A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice or snow flowing over ice sheets or snowfields. Flash floods may also occur after the collapse of a natural ice or debris dam, or a human structure such as a man-made dam, as occurred before the Johnstown Flood of 1889. Flash floods are distinguished from regular floods by having a timescale of fewer than six hours between rainfall and the onset of flooding.[1]
An underpass in Charlottesville, V.A. during normal conditions (upper) and after fifteen minutes of heavy rain (lower)Driving through a flash-flooded roadA flash flood after a thunderstorm in the Gobi, Mongolia
Flash floods are a significant hazard, causing more fatalities in the U.S. in an average year than lightning, tornadoes, or hurricanes. Flash floods can also deposit large quantities of sediments on floodplains and can be destructive of vegetation cover not adapted to frequent flood conditions.
Flash flooded road in Northern Mexico, after a 3–5 hour long thunderstorm that occurred during a drought that lasted nearly 1 year
Flash floods most often occur in dry areas that have recently received precipitation, but they may be seen anywhere downstream from the source of the precipitation, even many miles from the source. In areas on or near volcanoes, flash floods have also occurred after eruptions, when glaciers have been melted by the intense heat. Flash floods are known to occur in the highest mountain ranges of the United States and are also common in the arid plains of the Southwestern United States. Flash flooding can also be caused by extensive rainfall released by hurricanes and other tropical storms, as well as the sudden thawing effect of ice dams.[2][3] Human activities can also cause flash floods to occur. When dams fail, a large quantity of water can be released and destroy everything in its path.[3]
HazardsEdit
A flash flood greatly inundates a small ditch, flooding barns and ripping out newly installed drain pipes.
The United States National Weather Service gives the advice "Turn Around, Don't Drown" for flash floods; that is, it recommends that people get out of the area of a flash flood, rather than trying to cross it. Many people tend to underestimate the dangers of flash floods. What makes flash floods most dangerous is their sudden nature and fast-moving water. A vehicle provides little to no protection against being swept away; it may make people overconfident and less likely to avoid the flash flood. More than half of the fatalities attributed to flash floods are people swept away in vehicles when trying to cross flooded intersections.[4] As little as 2 feet (0.61 m) of water is enough to carry away most SUV-sized vehicles.[5] The U.S. National Weather Service reported in 2005 that, using a national 30-year average, more people die yearly in floods, 127 on average, than by lightning (73), tornadoes (65), or hurricanes (16).[6]
In deserts, flash floods can be particularly deadly for several reasons. First, storms in arid regions are infrequent, but they can deliver an enormous amount of water in a very short time. Second, these rains often fall on poorly absorbent and often clay-like soil, which greatly increases the amount of runoff that rivers and other water channels have to handle.[7] These regions tend not to have the infrastructure that wetter regions have to divert water from structures and roads, such as storm drains, culverts, and retention basins, either because of sparse population or poverty, or because residents believe the risk of flash floods is not high enough to justify the expense. In fact, in some areas, desert roads frequently cross a dry river and creek beds without bridges. From the driver's perspective, there may be clear weather, when a river unexpectedly forms ahead of or around the vehicle in a matter of seconds.[8] Finally, the lack of regular rain to clear water channels may cause flash floods in deserts to be headed by large amounts of debris, such as rocks, branches, and logs.[9]
Deep slot canyons can be especially dangerous to hikers as they may be flooded by a storm that occurs on a mesa miles away. The flood sweeps through the canyon; the canyon makes it difficult to climb up and out of the way to avoid the flood. For example, a cloudburst in southern Utah on 14 September 2015 resulted in 20 flash flood fatalities, of which seven fatalities occurred at Zion National Park when hikers were trapped by floodwaters in a slot canyon.[10]
Flash floods induce severe impacts in both the built and the natural environment. The effects of flash floods can be catastrophic and show extensive diversity, ranging from damages in buildings and infrastructure to impacts on vegetation, human lives and livestock. The effects are particularly difficult to characterize in urban areas.[11]
Researchers have used datasets such as the Severe Hazards Analysis and Verification Experiment (SHAVE) and the U.S. National Weather Service (NWS) Storm Data datasets to connect the impact of flash floods with the physical processes involved in flash flooding. This should increase the reliability of flash flood impact forecasting models.[12] Analysis of flash floods in the United States between 2006 and 2012 shows that injuries and fatalities are most likely in small, rural catchments, that the shortest events are also the most dangerous, that the hazards are greatest after nightfall, and that a very high fraction of injuries and fatalities involve vehicles.[13]......
An impact severity scale is proposed in 2020 providing a coherent overview of the flash flood effects through the classification of impact types and severity and mapping their spatial extent in a continuous way across the floodplain. Depending on the affected elements, the flood effects are grouped into 4 categories: (i) impacts on built environment (ii) impacts on man-made mobile objects,(iii) impacts on the natural environment (including vegetation, agriculture, geomorphology, and pollution) and (iv) impacts on the human population (entrapments, injuries, fatalities). The scale was proposed as a tool on prevention planning, as the resulting maps offer insights on future impacts, highlighting the high severity areas.[11]
Flash floods can cause rapid soil erosion.[14] Much of the Nile delta sedimentation may come from flash flooding in the desert areas that drain into the Nile River.[15] However, flash floods of short duration produce relatively little bedrock erosion or channel widening, having their greatest impact from sedimentation on the floodplain.[16]
Some wetlands plants, such as certain varieties of rice, are adapted to endure flash flooding.[17] However, plants that thrive in drier areas can be harmed by flooding, as the plants can become stressed by the large amount of water.[18][19]
^"Turn Around Don't Drown". from the original on 2018-11-29. Retrieved 2007-06-25.
^Campos, Priscila Celebrini de Oliveira; Paz, Igor (2020). "Spatial Diagnosis of Rain Gauges' Distribution and Flood Impacts: Case Study in Itaperuna, Rio de Janeiro—Brazil". Water. 12 (4): 1120. doi:10.3390/w12041120.
^McGuire, Thomas (2004). (PDF). Earth Science: The Physical Setting. Amsco School Pubns Inc. p. 571. ISBN0-87720-196-X. Archived from the original (PDF) on 2008-06-25. Retrieved 2008-07-17.
^Jahns, R.H. (1949). "Desert floods" (PDF). Engineering and Science. 12 (8): 10–14. (PDF) from the original on 30 April 2021. Retrieved 17 July 2021.
^Smith, James A.; Baeck, Mary Lynn; Yang, Long; Signell, Julia; Morin, Efrat; Goodrich, David C. (December 2019). "The Paroxysmal Precipitation of the Desert: Flash Floods in the Southwestern United States". Water Resources Research. 55 (12): 10218–10247. Bibcode:2019WRR....5510218S. doi:10.1029/2019WR025480.
^ abDiakakis M.; Deligiannakis G.; Antoniadis Z.; Melaki M.; Katsetsiadou K.N.; Andreadakis E.; Spyrou N.I. & Gogou M. (2020). "Proposal of a flash flood impact severity scale for the classification and mapping of flash flood impacts". Journal of Hydrology. 590: 125452. Bibcode:2020JHyd..59025452D. doi:10.1016/j.jhydrol.2020.125452. S2CID 225031085.
^Calianno, Martin; Ruin, Isabelle; Gourley, Jonathan J. (January 2013). "Supplementing flash flood reports with impact classifications". Journal of Hydrology. 477: 1–16. Bibcode:2013JHyd..477....1C. doi:10.1016/j.jhydrol.2012.09.036.
^Špitalar, Maruša; Gourley, Jonathan J.; Lutoff, Celine; Kirstetter, Pierre-Emmanuel; Brilly, Mitja; Carr, Nicholas (November 2014). "Analysis of flash flood parameters and human impacts in the US from 2006 to 2012". Journal of Hydrology. 519: 863–870. Bibcode:2014JHyd..519..863S. doi:10.1016/j.jhydrol.2014.07.004.
^Brilly, Mitja (2001). "The Integrated Approach to Flash Flood Management". Coping with Flash Floods: 103–113. doi:10.1007/978-94-010-0918-8_12. ISBN978-0-7923-6826-7.
^Labib, Tarik M. (September 1981). "Soil erosion and total denudation due to flash floods in the Egyptian eastern desert". Journal of Arid Environments. 4 (3): 191–202. Bibcode:1981JArEn...4..191L. doi:10.1016/S0140-1963(18)31560-X.
^Marchi, Lorenzo; Cavalli, Marco; Amponsah, William; Borga, Marco; Crema, Stefano (November 2016). "Upper limits of flash flood stream power in Europe". Geomorphology. 272: 68–77. Bibcode:2016Geomo.272...68M. doi:10.1016/j.geomorph.2015.11.005.
^Hattori, Yoko; Nagai, Keisuke; Ashikari, Motoyuki (February 2011). "Rice growth adapting to deepwater". Current Opinion in Plant Biology. 14 (1): 100–105. doi:10.1016/j.pbi.2010.09.008. PMID 20934370.
^Perata, Pierdomenico; Armstrong, William; Voesenek, Laurentius A. C. J. (April 2011). "Plants and flooding stress: Commentary". New Phytologist. 190 (2): 269–273. doi:10.1111/j.1469-8137.2011.03702.x. PMID 21443603.
^Tamang, Bishal; Fukao, Takeshi (17 December 2015). "Plant Adaptation to Multiple Stresses during Submergence and Following Desubmergence". International Journal of Molecular Sciences. 16 (12): 30164–30180. doi:10.3390/ijms161226226. PMC4691168. PMID 26694376.
Further readingEdit
Schmittner, Karl-Erich; Pierre Giresse (August 1996). "Modelling and application of the geomorphic and environmental controls on flash flood flow". Geomorphology. 16 (4): 337–47. Bibcode:1996Geomo..16..337S. doi:10.1016/0169-555X(96)00002-5.
External linksEdit
Wikimedia Commons has media related to Flash floods.
Wikivoyage has a travel guide for Flash floods.
Scottish Flash Flood on YouTube Public clip of the Fochabers flood in Moray September 9
, choosing an uncertainty analysis for flood modelling.
Great footage of flash floods in the arid midwest heading down dry washes after heavy rain.
Map of central Texas flash flood alley.
Workshop Proceedings Flash Flood Management
Workshop Proceedings Flash Flood Forecasting
Hydrologic Research Center
October 07, 2023
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The examples and perspective in this article may not represent a worldwide view of the subject You may improve this article discuss the issue on the talk page or create a new article as appropriate October 2022 Learn how and when to remove this template message A flash flood is a rapid flooding of low lying areas washes rivers dry lakes and depressions It may be caused by heavy rain associated with a severe thunderstorm hurricane or tropical storm or by meltwater from ice or snow flowing over ice sheets or snowfields Flash floods may also occur after the collapse of a natural ice or debris dam or a human structure such as a man made dam as occurred before the Johnstown Flood of 1889 Flash floods are distinguished from regular floods by having a timescale of fewer than six hours between rainfall and the onset of flooding 1 An underpass in Charlottesville V A during normal conditions upper and after fifteen minutes of heavy rain lower Driving through a flash flooded roadA flash flood after a thunderstorm in the Gobi MongoliaFlash floods are a significant hazard causing more fatalities in the U S in an average year than lightning tornadoes or hurricanes Flash floods can also deposit large quantities of sediments on floodplains and can be destructive of vegetation cover not adapted to frequent flood conditions Contents 1 Causes 2 Hazards 3 Flash flood impacts 4 See also 5 References 6 Further reading 7 External linksCauses Edit nbsp Flash flooded road in Northern Mexico after a 3 5 hour long thunderstorm that occurred during a drought that lasted nearly 1 yearFlash floods most often occur in dry areas that have recently received precipitation but they may be seen anywhere downstream from the source of the precipitation even many miles from the source In areas on or near volcanoes flash floods have also occurred after eruptions when glaciers have been melted by the intense heat Flash floods are known to occur in the highest mountain ranges of the United States and are also common in the arid plains of the Southwestern United States Flash flooding can also be caused by extensive rainfall released by hurricanes and other tropical storms as well as the sudden thawing effect of ice dams 2 3 Human activities can also cause flash floods to occur When dams fail a large quantity of water can be released and destroy everything in its path 3 Hazards Edit nbsp A flash flood greatly inundates a small ditch flooding barns and ripping out newly installed drain pipes The United States National Weather Service gives the advice Turn Around Don t Drown for flash floods that is it recommends that people get out of the area of a flash flood rather than trying to cross it Many people tend to underestimate the dangers of flash floods What makes flash floods most dangerous is their sudden nature and fast moving water A vehicle provides little to no protection against being swept away it may make people overconfident and less likely to avoid the flash flood More than half of the fatalities attributed to flash floods are people swept away in vehicles when trying to cross flooded intersections 4 As little as 2 feet 0 61 m of water is enough to carry away most SUV sized vehicles 5 The U S National Weather Service reported in 2005 that using a national 30 year average more people die yearly in floods 127 on average than by lightning 73 tornadoes 65 or hurricanes 16 6 In deserts flash floods can be particularly deadly for several reasons First storms in arid regions are infrequent but they can deliver an enormous amount of water in a very short time Second these rains often fall on poorly absorbent and often clay like soil which greatly increases the amount of runoff that rivers and other water channels have to handle 7 These regions tend not to have the infrastructure that wetter regions have to divert water from structures and roads such as storm drains culverts and retention basins either because of sparse population or poverty or because residents believe the risk of flash floods is not high enough to justify the expense In fact in some areas desert roads frequently cross a dry river and creek beds without bridges From the driver s perspective there may be clear weather when a river unexpectedly forms ahead of or around the vehicle in a matter of seconds 8 Finally the lack of regular rain to clear water channels may cause flash floods in deserts to be headed by large amounts of debris such as rocks branches and logs 9 Deep slot canyons can be especially dangerous to hikers as they may be flooded by a storm that occurs on a mesa miles away The flood sweeps through the canyon the canyon makes it difficult to climb up and out of the way to avoid the flood For example a cloudburst in southern Utah on 14 September 2015 resulted in 20 flash flood fatalities of which seven fatalities occurred at Zion National Park when hikers were trapped by floodwaters in a slot canyon 10 Flash flood impacts EditSee also List of flash floods Flash floods induce severe impacts in both the built and the natural environment The effects of flash floods can be catastrophic and show extensive diversity ranging from damages in buildings and infrastructure to impacts on vegetation human lives and livestock The effects are particularly difficult to characterize in urban areas 11 Researchers have used datasets such as the Severe Hazards Analysis and Verification Experiment SHAVE and the U S National Weather Service NWS Storm Data datasets to connect the impact of flash floods with the physical processes involved in flash flooding This should increase the reliability of flash flood impact forecasting models 12 Analysis of flash floods in the United States between 2006 and 2012 shows that injuries and fatalities are most likely in small rural catchments that the shortest events are also the most dangerous that the hazards are greatest after nightfall and that a very high fraction of injuries and fatalities involve vehicles 13 An impact severity scale is proposed in 2020 providing a coherent overview of the flash flood effects through the classification of impact types and severity and mapping their spatial extent in a continuous way across the floodplain Depending on the affected elements the flood effects are grouped into 4 categories i impacts on built environment ii impacts on man made mobile objects iii impacts on the natural environment including vegetation agriculture geomorphology and pollution and iv impacts on the human population entrapments injuries fatalities The scale was proposed as a tool on prevention planning as the resulting maps offer insights on future impacts highlighting the high severity areas 11 Flash floods can cause rapid soil erosion 14 Much of the Nile delta sedimentation may come from flash flooding in the desert areas that drain into the Nile River 15 However flash floods of short duration produce relatively little bedrock erosion or channel widening having their greatest impact from sedimentation on the floodplain 16 Some wetlands plants such as certain varieties of rice are adapted to endure flash flooding 17 However plants that thrive in drier areas can be harmed by flooding as the plants can become stressed by the large amount of water 18 19 See also EditCoastal flood Drowning Flash Flood Guidance Systems Flash flood warning Flash flood watch Freshet Huayco Lifesaving Kalla kadal Storm surge JokulhlaupReferences Edit Flash Flooding Definition National Weather Service Archived from the original on September 1 2017 Retrieved August 31 2017 WeatherEye 2007 Flash Flood Sinclair Acquisition IV Inc Archived from the original on 2009 02 27 Retrieved 2009 09 09 a b National Weather Service Forecast Office Morristown Tennessee 2006 03 07 Definitions of flood and flash flood National Weather Service Southern Region Headquarters Archived from the original on 2006 09 29 Retrieved 2009 09 09 Watches Warnings amp Advisories Flash Flood Warning National Weather Service Archived from the original on 2008 01 11 Retrieved 2007 06 25 A Preparedness Guide to flash floods 1 weather related killer in the United States U S Department of Commerce National Oceanic and Atmospheric Administration National Weather Service Federal Emergency Management Agency American Red Cross July 1992 Archived from the original on 2007 07 05 Retrieved 2007 06 25 Turn Around Don t Drown Archived from the original on 2018 11 29 Retrieved 2007 06 25 Campos Priscila Celebrini de Oliveira Paz Igor 2020 Spatial Diagnosis of Rain Gauges Distribution and Flood Impacts Case Study in Itaperuna Rio de Janeiro Brazil Water 12 4 1120 doi 10 3390 w12041120 McGuire Thomas 2004 Weather Hazards and the Changing Atmosphere PDF Earth Science The Physical Setting Amsco School Pubns Inc p 571 ISBN 0 87720 196 X Archived from the original PDF on 2008 06 25 Retrieved 2008 07 17 Jahns R H 1949 Desert floods PDF Engineering and Science 12 8 10 14 Archived PDF from the original on 30 April 2021 Retrieved 17 July 2021 Smith James A Baeck Mary Lynn Yang Long Signell Julia Morin Efrat Goodrich David C December 2019 The Paroxysmal Precipitation of the Desert Flash Floods in the Southwestern United States Water Resources Research 55 12 10218 10247 Bibcode 2019WRR 5510218S doi 10 1029 2019WR025480 a b Diakakis M Deligiannakis G Antoniadis Z Melaki M Katsetsiadou K N Andreadakis E Spyrou N I amp Gogou M 2020 Proposal of a flash flood impact severity scale for the classification and mapping of flash flood impacts Journal of Hydrology 590 125452 Bibcode 2020JHyd 59025452D doi 10 1016 j jhydrol 2020 125452 S2CID 225031085 Calianno Martin Ruin Isabelle Gourley Jonathan J January 2013 Supplementing flash flood reports with impact classifications Journal of Hydrology 477 1 16 Bibcode 2013JHyd 477 1C doi 10 1016 j jhydrol 2012 09 036 Spitalar Marusa Gourley Jonathan J Lutoff Celine Kirstetter Pierre Emmanuel Brilly Mitja Carr Nicholas November 2014 Analysis of flash flood parameters and human impacts in the US from 2006 to 2012 Journal of Hydrology 519 863 870 Bibcode 2014JHyd 519 863S doi 10 1016 j jhydrol 2014 07 004 Brilly Mitja 2001 The Integrated Approach to Flash Flood Management Coping with Flash Floods 103 113 doi 10 1007 978 94 010 0918 8 12 ISBN 978 0 7923 6826 7 Labib Tarik M September 1981 Soil erosion and total denudation due to flash floods in the Egyptian eastern desert Journal of Arid Environments 4 3 191 202 Bibcode 1981JArEn 4 191L doi 10 1016 S0140 1963 18 31560 X Marchi Lorenzo Cavalli Marco Amponsah William Borga Marco Crema Stefano November 2016 Upper limits of flash flood stream power in Europe Geomorphology 272 68 77 Bibcode 2016Geomo 272 68M doi 10 1016 j geomorph 2015 11 005 Hattori Yoko Nagai Keisuke Ashikari Motoyuki February 2011 Rice growth adapting to deepwater Current Opinion in Plant Biology 14 1 100 105 doi 10 1016 j pbi 2010 09 008 PMID 20934370 Perata Pierdomenico Armstrong William Voesenek Laurentius A C J April 2011 Plants and flooding stress Commentary New Phytologist 190 2 269 273 doi 10 1111 j 1469 8137 2011 03702 x PMID 21443603 Tamang Bishal Fukao Takeshi 17 December 2015 Plant Adaptation to Multiple Stresses during Submergence and Following Desubmergence International Journal of Molecular Sciences 16 12 30164 30180 doi 10 3390 ijms161226226 PMC 4691168 PMID 26694376 Further reading EditSchmittner Karl Erich Pierre Giresse August 1996 Modelling and application of the geomorphic and environmental controls on flash flood flow Geomorphology 16 4 337 47 Bibcode 1996Geomo 16 337S doi 10 1016 0169 555X 96 00002 5 External links Edit nbsp Wikimedia Commons has media related to Flash floods nbsp Wikivoyage has a travel guide for Flash floods Scottish Flash Flood on YouTube Public clip of the Fochabers flood in Moray September 9 Decision tree to choose an uncertainty method for hydrological and hydraulic modelling choosing an uncertainty analysis for flood modelling Great footage of flash floods in the arid midwest heading down dry washes after heavy rain Map of central Texas flash flood alley Workshop Proceedings Flash Flood Management Workshop Proceedings Flash Flood Forecasting Hydrologic Research Center Retrieved from https en wikipedia org w index php title Flash flood amp oldid 1178629861, wikipedia, wiki, book, books, library,
