潮优型河口动力对水深变化的响应机制研究——以葡萄牙Guadiana河口为例*
张萍(1995—), 女, 广东省韶关市人, 硕士研究生, 主要从事河口海岸动力学研究。E-mail: zhangp256@mail2.sysu.edu.cn |
Copy editor: 孙淑杰
收稿日期: 2019-04-09
要求修回日期: 2019-05-31
网络出版日期: 2020-01-09
基金资助
国家重点研发计划项目(2016YFC0402600)
国家自然科学基金项目(5170928)
河口海岸学国家重点实验室开放课题基金资助项目(SKLEC-KF201809)
广东省自然科学基金项目(2017A030310321)
广东省水利科技创新项目(2016-20)
版权
Response of tidal dynamics to the variation of water depth: case study of Guadiana estuary in Portugal
Received date: 2019-04-09
Request revised date: 2019-05-31
Online published: 2020-01-09
Supported by
National Key Research and Development Program of China(2016YFC0402600)
National Natural Science Foundation of China(5170928)
Open Research Found of State Key Laboratory of Estuarine and Coastal Research(SKLEC-KF201809)
Guangdong Provincial Natural Science Foundation of China(2017A030310321)
the Water Resource Science and Technology Innovation Program of Guangdong Province(2016-20)
Copyright
强人类活动(如航道疏浚)和自然气候变化(如海平面上升)对近岸河口环境不同影响的辨识是目前河口海岸学研究的热点和难点问题。在地形概化和动力简化条件下, 解析模型能够快速辨识强人类活动和自然气候变化对河口环境的影响, 它是探讨河口动力过程对外界干扰的响应机制的重要工具。本文基于前人对葡萄牙Guadiana河口不同分潮之间非线性相互作用的研究, 采用一维水动力解析模型探讨河口不同分潮潮波传播过程对水深变化(模拟航道疏浚和河道淤积过程)的响应机制。研究结果表明: 平均水深$\overline{h}$的变化影响无量纲河口地形参数γ和摩擦参数χ, 进一步影响河口动力参数包括潮波振幅参数ζ、流速振幅参数μ、波速参数λ、潮波振幅增大/衰减率参数δ以及流速与水位之间的相位差ϕ等; 平均水深变化对河口中下游段(x=0~60km)的潮汐动力影响较大, 而对河口上游段(x=60~78km)影响较弱; 主要半日分潮(M2、S2、N2)对水深变化的响应略大于全日分潮(K1、O1); 航道疏浚幅度小于2m时, 对河口潮汐动力格局影响不大, 而当疏浚幅度大于2m时, 将对河口潮汐动力格局及水环境(如盐水入侵等)产生较大影响; 河道淤积将导致潮汐动力减弱, 流速振幅、潮波振幅及传播速度减小, 流速和水位之间的相位差也减小。
关键词: 潮汐动力; 航道疏浚; 河道淤积; 解析模型; Guadiana河口
张萍 , 谢梅芳 , 杨昊 , 蔡华阳 , 欧素英 , 杨清书 . 潮优型河口动力对水深变化的响应机制研究——以葡萄牙Guadiana河口为例*[J]. 热带海洋学报, 2020 , 39(1) : 1 -11 . DOI: 10.11978/2019037
Quantifying the impacts of human-induced (such as dredging for navigational channels) or natural (such as global sea level rise) interventions on estuarine environment is an important issue for estuary and coastal studies. For given simplified geometry and dynamics, analytical models are capable of rapidly identify the influence of human-induced or natural interventions on estuarine environment, which are invaluable tools for exploring response of tidal dynamics to external forcing. In this study, a one-dimensional hydrodynamic analytical model was used to explore the response of tidal dynamics in terms of different constituents to variation of tidally averaged water depth (mimicking the channel dredging and deposition) in the Guadiana estuary in Portugal, building on previous studies on nonlinear frictional interaction between different tidal constituents. The results show that the influence of variable depth on tidal dynamics in the seaward reach (x=0-60 km) is stronger compared to that in the landward reach (x=60-78 km). In particular, the influence of variable depth on the predominant semi-diurnal tides (M2, S2, N2) is larger than that on diurnal tides (K1, O1). Analytical results also indicate that the basic tidal dynamic pattern along the estuary is more or less the same for a less intensive dredging of less than 2 m, while the pattern may substantially change for an intensive dredging activity. In addition, the channel bed deposition will weaken the tidal dynamics with a decrease of tidal amplitude, velocity amplitude, tidal wave celerity, and the phase lag between velocity and the elevation also decreases.
图2 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)流速振幅参数μ随着平均水深变化的等值线分布图红色实线代表实际平均水深$\overline{h}$=5.5m Fig. 2 Contour plot of velocity number μ for main tidal constituents (M2, S2, N2, K1, O1)under different mean water depth conditions with the red line indicating the actual mean depth $\overline{h}$=5.5 m |
图3 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)衰减率参数δ随平均水深变化的等值线分布图红色实线代表河口实际平均水深$\bar{h}$=5.5m; 蓝色线条为δ=0 Fig. 3 Contour plot of damping number{Invalid MML}δ for main tidal constituents (M2, S2, N2, K1, O1) under different mean water depth conditions. The red line indicates the actual mean depth $\overline{h}$=5.5 m, and the blue line indicates δ=0 |
图4 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)波速参数λ随平均水深变化的等值线分布图红色实线代表河口实际平均水深$\overline{h}$=5.5m。蓝色线条为λ=1 Fig. 4 Contour plot of celerity number λ for main tidal constituents (M2, S2, N2, K1, O1) under different mean water conditions. The red line indicates the actual mean depth $\overline{h}$=5.5 m, and the blue line indicates λ=1 |
图5 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)流速与水位之间的相位差ϕ随着平均水深变化的等值线分布图红色实线代表河口实际平均水深$\overline{h}$=5.5m Fig. 5 Contour plot of phase difference between current and elevation for main tidal constituents (M2, S2, N2, K1, O1)under different mean water depth condition. The red line indicates the actual mean depth $\overline{h}$=5.5 m |
表1 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)无量纲潮波变量参数相对河口实际平均水深条件下的变化量ψ(单位: m)和变化率σ(单位: %)Tab. 1 Change range (units: m) and relative change (units: %) in the main dimensionless parameters due to the depth variation when compared with the cause of actual mean water depth for different tidal constituents (M2, S2, N2, K1, O1) |
半日分潮 | 全日分潮 | |||||
---|---|---|---|---|---|---|
M2 | N2 | S2 | K1 | O1 | ||
流速参数(μ) | ψ1/σ1 | -0.14/-35.89 | -0.13/-39.92 | -0.12/-39.07 | -0.04/-21.07 | -0.03/-18.30 |
ψ2/σ2 | 0.04/10.74 | 0.06/17.90 | 0.05/16.36 | 0.002/0.78 | -0.001/-0.36 | |
ψ3/σ3 | 0.06/14.76 | 0.10/30.82 | 0.08/27.34 | -0.003/-1.75 | -0.007/-3.49 | |
ψ4/σ4 | 0.02/4.99 | 0.10/31.15 | 0.08/25.88 | -0.02/-12.55 | -0.03/-14.48 | |
潮波振幅衰减率参数(δ) | ψ1/σ1 | -0.37/-15.95* | -0.40/-3.01* | -0.41/-2.91* | -0.49/-4.87* | -0.48/-5.16* |
ψ2/σ2 | 0.13/5.66* | 0.17/1.259* | 0.17/0.18* | 0.12/-1.22* | 0.12/-1.23* | |
ψ3/σ3 | 0.22/9.46* | 0.30/2.27* | 0.29/2.10* | 0.19/1.93* | 0.18/1.92* | |
ψ4/σ4 | 0.29/12.36* | 0.44/3.32* | 0.43/3.04* | 0.25/2.47* | 0.23/2.45* | |
波速参数(λ) | ψ1/σ1 | 0.28/28.96 | 0.28/24.86 | 0.30/25.90 | 0.56/46.13 | 0.60/48.86 |
ψ2/σ2 | -0.17/-16.81 | -0.16/-14.14 | -0.17/-14.67 | -0.26/-21.12 | -0.26/-21.57 | |
ψ3/σ3 | -0.34/-34.19 | -0.34/-30.07 | -0.35/-30.87 | -0.48/-39.70 | -0.49/-40.23 | |
Ψ4/σ4 | -0.67/-68.13 | -0.732/-65.03 | -0.75/-65.48 | -0.87/-71.11 | -0.87/-71.41 | |
水位与流速之间的 相位差(ϕ) | ψ1/σ1 | -9.50/-12.85 | -11.84/-15.08 | -12.45/-15.04 | -1.50/-1.67 | -1.07/-1.19 |
ψ2/σ2 | 4.27/5.76 | 4.32/5.50 | 3.28/3.97 | 0.16/0.18 | 0.12/0.13 | |
ψ3/σ3 | 7.79/10.53 | 7.15/9.10 | 4.99/6.03 | 0.24/0.27 | 0.42/0.19 | |
ψ4/σ4 | 12.86/17.39 | 10.04/12.78 | 6.51/7.86 | 0.32/0.35 | 0.23/0.26 |
注: “*”表示倍数关系。 |
图7 Guadiana河口主要天文分潮(M2、S2、N2、K1、O1)反射系数ΨA在河口上游(x=78km)(a) 和沿程平均值 (b) 随平均水深增大的变化图Fig. 7 Variations of the reflection coefficient ΨA in the upstream boundary (x=78km) (a) and its spatially averaged value (b) for the main tidal constituents (M2, S2, N2, K1, O1) with increase of mean water depth |
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