
, from either a tropical cycloneA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
or an extratropical cycloneExtratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
, falls within this category.
Catastrophic floods
- Caused by a significant and unexpected event e.g. dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions...
breakage, or as a result of another hazard (e.g. earthquakeAn earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph...
or volcanic eruption).
Muddy floods
- A muddy flood
A muddy flood is produced by an accumulation of runoff generated on cropland. Sediments are then detached by runoff and carried as suspended matter or bedload...
is generated by run off on crop land.
A muddy flood is produced by an accumulation of runoff generated on cropland. Sediments are then detached by runoff and carried as suspended matter or bedload. Muddy runoff is more likely detected when it reaches inhabited areas.
Muddy floods are therefore a hillslope process, and confusion with mudflows produced by mass movements should be avoided.
Other
- Floods can occur if water accumulates across an impermeable surface (e.g. from rainfall) and cannot rapidly dissipate (i.e. gentle orientation or low evaporation).
- A series of storms moving over the same area.
- Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions...
-building beaverThe beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, Castor canadensis and Castor fiber . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...
s can flood low-lying urban and rural areas, often causing significant damage.
Primary effects
- Physical damage - Can range anywhere from bridges, cars, buildings, sewer
Sewer may refer to:*A system for transporting sewage:**Sanitary sewer, a system of pipes used to transport human waste**Storm drain, a collection and transportation system for storm water...
systems, roadways, canalCanals are artificial channels for water. There are two types of canal: aqueduct canals are used for the conveyance and delivery of water, and waterway canals are navigable transportation canals used for passage of goods and people, often connected to existing lakes, rivers, or oceans.The word...
s and any other type of structure.
- Casualties - People and livestock die due to drowning. It can also lead to epidemics and waterborne diseases.
Secondary effects
- Water supplies - Contamination of water
Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater. All water pollution affects organisms and plants that live in these water bodies and in almost all cases the effect is damaging either to individual species and populations but also to the natural...
. Clean drinking waterDrinking water or potable water is water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm...
becomes scarce.
- Diseases - Unhygienic conditions. Spread of water-borne diseases.
- Crops and food supplies - Shortage of food crops can be caused due to loss of entire harvest. However, lowlands near rivers depend upon river silt deposited by floods in order to add nutrients to the local soil.
- Trees - Non-tolerant species can die from suffocation.
Tertiary/long-term effects
- Economic - Economic hardship, due to: temporary decline in tourism, rebuilding costs, food shortage leading to price increase etc.
Flood control
In many countries across the world, rivers prone to floods are often carefully managed. Defences such as
leveeA levee, levée, dike , embankment, floodbank or stopbank is a natural or artificial slope or wall to regulate water levels...
s,
bundsBunding, also called a bund wall, is the area within a structure designed to prevent inundation or breaches of various types.-Liquid containment:...
, reservoirs, and
weirA weir , also known as a lowhead dam, is a small overflow-type dam commonly used to raise the level of a river or stream. Weirs have traditionally been used to create mill ponds in such places. Water flows over the top of a weir, although some weirs have sluice gates which release water at a level...
s are used to prevent rivers from bursting their banks. When these defences fail, emergency measures such as sandbags or portable inflatable tubes are used. Coastal flooding has been addressed in Europe and the Americas with coastal defences, such as sea walls,
beach nourishmentBeach nourishment - also referred to as beach replenishment - is a complementary term that describes a process by which sediment lost through longshore drift or erosion is replaced on a beach. It involves the transport of the nourishment material from one area to the affected area...
, and barrier islands.
Europe
Remembering the misery and destruction caused by the
1910 Great Flood of ParisIn late January 1910, following months of high rainfall, the Seine River flooded the French capital when water pushed upwards from overflowing sewers and subway tunnels, and seeped into basements through fully saturated soil....
, the French government built a series of reservoirs called Les Grands Lacs de Seine (or Great Lakes) which helps remove pressure from the
SeineThe Seine is a slow-flowing major river and commercial waterway within the regions of Île-de-France and Haute-Normandie in France and famous as a romantic backdrop in photographs of Paris, France. It is also a tourist attraction, with excursion boats offering sightseeing tours of the Rive Droite...
during floods, especially the regular winter flooding.
London[]London is the capital of England and the United Kingdom. It has been a major settlement for two millennia, and the history of London goes back to its founding by the Romans, when it was named Londinium. London's core, the ancient City of London, the 'square mile', retains its medieval boundaries...
is protected from flooding by a huge mechanical barrier across the
River ThamesThe River Thames is a major river flowing through southern England. While best known because its lower reaches flow through central London, the river flows through several other towns and cities, including Oxford, Reading and Windsor....
, which is raised when the water level reaches a certain point (see
Thames BarrierThe Thames Barrier is a large flood control structure on the River Thames, constructed between 1974 and 1982 at Woolwich Reach, and first used defensively in 1983...
).
VeniceVenice is a city in northern Italy, the capital of the region Veneto, a population of 271,367 . Together with Padua, the city is included in the Padua-Venice Metropolitan Area . The city historically was an independent nation...
has a similar arrangement, although it is already unable to cope with very high tides. The defences of both London and Venice would be rendered inadequate if sea levels were to rise.
The largest and most elaborate flood defences can be found in the
NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
, where they are referred to as
Delta WorksThe Delta Works are a series of constructions built between 1950 and 1997 in the southwest of the Netherlands to protect a large area of land around the Rhine-Meuse-Scheldt delta from the sea. The works consist of dams, sluices, locks, dikes, and storm surge barriers...
with the
OosterscheldeThe Oosterschelde is an estuary in Zeeland, the Netherlands, between Schouwen-Duiveland and Tholen on the north and Noord-Beveland and Zuid-Beveland on the south.During the Roman Era it was the major mouth of the Scheldt River. Before the St...
dam as its crowning achievement. These works were built in response to the
North Sea flood of 1953The North Sea flood of 1953 and the associated storm combined to create a major natural disaster which affected the coastlines of the Netherlands and England on the night of 31 January – 1 February 1953...
of 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
AfsluitdijkThe Afsluitdijk is a major causeway in the Netherlands, constructed between 1927 and 1933 and running from Den Oever on Wieringen in North Holland province, to the village of Zurich The Afsluitdijk (English: Closure Dike, Frisian: Ofslútdyk) is a major causeway in the Netherlands, constructed...
(closing occurred in 1932).
Currently the
Saint Petersburg Flood Prevention Facility ComplexThe Saint Petersburg Flood Prevention Facility Complex , unofficially the Saint Petersburg Dam, is a 25-kilometer complex of dams for flood control under construction near Saint Petersburg, Russia. The dam extends from Lomonosov northward to Kotlin Island , then turns east toward Cape Lisiy Nos...
is to be finished by 2008, in
RussiaRussia , officially known as both Russia and the Russian Federation , is a country in northern Eurasia . It is a semi-presidential republic, comprising 83 federal subjects...
, to protect
Saint PetersburgSaint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea. The city's other names were Petrograd and Leningrad...
from
storm surgeStorm surge is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean's surface. The wind causes the water to pile up higher than the ordinary sea level...
s. It also has a main traffic function, as it completes a
ring roadA beltway, loop , ring road, or orbital motorway is a circumferential highway found around or within many cities....
around Saint Petersburg. Eleven dams extend for 25.4 kilometres and stand eight metres above water level.
In
AustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.3 million people in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west...
, flooding for over 150 years, has been controlled by various actions of the
Vienna Danube regulationThe Vienna Danube regulation refers to estensive flood-control engineering along the Danube river in Vienna, Austria during the last 150 years. The first major dams or levees were built during 1870-75. Another major project was constructed during 1972-88, which created the New Danube and Danube...
, with dredging of the main
DanubeThe Danube is the longest river in the European Union and Europe's second longest river after the Volga.The river originates in the Black Forest in Germany as the much smaller Brigach and Breg rivers which join at the German town Donaueschingen, after which it is known as the Danube and flows...
during 1870-75, and creation of the New Danube from 1972-1988.
Americas
Another elaborate system of floodway defences can be found in the Canadian province of
ManitobaManitoba is a prairie province in Canada and has an area of . Manitoba is bordered by the provinces of Ontario to the east and Saskatchewan to the west, the territory of Nunavut to the north, and the U.S. states of North Dakota and Minnesota to the south...
. The
Red RiverThe Red River or ' and Red River of the North, is a North American river. Originating at the confluence of the Bois de Sioux and Otter Tail rivers in the United States, it flows northward through the Red River Valley and forms the border between the U.S. states of Minnesota and North Dakota before...
flows northward from the United States, passing through the city of
WinnipegWinnipeg is the capital and largest city of Manitoba, Canada. It is located near the longitudinal centre of North America, in south central Canada, near the eastern edge of the Canadian Prairies, at the confluence of the Red and Assiniboine Rivers...
(where it meets the
Assiniboine RiverThe Assiniboine River is a long river that runs through the prairies of Western Canada in Saskatchewan and Manitoba.It is a typical meandering river with a single main channel embanked within a flat, shallow valley at some places, and a steep valley at other places.The river takes its name from...
) and into
Lake WinnipegLake Winnipeg is a very large lake in central North America, in the province of Manitoba, Canada, about north of the city of Winnipeg. It is the largest lake within the borders of southern Canada, and it is part of the most undeveloped and pristine large watershed of southern Canada.It is the...
. As is the case with all north-flowing rivers in the temperate zone of the Northern Hemisphere, snowmelt 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 floodways (including the
Red River FloodwayThe Red River Floodway is an artificial flood control waterway in Western Canada, first used in 1969. It is a 47 km long channel which, during flood periods, takes part of the Red River's flow around the city of Winnipeg, Manitoba to the east and discharges it back into the Red River below the...
and the
Portage DiversionThe Portage Diversion is a water control structure on the Assiniboine River in Manitoba, Canada. The project was made as part of a larger attempt to prevent flooding in the Red River Valley...
). The system kept Winnipeg safe during the 1997 flood and which devastated many communities upriver from Winnipeg, including
Grand Forks, North DakotaGrand Forks is the third-largest city in the U.S. state of North Dakota and the county seat of Grand Forks County. In July 2007, its population was estimated at 51,740, and it had an estimated metropolitan population of 97,691...
and
Ste. Agathe, ManitobaSte. Agathe is a primarily francophone village in the Canadian province of Manitoba. It is located along the Red River in the Rural Municipality of Ritchot; its population as of 2007 was approximately 500....
. It also kept Winnipeg safe during the
2009 floodThe 2009 Red River flood along the Red River of the North in North Dakota and Minnesota in the United States and Manitoba in Canada brought record flood levels to the Fargo-Moorhead area. The flood is a result of saturated and frozen ground, Spring snowmelt exacerbated by additional rain and snow...
.
In the U.S., the
New Orleans Metropolitan AreaNew Orleans–Metairie–Kenner is a metropolitan area designated by the US Census encompassing seven parishes in the state of Louisiana, centering on the city of New Orleans...
, 35% of which sits below sea level, is protected by hundreds of miles of levees and flood gates. This system failed catastrophically, in numerous sections, during
Hurricane KatrinaHurricane Katrina of the 2005 Atlantic hurricane season was the costliest hurricane, as well as one of the five deadliest, in the history of the United States...
, in the city proper and in eastern sections of the Metro Area, resulting in the inundation of approximately 50% of the metropolitan area, ranging from a few centimetres to 8.2 metres (a few inches to 27 feet) in coastal communities. In an act of successful flood prevention, the Federal Government of the United States 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
wetlandA wetland is an area of land whose soil is saturated with moisture either permanently or seasonally. Such areas may also be covered partially or completely by shallow pools of water. Wetlands include swamps, marshes, and bogs, among others. The water found in wetlands can be saltwater, freshwater,...
s. 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.
Asia
In
ChinaThe Grand Canal of China , also known as the Beijing-Hangzhou Grand Canal is the longest ancient canal or artificial river in the world. Starting at Beijing it passes through Tianjin and the provinces of Hebei, Shandong, Jiangsu and Zhejiang to the city of Hangzhou...
, flood
diversionDiversion may refer to:*Diversion, a British television film later adapted into the 1987 movie Fatal Attraction*Yamaha Diversion, a motorcycle manufactured by Yamaha*Pharmaceutical diversion, the diversion of licit drugs for illicit purposes...
areas are rural areas that are deliberately flooded in emergencies in order to protect cities.
Many have proposed that loss of vegetation (
deforestationDeforestation is the clearance of naturally occurring forests by the processes of logging and/or burning of trees in a forested area. There are several reasons deforestation occurs: trees or derived charcoal can be sold as a commodity and used by humans, while cleared land is used as pasture,...
) will lead to a risk increase. With natural forest cover the flood duration should decrease. Reducing the rate of deforestation should improve the incidents and severity of floods.
Africa
In
EgyptEgypt , officially the Arab Republic of Egypt, is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Western Asia...
, both the
Aswan DamAswan Egypt is the city located near the first cataract of the Nile, which presented the first obstacle from the Mediterranean Sea for boats sailing on the river since antiquity...
(1902) and the Aswan High Dam (1976) have controlled various amounts of flooding along the
NileThe Nile is a major north-flowing river in Africa, generally regarded as the longest river in the world....
river.
Flood clean-up safety
Clean-up activities following floods often pose hazards to workers and volunteers involved in the effort. Potential dangers include: water polluted by mixing with and causing overflows from foul sewers,
electrical hazardsAn electric shock can occur upon contact of a human body with any source of voltage high enough to cause sufficient current through the muscles or hair. The minimum current a human can feel is thought to be about 1 milliampere ....
,
carbon monoxideCarbon monoxide is a colorless, odorless and tasteless gas, yet very toxic to humans. It consists of one carbon atom and one oxygen atom, connected by a covalent double bond and a dative covalent bond...
exposure, musculoskeletal hazards,
heatHyperthermia is an elevated body temperature due to failed thermoregulation. Hyperthermia occurs when the body produces or absorbs more heat than it can dissipate...
or
cold stressHypothermia is a condition in which an organism's temperature drops below that required for normal metabolism and body functions. In warm-blooded animals, core body temperature is maintained near a constant level through biologic homeostasis or thermoregulation...
,
motor vehicleA motor vehicle is a wheeled vehicle whose propulsion is provided by an engine or motor . The internal combustion engine is the most common motor choice, although electric motors or other types are sometimes used. Motor vehicles or road vehicles typically run on public roads...
-related dangers,
fireFire is the rapid oxidation of a combustible material releasing heat, light, and various reaction products such as carbon dioxide and water. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the...
,
drowningDrowning is death from suffocation caused by a liquid entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia and myocardial infarction...
, and exposure to hazardous materials. 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,
gogglesGoggles or safety glasses are forms of protective eyewear that usually enclose or protect the area surrounding the eye in order to prevent particulates, water or chemicals from striking the eyes. They are used in chemistry laboratories and in woodworking. They are often used in snow sports as...
, heavy work gloves, life jackets, and watertight boots with steel toes and insoles.
Benefits of flooding
There are many disruptive effects of flooding on human settlements and economic activities. However, floods (in particular the more frequent/smaller floods) can bring many benefits, such as recharging ground water, making soil more fertile and providing nutrients in which it is deficient. Flood waters provide much needed water resources in particular in arid and semi-arid regions where precipitation events can be very unevenly distributed throughout the year. Freshwater floods in particular play an important role in maintaining ecosystems in river corridors and are a key factor in maintaining floodplain biodiversity.
Periodic flooding was essential to the well-being of ancient communities along the Tigris-Euphrates Rivers, the
NileThe Nile is a major north-flowing river in Africa, generally regarded as the longest river in the world....
River, the Indus River, the Ganges and the
Yellow RiverThe Yellow River or Huang He / Hwang Ho is the second-longest river in China and the sixth-longest in the world at 5,464 kilometers . Originating in the Bayan Har Mountains in Qinghai Province in western China, it flows through nine provinces of China and empties into the Bohai Sea...
, among others. The viability for hydrological based renewable sources of energy is higher in flood prone regions.
Flood modelling
While flood modelling is a fairly recent practice, attempts to understand and manage the mechanisms at work in floodplains have been made for at least six millennia. The recent development in computational flood modelling has enabled engineers to step away from the tried and tested "hold or break" approach and its tendency to promote overly engineered structures. Various computational flood models have been developed in recent years either 1D models (flood levels measured in the channel) and 2D models (flood depth measured for the extent of the floodplain). HEC-RAS, the Hydraulic Engineering Centre model, is currently among the most popular if only because it is available for free. Other models such as TUFLOW combine 1D and 2D components to derive flood depth in the floodplain. So far the focus has been on mapping tidal and fluvial flood events but the 2007 flood events in the UK have shifted the emphasis onto the impact of surface water flooding.
Deadliest floods
Below is a list of the deadliest floods worldwide, showing events with death tolls at or above 100,000 individuals.
| Death Toll | | Event | | Location | | Date |
|---|
| 2,500,000–3,700,000 |
1931 China floods |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1931 |
| 900,000–2,000,000 |
1887 Yellow River (Huang He) flood |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1887 |
| 500,000–700,000 |
1938 Yellow River (Huang He) flood |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1938 |
| 231,000 |
Banqiao DamThe Banqiao Reservoir Dam and Shimantan Reservoir Dam are among 62 dams in Zhumadian Prefecture of China's Henan Province that failed catastrophically or were intentionally destroyed in 1975 during Typhoon Nina.-History:...
failure, result of Typhoon Nina. Approximately 86,000 people died from flooding and another 145,000 died during subsequent disease. |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1975 |
| 230,000 |
Indian Ocean tsunamiThe 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...
|
IndiaIndia, officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the west, and the Bay of Bengal...
(mostly in Tamil NaduTamil Nadu is one of the 28 states of India. Its capital and largest city is Chennai . Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by Puducherry , Kerala, Karnataka and Andhra Pradesh...
), ThailandThe Kingdom of Thailand is an independent country that lies in the heart of Southeast Asia.It is bordered to the north by Laos and Burma, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the west by the Andaman Sea and Burma...
, MaldivesThe Maldives , or Maldive Islands, officially Republic of Maldives, is an island country in the Indian Ocean formed by a double chain of twenty-six atolls stretching along north-south direction off India's Lakshadweep islands, between Minicoy Island and Chagos Archipelago...
|
2004 |
| 145,000 |
1935 Yangtze river flood |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1935 |
| more than 100,000 |
St. Felix's Flood The St. Felix's Flood happened on Saturday 5 November 1530, the name day of St. Felix. This day was later known as Evil Saturday. Large parts of Flanders and Zeeland were washed away, including the Verdronken Land van Reimerswaal. According to Audrey M. Lambert, "all the Oost Wetering of Zuid-...
, storm surge |
NetherlandsThe Netherlands is a country in Northwestern Europe, constituting the major portion of the Kingdom of the Netherlands. It is a parliamentary democratic constitutional monarchy. The Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east...
|
1530 |
| 100,000 |
HanoiHanoi , estimated population 6.232.940 , is the capital and second-largest city of Vietnam. From 1010 until 1802, with a few brief interruptions, it was the political centre of an independent Vietnam. It was eclipsed by Huế during the Nguyen Dynasty as the capital of Vietnam, but Hanoi served as...
and Red River DeltaThe Red River Delta is the flat plain formed by the Red River and its distributaries joining in the Thai Binh River in northern Vietnam. The delta measuring some 15,000 square km is well protected by a network of dikes. It is an agriculturally rich area and densely populated...
flood |
North Vietnam North Vietnam, also called the Democratic Republic of Vietnam , was a communist state that ruled the northern half of Vietnam from 1954 until 1976....
|
1971 |
| 100,000 |
1911 Yangtze river flood |
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
|
1911 |
See also
- Disaster preparedness
- Flood Risk Assessment
A flood risk assessment is an assessment of the risk of flooding, particularly in relation to residential, commercial and industrial land use.-England and Wales:...
- Flood control in the Netherlands
The Netherlands has been struggling against floods since the first people settled there. Over 60% of the country lies beneath mean sea-level. Countless people have lost their homes and their lives to floods from the sea or the rivers that could not be held by the flood-defences.The importance of...
- Floods in the Netherlands
This is a chronological list of floods that have occurred in the Netherlands, until 1500 most parts of the Netherlands were in Frisia.*838 December 26: A large part of the northwest of the Netherlands was flooded by a storm. Lack of good dikes was an important cause of this flood disaster...
- Floods in the United States
Floods in the United States are generally caused by excessive rainfall, excessive snowmelt, and dam failure. Below is a list of flood events that were of significant impact to the country, between 1901 and 2000.-Willow Creek, Oregon Flash Flood - June 1903:...
- Flood (Mythology)
A deluge myth or flood myth is a mythical story of a great flood sent by a deity or deities to destroy civilization as an act of divine retribution...
- List of floods
- Storm tides of the North Sea
External links