Impacts of secondary and quarter-diurnal tidal species on backwater hydrodynamics in tidal rivers
Impacts of secondary and quarter-diurnal tidal species on backwater hydrodynamics in tidal rivers
复制标题
次潮和四分之一日潮汐物种对潮汐河流回水水动力的影响
DOI：
10.1016/j.advwatres.2020.103660
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发表时间：
2020
影响因子：
4.7
通讯作者：
Tian Xin
中科院分区：
文献类型：
--
作者：
Zhang Min;Yang Hao;Tang Qibang;Cai Huayang;Zhu Zhenchang;Feng Aichun;Luo Min;Gao Hongkai;Tian Xin
河流入海时，受河口潮汐波动的影响，形成回水区，向陆方向的剩余水位（月均日）上升呈周期性变化。这被称为回水水动力，特别是受潮汐和河流流量相互作用控制的剩余水位变化，而这些水动力在上游河流为主的地区遵循传统的阶段-河流流量关系。然而，次级潮种（如日潮D1）、溢潮产生（如四分之一日潮D4）及其与河流流量的相互作用对剩余水位的潮汐不对称贡献知之甚少。在本研究中，我们的目的是了解二次和四分之一日潮物种对潮汐河流剩余水位增加的影响。为了量化不同分量的贡献，我们将数值计算的潮下摩擦分解为不同分量，分别代表河流流量、潮汐-河流相互作用和不同潮汐种之间非线性相互作用引起的潮汐不对称的贡献。结果表明：潮汐不对称对剩余水位的贡献较小，而河流流量和河潮相互作用对剩余水位的贡献占主导地位，在河口上游和下游分别占90%和80%以上。河流流量的贡献增大，潮河相互作用在向陆方向减小。半日潮种（D2）主要控制长江口沿岸潮河相互作用引起的剩余水位，占70%，而在潮河相互作用重要的临海河段，日潮种和四分之一日潮种的贡献较小，且量级相当。本研究提出的河流流量和不同潮汐物种对剩余水位贡献的量化方法将增强我们对河流和潮汐对河口回水水动力的影响的认识，并可用于指导长江口和其他大流量潮汐河流的有效和可持续的水管理。
As river flow debouches into the sea, it is affected by the tidal fluctuation at the estuary mouth, which results in a backwater zone, where the rising residual water level (averaged over a lunar day) in the landward direction is changing periodically. This is known as backwater hydrodynamics, especially the variation of the residual water levels that are controlled by the interplay between tide and river flows, while these hydrodynamics follow the traditional stage-river discharge relation in the upstream river-dominated region. However, the tidal asymmetry contributions to the residual water level that are caused by secondary tidal species (e.g., diurnal tide D1), overtide generation (e.g., the quarter-diurnal tide D4) and their interplay with river flow are poorly understood. In this study, we aim to understand the impacts of secondary and quarter-diurnal tidal species on the increase in residual water level in tidal rivers. To quantify the contributions made by different components, we decomposed the numerically computed subtidal friction into different components representing the contributions made by the river flow alone, the tide-river interaction, and tidal asymmetry due to the nonlinear interaction between different tidal species. The results show that the contribution by tidal asymmetry to the residual water level is minor, while the contributions by river flow and tide-river interaction are dominant, accounting for more than 90% and 80% at the upstream and downstream end of the estuary, respectively. The contribution made by river flow increases, while the tide-river interaction decreases in the landward direction. The semidiurnal tidal species (D2) predominantly control the residual water level induced by the tide-river interaction along the Yangtze estuary, which accounts for 70%, while the contributions made by the diurnal and quarter-diurnal tidal species are minor and comparable in magnitude in the seaward reach where tide-river interactions are important. The method proposed in this study to quantify the contributions of river flow and different tidal species to the residual water level will enhance our understanding of riverine and tidal impacts on estuarine backwater hydrodynamics and can be used to guide effective and sustainable water management in the Yangtze estuary and other tidal rivers with substantial river flow.