Preliminary Study On The Character And Transportation Of Suspended Sediments At Minjiang Estuary

Simultaneous observation at four stations at Minjiang estuary was carried out during spring tide in the flood season of 2007. Based on the observed data,we analyzed the suspended sediment distribution, character of sediment resuspension, their transport and the mechanism at Minjiang estuary in a tidal cycle.The result showed that the hydrodynamic conditions were complicated at Minjiang estuary,the vertical distribution of suspended sediment showed temporal changes. The turbidity maximum zone movement in tide cycle leaded to the change of suspended sediment in upstream or downstream, however, the high concentration period in Meihua channel was closely related to resuspension. Suspended sediment was mainly composed of fine silt, which was poor sorted, the grain grade was inclined to the side of coarse grain with a single peak, which suggested a uniform source. When the water depth decreased, both the standard deviation of the suspended sediment size fraction content and the sensitive components quantity increased, which reflected the effect of resuspension.The sediment at the estuary was often active, and the activity in flood tide was greater than that in ebb tide. The sediment activity was greatest in Meihua channel and resuspension was obvious. The sedimentary flux at the estuary is higher than the resuspension flux, which is comparatively low.Tide sediment transport in diurnal at A1 station was asymmetric and A2 station demonstrated high instantaneous flux rate and low net flux rate. Flood tide current played a much more important role than other factors in the suspended sediment transport in the first tide cycle. The intense resuspension is the major reason to result in greater instantaneous flux in the branch channel than that in the main channel. The advection, storks drift, tidal trapping and vertical shearing diffusion all played important roles in the transport of resuspended sediment.