| The Yangtze River Estuary, which combines land and sea transport, is located inYangtze River Delta Economic Zone in China. However, the development andregulation of the deep water channel in the estuary is affected by the sedimentdeposition. In order to improve the effects of channel regulation, it’s important tomake a systematic investigation on the suspended sediment transport. Considering theeffects of many factors on the settling speed of cohesive sediment, a three-dimensional numerical model based on the FVCOM was applied to the simulation ofan ideal estuary and the Yangtze River Estuary, and the sediment tansport for floodand dry seasons was simulated and analyzed.The main contents are summarized asfollows.(1) Through summarizing the research results on settling speed of cohesivesediment, a settling velocity formula including influences of sediment concentration,flow turbulence and salinity was presented, and the formula was added in theFVCOM three-dimensional model.(2) The hydrodynamics, salinity and suspended sediment of ideal estuary weresimulated. The water flow, salinity distribution and movement, spatio-temporalchanges and distribution of suspended sediment, and the influence of salinity on thesuspended sediment transport are analyzed in horizontal plane and vertical profile.(3) The model of hydrodynamics, salinity and suspended sediment based onFVCOM was verified through comparison between simulated and experimentalresults in flood and dry season, which shows that the present model is reasonable.(4) According the simulated results of hydrodynamics, salinity and suspendedsediment of Yangtze River Estuary, the salinity distribution shows similar trends forflood and dry season, while the salt intrusion moves further upstream in dry season.The suspended sediment concentration in dry seanson is less than that in flood season,and the turbidity zone also moves further upsream in dry seanson. The simulatedresults from the models with or without the effects of salinity on the settling speedshow the similar trend of sediment concentration ditribution, and the sedimentconcentrtion in the surface layer with salinity effects is close to that without thesalinity effects. However, the sediment concentrtion in the bottom layer with thesalinity effects is obviously larger. It is concluded that the salinity exerts significantinfluences on sediment transport, and it is also verified that the simulated results with salinity effects agree better with the measured data. |
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