On the Role of Anthropogenic Activity and Sea‐Level‐Rise in Tidal Distortion on the Open Coast of the Yellow Sea Shelf

Abstract

This study investigates how varied coastline strategies and rising mean‐sea‐level influence tidal distortion along the open coast of the Yellow Sea shelf. The major contributors to tidal distortion were first identified. Then, the primary tidal constituents causing changes in tidal propagation and distortion in response to shoreline reconstruction management and near‐future sea‐level‐rise (SLR) were determined. The intrinsic mechanisms causing tidal duration asymmetry (TDA) were investigated and found to differ in various types of coastal systems. Specifically, the nonlinear tidal interaction between M2/M4, M2/S2/MS4 and K1/O1/M2 are the top three dominant contributors to TDA. The interactions between M2/M4 and M2/S2/MS4 are most sensitive to different coastline configurations and produce the largest evolution in tidal distortion. Two primary factors are (i) the location of the amphidromic point of the semidiurnal tides in the deep ocean, which controls the M2 and S2 energy fluxes into embayment, and (ii) the nondimensional amplitude (A/h), which importantly indicates tidal nonlinearity and determines shallow tide generation. For the coast with a progressive tidal system, tidal distortion and shallow‐water tide genesis depend mainly on the influx of semidiurnal tides from offshore, which is controlled by the position of the M2 amphidrome. For a coast with quasistanding tidal behavior, however, the scales and positions of tidal flats and shoals play vital roles in tidal distortion and the genesis of shallow‐water tides. Model simulations suggest that hardened shoreline or SLR could dampen the advection and bottom dissipation, thus reducing tidal distortion.

Responses of tidal duration asymmetry to morphological changes in Lingding Bay of the Pearl River Estuary

“…If g 1 >0, the periods of flood tides are shorter than those of ebb tides, and conversely, if g 1 <0, the periods of ebb tides are shorter than those of flood tides. Furthermore, to quantify the contribution of different combinations of tidal constituents to TDA, Song et al (2011) derived a general framework for evaluating TDA by substituting Equation (2) into Equation (4), which is expressed as (Feng and Feng, 2021):…”

“…The sets of Equation ( 5) demonstrate that TDA can be generated or canceled only by interactions between two harmonic constituents with a frequency relationship 2w 1 =w 2 or among three constituents with a frequency relationship w 1 +w 2 =w 3 . Moreover, introducing b as the weight of TDA from the skewness caused by a specific pair or triplet of tidal constituents, the total TDA is equal to the cumulative effects of b (Feng and Feng, 2021):…”

“…To simplify the factors associated with the uncertainties in estimating the evolution of TDA owing to bathymetric and topographic influences, meteorological forcing and oceanic currents were not included in the model (e.g., Feng and Feng, 2021). The numerical model was run from November 10, 2016, to March 1, 2017, owing to low-stratified water columns and the weakest river discharges in the dry season.…”

Development History of the Numerical Simulation of Tides in the East Asian Marginal Seas: An Overview

“…Feng and Feng [81] explored the influence of coastline changes and a rising sea level on tidal asymmetry along the coast of Jiangsu and found that the interactions between M 2 /M 4 and M 2 /S 2 /MS 4 were most sensitive to coastline changes and contributed the largest part to tidal distortion. Using ROMS, Lin et al [9] studied the tidal response to changes in coastline and water depth related to land reclamation and waterway dredging in the Pearl River Estuary (PRE).…”