Quantification of Tidal Asymmetry and Its Nonstationary Variations

Quantification of Tidal Asymmetry and Its Nonstationary Variations

Guo, Leicheng (Shanghai Estuarine and Coastal Science Research Center)
Wang, Zhengbing (TU Delft Coastal Engineering)
Townend, Ian (University of Southampton)
He, Qing (Shanghai Estuarine and Coastal Science Research Center)

2019

Tidal wave deformation and tidal asymmetry widely occur in tidal estuaries and lagoons. Tidal asymmetry has been intensively studied because of its controlling role on residual sediment transport and large‐scale morphological evolution. There are several methods available to characterize tidal asymmetry prompting the need for an overview of their applicability and shortcomings. In this work we provide a brief review and evaluation of two methods, namely, the harmonic method and the statistical method. The latter comprises several statistical measures that estimate the probability density function and various forms of skewness. We find that both the harmonic and statistical methods are effective and have complementary advantages. The harmonic method is applicable to predominantly semidiurnal or diurnal regimes, while the statistical methods can be used in mixed tidal regimes. Assisted by harmonic data, a modified skewness measure can isolate the contribution of different tidal interactions on net tidal asymmetry and also reveal its subtidal variations. The application of the skewness measure to nonstationary river tides reveals stronger tidal asymmetry during spring tides than neap tides, and the nonlinear effects of river discharges on tidal asymmetry in the upper and lower regions of long estuaries.

harmonic
residual sediment transport
skewness
tidal asymmetry

http://resolver.tudelft.nl/uuid:85f5f3cf-a0ee-4fc5-bc53-3b616d8e2784

https://doi.org/10.1029/2018JC014372

2019-07-31

2169-9275

Journal Of Geophysical Research-Oceans, 124 (1), 773-787

Institutional Repository

journal article

© 2019 Leicheng Guo, Zhengbing Wang, Ian Townend, Qing He