Flood
Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rainwater on saturated ground in an areal flood. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, these changes in size are unlikely to be considered significant unless they flood property or drown domestic animals.
Floods can also occur in rivers when the flow rate exceeds the capacity of the river channel, particularly at bends or meanders in the waterway. Floods often cause damage to homes and businesses if they are in the natural flood plains of rivers. While riverine flood damage can be eliminated by moving away from rivers and other bodies of water, people have traditionally lived and worked by rivers because the land is usually flat and fertile and because rivers provide easy travel and access to commerce and industry.
Some floods develop slowly, while others can develop in just a few minutes and without visible signs of rain. Additionally, floods can be local, impacting a neighborhood or community, or very large, affecting entire river basins.
Etymology
The word "flood" comes from the Old English flod, a word common to Germanic languages (compare German Flut, Dutch vloed from the same root as is seen in flow, float; also compare with Latin fluctus, flumen).
Principal types
Areal
Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more rapidly than it can either infiltrate or run off. The excess accumulates in place, sometimes to hazardous depths. Surface soil can become saturated, which effectively stops infiltration, where the water table is shallow, such as a floodplain, or from intense rain from one or a series of storms. Infiltration also is slow to negligible through frozen ground, rock, concrete, paving, or roofs. Areal flooding begins in flat areas like floodplains and in local depressions not connected to a stream channel, because the velocity of overland flow depends on the surface slope. Endorheic basins may experience areal flooding during periods when precipitation exceeds evaporation.
Riverine (Channel)
Floods occur in all types of river and stream channels, from the smallest ephemeral streams in humid zones to normally-dry channels in arid climates to the world's largest rivers. When overland flow occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load. Localized flooding may be caused or exacerbated by drainage obstructions such as landslides, ice, debris, or beaver dams.
Slow-rising floods most commonly occur in large rivers with large catchment areas. The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be very intense in smaller areas of those basins.
Rapid flooding events, including flash floods, more often occur on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, or normally-dry channels. The cause may be localized convective precipitation (intense thunderstorms) or sudden release from an upstream impoundment created behind a dam, landslide, or glacier. In one instance, a flash flood killed eight people enjoying the water on a Sunday afternoon at a popular waterfall in a narrow canyon. Without any observed rainfall, the flow rate increased from about 50 to 1,500 cubic feet per second (1.4 to 42 m3/s) in just one minute. Two larger floods occurred at the same site within a week, but no one was at the waterfall on those days. The deadly flood resulted from a thunderstorm over part of the drainage basin, where steep, bare rock slopes are common and the thin soil was already saturated.
Flash floods are the most common flood type in normally-dry channels in arid zones, known as arroyos in the southwest United States and many other names elsewhere. In that setting, the first flood water to arrive is depleted as it wets the sandy stream bed. The leading edge of the flood thus advances more slowly than later and higher flows. As a result, the rising limb of the hydrograph becomes ever quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant.
Estuarine and coastal
Flooding in estuaries is commonly caused by a combination of sea tidal surges caused by winds and low barometric pressure, and they may be exacerbated by high upstream river flow.
Coastal areas may be flooded by storm events at sea, resulting in waves over-topping defenses or in severe cases by tsunami or tropical cyclones. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category. Research from the NHC (National Hurricane Center) explains: "Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases."
Urban flooding
Urban flooding is the inundation of land or property in a built environment, particularly in more densely populated areas, caused by rainfall overwhelming the capacity of drainage systems, such as storm sewers. Although sometimes triggered by events such as flash flooding or snowmelt, urban flooding is a condition, characterized by its repetitive and systemic impacts on communities, that can happen regardless of whether or not affected communities are located within designated floodplains or near any body of water. Aside from potential overflow of rivers and lakes, snowmelt, stormwater or water released from damaged water mains may accumulate on property and in public rights-of-way, seep through building walls and floors, or backup into buildings through sewer pipes, toilets and sinks.
In urban areas, flood effects can be exacerbated by existing paved streets and roads, which increase the speed of flowing water.
The flood flow in urbanized areas constitutes a hazard to both the population and infrastructure. Some recent catastrophes include the inundations of Nîmes (France) in 1998 and Vaison-la-Romaine (France) in 1992, the flooding of New Orleans (USA) in 2005, and the flooding in Rockhampton, Bundaberg, Brisbane during the 2010–2011 summer in Queensland (Australia). Flood flows in urban environments have been studied relatively recently despite many centuries of flood events. Some recent research has considered the criteria for safe evacuation of individuals in flooded areas.
Catastrophic
Catastrophic riverine flooding is usually associated with major infrastructure failures such as the collapse of a dam, but they may also be caused by drainage channel modification from a landslide, earthquake or volcanic eruption. Examples include outburst floods and lahars. Tsunamis can cause catastrophic coastal flooding, most commonly resulting from undersea earthquakes.
Causes
Upslope factors
The amount, location, and timing of water reaching a drainage channel from natural precipitation and controlled or uncontrolled reservoir releases determines the flow at downstream locations. Some precipitation evaporates, some slowly percolates through soil, some may be temporarily sequestered as snow or ice, and some may produce rapid runoff from surfaces including rock, pavement, roofs, and saturated or frozen ground. The fraction of incident precipitation promptly reaching a drainage channel has been observed from nil for light rain on dry, level ground to as high as 170 percent for warm rain on accumulated snow.
Most precipitation records are based on a measured depth of water received within a fixed time interval. Frequency of a precipitation threshold of interest may be determined from the number of measurements exceeding that threshold value within the total time period for which observations are available. Individual data points are converted to intensity by dividing each measured depth by the period of time between observations. This intensity will be less than the actual peak intensity if the duration of the rainfall event was less than the fixed time interval for which measurements are reported. Convective precipitation events (thunderstorms) tend to produce shorter duration storm events than orographic precipitation. Duration, intensity, and frequency of rainfall events are important to flood prediction. Short duration precipitation is more significant to flooding within small drainage basins.
The most important upslope factor in determining flood magnitude is the land area of the watershed upstream of the area of interest. Rainfall intensity is the second most important factor for watersheds of less than approximately 30 square miles or 80 square kilometres. The main channel slope is the second most important factor for larger watersheds. Channel slope and rainfall intensity become the third most important factors for small and large watersheds, respectively.
Time of Concentration is the time required for runoff from the most distant point of the upstream drainage area to reach the point of the drainage channel controlling flooding of the area of interest. The time of concentration defines the critical duration of peak rainfall for the area of interest. The critical duration of intense rainfall might be only a few minutes for roof and parking lot drainage structures, while cumulative rainfall over several days would be critical for river basins.
Downslope factors
Water flowing downhill ultimately encounters downstream conditions slowing movement. The final limitation in coastal flooding lands is often the ocean or some coastal flooding bars which form natural lakes. In flooding low lands, elevation changes such as tidal fluctuations are significant determinants of coastal and estuarine flooding. Less predictable events like tsunamis and storm surges may also cause elevation changes in large bodies of water. Elevation of flowing water is controlled by the geometry of the flow channel and, especially, by depth of channel, speed of flow and amount of sediments in it Flow channel restrictions like bridges and canyons tend to control water elevation above the restriction. The actual control point for any given reach of the drainage may change with changing water elevation, so a closer point may control for lower water levels until a more distant point controls at higher water levels.
Effective flood channel geometry may be changed by growth of vegetation, accumulation of ice or debris, or construction of bridges, buildings, or levees within the flood channel.
Coincidence
Extreme flood events often result from coincidence such as unusually intense, warm rainfall melting heavy snow pack, producing channel obstructions from floating ice, and releasing small impoundments like beaver dams. Coincident events may cause extensive flooding to be more frequent than anticipated from simplistic statistical prediction models considering only precipitation runoff flowing within unobstructed drainage channels. Debris modification of channel geometry is common when heavy flows move uprooted woody vegetation and flood-damaged structures and vehicles, including boats and railway equipment. Recent field measurements during the 2010–11 Queensland floods showed that any criterion solely based upon the flow velocity, water depth or specific momentum cannot account for the hazards caused by velocity and water depth fluctuations. These considerations ignore further the risks associated with large debris entrained by the flow motion.
Some researchers have mentioned the storage effect in urban areas with transportation corridors created by cut and fill. Culverted fills may be converted to impoundments if the culverts become blocked by debris, and flow may be diverted along streets. Several studies have looked into the flow patterns and redistribution in streets during storm events and the implication on flood modelling.
Effects
Primary effects
The primary effects of flooding include loss of life and damage to buildings and other structures, including bridges, sewerage systems, roadways, and canals.
Floods also frequently damage power transmission and sometimes power generation, which then has knock-on effects caused by the loss of power. This includes loss of drinking water treatment and water supply, which may result in loss of drinking water or severe water contamination. It may also cause the loss of sewage disposal facilities. Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases, which can include typhoid, giardia, cryptosporidium, cholera and many other diseases depending upon the location of the flood.
Damage to roads and transport infrastructure may make it difficult to mobilize aid to those affected or to provide emergency health treatment.
Flood waters typically inundate farm land, making the land unworkable and preventing crops from being planted or harvested, which can lead to shortages of food both for humans and farm animals. Entire harvests for a country can be lost in extreme flood circumstances. Some tree species may not survive prolonged flooding of their root systems.
Secondary and long-term effects
Economic hardship due to a temporary decline in tourism, rebuilding costs, or food shortages leading to price increases is a common after-effect of severe flooding. The impact on those affected may cause psychological damage to those affected, in particular where deaths, serious injuries and loss of property occur.
Urban flooding can cause chronically wet houses, leading to the growth of indoor mold and resulting in adverse health effects, particularly respiratory symptoms. Urban flooding also has significant economic implications for affected neighborhoods. In the United States, industry experts estimate that wet basements can lower property values by 10–25 percent and are cited among the top reasons for not purchasing a home. According to the U.S. Federal Emergency Management Agency (FEMA), almost 40 percent of small businesses never reopen their doors following a flooding disaster.[19] In the United States, insurance is available against flood damage to both homes and businesses.
Benefits
Floods (in particular more frequent or smaller floods) can also bring many benefits, such as recharging ground water, making soil more fertile and increasing nutrients in some soils. Flood waters provide much needed water resources in arid and semi-arid regions where precipitation can be very unevenly distributed throughout the year and kills pests in the farming land. Freshwater floods particularly play an important role in maintaining ecosystems in river corridors and are a key factor in maintaining floodplain biodiversity. Flooding can spread nutrients to lakes and rivers, which can lead to increased biomass and improved fisheries for a few years.
For some fish species, an inundated floodplain may form a highly suitable location for spawning with few predators and enhanced levels of nutrients or food. Fish, such as the weather fish, make use of floods in order to reach new habitats. Bird populations may also profit from the boost in food production caused by flooding.
Periodic flooding was essential to the well-being of ancient communities along the Tigris-Euphrates Rivers, the Nile River, the Indus River, the Ganges and the Yellow River among others. The viability of hydropower, a renewable source of energy, is also higher in flood prone regions.
Flood safety planning
In the United States, the National Weather Service gives out the advice Turn Around, Don't Drown" for floods; that is, it recommends that people get out of the area of a flood, rather than trying to cross it. At the most basic level, the best defense against floods is to seek higher ground for high-value uses while balancing the foreseeable risks with the benefits of occupying flood hazard zones.:22–23 Critical community-safety facilities, such as hospitals, emergency-operations centers, and police, fire, and rescue services, should be built in areas least at risk of flooding. Structures, such as bridges, that must unavoidably be in flood hazard areas should be designed to withstand flooding. Areas most at risk for flooding could be put to valuable uses that could be abandoned temporarily as people retreat to safer areas when a flood is imminent.
Planning for flood safety involves many aspects of analysis and engineering, including:
- observation of previous and present flood heights and inundated areas,
- statistical, hydrologic, and hydraulic model analyses,
- mapping inundated areas and flood heights for future flood scenarios,
- long-term land use planning and regulation,
- engineering design and construction of structures to control or withstand flooding,
- intermediate-term monitoring, forecasting, and emergency-response planning, and
- short-term monitoring, warning, and response operations.
- Each topic presents distinct yet related questions with varying scope and scale in time, space, and the people involved. Attempts to understand and manage the mechanisms at work in floodplains have been made for at least six millennia.
In the United States, the Association of State Floodplain Managers works to promote education, policies, and activities that mitigate current and future losses, costs, and human suffering caused by flooding and to protect the natural and beneficial functions of floodplains – all without causing adverse impacts. A portfolio of best practice examples for disaster mitigation in the United States is available from the Federal Emergency Management Agency.
Control
In many countries around the world, waterways prone to floods are often carefully managed. Defenses such as detention basins, levees, bunds, reservoirs, and weirs are used to prevent waterways from overflowing their banks. When these defenses fail, emergency measures such as sandbags or portable inflatable tubes are often used to try to stem flooding. Coastal flooding has been addressed in portions of Europe and the Americas with coastal defenses, such as sea walls, beach nourishment, and barrier islands.
In the riparian zone near rivers and streams, erosion control measures can be taken to try to slow down or reverse the natural forces that cause many waterways to meander over long periods of time. Flood controls, such as dams, can be built and maintained over time to try to reduce the occurrence and severity of floods as well. In the United States, the U.S. Army Corps of Engineers maintains a network of such flood control dams.
In areas prone to urban flooding, one solution is the repair and expansion of man-made sewer systems and stormwater infrastructure. Another strategy is to reduce impervious surfaces in streets, parking lots and buildings through natural drainage channels, porous paving, and wetlands (collectively known as green infrastructure or sustainable urban drainage systems (SUDS)). Areas identified as flood-prone can be converted into parks and playgrounds that can tolerate occasional flooding. Ordinances can be adopted to require developers to retain stormwater on site and require buildings to be elevated, protected by floodwalls and levees, or designed to withstand temporary inundation. Property owners can also invest in solutions themselves, such as re-landscaping their property to take the flow of water away from their building and installing rain barrels, sump pumps, and check valves.
Analysis of flood information
A series of annual maximum flow rates in a stream reach can be analyzed statistically to estimate the 100-year flood and floods of other recurrence intervals there. Similar estimates from many sites in a hydrologically similar region can be related to measurable characteristics of each drainage basin to allow indirect estimation of flood recurrence intervals for stream reaches without sufficient data for direct analysis.
Physical process models of channel reaches are generally well understood and will calculate the depth and area of inundation for given channel conditions and a specified flow rate, such as for use in floodplain mapping and flood insurance. Conversely, given the observed inundation area of a recent flood and the channel conditions, a model can calculate the flow rate. Applied to various potential channel configurations and flow rates, a reach model can contribute to selecting an optimum design for a modified channel. Various reach models are available as of 2015, either 1D models (flood levels measured in the channel) or 2D models (variable flood depths measured across the extent of a floodplain). HEC-RAS, the Hydraulic Engineering Center model, is among the most popular software, if only because it is available free of charge. Other models such as TUFLOW combine 1D and 2D components to derive flood depths across both river channels and the entire floodplain.
Physical process models of complete drainage basins are even more complex. Although many processes are well understood at a point or for a small area, others are poorly understood at all scales, and process interactions under normal or extreme climatic conditions may be unknown. Basin models typically combine land-surface process components (to estimate how much rainfall or snowmelt reaches a channel) with a series of reach models. For example, a basin model can calculate the runoff hydrograph that might result from a 100-year storm, although the recurrence interval of a storm is rarely equal to that of the associated flood. Basin models are commonly used in flood forecasting and warning, as well as in analysis of the effects of land use change and climate change.
Flood forecasting
Anticipating floods before they occur allows for precautions to be taken and people to be warned so that they can be prepared in advance for flooding conditions. For example, farmers can remove animals from low-lying areas and utility services can put in place emergency provisions to re-route services if needed. Emergency services can also make provisions to have enough resources available ahead of time to respond to emergencies as they occur. People can evacuate areas to be flooded.
In order to make the most accurate flood forecasts for waterways, it is best to have a long time-series of historical data that relates stream flows to measured past rainfall events. Coupling this historical information with real-time knowledge about volumetric capacity in catchment areas, such as spare capacity in reservoirs, ground-water levels, and the degree of saturation of area aquifers is also needed in order to make the most accurate flood forecasts.
Radar estimates of rainfall and general weather forecasting techniques are also important components of good flood forecasting. In areas where good quality data is available, the intensity and height of a flood can be predicted with fairly good accuracy and plenty of lead time. The output of a flood forecast is typically a maximum expected water level and the likely time of its arrival at key locations along a waterway, and it also may allow for the computation of the likely statistical return period of a flood. In many developed countries, urban areas at risk of flooding are protected against a 100-year flood – that is a flood that has a probability of around 63% of occurring in any 100-year period of time.
According to the U.S. National Weather Service (NWS) Northeast River Forecast Center (RFC) in Taunton, Massachusetts, a rule of thumb for flood forecasting in urban areas is that it takes at least 1 inch (25 mm) of rainfall in around an hour's time in order to start significant ponding of water on impermeable surfaces. Many NWS RFCs routinely issue Flash Flood Guidance and Headwater Guidance, which indicate the general amount of rainfall that would need to fall in a short period of time in order to cause flash flooding or flooding on larger water basins.
In the United States, an integrated approach to real-time hydrologic computer modelling utilizes observed data from the U.S. Geological Survey (USGS), various cooperative observing networks, various automated weather sensors, the NOAA National Operational Hydrologic Remote Sensing Center (NOHRSC), various hydroelectric companies, etc. combined with quantitative precipitation forecasts (QPF) of expected rainfall and/or snow melt to generate daily or as-needed hydrologic forecasts. The NWS also cooperates with Environment Canada on hydrologic forecasts that affect both the US and Canada, like in the area of the Saint Lawrence Seaway.
The Global Flood Monitoring System, "GFMS," a computer tool which maps flood conditions worldwide, is available online. Users anywhere in the world can use GFMS to determine when floods may occur in their area. GFMS uses precipitation data from NASA's Earth observing satellites and the Global Precipitation Measurement satellite, "GPM." Rainfall data from GPM is combined with a land surface model that incorporates vegetation cover, soil type, and terrain to determine how much water is soaking into the ground, and how much water is flowing into streamflow.
Users can view statistics for rainfall, streamflow, water depth, and flooding every 3 hours, at each 12 kilometer gridpoint on a global map. Forecasts for these parameters are 5 days into the future. Users can zoom in to see inundation maps (areas estimated to be covered with water) in 1 kilometer resolution.
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[40] | 1931 China floods | China | 1931 |
| 900,000–2,000,000 | 1887 Yellow River flood | China | 1887 |
| 500,000–700,000 | 1938 Yellow River flood | China | 1938 |
| 231,000 | Banqiao Dam failure, result of Typhoon Nina. Approximately 86,000 people died from flooding and another 145,000 died during subsequent disease. | China | 1975 |
| 230,000 | 2004 Indian Ocean tsunami | Indonesia | 2004 |
| 145,000 | 1935 Yangtze river flood | China | 1935 |
| 100,000+ | St. Felix's flood, storm surge | Netherlands | 1530 |
| 100,000 | Hanoi and Red River Delta flood | North Vietnam | 1971 |
| 100,000 | 1911 Yangtze river flood | China | 1911 |
In myth and religion
Flood myths (great, civilization-destroying floods) are widespread in many cultures.
Flood events in the form of divine retribution have also been described in religious texts. As a prime example, the Genesis flood narrative plays a prominent role in Judaism, Christianity and Islam.
List of floods
14th century
St. Mary Magdalene's flood occurred on the feast day on and around the feast day of St. Mary Magdalene, 25 July, the passage of a Genoa low the rivers Rhine, Moselle, Main, Danube, Weser, Werra, Unstrut, Elbe, Vltava and their tributaries inundated large areas. Even the river Eider north of Hamburg flooded the surrounding land. Many towns such as Cologne, Mainz, Frankfurt am Main, Würzburg, Regensburg, Passau and Vienna were seriously damaged. The affected area extended to Carinthia and northern Italy. The overall number of casualties is not known, but it is believed that alone in the Danube area 6000 people were killed.
15th century
The All Saints Day Flood of 1436 (German: Allerheiligenflut) on All Saints' Day (1 November) 1436 was a storm tide that hit the entire North Sea coast of the German Bight. In the North Frisian village of Tetenbüll alone 173 people died. Eidum on the island of Sylt was destroyed, its inhabitants left and founded the village of Westerland as a result. List on Sylt was also abandoned after the floods and rebuilt further west. Dykes burst along the river Oste and in Kehdingen. The island of Pellworm was separated from neighbouring Nordstrand, Germany and only diked again in 1550.
16th century
1530 St. Felix's flood
Mississippi River Flood of March 1543. The flooding reportedly lasted for 40 days.
17th century
The California Flood of 1605 was caused by heavy rains and covered many parts of California in water.
The Burchardi Flood was a storm tide that struck the North Sea coast of North Frisia and Dithmarschen on the night between 11 and 12 October 1634. Overrunning dikes, it shattered the coastline and caused thousands of deaths (8,000 to 15,000 people drowned).
18th century floods
Christmas Flood of 1717 – Flood in Netherlands, Germany, and Scandinavia. 14,000 drowned.
Mississippi River Flood of December 1734 to June 1735. New Orleans was inundated by the flooding.
New Hampshire Flood of 1740. The Merrimack River flooded in December. It is the first recorded flood in New Hampshire history.
New Hampshire/Maine Flood of October 1785. In New Hampshire, a significant flood struck the Cocheco, Baker, Pemigewasset, Contoocook and Merrimack rivers on 23 October which established records at Lowell which held until 1902.[2] The Androscoggin River flooded significantly, which destroyed many homesteads in what would become Bethel, Maine. Those that survived the flood moved uphill into less valuable, 100-acre (0.40 km2) plots. Turner's first mill was destroyed during this inundation.
Great Pumpkin Flood of October 1786. Central Pennsylvania flood. Received its name due to the pumpkins that were washed away in the flood on 5 October. It was a major flood in the Susquehanna River basin.
Mississippi River Flood of July 1788. Severe flooding of the Mississippi River resulted from a hurricane landfall
Storofsen Norway Flood of July 1789
Red River of the South Flood of 1800. According to the Caddo tribe, a "great flood" moved down the river and reinforced the "Great Log Raft" on the river. This raft was a natural dam that increased water levels on some of the Red River tributaries. This process formed Caddo Lake.
19th century
Mississippi River Flood of 1809. All of the lower Mississippi River was inundated by flooding.
Mississippi River Flood of 1825. The flood of 1825 is the last known inundation of New Orleans due to spring flooding
Great Mississippi River Flood of 1844. The largest flood ever recorded on the Missouri River and Upper Mississippi River in terms of discharge. This flood was particularly devastating since the region had few if any levees at the time. Among the hardest hit were the Wyandot who lost 100 people in the diseases that occurred after the flood. The flood also is the highest recorded for the Mississippi River at St. Louis. After the flood, Congress in 1849 passed the Swamp Act providing land grants to build stronger levees.
Great Mississippi River Flood of 1851. The flood occurred after record-setting rainfalls across the U.S. Midwest and Plains from May to August 1851. The State of Iowa experienced significant flooding extending to the Lower Mississippi River basin. Historical evidence suggest flooding occurred in the eastern Plains, from Nebraska to the Red River basin, but these areas were sparsely settled in 1851. Heavy rainfall also occurred in the Ohio River basin. In June, major flooding on the Mississippi River was experienced.
The Great Flood of 1862 struck the west coast of North America in December 1861 and January 1862. An atmospheric river from the tropics brought 43 days of rain to the U.S. states of California, Utah and Oregon as well as the Mexican state of Sonora. It was the worst disaster ever to strike California; the state's California was effectively an inland sea for months afterwards. State government temporarily moved to San Francisco because the capital, Sacramento, was under 10 feet (3.3 m) of water; the damage and the ensuing shortfall in tax revenues nearly bankrupted the state.
The 1872 Baltic Sea flood was a storm surge that affected the Baltic Sea coast from Denmark to Pomerania on the night of 12/13 November 1872. The flood cost the lives of at least 271 people on the Baltic Sea coast; 2,850 houses were destroyed or at least badly damaged and 15,160 people left homeless as a result.
Great Mississippi River Flood of 1874. Heavy spring rains caused the Mississippi River to overflow, breaching levees and flooding enormous swathes of the Lower Mississippi Valley. The flooding began in February and only began to recede on 20 May. According to the New Orleans Daily Picayune of 3 May, thirty-one of Louisiana's fifty-three parishes (home to some 375,000 people) were entirely or partially underwater. The Picayune also reported that breaches at Hushpakana[sic.] and Bolivar, Mississippi, had "transformed the Yazoo Valley into an inland lake."[3] Mayor Louis A. Wiltz of New Orleans published a circular on 30 May addressed to "the Mayors of thirty-four large American cities" seeking contributions of cash and provisions for relief efforts. In the circular, the Flood of 1874 was described as the highest on record. It also included the observations of former U.S. Surveyor General for Louisiana William J. McCulloh, who estimated that a total of 12,565,060 acres had been flooded across Louisiana (8,065,000), Mississippi (2,500,000), and Arkansas (2,000,000).
Mississippi River Flood of 1882. Intense spring rain storms beginning on 19 February 1882, led to a rapid rise of the Ohio River and flooding along the river from Cincinnati to St. Louis. The effects were much more devastating in the Lower Mississippi Valley, with an estimated 20,000 people made homeless in Arkansas alone. Such was the devastation that, in its wake, Southern Democrats and Midwestern Republicans in Congress hailing from those states afflicted by the flooding made common cause to increase appropriations for the Rivers and Harbor Act to $19 million, $5.4 million of which was earmarked for internal improvements and federal aid to the flooded areas. While not opposed to internal improvements on principle, President Chester A. Arthur nonetheless vetoed the Act on 1 August 1882. Congress overrode his veto the following day.
In 1889, the South Fork Dam broke, causing the massive Johnston Flood of 1889 that took 2,209 lives in Johnstown, Pennsylvania.
On 8 September 1900, in Galveston, TX, the storm made landfall, leaving about 7,000 to 12,000 dead. It remains to the present day the deadliest single day event in US history.[4]
20th century
1910s
In 1910, large areas of Paris were flooded when the river burst its banks.
In 1920, The Great Flood of Tokyo, when 3700 houses, were swept away, 2200, partially destroyed and nearly 400,000 damaged.
The Great Flood of 1913, which included the Great Dayton Flood, killed 650 people and destroyed 20,000 homes in the United States. It also damaged historic photographic plates belonging to Wilbur and Orville Wright. It ended canal transportation in Ohio.
The 1916 Clermont, Queensland flood was the worst flood in Clermont history.
The Hatfield Flood of San Diego, United States, of 1916 destroyed the Lower Otay Dam,[5] damaged the Sweetwater Dam,[6] and caused 22 deaths and $4.5 million in damages.
1920s
The Great Mississippi Flood of 1927 was one of the most destructive floods in United States history and the impetus for many later Flood Control Acts.
The Great Vermont Flood of 1927 which destroyed over 1200 bridges in Vermont, and one of the biggest floods in its history.
1930s
The 1931 Yellow River flood caused between 800,000 and 4,000,000 deaths in China, one of a series of disastrous floods on the Yellow River. It was one of the worst floods in history.
The Ohio River flood of 1937 occurred in late January and February 1937, causing damage along the Ohio River and several smaller tributaries from Pittsburgh, Illinois, to Cairo, Illinois. This flood left close to one million people homeless, 385 dead, and $50,000,000 worth of damage.
The Los Angeles flood of 1938 occurred from late February to early March 1938, causing the Los Angeles River and the Santa Ana River to overflow, causing $40,000,000 worth of damage and causing 115 lives to be lost.
The Great Hanshin flood of 1938 occurred in July 1938 in Kobe area in Japan, causing 925 lost lives as exceptionally heavy seasonal raining caused landsides at Rokko mountains.
1940s
The 1948 Berwickshire flood occurred on 12 August, when extremely heavy rain for the preceding six days caused the rivers Tweed, Blackadder, Whiteadder, Till and Eye Water in southern Scotland to rise more than 10 feet and wash away 20 bridges. Railway service was interrupted for months.[7]
1950s
The Lynmouth flood of 1952 killed 34 people, more than any other British flood up to then, it was also very destructive and destroyed over 80 buildings in the town of Lynmouth, Devon, United Kingdom.
The North Sea Flood of 1953 caused over 2,000 deaths in the Dutch province of Zeeland and the about 50 in the United Kingdom (the coastlines of East Anglia and Lincolnshire were worst hit) and led to the construction of the Delta Works in the Netherlands and the Thames Barrier in London.
1953 North Kyushu Flood killed at least 759 and the killed and missing amounted to 1,001 in the northern Kyushu area of Japan.
On 15 October 1954, Hurricane Hazel struck Toronto, Ontario, Canada. The resulting rainfall flooded the city, killing 81 people, destroying 20 bridges, and leaving over 2000 people homeless.[8]
The Hunter Valley floods of 1955 in New South Wales (Australia) destroyed over 100 homes and caused 45,000 to be evacuated.
In 1957, the storm surge from Hurricane Audrey flooded southwest Louisiana, killing about 400 people.
In 1957, the Great flood of Valencia in Spain.
In 1959, the Río Negro flooded the central region of Uruguay, with disastrous consequences.
1960s
In 1960, flooding from a tsunami (caused by the Great Chilean earthquake) affected the towns of Riñihue, Riñihuazo, Los Lagos, Antilhue, Pishuinco, and Valdivia (all in Chile).
The North Sea flood of 1962 killed almost 330 people along the coasts of southeastern England, Germany, and southern Denmark. 318 of the deaths occurred in Hamburg, Germany, and many millions of pounds' worth of damage was done.
In 1965, Hurricane Betsy flooded large areas of New Orleans, Louisiana, United States, for up to 10 days, drowning around 40 people.
In 1966, the flood of the Arno River killed dozens of people and damaged or destroyed millions of masterpieces of art and rare books in Florence, Italy.
1970s
On the night of 9 June 1972 the people of Rapid City, South Dakota in the United States were struck by a deadly flood that lasted two days. It took 238 lives and caused millions of dollars in damage.
In 1974, the dying cyclone Wanda triggered major flooding in Brisbane, Australia killing 6 people and leaving hundreds homeless.
In 2 July 1975, many areas of Romanian Cuverture Charpatinas (e.g. Buzau, Prahova County), were struck by major flooding.
In August 1975, the Banqiao Dam in China breaks apart under excess rainfall and damage from Typhoon Nina, drowning about 26,000 and caused the lives of another 140,000 in resulting epidemics.
1980s
During the 1980s, the Great Salt Lake reached record high water levels due to a large amount of rain and its lack of an outlet. Places such as Saltair were inundated.
The South African town of Laingsburg was basically destroyed on 25 January 1981, when 104 of its 900 inhabitants died during a flood that swept through the town and left only about 25 houses standing
In 1982, the river Jucar in Spain breaks the Tous Reservoir, flooding the surrounding land in a deluge of 16,000 m3/s of water, and killing 30 people.
In the winter of 1983, the Pacific Northwest of the United States saw one of the worst floods on record for that region, and some states recorded their wettest winter ever. Damage estimates are as high as $1.1 billion.
1990–2000
1992–3
January 1992 saw severe floods in South America, most notably Brazil.
In Alaska, United States, from May to September 1992 it was unusually wet, causing the 100 year flood. Snow melt only made the floods worse.
The Great Flood of 1993 was one of the most destructive floods in United States history.
March 1993 the "No Name" storm, silently brought major flooding to Citrus County, Florida.
The summer of 1993 was unusually wet for the United States, causing flooding in the southwest.
1994–5
1994 South Georgina floods
On 8 May 1995, severe floods caused extensive damage in Louisiana, United States.
1996–7
A dying typhoon hit Kyushu, Japan, in September 1996, causing severe floods in that region.
July 1996 saw severe floods in Central Honshū, Japan.
In August 1996, 86 people died due to a flood in Las Nieves camping, in Biescas, Spain.[9][10]
1997 Central European flood, the worst flood in Polish history hits the country in July 1997, killing 65 and causing extensive damage to Wroclaw and Opole.
The Red River Flood of 1997 (also called the Red River of the North Flood of 1997 in the United States) occurred in April and May 1997 along the Red River of the North in North Dakota, Minnesota (United States) and Manitoba. It was the most severe flooding of the river since 1826, causing so much water or camping down (?) water or not draining it all.
1998–2000
Bangladesh was flooded in 1998, with millions of people affected and hundreds killed.
The 1999 Pentecost flood (German: Pfingsthochwasser) was a 100-year flood around the Pentecost season in 1999 that mostly affected Bavaria, Vorarlberg and Tirol. It was caused by heavy rainfall coinciding with the regular Alpine meltwater. These were caused because of the low-lying area and they are replacing concrete with soil which affects the flow of water and can cause flash flooding.
The 2000 Mozambique flood, caused by heavy rains followed by a cyclone, covered much of the country for three weeks, killing thousands, leaving the country devastated for years afterwards.
21st century
2000s
2001
In June 2001, floods from Tropical Storm Allison killed over 30 people in the Houston, Texas, area.
2002–3
The 2002 Northern Chile floods and mudflow, hit Coquimbo and Valparaíso regions in Chile in June 2002 causing the deaths of 17 people.
In 2002, the 2002 Glasgow floods hit Glasgow, Scotland, causing severe damage.
In 2002, the 2002 European floods hit Central Europe, causing major damage.
2004–5
The 2004 Boscastle flood on 16 August in the village of Boscastle, Cornwall, United Kingdom, caused much damage to buildings in the Valency River valley. Further flooding took place in surrounding valleys, and in the town of Camelford.
In January 2005, flooding on the rivers Eden, Kent, Derwent, Greta and Cocker as well as others in Cumbria, England, flooded around 2,000 properties and caused in excess of £250 million of damage. At the time, it was the worst flood in Cumbrian history, but has since been overtaken by the Cumbria flooding of November 2009.[11]
One of Canada's most devastating floods occurred in southern Alberta in June 2005. The flooding affected many major metropolitan areas including Calgary. 4 deaths resulted from the three-week flood.
Flooding in Mumbai, India, in July 2005 left over 700 dead. Some areas went under 5 m of water.
Eighty percent of New Orleans, Louisiana, United States, was flooded due to the failure of several levees on 29 August 2005 during Hurricane Katrina. 1,833 people also died because of the hurricane.
Record rain across eastern Europe in August 2005 caused very severe flooding.
In November 2005, in the Indian states of Tamil Nadu and Andhra Pradesh, many villages were isolated due to heavy rains caused by low-pressure areas in the Bay of Bengal.
2006–7
Korea (both North Korea and South Korea) saw one of its worst floods ever in May 2006.
The Mid-Atlantic States flood of 2006 in the eastern United States is considered to be the worst in that region since the flooding caused by Hurricane David in 1979.
Ethiopia saw one of its worst floods ever in August 2006.
Surat a 5 million populated city of India witnessed huge flood in its history during 4 to 10 August 2006. 10 lac cusec water discharge for 30 hours from Ukai dam flooded city. 1 Lac evacuated on first day, many human and animal lost their lives.
Peninsular Malaysia, Sumatra, and Sabah suffered floods between December 2006 and January 2007. It killed hundreds and forced 100,000 people to be evacuated in Johor alone. Floods hit the country's capital Kuala Lumpur in January 2007, killing 80. It was the worst flood in Malaysia for over 100 years.
The 2007 Hunter Floods inundated large areas of the cities of Maitland and Newcastle in Australia in June 2007, claimed 11 lives and forced the evacuation of 4,000 people in Central Maitland.
Between late May 2007 and early August 2007, severe flash floods hit most of the United Kingdom, with the most affected area in the country being Yorkshire. The city of Sheffield (in Yorkshire) was the worst affected city in the country, a month's worth of rain fell on the city in just 18 hours on 25 June 2007, bursting the banks of the River Don in that city. There were also fears that the Ulley Reservoir in Sheffield would fail, if it did it would have killed hundreds. 6 people were killed across the country.
The 2007 Africa Floods was one of the worst and most destructive floods in recorded history on the continent of Africa with 14 countries affected.
In November 2007, Cyclone Guba, a slow moving storm caused deadly flooding in Papua New Guinea.
The 2008 Indian floods affected several states in India between July 2008 and September 2008 during an unusually wet monsoon season. The floods caused severe damage, and killed an estimated 2404 people.
2008–9
2008 Santa Catarina floods
2009 Brazilian floods and mudslides
In June 2009, minor flooding hit parts of Sheffield City Centre in Sheffield, England. Waters reached only about half a foot deep as the River Don broke its banks, but considerable damage was still caused.
In November 2009, record-breaking amounts of rain were dumped on Cumbria, England and Cork, Ireland, causing minor floods in Cork and major floods in Cumbria. During the floods, waters reached a UK record 8 ft deep in Cockermouth, Cumbria.
2010
January 2010 Rio de Janeiro floods and mudslides
Rio de Janeiro had its worst ever flood that killed over 250 people in April 2010.
2010 northeastern Brazil floods
Between June 2010 and August 2010, flooding in China affected more than 230 million people – with 15.2 million people evacuated and thousands dead.
On 26 July 2010, heavy monsoon rains flooded most of Pakistan in the 2010 Pakistan floods.
On 4 August 2010, at 9:25 am EST a major thunderstorm producing large hail and winds in excess of 60 mph (97 km/h) advanced at the leading edge of a cold front moving across the American Midwest, causing a flash flood that struck Louisville, Kentucky, and portions of the surrounding Kentuckiana region.
In November 2010, many areas of Cornwall, UK, were struck by floods. The worst hit area was the town of Par.
The November 2010 Colombia floods and associated landslides killed 138 people. 1.3 million were left homeless.
The November 2010 Thailand floods and 2010 north Malaysian floods.
The 2010–11 Queensland floods are some of the worst the country of Australia has ever seen.
2011
The January 2011 Brazil floods are considered the worst in the country's history. As of 18 January 2011, the floods had taken about 700 lives and 14,000 people were homeless mainly due to landslides.
The Mississippi River floods in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway.
In June 2011, flooding in China affected more than 4.8 million people, with 100,000 evacuated and 54 reported dead.
In late July, the 2011 Thailand floods spread through the provinces of Northern, Northeastern and Central Thailand along the Mekong and Chao Phraya river basins and persisted in some areas until mid-January 2012.
In August–September 2011, there was floods in Khammouane Province in Laos, and then in northeastern Thailand, then came to Cambodia, and was drained via Mekong river to Vietnam then South China Sea.
On 18 October 2011, Pulau Tioman of Malaysia was flooded in Kampung Tekek, and the jungle near the village, then came up to Salang on 23 October 2011, the drain was started in November.
Around November 2011, northern part of Malaysia was flooded, and then to Narathiwat Province in Thailand.
2012
In July 2012, heavy torrential rains caused floods in Kyushu, Japan, leaving 32 people dead or missing.
In 2012 Great Britain and Ireland floods caused many floods in the United Kingdom, in April floods and gales hit most of England causing flooding and power outages, on 28 June 2012 there were two severe supercell thunderstorms which traveled across the West Midlands causing flash flooding, on 6 July 2012 heavy rainfall brought floods to the South West of England with the Met Office issuing red rain warnings, flooding later returned to the UK on 21 November 2012, as heavy persistent rainfall fell in South West England which caused rivers to burst their banks, the rain later pushed into the Midlands overnight causing more flooding, on 24 November 2012 another band of rain pushed into South West England, The Environment Agency issued three severe flood warnings for the South West England and 90 flood warnings, the following day the Environment Agency issued 110 flood warning for the Midlands, most of which were for the River Avon and the River Severn.
2013
The 2013 North India floods and landslides caused by heavy rainfall. The floods struck the state of uttarakhand. These floods killed 5,700 people.
The 2013 European floods.
2013 Alberta flood — On 20 June 2013, widespread flooding in southern Alberta caused major damage in Canmore, Calgary and High River when the Cougar Creek, Highwood River, and other rivers and creeks overflowed caused by extensive rainfall. Other communities in the area were also affected, or were expected to be, by floods. Flooding also caused power outages and the closure of the Trans-Canada Highway and Highway 1A, as well as many other highways and roads. A man and a woman were reported missing after a mobile home was swept into the Highwood River near the town of Black Diamond; the man was later rescued, but the woman remained missing.
The 2013 Southwest China floods.
The 2013 Afghanistan–Pakistan floods.
2013 Colorado floods. At least four dead after floods in Colorado.
On 18 November 2013 the heavy flood caused by Cyclone Cleopatra killed 18 people in the Italian island of Sardinia.
2014
Many parts of the United Kingdom experienced flooding at the start of this year. In January and then again in February the River Thames breached its banks resulting in severe flooding to many homes and properties in heavily populated parts of the Thames Valley area.
In early April 2014, Cyclone Ita caused disastrous flooding across the Solomon Islands, killing at least 21 people.
Between 2 and 30 April 2014, flood events in the United-States, caused by an important tornado outbreak.
In May 2014, multiple floods affected a large area of Southeastern Europe. A low-pressure area named "Yvette" brought flooding from 14–16 May. Bosnia, Serbia and Romania were hit by the biggest flood in their modern history. Several cities were left behind without fresh water or food.
In June 2014, a flash flood in the Baghlan province of Afghanistan killed at least 73.
2014 Alberta floods — On 18 June 2014 the city of Claresholm, Alberta awoke to find its city streets flooded, and states of emergency were declared for many areas in southern Alberta including the Blood Reserve, Cardston, Claresholm, Coaldale, Crowsnest Pass, Lethbridge County, Medicine Hat, and Willow Creek.
2014 India–Pakistan floods- In September 2014, an estimated 557 people died in India and Pakistan as a result of flooding, which was caused by intense rainfall in the area.
2014 New York flood — Record setting rainfall creating 60 days of precipitation fell near New York, New York.
2015
2015 Northern Chile floods and mudflow
2015 Tbilisi flood
2015 Missouri floods
2015 Houston – Memorial Day Flood
2015 South Indian floods
2015 Poland Flood
2015 Myanmar Flood
2016
2016 São Paulo flood and mudslide
2016 Houston Tax Day floods
2016 Ethiopia flood
2016 European floods
2016 Oklahoma floods
2016 Maryland flood
2016 Niger flood
2016 Louisiana floods
2016 Johannesburg flood
2017
2017 China floods
2017 Southern Thailand floods a
2017 Peru flood
Quebec Floods
2017 Hurricane Harvey
2017 hurricane irma
2017 flood of chennai in Tamil Nadu
2018
2018 East Africa floods
2018 Japan floods
2018 Kerala floods
2018 Vietnam floods
2018 North Korean floods
2018 European floods
2019
2019 Iran floods
March 2019 north Iran floods
2019 Midwestern U.S. floods
2019 South Sulawesi floods
2019 Townsville flood
2019 Pakistan floods and storms
May 2019 Houston Flash Flooding
June 2019 Southern and Southeastern U.S. flooding
Source
O'Connor, Jim E. & John E. Costa (2004) The World's Largest Floods, Past and Present: Their Causes and Magnitudes [Circular 1254], Washington, DC: U.S. Department of the Interior, U.S. Geological Survey.
Thompson, M.T., (1964). Historical Floods in New England [Geological Survey Water-Supply Paper 1779-M]. Washington, DC: United States Government Printing Office.
Powell, W. Gabe, 2009, Identifying Land Use/Land Cover (LULC) Using National Agriculture Imagery Program (NAIP) Data as a Hydrologic Model Input for Local Flood Plain Management, Applied Research Project, [http://ecommons.txstate.edu/arp/296/ Texas State University–San Marcos
Wikipedia common
Σχόλια
Δημοσίευση σχολίου