Dynamics of fortnightly water level variations along a tide-dominated estuary with negligible river discharge
Dynamics of fortnightly water level variations along a tide-dominated estuary with negligible river discharge
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DOI：
10.5194/os-2021-58
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发表时间：
2021-07
期刊：
影响因子：
3.2
通讯作者：
E. Garel;Ping Zhang;H. Cai
中科院分区：
文献类型：
--
作者：
E. Garel;Ping Zhang;H. Cai
抽象的。观测结果表明，平均水位的两周波动幅度沿着潮汐为主的河口（瓜迪亚纳河口）的下半部分增加，河流流量可以忽略不计，但上游保持不变。再现半日波传播的解析解表明，这种模式的结果从河口头的反射效应。随着高水位和低水位逐渐接近静水，速度和高程之间的相位差从河口到头部（波浪具有站立性质）增加。因此，在上游方向上减少了流量的潮汐（涨潮-落潮）不对称性。它沿着河口上半部变得可以忽略不计，因为尽管由于波浪变浅而增加了摩擦力，但平均海平面保持不变。因此，沿河口上游的一个重要部分沿着的平的平均水位的观测比相位差更容易获得，可以表明在头部传播的半日波的显著反射。详细的分析模型表明，在平均深度或长度的半干旱河口，特别是宏潮位置的变化，影响每两周的潮汐振幅，从而上游质量运输和淹没制度。这对河口环境具有重大的潜在影响。
Abstract. Observations indicate that the fortnightly fluctuations in mean water level increase in amplitude along the lower half of a tide-dominated estuary (The Guadiana estuary) with negligible river discharge but remain constant upstream. Analytical solutions reproducing the semi-diurnal wave propagation shows that this pattern results from reflection effects at the estuary head. The phase difference between velocity and elevation increases from the mouth to the head (where the wave has a standing nature) as the high and low water levels get progressively closer to slack water. Thus, the tidal (flood-ebb) asymmetry in discharge is reduced in the upstream direction. It becomes negligible along the upper estuary half, as the mean sea level remains constant despite increased friction due to wave shoaling. Observations of a flat mean water level along a significant portion of an upper estuary, easier to obtain than the phase difference, can therefore indicate significant reflection of the propagating semi-diurnal wave at the head. Details of the analytical model shows that changes in the mean depth or length of semi-arid estuaries, in particular for macrotidal locations, affect the fortnightly tide amplitude, and thus the upstream mass transport and inundation regime. This has significant potential impacts on the estuarine environment.