Upload
annabel-butler
View
224
Download
0
Embed Size (px)
Citation preview
FLOODS
RIVER FLOODSStream overflows leveesMost destructive of all geologic hazardsCausesWeatherDams breaking
Floods of the 20th century
Cincinnati, OH
Des Moines, Iowa 1993
Mississippi 2001
Artificial Levees
To prevent river from floodingWalls made of-DirtSandbagsConcrete
levees
DutchEngland
US levees
floodplainsFlat area around a river; floodsPaving creates more run-offLeaving natural, acts like sponge
Flood plain useBest use? Leave it alone!OK use? Golf course, park, farmWorst use?
How to recognize a floodplain?
Floodplain map
100 year floodMisleading term1-in-a100 chance of river flooding every year! (1%)10 year flood?
1 in 100 chance
How can flooding be good?When river floods, nutrients from bottom of the river are distributed onto landProvides natural fertilizerGreat farmland!
See any problems?
Marquette, MI 2003tourist park
Flood uncovered glacier grooves
Flood insuranceMost homeowners do not haveGovernment assistanceReliefrelocation
Flash FloodsMost deadlyMost vehicle related
Due to impermeable ground
Storm sewer back up
Vassar, MI 1986
Stream gauges measures stream height to calculate crest
OR gauges measure stream discharge
hydrograph
Damsincrease erosion downstream (white water)Increased deposition upstreamMake river colder
Glen Canyon DamPurposes:Flood controlElectricityDrinking water
Glen Canyon Dam
Hoover dam
Grand Canyon Floodinghttp://youtube.com/watch?v=EIXn_KNI5dQ
To simulate natures floodsReplenish beaches
Water cycle