ADCP在长江口悬沙输运观测中的应用

声学多普勒流速剖面仪 (ADCP)是近年来发展起来的一种用于测量流速的声学仪器 ,同时还可以通过建立回声强度和现场取得水样的回归关系式而获得悬沙浓度的数据。本文利用在长江口两个站位的高频观测数据 ,对现场取得的悬沙作粒度分析 ,在此基础上对枯季长江口地区悬沙输送机制和悬沙粒度对水动力的响应进行了分析和探讨。结果表明 :平均流输运在整个悬沙输送中占主导地位 ,同时潮扩散和垂向扩散作用也是引起两站悬沙输运的重要因子 ;不同层次和不同时刻的悬沙粒度参数的变化 ,既和海 陆转换有关 ,也和潮相变化密切相关。

Suspended sediment behavior and transport in Changjiang River Estuary

The acoustic Doppler current profiler (ADCP) is widelly used to measure current velocities 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 acoustic 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