2002_Lenhart-Eckhardt-Fohrer-Frede_comparison-two-approaches-sensitivity-analysis-PCE.pdf

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1、PhysicsandChemistryoftheEarth27(2002)645–654www.elsevier.com/locate/pceComparisonoftwodifferentapproachesofsensitivityanalysisT.Lenhart*,K.Eckhardt,N.Fohrer,H.-G.FredeInstitutf€urLandeskultur,Justus-Liebig-Universit€atGiessen,Heinrich-Buff-Ring26-32,D-35392G

2、iessen,GermanyReceived10February2001;receivedinrevisedform16January2002;accepted16January2002AbstractDuetospatialvariability,budgetconstraintsoraccessdifficultiesmodelinputparametersalwaysareuncertaintosomeextent.Thereforetheknowledgeofsensitiveinputparamete

3、rsisbeneficialformodeldevelopmentandapplication.Itcanleadtoabetterunderstandingandtobetterestimatedvaluesandthusreduceduncertainty.Inthepresentpapertwosimpleapproachesofsensitivityanalysisarecomparedbytheuseofthephysicallybased,continuoustimehydrologicalmod

4、elSWAT.Inbothapproaches,oneparameterisvariedatatimewhileholdingtheothersfixed,butthewayofdefiningtherangeofvariationisdifferent.Similarresultsareobtainedsuggestingthatparametersensitivitymaybedeterminedwithouttheresultsbeinginfluencedbythechosenmethod.Mostsens

5、itiveparametersforhydrologyandwaterqualityarethephysicalsoilpropertiessuchasbulkdensity,availablewatercapacityorhydraulicconductivity.Plantspecificparameterslikemaximumstomatalconductanceormaximumleafareaindexaswellasslopelength,slopesteepness,andcurvenumbe

6、ralsoshowahighsensitivity.Bothapproachescanbeconsideredasequivalent,astheyprovidethesameoverallrankingintomoreandlesssensitiveparameters.Anidentificationofthesensitiveparametersispossibleindependentlyfromthechosenvariationrange.Ó2002ElsevierScienceLtd.Allri

7、ghtsreserved.Keywords:Sensitivityanalysis;Uncertainty;Modelcalibration;Waterquality;Distributedmodels1.Introductionrepresentedinthemodel.ParametersthatarenotwellunderstoodmaybeleftunchangedeventhoughtheyarePhysicallybasedmodelsareusedtosimulateawidesensiti

8、veorareadjustedtoimplausiblevalues.Notrangeofcomplexaspects.Thepurposeofusingamodelknowingthesensitivityofparameterscanalsoresultinistoestablishbaselinecharacteristicswheneverdataistimebeinguselesslyspentonno