黄河2009年调水调沙期间河口水动力及悬沙输移变化特征

Effect of water-sediment regulation in Yellow River on hydrodynamics and suspended sediment transport in its estuary

根据2009年7月黄河第九次调水调沙期间和结束后在黄河口两个站位观测的水文泥沙资料,对调水调沙期间和结束后河口的水动力和悬沙分布特征进行了对比分析,并对潮周期内悬沙输移过程进行了探讨。结果表明:调水调沙期间相比于结束后,落潮动力加强,涨潮动力有所减弱,尤其在水体表层表现明显,河口切变锋类型不同,其出现时间长度亦不同;调水调沙期间含沙量较大,垂向分布较复杂,而结束后含沙量低,垂向梯度变化较小;此外,调水调沙期间河口悬沙在输移过程中以沉降作用为主,并在涨急和落急时刻伴随着底沙的再悬浮,而结束后悬沙浓度降低幅度较大,泥沙再悬浮作用较强。

On the basis of the measurements of current velocity and suspended sediment at the two stations in the Yellow River Estuary during and after the water-sediment regulation period in July 2009,the hydrodynamics and distribution of suspended sediment are analyzed by comparing their characteristics in and after the water-sediment regulation period.Additionally,the transport process of suspended sediment in the estuary in the tidal cycle during the period of water-sediment regulation is discussed.The results show that the ebb dynamics intensified but the flood dynamics weakened compared with the tidal current after the water-sediment regulation period,which was especially evident at the water surface.Although the tidal shear front turned up during and after the water-sediment regulation,their types were different and their lasting times were not same.The suspended sediment concentration was high and its vertical distribution was complicated during the water-sediment regulation period.After the water-sediment regulation period,the suspended sediment concentration was low and the vertical gradient was small.Furthermore,during the period of the water-sediment regulation,the sedimentation process was dominant in the transport process of the suspended sediment and the re-suspension of bed sediment occured only during the maximum velocity of the flood and ebb tides;in general,the deposition of sediment was intense in the estuary.After the water-sediment regulation,the suspended sediment concentration decreasesd greatly and the sediment re-suspension was predominant in the process of suspended sediment transport.