FEATURE AND MECHANISM OF SEDIMENT DYNAMIC CHANGING PROCESSES IN THE MODERN YELLOW RIVER DELTA

Yellow River derived sediments will experience a series of dynamic changing processes including deposition, consolidation, liquefaction, erosion to re-suspension, seabed deformation to submarine landslide and post-reformation of seabed under the action of gravity, hydrodynamics and bioturbation et al. Over the past decade, our research team has conducted a series of laboratory and field physical simulation experiments and in-situ observations on the subaqueous delta to investigate the feature and mechanism of each dynamic changing process, primarily found that:consolidation of rapidly-deposited sediments is pretty fast, of which the strength can reach or even exceed the native seabed in 1-2 days, forming a significant depth profile of heterogeneity and "overlying crust layer". Silty seabed is easier to build up pore water pressures to induce seabed liquefaction, which will, on the one hand, change the erosion resistance of surface sediments; on the other hand, part of the fine-grained sediments will be pumped up to seabed surface and then become re-suspended sediments under the driving of seepage flows on seabed, i.e. part of re-suspended sediments originate from the interior of seabed. Slope of the modern Yellow River delta is extremely low, submarine landslide may occur over a nearly horizontal slope. It is possibly that stratum re-construction caused by wave-induced liquefaction or soil particle migration caused by seepage flows inside seabed could reform relatively homogeneous seabed into layered structure, which may provide a new insight into the formation mechanism of seabed stratification.