长江口北槽下游河道悬沙浓度垂向分布特征研究

发布时间：2018-05-14 11:07

本文选题：悬沙浓度分布 + 盐度梯度　；参考：《华东师范大学学报(自然科学版)》2017年06期

【摘要】：根据2013年10月26日至11月9日在长江口北槽下游河道从小潮到大潮连续14 d的现场定点水沙观测数据,对北槽下游河道悬沙浓度的垂向分布特征进行了研究,并探讨了盐度梯度和流速大小潮变化对悬沙浓度分布的影响.结果表明,北槽下游河道的水动力条件存在显著的大小潮差异,小潮具有流速弱、悬沙浓度低、盐度梯度大、盐度分层显著的特点,而大潮则具有流速强、悬沙浓度高、盐淡水混合程度高、盐度分层弱的动力特点.受较大盐度梯度和弱流速的影响,小潮期间的悬沙浓度分布主要为阶梯型和L型,强盐度密度分层使悬沙难以扩散到水体表层,高浓度悬沙仅出现在水体中下部.在强流速和弱盐度分层的影响下,大潮期间的悬沙浓度分布主要为线性分布,悬沙能够扩散到水体表层,盐度密度分层对悬沙浓度分布的影响显著削弱,在落潮后期悬沙浓度分布表现为典型的垂线型分布,悬沙在水体中充分混合.研究表明,小潮和大潮的悬沙浓度分布基本偏离Rouse分布,仅在小潮落憩时刻符合.在大潮期间,实测的线性分布都很好地符合Soulsby公式,利用该公式能够很准确地预测这些浓度分布.
[Abstract]:The vertical distribution characteristics of suspended sediment concentration in the lower reaches of the northern channel of the Yangtze River Estuary were studied based on the observation data of suspended sediment concentration in the lower reaches of the Yangtze River Estuary from October 26 to November 9, 2013, which lasted for 14 consecutive days from the small tide to the spring tide. The effects of salinity gradient and tidal current on suspended sediment concentration distribution are discussed. The results show that there are significant differences in the hydrodynamic conditions of the lower reaches of the northern channel. The low tide has the characteristics of weak velocity, low suspended sediment concentration, large salinity gradient and remarkable salinity stratification, while the spring tide has the characteristics of strong velocity and high suspended sediment concentration. The dynamic characteristics of high mixing degree of salt and fresh water and weak stratification of salinity. Under the influence of large salinity gradient and weak velocity, suspended sediment concentration distribution during the low tide is mainly ladder type and L type. Strong salinity density stratification makes it difficult for suspended sediment to spread to the surface of water body, and high concentration suspended sediment only appears in the middle and lower part of water body. Under the influence of strong velocity and weak salinity stratification, suspended sediment concentration distribution during spring tide is mainly linear distribution, suspended sediment can spread to the surface of water body, the influence of salinity density stratification on suspended sediment concentration distribution is obviously weakened. The suspended sediment concentration distribution shows a typical vertical distribution at the late stage of falling tide, and the suspended sediment is fully mixed in the water body. The results show that the suspended sediment concentration distribution of the small tide and the spring tide deviates from the Rouse distribution basically, and only accords with the open time of the low tide. During the spring tide, the measured linear distributions are in good agreement with the Soulsby formula, which can be used to predict these concentration distributions accurately.
【作者单位】：华东师范大学河口海岸学国家重点实验室;
【基金】：国家重点研发计划项目(2016YFA0600904) 国家自然科学基金(51479074,41176069)
【分类号】：TV148

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