The Research Of Sediment Transport And Seabed Evolution On The Kendong Area

During the past few years, for the frequent fluctuations riverway of the Yellow River variation import of water and sediment, submarine topography of the Yellow River Delta has also undergone a lot of changes. Part of the coast varying degrees of erosion back, lead to the great challenges of coastal protection. This thesis is based on field investigation and laboratory analysis, historical data of the seabed and coastal aspects of the mathematical model of sediment transport calculations. From the point of dynamic geomorphology, analysis the sedimentology of the Kendong waters sediment characteristics, coastal sedimentary type, bottom sand migration and the laws or characteristics of the sea-bed erosion, discuss the history of the evolution of the coastline (including shoreline changes Remote Sensing analysis diagram) analyze and evaluation the trend of the erosion or siltation, strength and stability of the shoreline segment.The result shows that the sediment of the Yellow River mouth spreading south does not affect the basic sediment deposition south of the Laizhou Bay. Since1976, the deposition rate is3.3～5.3cm/a of Laizhou Bay Central, that decreasing extremely disproportionate of the large amount sand southward, excessive of the Yellow River sediment is not deposit in this area. Laizhou Bay is just an transport channel of sediment. During the high tide, the flow of the south bank trend of the West and the West Bank clockwise turn to the north, jacking with the south west rising tide of the south estuaries; during the falling tide, the tide flows northeasterly direction. The flow field conducive to the outward migration of the Laizhou Bay sediment, the sediment transport to the northeast in the role of the flow field.the migration of the large amount of sand to the northeast by the Laizhou Bay, mitigate siltation of the estuary. Due to the specific impact of the flow field in the Laizhou Bay, a considerable amount of sediment transporting to the south transport to the northeast eventually in the flow path of the estuary of Laizhou Bay. The Yellow River sediments proliferation northeast to the central region of the Bohai Sea finally.After changeing branch in1996of Yellow River, the new port in front and the south side of the old entrance occurs siltation, the north side of the entrance and the old port in front eroded. Siltation is greater than erosion, the area of siltation is1.9times of erosion and the volume is1.7times the amount of erosion. Average annual siltation and erosion volume of4.27×108m3and2.56×108m3, the average maximum deposition and erosion thickness is lm and0.83m annual respectively. The distance of2m isobath maximum silt into4300m, the total deposition in an area of27km2, the total area of erosion is11km2and net siltation an area of16km2, the average siltation rate of2.5km2/a. The general trend of5m isobath is advancing to the sea with the largest silt distance of4300m and total siltation area43.6km2and total erosion area of7.4km2. The net silting area is36.3km2and the average siltation rate for5.8km2/a. The siltation area within10m isobath is56km2, the total erosion area is6.4km2and net deposition area is49.6km2, the average siltation rate is7.96km2/a. Overall, north of Yellow River estuary sea sediment transport direction from south to north, south of Yellow River estuary transport direction is from the north to the south.With the constant extension of mouth spit, both sides of the river present the gulf shape and water power abate, thus produce sediment deposition. Then both sides of the river siltation expands gradually. The entrance of the branches Qing8is the most strong siltation area, and old Yellow River estuary Diaodong branches is the most strong erosion area. More than80%of the sediment deposition in the bar, leading to1m average deposition rate annually. Due to the tidel current and the influence of river runoff, part of the sediment transport to south of the river. Due to the influence of the residual current, part of the sediment transport to the northwest along the15m contour. The north and south sides of Yellow River bank slope erosion is a decreasing trend. North of the Yellow River estuary shoreline erosion back by strong bank slope erosion and the lack of foreign sediment supply. the scour of the south bank slope is weak and tended to be relatively stable with the weakening of hydrodynamic conditions and trends of sediment deposition effect,.