IN-SITU OBSERVATION OF SEDIMENT DEPOSITION PROCESS IN CHENGDAO SEA AREA OF THE YELLOW RIVER ESTUARY

The in-situ measured amount of deposits was obtained in the Chengdao sea area off the Yellow River Estuary using a time-series sediment trap. Combined with the synchronous hydrodynamic observation and subsequent laboratorial grain size analysis, we firstly calculated the depositional flux, and subsequently analyzed the source of trapped sediments, then discussed the influence factors of depositional process, and finally evaluated its proportion in the resuspended sediments. The results indicate that the sediment depositional flux in the Chengdao sea area is around 120~280 g·m^-2·d^-1. The depositional fluxes show a positive correlation with the re-suspended deposits possibly indicating that the deposited sediments maybe mainly come from the re-suspension of bottom sediments. Sediment deposition still occurs even the excess shear stress is greater than zero, and the amount of deposition may be greater than that when excess shear stress is intermittently less than zero. This is inferred as the consequence of the liquefaction properties of silty seabed in the area. About 5% of the resuspended sediments deposit in-situ, and most of them remain in suspension or will be transported elsewhere, which may be the reason of intense erosion of seabed in this area.