Avertical(laterallyaveraged)two-dimensionalhydrodynamicmodelisdevelopedfortides,tidalcurrent,andsalinityinabranchedestuarinesystem.ThegoverningequationsaresolvedwiththehydrostaticpressuredistributionassumptionandtheBoussinesqapproximation.Anexplicitschemeisemployedtosolvethecontinuityequations.ThemomentumandmassbalanceequationsaresolvedimplicitlyintheCartesiancoordinatesystem.Thetributariesaregovernedbythesamedynamicequations.Acontrolvolumeatthejunctionsisdesignedtoconservemassandvolumetransportinthefinitedifferenceschemes,basedonthephysicalprincipleofcontinuummediumoffluid.Predictionsbythedevelopedmodelarecomparedwiththeanalyticsolutionsofsteadywind-drivencirculatoryflowandtidalflow.Themodelresultsforthevelocitiesandwatersurfaceelevationscoincidewithanalyticresults.ThemodelisthenappliedtotheTanshuiRiverestuarinesystem.Detailedmodelcalibrationandverificationhavebeenconductedwithmeasuredwatersurfaceelevations,tidalcurrent,andsalinitydistributions.Theoverallperformanceofthemodelisinqualitativeagreementwiththeavailablefielddata.ThecalibratedandverifiednumericalmodelhasbeenusedtoquantifythetidalprismandflushingrateintheTanshuiRiver-TahanStream,HsintienStream,andKeelungRiver.
