Thetidalasymmetry-inducedsiltationbelowtidalbarriersisaworldwideproblemthatrestrictsregionalsocio-economicandenvironmentaldevelopment.Thehydrodynamicprocessesofthesmallmudestuaryalsofeatureahighuncertaintyafterestuaryrestorationmeasures.Inthisstudy,ahydrodynamicmodelbasedontheMIKE21isusedtoquantifytheresponsesoftidalasymmetrytoatwo-phaserestorationprojectinShuanglongEstuary,BohaiBay,China.Accordingtothenumericalmodelingresults,thetidalflatremovalintheupperestuary(first-phaserestoration)inducesthefloodasymmetryswitchingtotheebbasymmetryinunrestoredreachbutenhancesfloodasymmetryinwideningrestoredreach.Althoughthetidalasymmetryrevertstoflood-dominatedpatternafterfullrestorationovertheestuary,theimbalancebetweenfloodandebbvelocitiesisrelieved.Apossiblenetsedimenttransportpatternbasedonacomparisonofdominantasymmetriccurrentandactualsedimenttransportperiodshowsnetsedimentsintheupperestuaryandinlettransportseawardandlandward,respectively,inthefirst-phaserestoration,whereaslandwardnetsedimenttransportoccursinthewholeestuaryunderthesecond-phaserestorationscenario.Giventheseresults,weassumethataswitchfromtheflood-dominatedestuarytoebb-dominatedestuarycanbecausedbyredesigningthecross-sectionalprofile.ThequantitativecomparisonofLagrangianresidualcurrentsalsoimpliesthatachannel–shoalstructureratherthanaflatbathymetrycanpromotethemasstransport.Therefore,reshapingthechannel–tidalflatsysteminrestorationprojectscanpreventthesedimentationoftheestuaryandimprovethewaterenvironment.
