Material component to non-linear relation between sediment yield and drainage network development: an flume experimental study

(整期优先)网络出版时间:2001-03-13
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ThispaperexaminestheexperimentalstudyoninfluenceofmaterialcomponenttononlinearrelationbetweensedimentyieldanddrainagenetworkdevelopmentcompletedintheLab.Theareaofflumedrainagesystemis81.2m2,thelongitudinalgradientandcrosssectionslopearefrom0.0348to0.0775andfrom0.0115to0.038,respectively.Differentmodelmaterialswithamediumdiameterof0.021mm,0.076mmand0.066mmcoverthreeexperimentseach.Anartificialrainfallequipmentisasprinkler-systemcomposedof7downwardnozzles,distributedbyhexagontypeandagivenrainfallintensityis35.56mm/hr.cm2.Threeexperimentsaredesignedbyprocess-responseprincipleatthebeginningtheψshapedsmallnetworkisdugintheflume.Runningtimespansare720m,1440minutesand540minutesforRunsⅠ,ⅣandⅥ,respectively.Threeexperimentsshowthatthesedimentyieldprocessesarecharacterizedbydelayingwithavibration.Duringnetworkdevelopmenttheenergyofadrainagesystemisdissipatedbytwoways,ofwhichoneisincreasingthenumberofchannels(rillandgully),andtheotheroneisenlargingthechannellength.Thefractaldimensionofadrainagenetworkisexactlyanindexofenergydissipationofadrainagemorphologicalsystem.Changeofthisindexwithtimeisanunsymmetricalconcavecurve.Comparisonofthreeexperimentsexplainsthatthevibrationandthedelayingratioofsedimentyieldprocessesincreasewithmaterialcoarsening,whilethenumberofchanneldecreases.Thelengthofchannelenlargeswithmaterialfining.Thereexistsnon-linearrelationshipbetweenfractaldimensionandsedimentyieldwithanunsymmetricalhyperboliccurve.Thebsolutevalueofdelayingratioofthecurvereduceswithtimeunningandmaterialfining.Itischaracterizedbysubstitutionofsituationtotime.