Experimentalstudyoninitiationofbivalveshellmotiononahorizontalsandbed,underaunidirectionalflowofwater,ispresented.Experimentswerecarriedoutinaflumewiththreetypesofbivalveshells,namelyCoquinaClam,Cross-barredChioneandPonderousArk,totesttheconditionforinitiationofmotion.Theshapeparametersofbivalveshellsaredefinedappropriately.Experimentswereconductedinaflumewithahorizontalbed,andthecriticalshearstresseswereestimatedusingVanoni'sside-wallcorrection.Thecharacteristicparametersaffectingtheinitiationofshellmotiononahorizontalbedinrough-turbulentregimeidentifiedbasedonthephysicalreasoninganddimensionalanalysisaretheShieldsparameter(nondimensionalcriticalshearstress),nondimensionalcompetentmeanvelocity,nondimensionalsandroughness,nondimensionalflowdepthandshapeparameter.EquationsofShieldsparameterandnondimensionalcompetentmeanvelocityfortheinitialmovementofshellsonahorizontalsandbedwithconvexupwardanddownwardconditionsareobtainedusingexperimentaldata.
