地下水水文學(麻省理工講義)

1、1.72,GroundwaterHydrologyProf.CharlesHarveyLecturePacket1Page of15地表徑流Moistureoverland低滲透地層Surfffrunof地下水流動Groundwat已rflow61EvaporationfromthelandLowpermeabilitystrata100Precipitationonland424Evaporationfromtheocean純335Procipitationon亡總自n1Graunctwacerdischarge徑流排泄m!.：蒸騰和蒸發(fā)andration滲透：1I*地下水補給WGround

2、waterrechargeHydrologiccyclewithyearlyflowvolumesbasedonannualsurfaceprecipitationonearth,119,000km3/year.1.72,GroundwaterHydrologyProf.CharlesHarveyLecturePacket#1:CourseIntroduction（課程簡介）,WaterBalanceEquation（水量平衡）Wheredoeswatercomefrom?Itcycles,Thetotalsupplydoesntchangemuch.3000BC-Ecclesiastes傳道

3、書1:7（Solomon）“Alltheriversrunintothesea;yettheseaisnotfull;unto（直至U）theplacefromwhencetheriverscome,thithertheyreturnagain.”GreekPhilosophers（Plato,Aristotle柏拉圖，亞里士多德）embracedtheconcept（接受這個概念）,butmechanismswerenotunderstood.17thCentury-PierrePerraultshowedthatrainfall（降雨）wassufficienttoexplainflowo

4、ftheSeine.Theearthsenergy(radiation輻射、放射物)cycleTheEarthsEnergy(Radiation)Cycle:Spatialdistributionofenergyandtemperaturedrivescirculation-bothglobalandlocal:PolarHighPolareasterliesPolarHighPolarfront/subarcticlowPolarfront/subarcticlowPolareasterliesSubtropicalhighWesterliesTradewindsEquitoriallowW

5、esterliesTradewindsSubtropicalhighCoupledEarthCyclesEnergyCycleHydrologicCycleMaterial物質CycleEstimatesfromriveroutflowsindicate17x109Tons/YearofmaterialistransportedintotheOcean.Another2or3x109Tons/Yearistrappedinreservoirs.80%ofmaterialtransportedisparticulate20%isdissolved0.05mm/yr(mayhavebeenacce

6、leratedbyman,andactualratesmaybemuchlarger)Localratesdependonrelief,precipitation,androcktype.GlaciersFreshWaterAtmosphereOceansRelativevolumesofwateringlaciers,freshwater,atmosphereandoceans.EstimateoftheWorldWaterBalanceParameterSurfacearea(km2)X106Volume(km3)X106Volume%Equivalentdepth(m)Residence

7、TimeOceansandseas36113709425004000yearsLakesandreservoirs水庫1.550.130.010.2510yearsSwamps濕地0.10.010.010.0071-10yearsRiverchannels0.10.010.010.0032weeksSoilmoisture土壤濕度1300.070.010.132weeks-1yearGroundwater1306041202weeks-10,000yearsIcecaps冰蓋andglaciers冰川17.83026010-1000yearsAtmosphericwater5040.010.0

8、10.02510daysBiosphericwater0.10.010.010.0011weekAmazonis6,000km3/yr(5xmorethanZaire-Congo)0.0003%ispotableandavailable.Whatarewaterneedsforhumans?Primitiveconditions3to5gallons/dayUrbanuse-150gallons/dayUSFreshWaterUse-1,340gallons/dayWheredoesthewatergo?Tomakethings.tocleanthingsItemGallons1poundof

9、cotton2,0001poundofgrain-fedbeef8001loafofbread1501car100,0001kilowattofelectricity801poundofrubber1001poundofsteel251gallonofgasoline101loadoflaundry601ten-minuteshower25-50Somepoints:Alotofwaterisusedforagricultureo56%(76BGD)isconsumptiveuseo20%(28BGD)islostinconveyanceo24%(33BGD)isreturnflowAloto

10、fwaterisusedforthermoelectricpowergenerationo87%ofallindustrialwateruseAsmallsavingsineitherofthesecategorieswouldfreeupsignificantquantitiesforpublicsuppliesWaterUseintheUSin1990FreshWaterUse1990Total339BGDCalifornia35.1Texas20.1Idaho19.7Illinois18.0Colorado12.7Louisiana11.7Michigan11.6NewYork10.5P

11、ennsylvania9.8Indiana9.4Montana9.3Fourstatesaccountfor27%11statesaccountfor50%Analysisofhumanappropriationofrenewablefreshwatersupply(RFSW)onland.FigureadaptedfromPosteletal.,Science,(271)p.758,Feb.9,1996Posteletal.sCalculations1)CalculationofappropriatedET一indirect132billiontonsofbiomassproducedaye

12、ar(Vitousek,1992).30%usedbypeople.ApproximatepeoplesuseofETfromtheproportionofbiomass-30%.Subtractagriculturalirrigation(2,000km3/year)andassumehalfthewater.fromparksandlawnsisirrigation(80km3/year).2)InaccessiblerunoffAccessiblerunoff=95oftheAmazon,HalfoftheZaire-CongoandallofthePolarrivers7774.km3

13、/year(didnotconsiderothernorthernrivers一conservative?).Floodwater.11,100km3/yearofrunoffisbaseflow(6).adjustedforaccessibleCapacityofman-madereservoirsis5,500km3/year.Baseflow+reservoircapacity=12,500.3)Withdrawals(consumed)12,000m3/haaverageirrigationwaterapplication.240,000,000haofworldirrigatedar

14、ea.2,880km3/year.65%consumed=1,870km3/year.Industrialuse:975km3/year,9%consumed,90km3/year.Municipaluse:300km3/year,17%consumed,50km3/year.Reservoirlosses-5%loss,275km3/year.Totalconsumed=2,285km3/year.4,700km3/year.ReturnFlaw4)Instreamuse28.3L/sper1,000population,appliedto1990population,Assuming50%

15、ofwastegetstreatment-2,350km3/year.Neglectsdispersedpollution(agricultural)andfloodwatersSourceSurfaceWater0.6966.4%50.2%33.7%13.2%2.7%9.5%9.1%gg.s%97.3%52,0%.L%0.4%Irriqatian-Livestock2E.39656.2%.6i.g%30.1%43.0%259bgd76.S%191Bgd30.6%24SQgd72.2%141Bgd44.7%EstimatedwateruseintheUnitedStates,billionga

16、llonsperday(bgd),fordomesticandcommercialpurposes.AdaptedfromSolley,Pierce,andPerlman,1993.Domestic-Commercial4.1%39.1Bgd4l.S%17.35695.2%83.7%10.7%JU5EPublicSupplv9.SBgd06.3%-du13.S%39.1%0.2%Industrial-Mining59.0%27.GBgcB.296lfi.l%S3.9%18.7%21.5%hermoelectricConsurnptiveUss7.2%9+Bgd27.3%4.B1%3.7%8斗竹

17、DispositionGroundwater7Q.4hdq23.5%19.0%7.5%0.79667.6%RelativeMeritsofSurfaceandSubsurfaceReservoirsSurfaceReservoirsSubsurfaceReservoirsDisadvantagesAdvantagesFewnewsitesfree(inUSA)Manylarge-capacitysitesavailableHighevaporativeloss,evenwherehumidclimateprevailsPracticallynoevaporativelossNeedlargea

18、reasoflandNeedverysmallareasoflandMayfailcatastrophicallyPracticallynodangeroffailureVaryingwatertemperatureWatertemperatureuniformEasilypollutedUsuallyhighbiologicalpurity,althoughpollutioncanoccurNotrapidlycontaminatedbyradioactivefallout1.72,GroundwaterHydrologyProf.CharlesHarveyLecturePacket1Pag

19、e of15EasilycontaminatedbyradioactivefalloutWatermustbeconveyedActasconveyaneesystems,thusobviatingtheneedforpipesorcanals01.72,GroundwaterHydrologyProf.CharlesHarveyLecturePacket1Page of151.72,GroundwaterHydrologyLecturePacket1Prof.CharlesHarveyPage of15WatershedHydrologicBudgetsDelineationofawater

20、shed(drainagebasin,riverbasin,catchment)Areathattopographicallyappearstocontributeallthewaterthatflowsthroughagivencrosssectionofastream.Inotherwords,theareaoverwhichwaterflowingalongthesurfacewilleventuallyreachthestream,upstreamofthecross-section.Horizontalprojectionofthisareaisthedrainagearea.The

21、boundariesofawatershedarecalledadivide,andcanbetracedonatopographicmapbystartingatthelocationofthestreamcross-sectionthendrawingalineawayfromthestreamthatintersectsallcontourlinesatrightangles.Ifyoudothisright,thelinesdrawnfrombothsidesofthestreamshouldintersect.MovingtoeithersideWaterBalanceEquatio

22、ndS-dt=PG+in-(Q+ET+Gout)dSAtsteady-state:一=0dtPG+=+(QET+G)inoutHydrologicProductionRunoff,orHydrologicCirculationQandParetheonlyquantitiesthatwecantrytomeasuredirectly.Ifsteadystateisassumed,thesemeasurementscanbeusedtocalibratemodelsofevapotranspirationandgroundwaterflow.Fromandengineeringpointofvi

23、ewweareinterestedinunderstandingwhatcontrolsQ.Q=P+(G-G)-ETinoutHowmuchofQisavailabletohumanuse?HowcanweincreaseQ?LakeParabola-2-1012(Asimplequadraticmodelofthecrosssectionofacircularlake)=cr2A=nHcnr2=HJ卩VH()=0Ahdh()=J_cnHdh=_2cH2oDischargeintoLakeParabolaIfthereisconstantvolumefluxQm3/dayintothelake

24、,howdoesthedepthdependontime?(Attime0,thedepthisHm)Sincethereisnooutflow,thechargeinstoragemustequaltheinflowMass-balance(waterbalance)equationdVH()ndH(2)ndHQ-=Hdt2cdtcdtThisdifferentialequationcanbesolvedbyseparationofvariablesTHcQJJndt=HhdhHo1.72,GroundwaterHydrologyProf.CharlesHarveyLecturePacket1Page of15cQTn2Hm1TdaysDischargeintoandEvaporationoutofL