View stunning SlideShares in full-screen with the new iOS app!Introducing SlideShare for AndroidExplore all your favorite topics in the SlideShare appGet the SlideShare app to Save for Later — even offline
View stunning SlideShares in full-screen with the new Android app!View stunning SlideShares in full-screen with the new iOS app!
FloodFrom Wikipedia, the free encyclopediaJump to: navigation, searchFor other uses, see Flood (disambiguation).Contemporary picture of the flood that struck the North Sea coast of Germany and Denmark inOctober 1634.People seeking refuge from flood in Java.ca. 1865–1876.Flooding of a creek due to heavy monsoonal rain and high tide in Darwin, Northern Territory,Australia.
Jeddah Flood, covering King Abdullah Street in Saudi Arabia.Flooding near Key West, Florida, United States from Hurricane Wilmas storm surge in October2005.Flash flooding caused by heavy rain falling in a short amount of time.
Dozens of villages were inundated when rain pushed the rivers of northwestern Bangladesh overtheir banks in early October 2005. The Moderate Resolution Imaging Spectroradiometer(MODIS) on NASA’s Terra satellite captured the top image of the flooded Ghaghat and AtraiRivers on October 12, 2005. The deep blue of the rivers is spread across the countryside in theflood image.A flood is an overflow of water that submerges land. The European Union (EU) FloodsDirectivedefines a flood as a covering by water of land not normally covered by water. In thesense of "flowing water", the word may also be applied to the inflow of the tide. Flooding mayresult from the volume of water within a body of water, such as a river or lake, which overflowsor breaks levees, with the result that some of the water escapes its usual boundaries, or may bedue to 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 precipitationand snow melt, it is not a significant flood unless such escapes of water endanger land areas usedby man like a village, city or other inhabited area.Floods can also occur in rivers, when flow exceeds the capacity of the river channel, particularlyat bends or meanders. Floods often cause damage to homes and businesses if they are placed innatural flood plains of rivers. While flood damage can be virtually eliminated by moving awayfrom rivers and other bodies of water, since time out of mind, people have lived and worked bythe water to seek sustenance and capitalize on the gains of cheap and easy travel and commerceby being near water. That humans continue to inhabit areas threatened by flood damage isevidence that the perceived value of living near the water exceeds the cost of repeated periodicflooding.The word "flood" comes from the Old Englishflod, a word common to Germanic languages(compare German Flut, Dutch vloed from the same root as is seen in flow, float; also comparewith Latin fluctus, flumen). Deluge myths are mythical stories of a great flood sent by a deity or
deities to destroy civilization as an act of divine retribution, and are featured in the mythology ofmany cultures.Contents[hide] 1 Principal types and causes o 1.1 Areal o 1.2 Riverine o 1.3 Estuarine o 1.4 Coastal o 1.5 Catastrophic o 1.6 Human-induced 2 Effects o 2.1 Primary effects o 2.2 Secondary effects o 2.3 Tertiary and long-term effects 3 Control o 3.1 Europe o 3.2 North America o 3.3 Asia o 3.4 Africa o 3.5 Clean-up safety 4 Benefits 5 Computer modelling 6 Deadliest floods 7 See also 8 References 9 Bibliography 10 External links Principal types and causes Areal Floods often happen over flat or low-lying areas when the ground is saturated and water either cannot run off, or cannot run off quickly enough to stop accumulating. This may be later followed by a river flood as water moves away from the areal floodplain into local rivers and streams. Floods can occur if water accumulates across an impermeable surface (e.g. from rainfall) and cannot rapidly dissipate (i.e. gentle orientation or low evaporation). A series of storms moving over the same area can cause areal flash flooding.
A muddy flood is produced by an accumulation of runoff generated on cropland. Sediments are then detached by runoff and carried as suspended matter or bed load. Muddy runoff is more likely detected when it reaches inhabited areas. Muddy floods are therefore a hill slope process, and confusion with mudflows produced by mass movements should be avoided. Riverine Slow kinds: Runoff from sustained rainfall or rapid snow melt exceeding the capacity of a rivers channel. Causes include heavy rains from monsoons, hurricanes and tropical depressions, foreign winds and warm rain affecting snow pack. Unexpected drainage obstructions such as landslides, ice, or debris can cause slow flooding upstream of the obstruction. Fast kinds: include river flash floods resulting from convective precipitation (intense thunderstorms) or sudden release from an upstream impoundment created behind a dam, landslide, or glacier. Dam-building beavers can flood low-lying urban and rural areas, often causing significant damage. Estuarine Commonly caused by a combination of sea tidal surges caused by storm-force winds and high river stages due to heavy rain. Coastal Caused by severe sea storms, or as a result of another hazard (e.g. tsunami or hurricane). A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category. Catastrophic Caused by a significant and unexpected event e.g. dam breakage, or as a result of another hazard (e.g. earthquake or volcanic eruption). See outburst flood. Human-induced Accidental damage by workmen to tunnels or pipes. Effects Primary effects Physical damage – damage to structures, including bridges, buildings, sewerage systems, roadways, and canals.
 Secondary effects Water supplies – Contamination of water. Clean drinking water will become scarce. Diseases – Unhygienic conditions. Spread of water-borne diseases. Crops and food supplies – Shortage of food crops can be caused due to loss of entire harvest. However, lowlands near rivers depend upon river silt deposited by floods in order to add nutrients to the local soil. Trees – Non-tolerant species can die from suffocation. Transport – Transport links destroyed, so hard to get emergency aid to those who need it. Tertiary and long-term effects Economic – economic hardship due to temporary decline in tourism, rebuilding costs, food shortage leading to price increase, etc. Psychological – flooding can be highly traumatic for individuals, in particular where deaths, serious injuries and loss of property occurs. Control Main article: Flood controlAutumn Mediterranean flooding in Alicante (Spain), 1997.
The River Berounka, Czech Republic, burst its banks in the 2002 European floods and houses inthe village of HlásnáTřebaň, Beroun District, were inundated.Debris and bank erosion left after the 2009 Red River Flood in Winnipeg, Manitoba.Pittsburgh floods in 1936Flooding near Snoqualmie, Washington, 2009.Floods in Bangladesh 2009
In many countries across the world, rivers prone to floods are often carefully managed. Defensessuch as levees,bunds, reservoirs, and weirs are used to prevent rivers from bursting their banks.When these defenses fail, emergency measures such as sandbags or portable inflatable tubes areused. Coastal flooding has been addressed in Europe and the Americas with coastal defences,such as sea walls, beach nourishment, and barrier islands. EuropeRemembering the misery and destruction caused by the 1910 Great Flood of Paris, the Frenchgovernment built a series of reservoirs called Les GrandsLacs de Seine (or Great Lakes) whichhelps remove pressure from the Seine during floods, especially the regular winter flooding.London is protected from sea flooding by the Thames Barrier, a huge mechanical barrier acrossthe River Thames, which is raised when the sea water level reaches a certain point.Venice has a similar arrangement, although it is already unable to cope with very high tides; anew system of variable-height dikes is under construction. The defences of both London andVenice would be rendered inadequate if sea levels were to rise.The Adige in Northern Italy was provided with an underground canal that allows to drain part ofits flow into the Garda Lake (in the Po drainage basin), thus lessening the risk of estuarinefloods. The underground canal has been used twice, in 1966 and 2000.The largest and most elaborate flood defences can be found in the Netherlands, where they arereferred to as Delta Works with the Oosterschelde dam as its crowning achievement. Theseworks were built in response to the North Sea flood of 1953 of the southwestern part of theNetherlands. The Dutch had already built one of the worlds largest dams in the north of thecountry: the Afsluitdijk (closing occurred in 1932).Currently the Saint Petersburg Flood Prevention Facility Complex is to be finished by 2008, inRussia, to protect Saint Petersburg from storm surges. It also has a main traffic function, as itcompletes a ring road around Saint Petersburg. Eleven dams extend for 25.4 kilometres and standeight metres above water level.In Austria, flooding for over 150 years, has been controlled by various actions of the ViennaDanube regulation, with dredging of the main Danube during 1870–75, and creation of the NewDanube from 1972–1988.In Northern Ireland flood risk management is provided by Rivers Agency. North AmericaAnother elaborate system of floodway defences can be found in the Canadian province ofManitoba. The Red River flows northward from the United States, passing through the city ofWinnipeg (where it meets the Assiniboine River) and into Lake Winnipeg. As is the case with allnorth-flowing rivers in the temperate zone of the Northern Hemisphere, snowmelt in southern
sections may cause river levels to rise before northern sections have had a chance to completelythaw. This can lead to devastating flooding, as occurred in Winnipeg during the spring of 1950.To protect the city from future floods, the Manitoba government undertook the construction of amassive system of diversions, dikes, and floodways (including the Red River Floodway and thePortage Diversion). The system kept Winnipeg safe during the 1997 flood that devastated manycommunities upriver from Winnipeg, including Grand Forks, North Dakota and Ste. Agathe,Manitoba. It also kept Winnipeg safe during the 2009 flood.In the U.S., the New Orleans Metropolitan Area, 35% of which sits below sea level, is protectedby hundreds of miles of levees and flood gates. This system failed catastrophically, in numeroussections, during Hurricane Katrina, in the city proper and in eastern sections of the Metro Area,resulting in the inundation of approximately 50% of the metropolitan area, ranging from a fewcentimetres to 8.2 metres (a few inches to 27 feet) in coastal communities. In an act ofsuccessful flood prevention, the Federal Government of the United States offered to buy outflood-prone properties in the United States in order to prevent repeated disasters after the 1993flood across the Midwest. Several communities accepted and the government, in partnership withthe state, bought 25,000 properties which they converted into wetlands. These wetlands act as asponge in storms and in 1995, when the floods returned, the government did not have to expendresources in those areas. AsiaIn India, Bangladesh and China, flood diversion areas are rural areas that are deliberately floodedin emergencies in order to protect cities.Many have proposed that loss of vegetation (deforestation) will lead to a risk increase. Withnatural forest cover the flood duration should decrease. Reducing the rate of deforestation shouldimprove the incidents and severity of floods. AfricaIn Egypt, both the Aswan Dam (1902) and the Aswan High Dam (1976) have controlled variousamounts of flooding along the Nile river. Clean-up safetyClean-up activities following floods often pose hazards to workers and volunteers involved in theeffort. Potential dangers include: water polluted by mixing with and causing overflows fromsanitary sewers, electrical hazards, carbon monoxide exposure, musculoskeletal hazards, heat orcold stress, motor vehicle-related dangers, fire, drowning, and exposure to hazardousmaterials. Because flooded disaster sites are unstable, clean-up workers might encounter sharpjagged debris, biological hazards in the flood water, exposed electrical lines, blood or other bodyfluids, and animal and human remains. In planning for and reacting to flood disasters, managersprovide workers with hard hats, goggles, heavy work gloves, life jackets, and watertight bootswith steel toes and insoles.
 BenefitsThere are many disruptive effects of flooding on human settlements and economic activities.However, floods (in particular the more frequent/smaller floods) can also bring many benefits,such as recharging ground water, making soil more fertile and providing nutrients in which it isdeficient. Flood waters provide much needed water resources in particular in arid and semi-aridregions where precipitation events can be very unevenly distributed throughout the year.Freshwater floods, particularly play an important role in maintaining ecosystems in rivercorridors and are a key factor in maintaining floodplain biodiversity. Flooding adds a lot ofnutrients to lakes and rivers which leads to improved fisheries for a few years, also because ofthe suitability of a floodplain for spawning (little predation and a lot of nutrients). Fish like theweather fish make use of floods to reach new habitats. Together with fish also birds profit fromthe boost in 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, amongothers. The viability for hydrological based renewable sources of energy is higher in flood proneregions. Computer modellingWhile flood modelling is a fairly recent practice, attempts to understand and manage themechanisms at work in floodplains have been made for at least six millennia. The recentdevelopment in computational flood modelling has enabled engineers to step away from the triedand tested "hold or break" approach and its tendency to promote overly engineered structures.Various computational flood models have been developed in recent years; either 1D models(flood levels measured in the channel) and 2D models (variable flood depth measured across theextent of the floodplain). HEC-RAS, the Hydraulic Engineering Centre model, is currentlyamong the most popular if only because it is available free of charge. Other models such asTUFLOW combine 1D and 2D components to derive flood depth across the river channel andfloodplain. To date the focus has primarily been on mapping tidal and fluvial flood events, butthe 2007 flood events in the UK have shifted the emphasis there onto the impact of surface waterflooding. Deadliest floodsMain article: List of deadliest floodsBelow is a list of the deadliest floods worldwide, showing events with death tolls at or above100,000 individuals.
Death toll Event Location Date2,500,000– 1931 China floods China 19313,700,000900,000– 1887 Yellow River (Huang He) China 18872,000,000 flood 1938 Yellow River (Huang He)500,000–700,000 China 1938 flood Banqiao Dam failure, result of Typhoon Nina. Approximately231,000 86,000 people died from flooding China 1975 and another 145,000 died during subsequent disease.230,000 Indian Ocean tsunami Indonesia 2004145,000 1935 Yangtze river flood China 1935100,000+ St. Felixs Flood, storm surge Netherlands 1530100,000 Hanoi and Red River Delta flood North Vietnam 1971100,000 1911 Yangtze river flood China 1911 See also Environment portal Ecology portal Chicago Flood, man-made flood under downtown Chicago Disaster preparedness Flood control in the Netherlands Flood pulse concept Flood Risk Assessment Floods directive Floods in Australia Floods in the Netherlands Floods in the United States List of floods SMS (hydrology software) Storm tides of the North Sea References 1. ^ MSN Encarta Dictionary. Flood. Retrieved on 2006-12-28. Archived 2009-10-31. 2. ^Directive 2007/60/EC Chapter 1 Article2. eur-lex.europa.eu. Retrieved on 2012-06-12. 3. ^ Glossary of Meteorology (June 2000). Flood. Retrieved on 2009-01-09. 4. ^http://www.southasianfloods.org
5. ^ Stephen Bratkovich, Lisa Burban, et al., "Flooding and its Effects on Trees", USDA Forest Service, Northeastern Area State and Private Forestry, St. Paul, MN, September 1993, webpage: Na.fs.fed.us-flood- cover. 6. ^ Henry Petroski (2006). Levees and Other Raised Ground. 94. American Scientist. pp. 7–11. 7. ^ See Jeffrey H. Jackson, Paris Under Water: How the City of Light Survived the Great Flood of 1910 (New York: Palgrave Macmillan, 2010). 8. ^United States Department of Commerce (June 2006). "Hurricane Katrina Service Assessment Report" (PDF). http://www.weather.gov/om/assessments/pdfs/Katrina.pdf. Retrieved 2006-07-14. 9. ^ Amanda Ripley. "Floods, Tornadoes, Hurricanes, Wildfires, Earthquakes... Why We Dont Prepare."Time. August 28, 2006. 10. ^"China blows up seventh dike to divert flooding."China Daily. 2003-07-07. 11. ^ Bradshaw CJ, Sodhi NS, Peh SH, Brook BW. (2007). Global evidence that deforestation amplifies flood risk and severity in the developing. Also a flood has recently hit Pakistan which is said to be more devastating then the Tsunami of 2005 world. Global Change Biology, 13: 2379–2395. 12. ^ United States National Institute for Occupational Safety and Health (NIOSH). Storm and Flood Cleanup. Accessed 23 September 2008. 13. ^ NIOSH. NIOSH Warns of Hazards of Flood Cleanup Work. NIOSH Publication No. 94-123. 14. ^ WMO/GWP Associated Programme on Flood Management "Environmental Aspects of Integrated Flood Management." WMO, 2007 15. ^Extension of the Flood Pulse Concept. Kops.ub.uni-konstanz.de. Retrieved on 2012-06-12. 16. ^Birdlife soars above Botswanas floodplains. Africa.ipsterraviva.net (2010-10-15). Retrieved on 2012-06- 12. 17. ^Dyhouse, G. "Flood modelling Using HEC-RAS (First Edition)." Haestad Press, Waterbury (USA), 2003. 18. ^ United States Army Corps of Engineers. Davis, CA. Hydrologic Engineering Center. 19. ^ BMT WBM Pty Ltd., Brisbane, Queensland. "TUFLOW Flood and Tide Simulation Software." 20. ^ Cabinet Office, UK. "Pitt Review: Lessons learned from the 2007 floods." June 2008. 21. ^Worst Natural Disasters In History. Nbc10.com (2012-06-07). Retrieved on 2012-06-12. Bibliography OConnor, Jim E. and John E. Costa. (2004). The Worlds Largest Floods, Past and Present: Their Causes and Magnitudes [Circular 1254]. Washington, D.C.: 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, D.C.: 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. Texas State University – San Marcos. External links Wikimedia Commons has media related to: Flood Wikinews has related news: Flood This articles use of external links may not follow Wikipedias policies or guidelines. Please improve this article by removing excessive or inappropriate external links, and converting useful links where appropriate into footnote references. (January 2011)
Website on the Great Flood of Paris in 1910U.S. Centers for Disease Control and Prevention (CDC) Healthy Water – Flood WaterExposure Health risks, cleanup of flood waters, and links to flood resourcesAmerican Water Resources AssociationAssociated Programme on Flood Management from World Meteorological OrganizationDartmouth Flood ObservatoryDecision tree to choose an uncertainty method for hydrological and hydraulic modelling,Choosing an uncertainty analysis for flood modeling.DeltaWorks.Org Flood protecting dams and barriers project in the NetherlandsVideo: Monsoon flooding, in Phnom Penh, CambodiaEurope floods 2006Flood Risk Management Research ConsortiumInternational Flood InitiativeInternational teaching module "Integrated Flood Risk Management of Extreme Events"(Floodmaster)Predictions Off for Global Warming Flood Risk – Study.Protecting against the Next Katrina – Scientific American Magazine (October 2005)Related articles at Appropedia, a wiki for non-Wikipedia (projects & practical "how to")content.Safecoast Knowledge exchange on coastal flooding and climate change in the North SearegionSocial & Economic Benefits/Costs of Heavy Rain & Flooding NOAA EconomicsRiversagencyni.gov.uk, Rivers Agency of Northern IrelandUN-CECAR research and courses on flood disaster risk management and climate changeadaptation