Difference Of Hydrodynamics And Sediment Characters At Typical Reaches & Analysis To Factors In The Yangtze Estuary

The Yangtze Estuary is located in the coastal area of east China. The conditions of hydrodynamics and sediment transport are complex under runoff current, tidal current, wind and other factors in the Yangtze Estuary. There exist several important reaches and key interfaces in the Yangtze estuary. The estuary process is restricted by these interactional interfaces in some degree.To several reaches and interfaces, Methods of hydrology, sediment transport and statistics etc. are used to study and summarize the difference of hydrodynamics and sediment characters. And the author analyses primarily factors on sediment characters in order to offer the scientific theory for empoldering and utilizingresources in the Yangtze estuary.The results show that there are different characters in hydrodynamics andsediment hands to several reaches and interfaces. Firstly, water levels are difference in the several typical reaches and key interfaces. Change of water level gradually reduce from Datong(the upper limit affected by tides during dry seasons) to down. Because of the impact on tidal currents the range of water level changes smooth from Jiangyin(the upper limit affected by tidal currents during flood seasons)to mouth bar straightly. Secondly, tidal velocity and direction exist in otherness. The ebb current takes as the role under the control of runoff currents in the upper reach. The flood current gradually become stronger by the tidal current in the reach from Jiangyin to mouth bar. Moreover, the waves affect hydrology of the estuary in some degree. Due to the open delta estuary, stormy waves show obvious driving in the offshore area. It becomes weak gradually from the mouth bar to the upper reach. Thirdly, Suspended sediment concentration that is different takes on the change of "higher-lower-higher" along the channel. The reach from Jiangyin to Nantong is controlled mainly by the runoff current, in which suspended sediment concentration is stable. Suspended sediment concentrations of downstream from Xuliujing are different because of the different runoff distribution. At last, the characters of sediment granularity are different. From downstream Datong hydrological station to mouth bar suspended sediment grain-size recognized as "coarser-finer-coarser-finer" were differentiated. The grain-size of bed load is provided with variety rule obviously in terms of along channel. In median diameter,...