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简介：WaterandsedimentqualitiesarestudiedbyanalyzingsamplestakingfromthemouthsoftheHaihe,Duliujian,NewZiyaandBeipairiversintheHaiheriverbasininnorthChinain2005and2001,inordertofindthechangesofwaterandsedimentpollutions.Theconcentrationsofheavymetals,arsenic,totalnitrogen(TN)andtotalphosphorus(TP)areanalyzedandresultshavebeencomparedforthetwotimes.Thein-situmeasurementforDissolvedOxygen(DO)andSedimentOxygenDemand(SOD)rateswerecarriedattheHaiheandDuliujianrivermouthsin2006.Theresultsshowthatthewatersofthe4rivermouthsarestillseriouslypolluted,thoughmuchimprovedinthecaseoftheHaiheandDuliujianrivers.ThemainpollutantsareTPandTNintheNewZiyaandBeipairiversandmercury(Hg)atall4rivermouths.Comparedwiththosein2001,theconcentrationsofalmostallmetalsandarsenicinthe4rivermouthshavedecreased.WaterqualityatHaiheandDuliujianshowsanimprovingtrend,whilethewaterqualityatBeipaiissimilartothatof2001.Incontrast,waterattheNewZiyarivermouthismoreseverelypolluted.Thesedimentsinthe4rivermouthsarenotseriouslypollutedbyheavymetalsbutarepollutedbynitrogenandphosphorus.Mostofthepollutantcontentsinthesedimentsshowlittlechangebetween2001and2005.Thein-situDOandSODmeasurementshowsthatthewatersattheHaiherivermouthisinthestateofoxygendepletion,andSODisimportantconsumerofDOattherivermouths.Theoverallanalysisshowsthatincreasingwaterpollutionandeutrophicationinwatersfarfromcitiesareongoingcausesofconcern.

简介：InordertosimulatethecharacteristicsofhydrodynamicfieldandmasstransportprocessesintheYuqiaoReservoir(YQR),a2-Dcoupledmodelofhydrodynamicsandwaterqualitywasdeveloped,andthewater-qualityrelatedstatevariablesinthismodelincludedCODMn,TNandTP.Thehydrodynamicmodelwasdrivenbyemployingobservedwindsanddailymeasuredflowdatatosimulatetheseasonalwatercycleofthereservoir.ThesimulationofthemasstransportandtransformationprocessesofCODMn,TNandTPwasbasedontheunsteadydiffusionequations,drivenbyobservedmeteorologicalforcingandexternalloadings,withthefluxesformthebottomofreservoirandtheplantphotosynthesisandrespirationasinternalsourcesandsinks.AfinitevolumemethodandAlternatingDirectionImplicit(ADI)schemewereusedtosolvetheseequations.ThemodelwascalibratedandverifiedbyusingthedataobservedfromYQRintwodifferentyears.TheresultsshowedthatinYQR,thewind-drivencurrentwasanimportantstyleoflakecurrent,whiletheconcentrationofwaterqualityitemwasdecreasingfromeasttowestbecauseoftheexternalpollutantloadings.Therewasagoodagreementbetweenthesimulatedandmeasuredvalues,withtheminimalcalculationerrorpercentof0.1%and2.6%andthemeanerrorpercentof44.0%and51.2%forTNandTPseparately.Thesimulationalsoshowedthat,inYQR,theconvectionwasthemainprocessinestuariesofinflowriver,anddiffusionandbiochemicalprocessesdominateincenterofreservoir.Soitwasnecessarytobuildapre-pondtoreducetheexternalloadingsintothereservoir.

简介：Inthisstudy,wefocusonchangesinthreeimportantcomponentsofthehydrological-cycleintheHaiheRiverbasin(HRB)during1957-2005:precipitation(Prep),actualevaportranspiration(ETa),andpanevaporation(PE)-ameasureofpotentialevaporation.ThechangesinthesecomponentshavebeenevaluatedinrelationtochangesintheEastAsiansummermonsoon.SummerPrepforthewholebasinhasdecreasedsignificantlyduring1957-2005.Recentweakeningoftheconvergenceoftheintegratedwatervaporflux,incombinationwithachangefromcyclonic-likelarge-scalecirculationconditionstoanti-cyclonic-likeconditions,ledtothedecreaseinthesummerPrepintheHRB.ETaispositivelycorrelatedwithPrepontheinterannualtimescale.Onlongertimescales,however,ETaislessdependentonPreporthelarge-scalecirculation.WefoundnegativetrendsinETawhentheERA40reanalysisdatawereused,butpositivetrendsinETawhentheNCEP/NCARreanalysisdatawereused.PEdeclinedduringtheperiod1957-2001.ThedecliningofPEcouldbeexplainedbyacombinationofdecliningsolarradiationanddecliningsurfacewind.However,thedecliningsolarradiationmayitselfberelatedtotheweakeningwinds,duetoweakerdispersionofpollution.Ifso,thedownwardtrendofPEmaybemainlycausedbyweakeningwinds.

简介：Inordertoreducetheenvironmentalandecologicalproblemsinducedbywaterresourcesdevelopmentandutilization,thispaperproposesaconceptofenvironmentalandecologicalwaterrequirement.Itisdefinedastheminimumwateramounttobeconsumedbythenaturalwaterbodiestoconserveitsenvironmentalandecologicalfunctions.Basedonthedefinition,themethodsoncalculatingtheamountofenvironmentalandecologicalwaterrequirementaredetermined.InthecasestudyonHaihe-Luanheriversystem,thewaterrequirementisdividedintothreeparts,i.e.,thebasicin-streamflow,waterrequirementforsedimenttransferandwaterconsumptionbyevaporationofthelakesoreverglades.Theresultsofthecalculationshowthattheenvironmentalandecologicalwaterrequirementintheriversystemisabout124×108m3,including57×108m3forbasicin-streamflow,63×108m3forsedimenttransferand4×l08m3fornetevaporationlossoflakes.Thetotalamountofenvironmentalandecologicalwaterrequirementaccountsfor54%oftheamountofrunoff(228×108m3).However,itshouldberealizedthattheamountofenvironmentalandecologicalwaterrequirementmustbemorethanthatwehavecalculated.Accordingtothisresult,weconsiderthattherationalutilizationrateoftherunoffintheriversystemsmustnotbemorethan40%.Sincethecurrentutilizationrateoftheriversystem,whichisover80%,hasbeenfarbeyondthelimitation,theproblemsofenvironmentandecologyarequiteserious.Itisimperativetocontrolandadjustwaterdevelopmentandutilizationtoeliminatetheexistingproblemsandtoavoidthepotentialecologicalorenvironmentalcrisis.

简介：Thepaperpresentsthe3DfiniteelementsimulationoftidalflowandSedimenttransportintheestuarineregionoftheHaiheriver.Theproposedmodeladoptssigma-transformationofthehydrodynamicandsedimenttransportequations.Thehydrodynamicandsedimenttransportmodelsareverifiedincaseofasimpletestproblemforwhichanalyticalsolutionsareavailable.FinallythemodelsareappliedtomuddyHaiheriverestuaryofNorthChinaanditisclaimedthathydrodynamicandsedimenttransportmodelsgiveareliablecomparisonwiththeobservedfielddata.However,therearecertaindiscrepancies,andsomereasonablequestionsregardingthepresentstate-of-art,inthemodelingofthree-dimensionalmultilevelhydrodynamicsandsedimenttransport,whichareprovidedbelowforanswer.