关键词: ADCP, 悬沙浓度, 粒度参数, 输运机制, 长江口

Abstract: The acoustic Doppler current prof iler (ADCP) is widelly used to measure current velocit ies in recent years. In this contribution, the high-frequency velocity data were measured by using the 600Hz ADCP at two stations in the Changjiang estuary; and the suspended sediment samples were collected and analyzed to obtain grain size parameters, i. e. mean grain size, sorting coefficient, skewness,and kurtosis. Further, the acoust ic signals are transferred into suspended sediment concentrations by establishing the regression relationship between echo intensities and the concentrations from in situ water samples. The mechanism of suspended sediment transport and the variations of grain size parameters related to the hydrodynamics in atidal cycle are analyzed. The results indicate that the suspended sediment transport in the estuary is dominated by river flow. Moreover, the storks drift, tidal dispersion and vertical dispersion also play an important role in the suspended sediment transport. The variations of hydrodynamic condition from sea to land and during a tidal cycle result in the changes of grain size parameters of suspended sediment at different layers: the suspended sediment with finer grain size and wider kurtosis is badly sorted, positively skewed, and the component of clay is also increased. The grain size during flood phase with coarser grain size, small sorting coefficient is more negatively skewed and narrowly kurtosis than that during ebb. Furthermore, these parameter variations in a tidal cycle also indicate the influence of resuspension. The value of standard deviation increases with the decreasing of water depth.

Key words: ADCP, suspended sediment concentration, grain size parameters, mechanism of sediment transport, Changjiang River Estuary