United States

Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. The United States is home to many cultures and a wide variety of ethnic groups, traditions, and values. Aside from the Native American, Native Hawaiian, and Native Alaskan populations, nearly all Americans or their ancestors settled or immigrated within the past five centuries.


thunderstormssevere thunderstormelectrical storm
Flash flooding is the process where a landscape, most notably an urban environment, is subjected to rapid floods. These rapid floods occur more quickly and are more localized than seasonal river flooding or areal flooding and are frequently (though not always) associated with intense rainfall. Flash flooding can frequently occur in slow-moving thunderstorms and is usually caused by the heavy liquid precipitation that accompanies it. Flash floods are most common in densely populated urban environments, where few plants and bodies of water are present to absorb and contain the extra water.


earthfilldamsconcrete-face rock-fill dam
The resulting lakes often flood inhabited areas, while a catastrophic failure of the dam could cause even greater damage, such as the failure of western Wyoming's Gros Ventre landslide dam in 1927, which wiped out the town of Kelly and resulted in the deaths of six people. Beavers create dams primarily out of mud and sticks to flood a particular habitable area. By flooding a parcel of land, beavers can navigate below or near the surface and remain relatively well hidden or protected from predators.

Washout (erosion)

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Motorists have also driven into flooded streams at night, unaware of a new washout on the road in front of them until it is too late to brake, sometimes prompting a high-water rescue. Major washouts can also ruin pipelines or undermine utility poles or underground lines, interrupting public utilities. Bridge scour. Flash flood. Washaway.

List of floods

19752013 flood2015 China floods
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.

Global storm activity of 2010

2009–10 North American winter storms2009–10 North American winter storm season2010 Global storm activity
As the fourth and second strongest of the week's storms slammed into California, officials predicted as much as four feet (1.2 metres) of snow would fall in Northern California. Freshly fallen snow blanketed the north side of the San Gabriel Mountains on the morning after the fourth storm of the week dissipated on January 23, 2010, northwest of Wrightwood, California. Snow was reported in many parts of California. On January 24, the 5th and strongest storm caused heavy rain fell in parts of Los Angeles. 500 people were evacuated from a small village in La Paz County, Arizona due to a flash flood.


earthquakesseismic activityseismic
Large waves produced by an earthquake or a submarine landslide can overrun nearby coastal areas in a matter of minutes. Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them. Ordinarily, subduction earthquakes under magnitude 7.5 on the Richter magnitude scale do not cause tsunamis, although some instances of this have been recorded. Most destructive tsunamis are caused by earthquakes of magnitude 7.5 or more. Floods may be secondary effects of earthquakes, if dams are damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods.

List of mass evacuations

largest evacuations
October 2007 – California wildfires forced more than 900,000 people in Southern California to evacuate, making it the largest evacuation in California's history and the largest evacuation for fire in United States history. May 2008 – 2008 Sichuan earthquake: Approximately 200,000 people are evacuated in Beichuan County, China because of flooding fears after a landslide created dam became unstable. August 2008 – At least 1.9 million people were evacuated from coastal Louisiana, including New Orleans, for Hurricane Gustav. In western Cuba, at least 300,000 people were evacuated.


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Another landslide-tsunami event occurred in 1963 when a massive landslide from Monte Toc entered the Vajont Dam in Italy. The resulting wave surged over the 262 m (860 ft) high dam by 250 metres (820 ft) and destroyed several towns. Around 2,000 people died. Scientists named these waves megatsunamis. Some geologists claim that large landslides from volcanic islands, e.g. Cumbre Vieja on La Palma in the Canary Islands, may be able to generate megatsunamis that can cross oceans, but this is disputed by many others. In general, landslides generate displacements mainly in the shallower parts of the coastline, and there is conjecture about the nature of large landslides that enter the water.


rainfallrainstormtorrential rain
Excessive rain during short periods of time can cause flash floods. Cultural attitudes towards rain differ across the world. In temperate climates, people tend to be more stressed when the weather is unstable or cloudy, with its impact greater on men than women. Rain can also bring joy, as some consider it to be soothing or enjoy the aesthetic appeal of it. In dry places, such as India, or during periods of drought, rain lifts people's moods. In Botswana, the Setswana word for rain, pula, is used as the name of the national currency, in recognition of the economic importance of rain in its country, since it has a desert climate.

Mediterranean climate

warm-summer Mediterranean climateMediterraneanCsb
Aquatic communities in Mediterranean climate regions are adapted to a yearly cycle in which abiotic (environmental) controls of stream populations and community structure dominate during floods, biotic components (e.g. competition and predation) controls become increasingly important as the discharge declines, and environmental controls regain dominance as environmental conditions become very harsh (i.e. hot and dry); as a result, these communities are well suited to recover from droughts, floods, and fires. Aquatic organisms in these regions show distinct long-term patterns in structure and function, and are also highly sensitive to the effects of climate change.

Landslide dam

debris dambarrier lakelandslide lake
The water impounded by a landslide dam may create a dam reservoir (lake) that may last from short times to several thousand years. Because of their rather loose nature and absence of controlled spillway, landslide dams frequently fail catastrophically and lead to downstream flooding, often with high casualties. A common failure scenario is overflowing with subsequent dam breach and erosion by the overflow stream. Landslide dams are responsible for two types of flooding: backflooding (upstream flooding) upon creation and downstream flooding upon failure.


Short radio episode California Glaciers from The Mountains of California by John Muir, 1894. California Legacy Project. Dyanamics of Glaciers. GletscherVergleiche.ch – Before/After Images by Simon Oberli.


volcanicvolcanoesextinct volcano
Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome. Because siliceous magmas are so viscous, they tend to trap volatiles (gases) that are present, which cause the magma to erupt catastrophically, eventually forming stratovolcanoes. Pyroclastic flows (ignimbrites) are highly hazardous products of such volcanoes, since they are composed of molten volcanic ash too heavy to go up into the atmosphere, so they hug the volcano's slopes and travel far from their vents during large eruptions.

Thomas Fire

Thomas wildfireThomas
The area, along with most of Southern California, experienced the driest March-through-December period on record. While November is the typical beginning of the rainy season in California, the first measurable rain for the area fell on January 8, 2018, more than a month into the fire. With the natural vegetation burnt, flash floods and mudflows damaged homes in Montecito when the rains arrived. Evacuations were ordered or anticipated for neighborhoods that sit below areas recently burned by the Thomas Fire and other wildfires. By January 10, at least 21 people had been killed by the sudden flooding and debris flows that followed the heavy rains, which also destroyed over 100 homes.

Coastal flood

coastal floodingCoastal Flood Warningcyclone-generated wave washover
Quantifying the effectiveness of natural buffering systems, such as mangroves, against coastal flooding. Better engineering design and practices or alternative mitigation strategies to engineering. 2004 Indian Ocean earthquake and tsunami. Canterbury Bight. Coastal flood advisory, watch, warning (U.S.). Coastal management. Flash flood. Flood barrier. Hurricane Katrina. Intergovernmental Panel on Climate Change. Saltwater intrusion. Sea level rise. Thames Barrier. Tsunami.


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First, flood mitigation schemes, intended to protect infrastructure built on floodplains, have had the unintended consequence of reducing aquifer recharge associated with natural flooding. Second, prolonged depletion of groundwater in extensive aquifers can result in land subsidence, with associated infrastructure damage – as well as, third, saline intrusion. Fourth, draining acid sulphate soils, often found in low-lying coastal plains, can result in acidification and pollution of formerly freshwater and estuarine streams.

Pineapple Express

rains of 2005
Many Pineapple Express events follow or occur simultaneously with major arctic troughs in the northwestern United States, often leading to major snow-melt flooding with warm, tropical rains falling on frozen, snow laden ground. Examples of this are the Christmas flood of 1964, Willamette Valley Flood of 1996, New Year's Day Flood of 1997, January 2006 Flood in Northern California, Great Coastal Gale of 2007, January 2009 Flood in Washington, and the January 2012 Flood in Oregon. Early in 1862, extreme storms riding the Pineapple Express battered the west coast for 45 days.

Fire ecology

firefire cyclefire ecologist
More generally, fire is now regarded as a 'natural disturbance', similar to flooding, wind-storms, and landslides, that has driven the evolution of species and controls the characteristics of ecosystems. Fire suppression, in combination with other human-caused environmental changes, may have resulted in unforeseen consequences for natural ecosystems. Some large wildfires in the United States have been blamed on years of fire suppression and the continuing expansion of people into fire-adapted ecosystems, but climate change is more likely responsible.

2018 Japan floods

disastrous floodings in western Japan2018 West Japan rain disasterextraordinarily heavy rainfall in Western Japan
The torrential rain triggered landslides and flash flooding, with water levels reaching 5 m in the worst hit areas. Motoyama, Kōchi, saw 584 mm of rain between 6 and 7 July. One town in Kōchi measured 263 mm of rain in two hours. Mount Ontake observed its greatest three-day rainfall on record at 655.5 mm. Although the Yura River remained within its banks in northern Kyoto Prefecture, an embankment built after Typhoon Tokage in 2004 prevented runoff from flowing into the river. This inadvertently led to flooding in Maizuru after the flood gate was closed.


1970 birthsOctober 1970
October 30 – In Vietnam, the worst monsoon to hit the area in six years causes large floods, kills 293, leaves 200,000 homeless and virtually halts the Vietnam War. November 1. Club Cinq-Sept fire in Saint-Laurent-du-Pont, France, kills 146. Three Pakistanis and a Polish Deputy Foreign Minister, Zygfryd Wolniak, are killed at Karachi airport, Pakistan. November 3. Democrats sweep the U.S. Congressional midterm elections; Ronald Reagan is reelected governor of California; Jimmy Carter is elected governor of Georgia. Salvador Allende takes office as president of Chile. November 4.

Tropical Storm Talas (2011)

TalasTropical Storm TalasTyphoon Talas
Heavy rains triggered flash flooding, which killed one person, and injured 17 leaving three more missing soon after the landfall. Some 3,200 people were evacuated in 16 prefectures after the typhoon slammed the island nation with extremely heavy rains. The Central Japan Railway Company had to suspend its bullet train services on the Tokaido Shinkansen Line between Gifu-Hashima and Maibara railway stations because of the storm. More than 300 houses were flooded while several landslides were reported since the storm's landfall in southern Japan. Also, since the storm was moving unusually slow, it worsened the condition.

Typhoon Bopha

Typhoon Bopha (Pablo, 2012)BophaPablo
Typhoon Bopha packed winds of up to 175 mph when it struck the island nation, bringing torrential rains that flattened entire villages, leaving thousands homeless, as well as washing out roads and bridges needed by rescue personnel trying to reach stricken regions. The death toll from Bopha rose to 82 as rescuers battled to reach areas cut off in flash floods and mudslides. There were 49 fatalities in a mudslide in the mountainous town of New Bataan alone, and another 33 died in rural settlements elsewhere in Mindanao. Joe Curry, the Philippines head of Catholic Relief Services, said, "Authorities seem more prepared to deal with this storm.

Yauza River

Raised water levels in the downtown portion of the Yauza basin led to long-term flooding and death of trees deep inside Losiny Ostrov. Within the city of Moscow the Yauza is spanned by 21 road bridges, five railroad bridges, one dedicated tram bridge, two Moscow Metro bridges, numerous pedestrian bridges and the historical Rostokino Aqueduct. Spring floods due to low clearance under old bridges were common, with four in the 1950s alone (1951, 1952, 1955 and 1957); they were practically eliminated when these bridges were rebuilt to modern standards. The most recent flash flood on the Yauza occurred August 14, 2003, following a record-setting rainfall.

Places of interest in the Death Valley area

Panamint Charcoal Kilnsalso protectsArtist's Palette
Periodic flash floods carry rocky debris (sediment) eroded from Mosaic Canyon and the surrounding hillsides toward the valley below. At the canyon mouth water spreads out and deposits its sediment load, gradually building up a large wedge-shaped alluvial fan that extends down toward Stovepipe Wells. This canyon was formed through a process of cut and fill which included periodic erosive floods followed by long periods of deposition and uplift. But due to the uplift when the next flood hit the area it would deeply cut the streambed which forms stairstep-shaped banks. Mosaic Canyon's polished marble walls are carved from the Noonday Dolomite and other Precambrian carbonate rocks.