简介：Inestuarineandcoastalareas,theseabedisinaconstantprocessofdynamicchangeundermarineconditions.Seabedsedimenterosionandresuspensionareimportantprocessesthatsafelycontrolthegeologicalenvironment.FieldtripodobservationsconductedintheJiaozhouBayinChinaarereported,toinvestigatetheeffectsofhydrodynamicconditionsontheerosionandresuspensionprocessesoftheseabed.Theobservationalresultsshowthatthemaximumshearstresscreatedbytidalcurrentscanreach0.35N/m~2,whichishigherthanthewave-inducedshearstressduringfairweatherconditions.Aseabederosionfrequentlyoccursduringthefloodtide,whereasaseabeddepositionoccursduringebbtide.WavescanproduceabottomshearstressapproximatelyequivalenttothatinducedbycurrentswhenthelocalwindreachesForce4withaspeedof5m/s.Whenthewindreaches7m/sandthesignificantwaveheightreaches26cm,wavesplayamoresignificantrolethancurrentsinthedynamicprocessesoftheseabedsedimentresuspensionandleadtoahighvalueofturbiditythatisapproximatelytwotoeighttimeshigherthanthatinfairweather.Theseanalysesclearlyillustratethatperiodiccurrent-inducedsedimenterosionandresuspensionaredominantinfairweather,whereasepisodichighwavesareresponsibleforsignificantsedimentresuspension.AdditionalworkisneededtoestablishamorethoroughunderstandingofthemechanismsofsedimentdynamicsintheJiaozhouBay.

简介：Ascientifichypothesisisproposedandpreliminarilyverifiedinthispaper:underthedrivingofseepageflows,theremightbeaverticalmigrationoffine-grainedsoilparticlesfrominteriortosurfaceofseabed,whichisdefinedas‘sub-bottomsedimentpumpaction’inthispaper.FieldexperimentswereperformedtwiceontheintertidalflatoftheYellowRiverdeltatostudythisprocessviabothtrappingthepumpedmaterialsandrecordingtheporepressuresinthesubstrate.Experimentalresultsarequiteinterestingaswedidobserveyellowslurrywhichismainlycomposedoffine-grainedsoilparticlesappearingontheseabedsurface;seepagegradientswerealsodetectedintheintertidalflat,undertheactionoftidesandsmallwindwaves.Preliminaryconclusionsarethat‘sedimentpump’occurswhenseepageforceexceedsacertainthreshold:firstly,itisbigenoughtodisconnectthesoilparticlesfromthesoilskeleton;secondly,thedegreeofseabedfluidizationorbioturbationisbigenoughtoprovidepreferredpathsforthedetachedmaterialstomigrateupwards.Thentheywouldbefirstlypumpedfrominteriortothesurfaceofseabedandtheneasilyre-suspendedintooverlyingwatercolumn.Influentialfactorsof‘sedimentpump’aredeterminedashydrodynamics(waveenergy),degreeofconsolidation,indexofbioturbation(permeability)andcontentoffine-grainedmaterials(sedimentaryage).Thisnewperspectiveof‘sedimentpump’mayprovidesomeimplicationsforthemechanisminterpretationofseveraluncleargeologicalphenomenaintheYellowRiverdeltaarea.