CHARACTERISTICS OF DISPERSAL OF THE YELLOW RIVER WATER AND SEDIMENT TO THE SEA DURING WATER-SEDIMENT REGULATION PERIOD OF THE YELLOW RIVER AND ITS DYNAMIC MECHANISM

Data of current velocity, water temperature, salinity and concentration of suspended sediment were collected from 3 time-series survey transects of 3 boats off the Yellow River delta and 24 grid survey stations in the adjacent Bohai Sea during water-sediment regulation period of the River. Based on the collected data,the dispersal characteristics of the river water and sediment to the sea were analyzed, and the residual current and sediment flux of the time-series stations were calculated. The results show that the dispersal area of the Yellow River sediment to the sea was basically limited within the coastal zone to 20 km from the coast, extending to the southwest of the Laizhou Bay in the south and to 38°N in the north. The diluted river water dispersed widely. Covering the north and middle parts of the whole Laizhou Bay, the diluted water could extend to the Longkou City at its farthest southeast end,indicating that the dispersal pattern of the river sediment was quite different from the water dispersal pattern. There were two centers with high sediment concentrations. One of them was located in the river mouth area, and the other was around the abandoned Diaokou River mouth area, corresponding to sediment from the river mouth and sediment from resuspension of the surface sediment in the abandoned river mouth, respectively. The barred and convergent effects of the tidal shear fronts near the river mouth and off the delta coast were responsible for the limited dispersal of the Yellow River sediment within 13 m of the water depth. The wide dispersal of the river diluted water was controlled by the surface residual currents. There was little sediment exchange between the two high sediment concentration centers due to the directions of the residual currents and weak vertical mixing. The residual currents and the sediment flux showed that the direction of the sediment dispersal was basically northeastward.