A flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers and streams. It is caused by heavy rain associated with a thunderstorm A thunderstorm, also known as an electrical storm, a lightning storm, or a storm is a form of weather characterized by the presence of lightning and its effect: thunder. It is usually accompanied by heavy rain and sometimes snow, hail, or no precipitation at all. Thunderstorms may line up in a series, and strong or severe thunderstorms may rotate, hurricane, or tropical storm. Flash floods can also occur after the collapse of an ice dam Sometimes a glacier flows down a valley to a confluence where the other branch carries an unfrozen river. The glacier blocks the river, which backs up into a lake, which eventually overflows or undermines the ice dam, suddenly releasing the impounded water, or a human structure, such as a dam, for example, the Johnstown Flood of 1889. Flash floods are distinguished from a regular flood A flood is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Flooding may result from the volume of water within a body of water, such as a river or lake, which overflows or breaks levies, with the result that some of the water by a timescale less than six hours.[1]
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Causes
Flash flooding occurs when the ground becomes saturated with water that has fallen too quickly to be absorbed. The runoff collects in low-lying areas and rapidly flows downhill. Flash floods most often occur in normally dry areas that have recently received precipitation, but may be seen anywhere downstream from the source of the precipitation - even dozens of miles from the source. In areas on or near volcanic mountains, flash floods have also occurred after eruptions, when glaciers A glacier is a large mass of ice moving slowly over some land surface or down a valley, formed over long periods from the accumulation of snow in areas where the amount of snow that falls exceeds the amount that melts. The word glacier comes from French via the Vulgar Latin glacia, and ultimately from Latin glacies meaning ice have been melted by the intense heat.
Hazards
The United States National Weather Service The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. It is tasked with providing "weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent gives the advice "Turn Around, Don't Drown" in reference to flash floods; that is, it recommends that people get out of the area of a flash flood, rather than trying to cross it. Most people tend to underestimate the dangers of flash floods.
Flash floods are extremely dangerous because of their sudden nature. Being in 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.[2] As little as two feet of water (60 cm) can be enough to carry away most SUV A sport utility vehicle is a generic marketing term for a vehicle similar to a station wagon, but built on a light-truck chassis. Usually equipped with four-wheel drive for on or off-road ability, some SUVs include the towing capacity of a pickup truck with the passenger-carrying space of a minivan. Since SUVs are considered light trucks and often-sized vehicles.[3] In the United States, the National Weather Service (part of the National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding) reported in 2005 that, using a national 30-year average, more people die yearly in floods (127 on average) than by lightning Benjamin Franklin endeavored to test the theory that sparks shared some similarity with lightning by using a spire which was being erected in Philadelphia. While waiting for completion of the spire, he got the idea to use a flying object such as a kite. During the next thunderstorm, which was in June 1752, it was reported that he raised a kite, (73), tornadoes A tornado is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud (65), or hurricanes A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic (16).[4]
The desert southwestern U.S. is especially dangerous for both hikers and vehicles from the sudden onslaught of water from isolated thunderstorms. These rains fill poorly-absorbent and often clay Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired. Clay deposits are mostly composed of clay minerals , minerals which impart plasticity and harden when fired and/or dried, and variable amounts of-like dry riverbeds. A moving flood will usually be headed by a debris pile that may have wood branches and/or logs. Deep slot canyons can be especially dangerous to hikers as they may be flooded by a storm that occurs on a mesa A mesa is an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape. It is a characteristic landform of arid environments, particularly the southwestern United States. Many examples are also found in Spain, North and South Africa, Arabia, India, Australia, and the miles away, sweeping through the canyon, making it difficult to climb up and out of the way to avoid the flood. Valley roads frequently cross dry river and creek beds without bridges. From the driver's perspective, there may be clear weather, when unexpectedly a river forms ahead of or around the vehicle in a matter of seconds.[5]
Historical examples
- The Lynmouth disaster Lynmouth is a village in Devon, England, on the north edge of Exmoor of August 1952.
- 1967 1967 was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar Lisbon Lisbon is the capital and largest city of Portugal. It is also the seat of the district of Lisbon and capital of the Lisbon region. Its municipality, which matches the city proper excluding the larger continuous conurbation, has a municipal population of 564,477 in 84.8 km2 (33 sq mi), while the Lisbon Metropolitan Area in total has around 2.8 flash-flood A flash flood is a rapid flooding of geomorphic low-lying areas - washes, rivers and streams. It is caused by heavy rain associated with a thunderstorm, hurricane, or tropical storm. Flash floods can also occur after the collapse of an ice dam, or a human structure, such as a dam, for example, the Johnstown Flood of 1889. Flash floods are Lisbon Lisbon is the capital and largest city of Portugal. It is also the seat of the district of Lisbon and capital of the Lisbon region. Its municipality, which matches the city proper excluding the larger continuous conurbation, has a municipal population of 564,477 in 84.8 km2 (33 sq mi), while the Lisbon Metropolitan Area in total has around 2.8, Portugal Portugal /ˈpɔrtʃəɡəl/ , officially the Portuguese Republic (Portuguese: República Portuguesa), is a country on the Iberian Peninsula. Located in southwestern Europe, Portugal is the westernmost country of mainland Europe and is bordered by the Atlantic Ocean to the west and south and by Spain to the north and east. The Atlantic archipelagos. 464 dead.
- 1971 Kuala Lumpur floods (in Malaysia)
- 1997 flash flood kills eleven in Antelope Canyon Antelope Canyon is the most-visited and most-photographed slot canyon in the American Southwest. It is located on Navajo land near Page, Arizona. Antelope Canyon includes two separate, photogenic slot canyon sections, referred to individually as Upper Antelope Canyon or The Crack; and Lower Antelope Canyon or The Corkscrew.
- 1998 flash flooding in San Marcos, Texas San Marcos is a city in the U.S. state of Texas, and is the county seat of Hays County. San Marcos is located on the Interstate 35 corridor, between Austin and San Antonio. Founded on the banks of the San Marcos River, the area is considered to be among the oldest continuously inhabited sites in the Northern Hemisphere. San Marcos is home to Texas resulted from rains totaling from 15 to 30 inches (760 mm).
- Boscastle Boscastle is a village and fishing port on the north coast of Cornwall, England in the civil parish of Forrabury and Minster. It is situated 14 miles (23 km) south of Bude and 5 miles (8 km) north-east of Tintagel flooding of 2004.
- 2006 Mount Rainier National Park Flooding. [6]
- 2006 flash flooding kills 125 in Ethiopia.[7]
- 2007 Sudan floods On 3 July 2007, flash floods started to devastated many parts of Sudan, including some areas in conflict-battered Darfur and war-torn Southern Sudan
- Shadyside, Ohio flooding on June 14 June 14 is the 165th day of the year in the Gregorian calendar. There are 200 days remaining until the end of the year, 1990 1990 was a common year starting on Monday (link displays the 1990 Gregorian calendar)[8]
- The Quad Cities The Quad Cities is a geographic region of the Mid-Mississippi Valley of the United States that includes several communities in the states of Iowa and Illinois. As of 2008, the population is 377,625. The five most populous cities in the region are: Duck Creek Floods of 1990[9]
- The June 12-13, 2008 2008 was a leap year that started on Tuesday of the Anno Domini era (or Common Era) Floods around Duck Creek in Davenport, Iowa[10]
- The 1976 Big Thompson River flood The Big Thompson River is a tributary of the South Platte River, approximately 78 miles long, in the U.S. state of Colorado, which killed 143 people in Colorado
See also
Further reading
- Schmittner, Karl-Erich; Pierre Giresse (August 1996). "Modelling and application of the geomorphic and environmental controls on flash flood flow". Geomorphology 16 (4): 337–347. doi The Digital Object Identifier System is a managed system for persistent identification of content-related entities on digital networks. These entities may be content items (digital files, physical objects, abstract works), or any related entities in a content transaction (e.g. licenses, parties, etc.). "DOI" is sometimes used to mean the:10.1016/0169-555X(96)00002-5.
References
- ^ "Definitions of flood and flash flood". National Weather Service. http://www.srh.noaa.gov/mrx/hydro/flooddef.php. Retrieved on 2008-08-19.
- ^ "Watches, Warnings & Advisories—Flash Flood Warning". National Weather Service. http://forecasts.weather.gov/wwamap/wwatxtget.php?cwa=usa&wwa=Flash%20Flood%20Warning. Retrieved on 2007-06-25.
- ^ "A Preparedness Guide to flash floods #1 weather-related killer in the United States". U.S. Department of Commerce The United States Department of Commerce is the Cabinet department of the United States government concerned with promoting economic growth. It was originally created as the United States Department of Commerce and Labor on February 14, 1903. It was subsequently renamed to the Department of Commerce on March 4, 1913, and its bureaus and agencies, National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding National Weather Service The National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration (NOAA) of the United States government. It is tasked with providing "weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent, FEMA The Federal Emergency Management Agency, or FEMA, is an agency of the United States Department of Homeland Security, initially created by Presidential Order on April 1, 1979. The primary purpose of FEMA is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and state, American Red Cross The American Red Cross is a humanitarian organization that provides emergency assistance, disaster relief and education inside the United States, and is the designated U.S. affiliate of the International Federation of Red Cross and Red Crescent Societies. July 1992. http://www.nws.noaa.gov/om/brochures/ffbro.htm. Retrieved on 2007-06-25.
- ^ "Turn Around Don't Drown". http://www.srh.noaa.gov/tadd/. Retrieved on 2007-06-25.
- ^ McGuire, Thomas (2004). "Weather Hazards and the Changing Atmosphere". Earth Science: The Physical Setting. Amsco School Pubns Inc. pp. 571. ISBN 0-87720-196-X.
- ^ "November 2006 Flooding". NPS. http://www.nps.gov/mora/parknews/november-2006-flooding.htm. Retrieved on 2008-01-08.
- ^ "Flash floods kill 125 in Ethiopia". BBC. http://news.bbc.co.uk/2/hi/africa/4791813.stm. Retrieved on 2007-07-03.
- ^ Shadyside, Ohio Floods of 1990. NOAA The National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. NOAA warns of dangerous weather, charts seas and skies, guides the use and protection of ocean and coastal resources, and conducts research to improve understanding. Report In writing, a report is a document characterized by information or other content reflective of inquiry or investigation, which is tailored to the context of a given situation and audience. The purpose of reports is usually to inform. However, reports may include persuasive elements, such as recommendations, suggestions, or other motivating. Retrieved on May, 13, 2009.
- ^ "Flood Facts". QC Memory. http://www.qcmemory.org/Page/Flood_Facts.aspx?nt=266. Retrieved on 2009-04-16.
- ^ "Duck Creek Flooding Closes Davenport Streets". Quad Cities Online. http://www.qconline.com/archives/qco/display.php?id=391015. Retrieved on 2009-04-17.
External links
- Decision tree to choose an uncertainty method for hydrological and hydraulic modelling, choosing an uncertainty analysis for flood modelling.
- Flash Flood Alley movie and video clips.
- Flash Flood Safety information.
- 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
Categories: Flood Categories: Bodies of water | Weather | Natural hazards | Water waves
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Australia Queensland declares state of emergency
unknown
Wed, 01 Jul 2009 19:17:55 GM
THE public are being warned of . flash flooding. , as the heatwave looks set to trigger heavy downpours in South Wales and South West England on Thursday (July 2).
