VERTICAL AND TIDAL CHANGES IN SSC IN TURBIDITY MAXIMUM IN THE YANGTZE RIVER MOUTH

摘要

The variability of suspended sediment concentration (SSC) in different estusary has been noticed by many researchers, especially in the turbidity maximum. The Yangtze River is the third longest and the fourth largest river in the world, transports 3.52 x 10~8 t · y~(-1) of fine-grained sediment into East China Sea during 1985-2000 years. Thus, it is necessary to study the changes in SSC in turbidity maximum of Yangtze River Mouth. An OBS-3A made in USA was used to measure the turbidity near the surface and vertical profiles of landward of maximum turbidity in the south passage of Yangtze River Mouth. Meanwhile, an ENDECO--174SSM (made in U.K) was applied for measurement of current speed and direction. OBS turbidities were calibrated with in situ water samples. Data of tidal level were collected from an adjacent hydrological station. Results include: (1) SSC increased in all profiles. (2) Spring SSC was significantly greater than neap SSC. (3) Currents were main dominated by ebb. It is turn out that tidal and vertical variability in SSC in the study area was mainly influenced by advection and resuspension/settling processes, and wind waves may also have some effect on SSC.