100 t24 rivers - university of...
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GEOL100(PlanetEarth)#24Sculp9ngEarthwithWater-Rivers
Smith River in northwest California
RiversandCiviliza9onRivers play huge role in society. Civilizations developed around rivers, e.g., Nile River - Ancient Egypt.
Nile River and Pyramid of Cheops
Nile River and its delta from space
RiversandCiviliza9onAncient Mesopotamia, “Cradle of civilization”, between Tigris, Euphrates rivers
RiversandCiviliza9onMany US cities, including Pittsburgh, St. Louis, New Orleans, located along rivers. Gateway Arch and St. Louis -
next to Mississippi River
Allegheny, Monongahela, and Ohio Rivers - Pittsburgh
New Orleans and Mississippi River
ImportanceofRiversWhy are rivers so important to society?
Societal Benefits Hazards Geological Study
ImportanceofRivers-SocietalBenefitsRivervalleyciviliza0ons,e.g.,Egypt,Mesopotamia,usedspringfloodsassourceofirriga9onwater(drinkingwater),fer9lesoil
Colorado River water for irrigation
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ImportanceofRivers-SocietalBenefitsBarges-cheaptomovebulkycommodi0es,e.g.,coal,ironore,grain
Towboat pushing barges with coal along Ohio River
ImportanceofRivers-SocietalBenefits
Food
Fly fishing for trout
ImportanceofRivers-SocietalBenefitsHydroelectricity-rela0velyclean,reliable,cheaprenewableenergy
Hoover Dam - along Colorado River
SocietalBenefitsofRiversRecrea9on
White water canoeing along Big South Fork of Cumberland River, Tennessee
Tubing in Jamaica
swimming,boa0ng,fishing,tubing
ImportanceofRivers-SocietalBenefitsScenicbeautyLarge bend in Moselle River, Germany
Ecosystem
HazardsofRivers-FloodsFloods,e.g.,quicklydeveloped,devasta0ngflashfloods
Stillaguamish River, WA record flood in 2006
VideoofflashfloodinToowoomba,AustraliaonJanuary10,2011(YouTube,0:25-3:30,4-4:10,5:15-5:30;hUps://www.youtube.com/watch?v=kYUpkPTcqPY)
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HazardsofRivers-FloodsLargerrivers-slowlydeveloped,longlas9ngfloodsaffecthugeareas
2009 Red River flood in Moorhead, MN
GeologicalStudyofRivers
Sedimentarydeposi9onalenvironment
Mississippi River Delta - river-deposited sediment
GeologicalStudyofRiversShapeslandscapes-erosion,deposi0on Gunnison River at Black Canyon
of Gunnison National Park, CO
RiverDefinedFlowingwateratEarth'ssurfaceusuallyconfinedtolowarea(channel).Flowingwaterdis0nguishesriversfromlakes(liUleflow).AtEarth'ssurfacedis0nguishesriversfromgroundwater(undergroundflowingwater)Confinedtochanneldis0nguishesriversfromunchannelizedsurfacerunoffa^erheavyrainstorm.
Rouvre River in France’s Normandy Region
River-SourceofWater,FlowRiverwaterfromrain(snowmelt),movesoverlandorthroughgroundintoriver.Riversflowdownhillduetogravity,headtowardsocean.
Pouring rain in river in Adirondacks, NY
RiverLoadMaterialcarriedbyriver=load,includesgrains(clay!boulders)carriedinsuspensionorrolledalongboUom.With↑velocity,riverscancarry↑sedimentload,largergrains.Loadincludesdissolvedsalt.
Big Muddy River, Illinois, has high sediment load
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River-LongitudinalProfileRiverGradient=slope,changeineleva0ondividedbyhorizontaldistance(rise/run)
Coarse grains deposited near river’s source
Typical longitudinal profile of river
Characteris0cgradient=longitudinalprofile,eleva0onalongflowdirec0on(figure).Majorriverso^enbegin(source)inmountains,i.e.,steepgradient.Sedimentgrainsofallsizesproducedbyweathering,erosion;coarsegrainsdeposited;medium,finegrainscarrieddownstream
River-LongitudinalProfileRiverflowsintoplains,flatgradient.Sand,graveldeposited;finegrainscarrieddownstream.
Fine grains deposited at river’s mouth
Sand deposited by river in plains
Eventually,riveremp0esintooceanorlake(liUle!nocurrent),finegrainsdepositedatriver’smouth
RiverVelocityTrendsRivers’maximumvelocityusually↑slightlydownstreamfrommountainstoplains.Counterintui0ve;steepgradientshouldcreatefasterflowthanflatgradient.
Whydoesmaximumrivervelocity↑downstream?
Mississippi River near Memphis, Tennessee
KindsofRivers-MountainRivers
Severalkindsofrivers,emphasizingmountainrivers,meanderingrivers.
Yellowstone River in Wyoming
Mountainriversfoundinmountainousareasnearsource.Cross-sec0on-valleysshapedlikeleUerv,channeloccupies~allofvalleyboUom.Mapview-channelfollows~straightpath,waterseeksshortestdistancedownsteepslope.
KindsofRivers-MeanderingRiversMeanderingriversmovebackandforthacrossfloodplain-broad,flatareawithsedimentdepositedduringflood;broadvalleys;riverbend=meander;plainsnearmouth
Cuckmere River in England
MeanderingRiversMeandering river on Yamal tundra, Siberia, Russia
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MeanderingRivers MeanderingRiversMeandering river in flood stage
KindsofRivers-MeanderingRiversMeanderingriversconstantlychangecourse,erosionanddeposi0onalongmeanders.Whenriverchangesdirec0on,maximumvelocityzoneshi^sfrommiddletoouterpart(iner0a),causeserosionthere.Innerpartofmeanderhas↓velocity,causesdeposi0onofsandandgravelthere.
Sand deposit on inner part of meander, Innoko River, Alaska
Whichdirec0onwillmeandersonrightmoveover0me?
KindsofRivers-MeanderingRivers
Sand deposit on inner part of meander, Innoko River, Alaska
Whichdirec0onwillmeandersonle^moveover0me?
Migra9onofRiverMeanders
Meanderswingscangetexaggerated,rivercutsstraighterchannelpath,abandonedrivermeander(oxbowlake)
Migra9onofRiverMeanders-OxbowLakesAbandonedrivermeander(oxbowlake)
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Migra9onofRiverMeanders-OxbowLakes OxbowLakes
OxbowLake Migra9onofRiverMeanders-OxbowLakesMeander scars and oxbow lakes in floodplain of Rio Negro River, Argentina
Migra9onofRiverMeanders-PropertyDamageMeanderingriversaredynamicsystems,constantlychangingcourse.
January,1965
Twomonthslater
Canthreatennearbystructures
DrainageBasinAreadrainedbyriverandtributaries(smallriversdrainintolargerones);bigorsmall
Continental divides of North America
Highgroundseparatesdrainagebasins,e.g.,drainagedivide,con0nentaldivide(separatesflowtodifferentoceans)
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Dendri9cDrainagePaYernPaUernofriverandtributariesthatresemblesleafveins;commonDendritic drainage pattern of Yarlung Tsangpo River, Tibet, from space: snow cover melted in valleys
DeltaLandformofdepositedsedimentatrivermouth.Mapview-deltashapeo^entriangle,GreekleUercapitaldelta(Δ)
Satellite photo Nile Delta (false color)