基于卫星数据分析云南火电厂对地区水质的影响

UnderstandingtheEffectsofThermal

PowerPlantsonRegionalWaterQualityBasedonSatellite-derivedDatainYunnan

PlanetDataInc.2020.12.30

1

IBackground

Withtherapidgrowthofeconomy,thedemandofelectricityconsumptionfordaily

productionandpeople’sdailylifeisexponentiallyincreasing.ThermalpowergenerationisstillthemainmodeinChina.In2017,Thetotalpowergenerationreaches6.5trillionkwh.Amongthem,thermalpowerplantsaccountformorethan71%ofpowergeneration.In

additiontoair,waterisusuallychosenasthecoolingmedium.

In2015,theStandingCommitteeofthePoliticalBureauoftheCentralCommitteedeliberatesandapprovestheActionPlanforthePreventionandControlofWaterPollution(Water10),aimingtostrengtheneffortstopreventandcontrolwaterpollutionandensurenationalwatersecurity.Theplancallsformorethan70percentofsevenriverbasins,includingtheYangtzeRiverandZhuhai,tohavewaterthatreachesorexceedsqualitycategoryIIIby2020.

YunnanprovinceislocatedattheconfluenceoftheYangtzeRiverbasinandthePearlRiverBasin.AlthoughthebasinareaofnineplateaulakesrepresentedbyYangzonghaiandDianchi

lakesonlyaccountsfor2.1%intheareaofYunnanProvince,theyplayanimportantroleintheeconomicandsocialdevelopmentofYunnanprovinceandaccountformorethan

one-thirdoftheprovincialGDPannually.

Inrecentyears,astheindustryandtourismdevelop,YangzonghaiandDianchiwitnessa

rapiddegradationinwaterquality.YunnanprovincialgovernmentandProvincial

EnvironmentalProtectionBureauattachgreatattentiontothecomprehensivecontrolofwaterpollutioninYangzonghaiandDianchiandtreatitasamajorimplementofsustainable

development.However,duetotheinfluenceofenvironmentalfactors,waterexchangeperiodsoftwolakesarelongandtheecosystemsarefragile.Thehigh-densitypopulationbroughtbythedevelopedeconomyaggravatestheloadofpollutioninlakes.Themultifarioustypesof

pollutantsinteractwitheachother,whichincreasesthedifficultyofimplementingwater

qualitymanagementandleadstolong-termaccumulationofpollutants.Duetotheintense

urbanization,thebufferzoneisunderdeveloped,whichleadstofragileplantcommunitiesandthedeclineofself-purificationcapacityoflakes.Therefore,dischargecontroliscriticalin

improvingthewaterqualityofYangzonghaiandDianchiandpassingthewindowperiodofecologicalrestoration.

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Toidentifyillegaldischargesfromenterprisesandindividuals,monitorthedischargeofmajorpollutionsourceandprovidetheoreticalanddatasupportforfurtherdevelopmentofpollution

controlpolicies,adetailedevaluationofthetemporalandspatialchangesinwater

temperature,chlorophyllconcentrationandwatertransparencyisrequired.However,duetothecostanddifficultyofimplementingfieldtrips,thedataobtainedhavelimitedcoverageintimeandspace,whichwillleadtoafailureincarryingoutlong-termspatialandtemporal

analysisofYangzonghaiandDianchi.

Withthedevelopmentofremotesensingtechnology,methodsofusingempiricalformulatoevaluatewaterqualityhasbeenoptimizedandpopularizedbyresearchers.Comparedtothetraditionalsamplingmethods,environmentalremotesensingtechnologyhashigherspatialandtemporalresolution.Toinvestigatetherelationshipamongwatertemperature,

transparency,andchlorophyllconcentration,andtheirtemporaladspatialvariations,we

developthreemodelstorespectivelyrepresenthistoricalsituations.Takingadvantageofthesatellite-basedmodels,weanalyzethelong-termtrendandwholescalevariations.

Hypothesesareproposedthatdischargedwarmwatercoulddeteriorateaquaticecosystembyprovidingawarmandnutrient-richenvironmentforplanktonandplants.Previousstudies

havepointedoutthatthedischargedwarmwaterfromthermalpowerplantsmaycausemultiplekindsofdamagetowaterquality,includingincreasingthewatertemperature(thermalpollution),increasingtheconcentrationofsuspendedparticulatematter,andchangingchemicalcompositionofwaterbody.

However,theremotesensingtechnologymainlyworksforrevealingcorrelations,ratherthancasualrelationships,theintermediateprocessesarenotdiscussedinthisreport.Analysesaremerelybasedonsatellite-derivedobservations.Weignoretheprinciplesoftheintermediatereactionsamongpollutantsandaquaticorganisms.Forinstance,thewaythatdischarged

warmwaterimpactsthevigorofplanktonandplant

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IIMethod

1.StudyArea

1)Yangzonghai

Yangzonghai,locatedinthesoutheastofKunming,coversanareaof31.9squarekilometers,withanaveragewaterdepthof20meters.Itstores604millioncubicmetersofwater,whichisabouthalfofthewatervolumeofDianchiLake.Accordingtothe2015Environmental

statusBulletinofYunnanProvince,thewaterqualityofYangzonghaiin2015isclassifiedasClassIV.ArsenicconcentrationisclassifiedasClassIV,whichis0.05timesabovethe

standard.Phosphorusandchemicaloxygenare0.36timesand0.17timesabovethestandardrespectively.Theaveragenutritionalstatusindexofthewholelakeis41.2,whichisclassifiedasmesoeutrophic.

2)Dianchi

DianchiisthelargestlakeinsouthwestChina,belongingtotheYangtzeRiverBasin.Itisinthesouth-centralpartofKunmingBasin.Thelakecoversanareaof300squarekilometersandtheshorelineisabout150kilometerslong.Inthenorthofthelake,thereisan

embankmentstretchingfromeasttowest,whichis3.5kilometerslongand300meterswide.

ItdividesDianchiintotwoparts.Southoftheembankment,knownastheoutersea,isthe

mainpartoftheDianchi,coveringanareaof289.065squarekilometers,accountingfor97.2%ofthetotalarea.Northoftheembankmentiscalledinnersea,whichisalsoknownasgrass

sea,occupyinganareaofabout10squarekilometers.TheaveragedepthofDianchiisabout5meters.

2.Dataacquirementandpre-processing

Inordertoobtainsufficientdatafortimeseriesanalysis,weexpandthetimeperiodto2006to2018.Forthedatapre-processing,wefirstlyconductradiometriccalibrationforLandsat5TMandLandsat8OLIimages,andthecalibrationtypeisradiometricbrightness.Secondly,we

calibratetheimagesbasedonsensortypes,theparametersacquiredbyeachimage(season,aerosolmodel,atmosphericmodel,visibility,etc.),thealtitudeandregionaltypeofthestudyarea.Thirdlyweusetheobject-orientedimagesegmentationtechnologytoextractthevectorboundaryofYangzonghaiandDianchiLake.Then,weutilizethevectorboundaryasamask

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toextractareasofYangzonghaiandDianchiLake.Finally,forareascoveredbyclouds,weremovethenoisebasedonspectrumsignature.

3.Modeling

1)Watersurfacetemperaturemodel

Theinversionofwatersurfacetemperatureisbasedonatmosphericcorrectionmethod.Theexpressionfortheinfraredthermalluminancevalueireceivedbythesatellitesensor:

i=[ε#(s)+(1−ε)i]τ+iu（1）Where,εisthesurfaceemissivity,sisthetruetemperature(K),#(s)为istheluminanceoftheblackbodyattemperatureT,τistheatmospherictransmittanceinthermalinfraredband,iuisupwardatmosphericluminance,andiisdownwardatmosphericluminance.The

luminanceoftheblackbodyattemperatureT#(s)isexpressedasfollowing:

#(s)=[i−iu−τ(1−ε)i]/τε（2）

siscalculatedbyPlanckformula:

s=x2/ln(x1/#(s)+1)（3）

2)Watertransparencymodel

Thechangeofwatertransparency(SD)ismainlyaffectedbytheopticalcomponents(algae,non-algalparticles,yellowsubstances).Transparencyisalsoanimportantindextoevaluateeutrophication,whichdirectlyreflectstheclarityandturbiditydegreeofthelake.The

reflectanceofredandnear-infraredbandsiseasilyaffectedbysuspendedmatters.Suspendedmattershaveastrongnegativecorrelationwithtransparency.However,itisrarelyusedduetothestrongabsorptionofnear-infraredbandsinwater.Basedonthereflectancecharacteristicsofeachband,weselecttheratioofredandgreenbandstoconstructawatertransparency

model:

Ln(SD)=a*(BGreen/BRed)–b(4)

3)Chlorophyllconcentrationmodel

Basedontheempiricalmodelsforthesamewaterarea,theratioofnear-infraredbandto

visibleredbandisusedasasub-factor,whichcaneffectivelyminimizetheinfluenceoftheatmosphericeffect.Themodelestablishedistherelationshipbetweenthenaturallogarithmof

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chlorophyllA(chla)andBNIR/Bred:

Ln(chla)=a-b/(BNIR/Bred)（5）

4)Evaluatingmodel

AccordingtotherequirementsfromChina'senvironmentalmonitoringstation‘surfacewaterenvironmentalqualityassessmentmethod’,theevaluationofsurfacewaterqualityis

referencedbystandardGB3838-2002.Lakesandreservoirsnutritionalstatusevaluation

indexesincludethechlorophylla(chla),totalphosphorus(TP),totalnitrogen(TN),

transparency(SD)andpotassiumpermanganateindex(CODMn).Thenutritionlevelrangersfrom1to5whichisfrompoortosevereeutrophication.

TLI（chla）=25+10.86lnchla(

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TLI（TP）=94.36+16.24lnTP(

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TLI（TN）=54.53+16.94lnTN(

8)

TLI（SD）=51.18-19.4lnSD(

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TLI（CODMn）=1.09+26.61lnCODMn(

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Wheretheunitofchlaismg/m3,andtheunitofSDism.Unitsofotherindicatorsaremg/L.Inthisstudy,insteadofchlorophyllconcentrationandwatertransparency,TLI(chla)andTLI(SD)areusedaswaterqualityevaluationindexes.

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IIIResult

1.Yangzonghai

1）Watertemperature

Figure1.Yangzonghailanduses(left)andresearchareadivision(right)

ThelandusesalongtheYangzonghaicoastarediverse(Figure1),mainlyincludingtowns,woodland,andpaddyfields.Thesouthbankismajorlyoccupiedbyagriculturalland.The

landusesinthewestbankincludetowns,cities,woodlandorchards,andmining.AccordingtotheManualofDischargeCoefficientofLivestockandPoultryIndustry,thepollutionalongthesouthwestshorelineofYangzonghaimainlycomesfromlivestockbreeding.Thenorthernpartisaclusteroftownsandindustries.Basedonthestatisticsfromthesecondnational

pollutioncensus,industrialpollutionintheYangzonghaiBasinmainlycomesfromthe

northernpart,accountingfor63.1%ofthetotaldischargesin2018.Ninecompanies,

includingtheYangzonghaiPowerPlant,discharge362,100tonsofwastewater.Accordingtotheaboveinformation,wedividethewatersofYangzonghaiintosouthern,central,and

northernregionstodistinguishtheeffectsofvariouslanduses.

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Figure2.Yangzonghaimaximum(left)andaverage(right)watertemperatureinwinter

DuetothelimitationsofLandsattemporalresolutionandclimaticconditions,aswellastheconsiderationofamplifyingtheimpactofagriculturalwater,residentialwateranddischargedwarmwater,datafromwinter(December,January,andFebruary)dataaremainlyselectedforanalysis.Intermsofspatialdistribution,thehighestwatertemperatureisfoundintheriver

channelsandcoastalareasdominatedbyurban.Weassumethatthehighesttemperature

representsthetemperatureofpollutants(includingwateritself),andthelocationwheretheyappearisthesourceofpollution.Variationsinaveragetemperaturesindifferentregions

indicatethatthereisasignificantfeatureinthespatialdistributionofthetemperaturein

Yangzonghai.From2006to2018,thehighestwatertemperatureinthenorthernYangzonghaiisalwayshigherthanthatinthecentralandsouthernpart,aswellastheaveragewater

temperature.Theaveragetemperatureinthenorth,centralandsouthofthe12yearsis13.6□,13.1□and13.0□,respectively.Therefore,outpreliminaryanalysissuggeststhatthemain

sourceoftheoveralltemperatureriseofYangzonghaiisindustrialclusterrepresentedbytheYangzonghaiPowerPlantinthenorthernpart.

Inordertoinvestigatetheinfluenceonthewatertemperaturefromoutside,wevisualizethewatertemperaturebytakingthetemperatureofunaffectedwaterasthereferencetemperature.Therearetwomainmethodstocalculatethereferencetemperature.Thefirstistheaveragetemperatureobtainedfromthecoreareathatisnotaffectedbytheoutside.Thesecondistotaketheaveragewatertemperatureofthewholeresearchareaasareference,andthen

calculatetheaveragetemperatureafterexcludingtheareasthathavehighertemperaturethantheaverage.Regionsabovethebasetemperatureisknownasthewarmingzones.We

determinethereferencetemperaturebyreferringthesecondmethod.

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Figure3.DistributionofYangzonghaiwarmingzonesin2009(left)anddistributionofYangzonghai

NorthCoastwarmingzones(right)

Aftercalculatingthereferencetemperatureandvisualizingwarmingzones,theresults(Figure3)areconsistentwiththehypothesis.Thesouthwestcoastisaffectedbythepollutionfrom

large-scalelivestockbreeding.Thewatertemperatureismuchhigherthanthereference

temperature.However,duetotheaveragedepthofYangzonghai,thedischargedwatercannotthreatenthecorearea,andthewarmingareaiszonallydistributedalongthesouthwestcoast.Differentfromthesouthwestcoast,thedischargedwarmwaterfromthenorthcoastenterstheYangzonghaithroughchannelsneartheYangzonghaipowerplant,andthewarmingzone

extendsforwardthecoreareainaradiativepattern.

Figure4.Distributionofwarmingzones

Sincethewatertemperatureinwinteristhelowestallyearround,andthetemperature

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differencebetweendischargedwarmwaterandthenaturalwaterbodyisthelargest,the

distributionofwarmingzonescanbemoreclearlyobserved.Althoughotherlandusesinthenorthernpart,suchasparks,agriculture,andtourism,alsoimpactwatertemperature,dataandimagesovertheyearsshowthatdischargedwarmwaterfromchannelsneartheYangzonghaiPowerPlantcontributessignificantlyonwatertemperatureinthenorthernYangzonghai.

Figure5.AreaproportionofYangzonghaiwarmingzonesinspring(left)andwinter(right)

Figure6.AreaofYangzonghaiwarmingzonesinspringandwinter

Figure5showstheproportionofYangzonghaiwarmingzonesinspringandwinter,aswellasthetrend.Eachbarrepresentsthepercentageoftheareaabovethereferencetemperature.Theorangeandgraypartsinthecolumnrespectivelyrepresentstheproportionoftheareasthatare1□and2□higherthanthereferencetemperature.Fromfigure6,wefindthatduring2006-2007,theareaofspringwarmingzoneissignificantlylargerthanthatofwinter,withadifferenceofnearly10km2.

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2）TLI（chla）andTLI（SD）

Figure7.Spatialdistributionofwatersurfacetemperature(left),TLI(chla)(middle)andTLI(SD)

(right)innorthernYangzonghaiin2017

Figure8.CorrelationsofwatersurfacetemperaturewithTLI(chla)(left)andTLI(SD)(right)

Figure7showsthespatialdistributionofwatertemperature,TLI(chla),andTLI(SD)in2017winter.Ingeneral,theconcentrationalongtheshorelineishigherthaninthecentral,andtheconcentrationinthenorthishigherthaninthesouth.TheaverageTLI(chla)valueismaintainedabove60.Besides,thehighvaluesareclusteredneartheindustrialareainthenorth.Thereisadownwardtrendfrom2015to2017inTLI(chla).In2017,TLI(chla)insouthernandcentralYangzonghaidecreasedto30-40,indicatingastateofmediumnutrition.IntermsofTLI(SD),thedistributionpatternofhighvaluesissimilarwiththatofTLI(chla).OneconjectureisthatdischargedwarmwaterwithacertainvelocitypromotedtheupperandlowercirculationofthelakewhenitenterstheYangzonghai,causingupwardmovementofsuspendedordepositedparticles,whichbringsnutrientsforplankton,reducingthetransparencyofthewater.Accordingtothestatisticsshowninfigure8,wefoundthatthe

correlationcoefficientbetweenwatersurfacetemperatureandchlorophyllconcentrationTLI(chla)wasupto0.66,andthecorrelationcoefficientwithwatertransparencywasupto0.73.

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2.Dianchi

1）Watertemperature

Figure9.Dianchilanduses(left)andresearchareadivision(right)

In2010,thelandusesalongtheDianchiaredominatedbytowns,greenhouses,woodland,andgrassland.Duetothegeographicalenvironment,theurbandevelopmentbeginstoshifttothesouthandwestshorelineofDianchi.InordertoexploretheinfluenceofKunmingThermalPowerPlanttowaterquality,wedividedthewaterbodyintoinnersea,whereKunming

ThermalPowerPlantislocated,andoutersea.

Figure10.Maximum(left)andaverage(right)watertemperatureinwinter

Intermsofthehighestwatertemperature,innerseasharesasimilaritywithoutersea.In2007,

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2008,and2013,extremeeventsoccur,withthehighestwatertemperatureexceeding30□.From2003to2017,theoveralltrendshowedadownwardtendency.Duringthisperiod,theaveragewatertemperaturefluctuatesaround15□,andthefloatingrangegraduallyconverges.Accordingtothestatistics,theaveragetemperatureofinnerseainwaterfrom2003to2009is14.7□,andtheaveragetemperaturefrom2010to2017is13.5□.AftertheshutdownofKunmingpowerplant,theaveragetemperatureofinnerseainwinterdropsbymorethan1□.Overall,theaveragewatertemperatureofinnerseaisstillhigherthanthatofoutersea,evenaftertheKunmingpowerplantceases.Themainreasonmaybethattheinnerseaissurroundedbyurbanland,theloadofindustrialdischargeandresidentialwaterdischargeislarge.Besides,innerseahasaweakercapacityinpurificationandcoolingbecauseofthepoorwaterstoragecapacity,resultingintheaveragewatertemperatureishigherthantheouterseaalltheyearround.

Figure11.DistributionofwarmingzonesinWinter,2013(left),2016(middle)and2017(right)

Figure11showsthedistributionofwarmingzonesinDianchiinthewinterof2013,2016and2017.Duetotherapidurbanization,thedistributionofwarmingzonesisvarious.Ingeneral,thecentralandnorthernDianchiareregionswithlittleinfluence,whichiswithin0.5□higherthanthereferencetemperature.ChenggongdistrictposesagreatthreattothecoreareaofDianchi.AlthoughthewaterstoragevolumeofDianchiistwicethatofYangzonghai,theaveragedepthis5meterswhichmakesdischargedwarmwatermorelikelytospread

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outwardly.

Figure12ProportionofwarmingzonesinJanuary,February,April,andNovember

By2018,warmingzonesofthewholelakedecreasesto80%(210km2),andthewarming

zonesabove1□accountsforlessthan20%.ExtremeeventsoccurinJanuary2004andNovember2008,withmorethan60%oftheareaexceeding1□abovethereferencetemperature.

Figure13.LandusesalongDianchiin2005(left),2010(middle)and2015(right)

In2010,theurbanareaalongDianchiexceeds330km2,accountingformorethan30%ofland

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uses.Theforestlandareais84.06km2,accountingfor7.81%ofthetotalarea.Greenhouses,withanareaof82.03km2,aremainlydistributedaroundChenggongdistrictandJinningdistrict.WiththeplanninganddevelopmentofJinningdistrictafter2010,theurbancoveragerateofthisdistrictis8timesthatof2003by2017.ThegrowthrateofChenggongdistrictcomesthesecond,andtheurbancoveragerateof2017is3timesthatof2003.Bycomparingthelayoutsofurbanization,wefindthatthereisacorrelationbetweentheurbanizationandtheriseincoastalwatertemperature.Oneguesswemakeisthatduringthetransformationfromagriculturallandtourbanland,nutrients,andparticulatemattersflowintothenearbywaters,affectingwatertemperature,chlorophyllconcentration,andwatertransparency.Todistinguishtheimpactofurbanizationdevelopmentindifferentregions,weredividethestudyareaintoGuandudistrict,Xishandistrict,ChenggongdistrictandJinningdistrict.

Figure14.MinimumwatertemperatureinJanuary,February,April,andNovember

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Figure15.MaximumwatertemperatureinJanuary,February,April,andNovember

Asshowninfigure14,thelowesttemperaturesineachdistrictareclosetoeachother.Thismaybeascribedtotheexistenceofundevelopednaturallandalongtheshorelineofeachdistrict,sothestatisticalresultsshowsimilarvalues.InApril2009,thelowesttemperatureinJinningdistrictandXishandistrictis4□higherthantheothertwodistricts.Figure15showsthatwhetherKunmingpowerplantisshutdownornot,thehighesttemperatureinXishandistrictisalwayshigherthantheotherthreedistricts.InAprilandNovember2008,thehighesttemperatureinXishandistrictandJinningdistrictaresignificantlyhigherthantheothertwodistricts.After2010,theurbancoveragerateofJinningdistrictdoubles.ThehighesttemperatureinJinningdistrictsignificantlyincreasesafterthistimenodeandbecomesclosetotheXishandistrict.

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2）TLI（chla）andTLI(SD)

Figure16.SeasonalTLI(chla)andTlI(SD)inDianchi

Asfigure16shows,from2008to2018,thechlorophyllconcentrationinDianchiLakeshowsatrendofslightdecline.Chlorophyllconcentrationthroughouttheyearin2008-2010TLI(chla)valuesremainabove80forthewholeyear,thewaterqualityis□class.From2011to2013,itdecreasesyearbyyear,andmaintainsmesoeutrophicinwinter.Intermsofseasonalcharacteristics,chlorophyllconcentrationispositivelycorrelatedwithtemperature,andsummeristheseasonwhenchlorophyllreachesitspeakallyearround.ThetransparencyevaluationindexTLI(SD)showsadecreasingtrend.

Figure17.DianchiTLI(chla)(left)andcompositetrophicindex(right)variationtendency

Figure17showsthatthevariationtendencyofTLI(chla),asoneoftheparameters,isconsistentwiththatofcompositetrophicindex,whichisevaluatedbyaconfidentialorganization.Withinatimeperiodfrom2008to2018,thetrophicstatedropsfromhypereutrophictomesoeutrophic.

Watertransparencysharesasimilardecreasingtendency,butthereislittlevariationinseasonality.BesidesKunmingThermalPowerPlant,landusesconsistoflivestockfarming,agricultureandresiduallandaremajorfactorsthreatingthewaterquality.

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IVDiscussionandconclusion

1)KunmingpowerPlantandYangzonghaipowerPlantcanbesuspectswhoworsewaterqualitybyinfluencingwatertemperature,chlorophyllconcentrationandwatertransparency

InYangzonghaibasin,theaveragetemperatureinthenorthernpartisconstantlyhigherthantherestofwaterbody.Basedonourobservations,wefindthatthechannelnearYangzonghaiThermalPowerPlantisthemajorheatsourceandstrongcorrelationsexist.TheconclusioncanbedrawnthataswarmwaterisdischargedfromthechannelnearYangzonghaiThermalPowerPlant,areaswithhighertemperaturemaintainhigherchlorophyllconcentrationandworsestatusinwatertransparency.Throughtheinversionbasedonsatellitedata,wefindthatnearly60%(about20km2)areasofYangzonghaiareabovethereferencetemperature,andtheriverchannelofYangzonghaipowerplantisthemainheatsource.Thecorrelationsbetweenwatertemperatureandchlorophyllconcentrationandtransparencyaremorethan0.66.

DuetothenumeroustypesoflandusesaroundDianchi,theprocessofidentifyinganddistinguishingsourcesofpollutantsiscomplicatedandhardtobefulfilled.TheshutdownofKunmingThermalPowerPlant,whichislocatedtothewestofinnersea,becomesatimenodethatthegapbetweentheaveragewatertemperatureofinnerseaandouterseanarrows.Intermsofchlorophyllconcentration,aslightdeclineisobservedfrom2008to2018.Itishighlycorrelatedwithseasons,asthemaximummostlyappearsinsummer.

2)Advantagesandlimitationsofusingsatelliteremotesensingdataformonitoring

Remotesensinghasbecomemoreandmorepopularamongwaterresearchersinrecentyears.Comparedwithgroundstations,satellitedatahastheadvantagesofwidecoverage,goodcontinuityofhistoricaldataandlowcost.Alldatausedinthisprojectispubliclyavailableandapplicabletoallwaters.

Therearesomelimitationsinretrievingchlorophyllconcentrationandwatertransparencyfromsatellitedata.Theaccuracyofthetwoparametersobtainedfromsatelliteislowerthanthegroundmeasurement.Duetotheinfluenceofclimaticconditionsandotherfactors,somesatelliteimagesaredisturbedbyclouds,resultinginthereductionofhistoricaldatacontinuity.Ourresearchhopestointegratesatellitedataandgroundobservationdata,andmakeupthe

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gapoftimeperioddisturbedbycloudsbymachinelearning,toobtainmorecontinuousdataandconductyear-roundtimeseriesanalysis.

3)Policyrecommendation

Thedemandofelectricityconsumptionfordailyproductionandpeople’sdailylifeisexponentiallyincreasing.Shuttingdownpowerplantswithoutalternativeswillcausedissatisfactionamongthepublic.Stakeholdershaveconflictsaswellascommoninterestswhichmakethemunabletodecouplefromeachother.Thisprojectcanbeareferenceforwaterpollutioncontrolorsiteselectionofthermalpowerplants.Althoughthemechanismofaquat