floods. river floods stream overflows levees stream overflows levees most destructive of all...
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FLOODS
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RIVER FLOODSStream overflows leveesMost destructive of all geologic hazardsCausesWeatherDams breaking
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Floods of the 20th century
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Cincinnati, OH
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Des Moines, Iowa 1993
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Mississippi 2001
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Artificial Levees
To prevent river from floodingWalls made of-DirtSandbagsConcrete
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levees
DutchEngland
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US levees
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floodplainsFlat area around a river; floodsPaving creates more run-offLeaving natural, acts like sponge
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Flood plain useBest use? Leave it alone!OK use? Golf course, park, farmWorst use?
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How to recognize a floodplain?
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Floodplain map
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100 year floodMisleading term1-in-a100 chance of river flooding every year! (1%)10 year flood?
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1 in 100 chance
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How can flooding be good?When river floods, nutrients from bottom of the river are distributed onto landProvides natural fertilizerGreat farmland!
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See any problems?
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Marquette, MI 2003tourist park
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Flood uncovered glacier grooves
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Flood insuranceMost homeowners do not haveGovernment assistanceReliefrelocation
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Flash FloodsMost deadlyMost vehicle related
Due to impermeable ground
Storm sewer back up
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Vassar, MI 1986
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Stream gauges measures stream height to calculate crest
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OR gauges measure stream discharge
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hydrograph
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Damsincrease erosion downstream (white water)Increased deposition upstreamMake river colder
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Glen Canyon DamPurposes:Flood controlElectricityDrinking water
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Glen Canyon Dam
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Hoover dam
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Grand Canyon Floodinghttp://youtube.com/watch?v=EIXn_KNI5dQ
To simulate natures floodsReplenish beaches
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Water cycle