AssessmentofeutrophicationinYenSoLakeusingSentinel-2imagesandCo-kriging

Abstract

Thisstudyaimstomapthespatialdistributionofthetrophicstateindex(TSI)inYenSoLakeutilizinganin-situdatasetofChlorophyll-a(Chla)collectedfrom23samplingpointswithintheYenSoLakeon29/11/2021;3/4/2022;14/12/2023and69samplingpointsinWestLakeon4/12/2021;18/1/2022;7/7/2023coupledwithSentinel-2(S2)satelliteimageryacquiredonthesedates,therebyhelpingtooptimizeassessmentofeutrophicationinYenSoLake.ByleveragingthecorrelationbetweenTSIChlaandthespectralratioofband7toband3oftheS2images(withacorrelationcoefficientof0.83),thisbandratiowasincorporatedasanauxiliaryvariabletoenhancetheaccuracyofCo-krigingpredictions,withanotableimprovementinthedeterminationcoefficients(R2)andthestandarderrors(RMSE),increasingfrom0.17÷0.63to0.67÷0.89andfrom2.33÷4.22to0.32÷0.58,respectively.TheresultsshowthatYenSoLakeishypertrophicwithTSIChla>78atallmeasurementtimes.TheTSIChlavaluesexhibitedseasonalvariations,beinglowerduringthedryseason(NovembertoDecember)andhigherduringtherainyseason(April).Spatially,elevatedTSIChlavalueswereprimarilyobservednearthedrainagechannelinletsalongthelakeshoreandinthethreesmallerlakeswithinYenSoPark.ThesefindingshighlighttheutilityofS2imageryasaneffectivetoolformonitoringandevaluatingeutrophicationinYenSoLak