简介:TopographyaroundtheYellowRivermouthhaschangedgreatlyinrecentyears,butstudiesonthecurrentstateofma-rinedynamicsofftheYellowRivermoutharerelativelyscarce.Thispaperusesatwo-dimensionnumericalmodel(MIKE21)torevealthetidalandwavedynamicsin2012,andconductscomparativeanalysisofthechangesfrom1996to2012.TheresultsshowthatM2amphidromicpointmovedsoutheastwardby11km.ItfurtherrevealsthatthetidesaroundtheYellowRivermoutharerelativelystableduetothesmallvariationsinthetidalconstituents.Overthestudyperiod,thereisnonoticeablechangeinthedistributionoftidaltypesandtidalrange,andthemeantidalrangeofftherivermouthduringtheperiodstudiedis0.5–1.1m.However,thetidalcurrentschangedgreatlyduetolargechangeintopography.Itisobservedthattheareawithstrongtidalcurrentsshiftedfromtheoldrivermouth(1976–1996)tothemodernrivermouth(1996–present).Whilethetidalcurrentspeedsdecreasedcontinuallyofftheoldrivermouth,theyincreasedoffthemodernrivermouth.TheMaximumTidalCurrentSpeed(MTCS)reached1.4ms-1,andthemaximumcurrentspeedof50-yearreturnperiodreached2.8ms-1.Wavesalsochangedgreatlyduetochangeintopography.Thesignificantwaveheight(H1/3)of50-yearreturnperiodchangedproportionatelywiththewaterdepth,andtheratioofH1/3todepthbeing0.4–0.6.H1/3ofthe50-yearreturnperiodinerosionzoneincreasedcontinuallywithincreasingwaterdepth,andtherateofchangevariedbetween0.06and0.07myr-1.Basedontheresultsofthisstudy,weinferthatinthefuture,themodernrivermouthwillprotrudegraduallynorthward,whiletheerosionzone,comprisingtheoldrivermouthandareabetweenthemodernrivermouthandtheoldrivermouth(Intermediateregion)willcontinuetoerode.Asthemodernrivermouthprotrudestowardsthesea,therewillbeagradualincreaseinthecurrentspeedanddecreaseinwaveheight.Conversely,theold
简介:Researchingthedynamicdistributioncharacteristicsandtrendevolutionofagriculturalcarbonemissionsisofconsiderablesignificanceinformulatinganeffectiveagriculturalcarbonreductionpolicy.Basedonmeasurementofagriculturalcarbonemissionsof31provincesovertheperiod2002-2011,thestudyobservedregionaldifferencesandthedynamicevolutionofdistributionofagriculturalcarbonemissionsusingagriculturalcarbonintensityastheindicator,accompaniedbyGinicoefficientsandthekerneldensityestimationmethod.TheresultsdemonstratefirstthatagriculturalcarbonemissionsforChinashowanobviousnonequilibriumnatureinregardtospatialdistribution.Accordingtothedifferencesinagriculturalcarbonemissionsdynamictrends,wedividedthe31regionsintofourtypes-continuousdecline,fluctuatingdecline,continuousincrease,andfluctuatingincrease.Further,agriculturalcarbonemissionsintensityshowedadownwardtrendwithsignificantdifferencesintheresearchareas.Second,thegapinspatialdistributionofnationalagriculturalcarbonemissionsisgraduallyexpandingbasedontheresultscalculatedbyGinicoefficient.Fromtheperceptionofregionaldifferencesinagriculturalcarbonemissions,theeasternregionshowedanaveragelevel,thegapwasmoreobviousinthecentralregion,whilewesternregionshowedatrendoffluctuatingdownward.Third,accordingtoestimationbykerneldensity,theregionaldisparityinagriculturalcarbonemissionshadadownward,butlimited,trend.Inregardtoagriculturalcarbonemissionsoverthethreeareas,theregionalgapnotonlytendedtodecreasebutalsoshoweda"fourway"differentiationphenomenonintheeasternregion.Thedifferenceinthecentralregiondifferencewasnarrower.Onthewhole,thegapforthewesternregionreducedsteadilyoverasmallrange.