Tide‐modulated hyperpycnal flows off the Huanghe (Yellow River) mouth, China
Tide‐modulated hyperpycnal flows off the Huanghe (Yellow River) mouth, China
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DOI：
10.1002/esp.2032
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发表时间：
2010-09
影响因子：
3.3
通讯作者：
Houjie Wang;N. Bi;Yan Wang;Y. Saito;Zuosheng Yang
中科院分区：
文献类型：
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作者：
Houjie Wang;N. Bi;Yan Wang;Y. Saito;Zuosheng Yang
在海洋环境中很少观察到超密度流，尽管它们被认为在河口和三角洲沉积体系中的沉积物分散中起着关键作用。本文介绍了黄河口海域高密度流的观测结果、高密度流与潮汐周期的关系以及高密度流的形成机制。1995年汛期黄河口6个系泊站的同步观测结果表明，黄河口高密度流是由高浓度的泥沙输入引起的，并受潮汐的调制。高密度流在落潮结束时开始，此时近底悬浮泥沙浓度（SSC）迅速增加，盐度急剧下降（逆盐楔）。超密度层内悬浮颗粒的中值粒径增加，导致水柱中悬浮沉积物的强烈分层。接近尾声的涨潮，hypercnal流衰减，由于摩擦的流量和潮汐混合，崩溃的水柱分层的上，下边界。底层含沙量和悬浮颗粒中值粒径均显著降低。较粗的泥沙颗粒沉积下来，高密度流停止了。高密度流的潮内行为与SSC、盐度和水柱分层的变化密切相关。黄河口的高密度水流和黄河的高含沙量，使黄河三角洲在洪水期有近90%的泥沙入海。版权所有© 2010约翰威利父子有限公司.
Few hyperpycnal flows have ever been observed in marine environments although they are believed to play a critical role in sediment dispersal within estuarine and deltaic depositional systems. The paper describes hyperpycnal flows observed in situ off the Huanghe (Yellow River) mouth, their relationship to tidal cycles, and the mechanisms that drive them. Simultaneous observations at six mooring stations during a cruise off the Huanghe mouth in the flood season of 1995 suggest that hyperpycnal flows observed at the river mouth are initiated by high concentrations of sediment input from river and modulated by tides. Hyperpycnal flows started near the end of ebb tides, when near‐bottom suspended sediment concentration (SSC) increased rapidly and salinity decreased drastically (an inverse salt wedge). The median grain size of suspended particles within the hyperpycnal layer increased, causing strong stratification of the suspended sediments in the water column. Towards the end of flood tides, the hyperpycnal flow attenuated due to frictions at the upper and lower boundaries of the flow and tidal mixing, which collapsed the stratification of the water column. Both sediment concentration and median grain size of suspended particles within the bottom layer significantly decreased. The coarser sediment particles were deposited and the hyperpycnal flows stopped. The intra‐tidal behaviors of hyperpycnal flows are closely associated with the variations of SSC, salinity, and stratification of the water column. As nearly 90% of riverine sediment is delivered to the sea during the flood seasons when hyperpycnal flows are active, hyperpycnal flows at the Huanghe mouth and the river's high sediment loads have caused rapid accretion of the Huanghe delta. Copyright © 2010 John Wiley & Sons, Ltd.