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![Map of the Bohai Sea, Yellow Sea and East China Sea (a). Subplot (b) shows the co-tidal charts of the M2 constituent for the southern Yellow Sea. Amplitude is shown in cm, and phase in degrees (from [23]). Subplot (c) indicates the Jiangsu Coastline evolution from 1855 to 2007, transport pattern of the sediment eroded from the Abandoned Yellow River Delta and the location of measured profiles. The locations of the Abandoned Yellow River Delta and the Radial Sand Ridges are labelled in (a), and the historical shoreline location in (c) is collected from [24], in which there is a detailed description of the shoreline data.](publication/350298811/figure/fig2/AS:1004357445222407@1616468883919/Map-of-the-Bohai-Sea-Yellow-Sea-and-East-China-Sea-a-Subplot-b-shows-the-co-tidal.png)
Map of the Bohai Sea, Yellow Sea and East China Sea (a). Subplot (b) shows the co-tidal charts of the M2 constituent for the southern Yellow Sea. Amplitude is shown in cm, and phase in degrees (from [23]). Subplot (c) indicates the Jiangsu Coastline evolution from 1855 to 2007, transport pattern of the sediment eroded from the Abandoned Yellow River Delta and the location of measured profiles. The locations of the Abandoned Yellow River Delta and the Radial Sand Ridges are labelled in (a), and the historical shoreline location in (c) is collected from [24], in which there is a detailed description of the shoreline data.
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![Figure 1. A profile view of sediment zonation (modified from [11]).](publication/350298811/figure/fig1/AS:1004357445251072@1616468883876/A-profile-view-of-sediment-zonation-modified-from-11_Q320.jpg)
Tidal flats play an important role in promoting coastal biodiversity, defense against flooding, land reclamation and recreation. Many coastal tidal flats, especially the tide-dominant ones, are muddy. However, the number of studies on the profile shape and surficial sediment distribution of muddy tidal flats is small compared to sandy beaches. Base...
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... Jiangsu Coast (Figure 2c) is situated between the Yangtze River and the Xiuzhen River Estuary [20]. Tidal flats along the Jiangsu Coastline are characterized by (1) its large width (with a mean width of 8 km), (2) abundant sediment supply from the two large rivers (from the Yangtze River during the end of the late Pleistocene and from the Yellow River from 1128-1855 AD), and (3) silt dominant sediments [21]. ...
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... suspended sediments in the coastal areas are since then mainly generated by bed erosion, instead of fluvial supply, and the whole coastal areas can be treated as a quasi-enclosed sediment system [30,31]. As a result, severe coastal erosion took place around the AYRD due to the cutoff of sediment supply (Figure 2c). ...
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... tidal wave first enters the southern Yellow Sea and part of it is reflected by the Shandong Peninsula, forming an anticlockwise rotational tidal wave system. The rotational wave and the progressive wave from the southern Yellow Sea converge near Jianggang ( Figure 2b). The convergence of these two tidal waves leads to the formation of an approximately standing tidal wave and the radial tidal current field in this area [23,33- 34]. ...
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... large-scale investigations were performed between 2006 and 2008. Fifty cross-shore profiles starting from Xiuzhen estuary to Lvsi (Figure 2c) were defined along the Jiangsu Coast. The bed elevation was measured along these 50 profiles and 173 bed surface sediment samples were taken along only 36 of these profiles. ...
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... the seaward end of the profile, as we link the satellite images ( Figure 5) to the measured profile data ( Figure 6), we can find that in the region of the RSRs, the intertidal flat is cut through by tidal creeks of different sizes at many places, and these tidal creeks change their locations continuously. Here, we took profile JD 38 (see Figure 2c) for example. As we see in Figure 5, the profile JD38 shows strong fluctuations. ...
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... force is the main driver influencing the sediment erosion and transport processes along the Jiangsu Coast. The tidal range is much larger in the south part than in the north (Figures 2b and 3). Larger tidal range favors wider flats [44]. ...
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... width of intertidal zone at equilibrium is positively related to sediment supply, which means higher sediment supply leads to wider and flatter tidal flats [52]. The southward beach flattening tendency coincides with the shoreline evolution state that the north part of the Jiangsu Coast is eroding while the south part is accreting (Figure 2c). This means that the north part is losing sediment forming a sediment source for the south part. ...
Citations
... The calculated results show that there is a very high rate of bed erosion in the study area. One reason for this is that the tidal flats near the SYRE are currently experiencing severe erosion due to severe sediment supply deficiency [13], which results in an increase in bed slope [16,64], and the wave action strengthens, which then further aggravates the increase in the bed erosion rate. Another reason is due to limitations in the observation methods used in this paper. ...
Tidal flats are accumulations of fine-grained sediment formed under the action of tides and play a very important role in coastal protection. The northern part of Jiangsu coast, as a typical example of muddy coasts found all over the world, has experienced serious erosion since the Yellow River shifted northward, and the range of erosion has been gradually extending southward, now reaching the south of the Sheyang River estuary (SYRE). In order to address coastal erosion near the SYRE through protective measures, there is an urgent need for research on the spatial and temporal variation of coastal erosion processes and their control mechanisms in the SYRE and adjacent coastal areas. For this study, the tidal flats on the south side of the SYRE were selected as the study area, and the sediment dynamics in the upper and lower intertidal flat were observed in different seasons to investigate the erosion processes and their dynamic mechanisms. The results show that the tidal current and wave action in the observed intertidal flats are stronger in winter than in summer, and these intertidal flats erode under the combined action of waves and currents. During winter, the net transport of the near-bottom suspended sediment and bedload is primarily towards the southeast, while in summer, the direction tends toward the north and northeast. The net transport fluxes are larger in the lower part of the intertidal flat than in the upper part in summer and also larger in winter than in summer within the lower intertidal flat. Furthermore, the tidal flat erosion in the study area manifests as shoreline retreat and flat surface erosion. The average shoreline retreat rate increased from 23.3 m/a during 2014–2019 to 43.5 m/a during 2019–2021, and the average erosion depth of the lower and upper parts of the intertidal flat over a tidal cycle is, respectively, 1.98 cm and 0.24 cm in winter and 1.65 cm and 0.26 cm in summer. The ratio of the wave-induced bottom shear stress to the tidal current-induced bottom shear stress is 0.40~0.46 in the lower intertidal flat and increases to 0.66~0.67 in the upper intertidal flat, indicating that the intertidal flat erosion in the study area is primarily driven by tidal currents, with significant contributions from wave action, especially in the upper intertidal flat.
... The intertidal flats in straight shorelines exhibit the convex-up shape in the tide-dominant environment and the concaveup shape in case of wave dominance, respectively . The intertidal flat sedimentation zonation generally presents a shoreward fining pattern (Alexander et al., 1991;Whitehouse et al., 2000;Kuai et al., 2021), and this zonation is influenced by the tidal currents, wind waves, sediment properties and sediment supply as well (Zhou et al., 2015). ...
... In our previous field data study (Kuai et al., 2021), we found several morphological and sediment distributions patterns on the Jiangsu Coast, China (Fig. 1), a typical tide-dominated muddy open coast with significant alongshore tidal current. ...
... This pattern was attributed to the occurrence of two different erosion resistant mechanisms, viz. self-weight consolidation and armoring effect (Fig. 3), when the flat erodes to an erosion resistant layer (Kuai et al., 2021). ...
Intertidal flats are of great socio-economic and ecological importance in defending the coastal cities from flooding, providing resources for land reclamations and habits for wildlife. On the intertidal flats, milder profiles are usually featured with finer sediment. However, we find the opposite relationship between the alongshore variation in intertidal slope and sediment grain size on the intertidal flat along the Jiangsu Coast. With a conceptual figure of the hydrodynamics and shoreline evolution on this coast, we hypothesize that the unexpected pattern is caused by the alongshore gradient in hydrodynamic forcing. In order to test our hypothesis, we carry out a series of numerical model simulations in a highly schematized manner to investigate the real mechanism behind this unexpected pattern. Through the analysis, we find that only the southwards coarsening pattern is inconsistent with the shoreline evolution pattern. This inconsistency is not induced by alongshore hydrodynamic gradient, and can only be explained by different sediment provenances. We also find that the alongshore shoreline evolution pattern is not only determined by the alongshore gradient in hydrodynamic forcing, but also influenced by the alongshore variation in bed composition. In the erosion/sedimentation transition zone, the bed composition factor plays the major role.
... Originally, two types of sediment mixtures were distinguished: a silt-enriched mixture with a median grain size of 46 μm and a very fine sand-enriched mixture with a median grain size of 88 μm. Based on bed sample surveys in silt-dominated systems, the silt content at the Jiangsu coast ranges from 10% to 80% (Kuai et al., 2021) and 48%-85% at the Modern Yellow River Delta (Jia et al., 2020). Therefore, the collected sediment samples were first separated into several different sediment fractions and then remixed into seven groups of sand-silt mixtures with different compositions to cover the field variations. ...
... The Modern Yellow River Delta and the Jiangsu coast are two typical silt-dominated systems influenced by the silt-enriched Yellow River (Su et al., 2017a(Su et al., , 2017b. The silt content is approximately 48%-85% in the Modern Yellow River Delta (Jia et al., 2020) and 10%-80% along the Jiangsu coast (Kuai et al., 2021). Li and Cao (2009) reported that the wet bulk density of the deposit of a silty tidal flat (Rudong in the Jiangsu coast) is approximately 1.8 kg/m 3 after 24 hr. ...
... To this end, it is better to derive a relationship between D 50 and the silt content in mixtures. We have collected and recompiled several field survey data on bed compositions in silt-dominated systems, such as the Jiangsu coast (Kuai et al., 2021) and Modern Yellow River Delta (Jia et al., 2020). Curve fitting between D 50 and silt content in mixtures depicts a negative and linear relationship (R 2 = 0.996). ...
The erosion threshold, beyond which bed sediments start to move, is a key parameter describing sediment transport processes. For silt‐dominated mixtures, in which the grain size is between sand and clay, existing experimental studies exhibit contradictory observations. That is, the erosion was either sand‐like or clay‐like, suggesting transitional erosion behavior. To explore the underlying mechanism of the transitional erosion behavior of silt‐sized sediment, we revisited the topic of the erosion threshold of sand‐silt mixtures by carrying out a series of erosion experiments for different bed compositions. The results suggest that there exists a critical silt content of approximately 35%, separating two domains. Below this critical value, the critical bed shear stress follows the Shields criterion, whereas above this value, the erosion threshold of a mixed bed increases abruptly and remains relatively constant with a further increase in silt content. By combining with existing data, we found that the proposed critical silt content acts as a tipping point, beyond which the mixed bed shifts from a sand‐dominated to a silt‐dominated domain. For the silt‐dominated domain, a stable silt skeleton can be formed by attraction forces that resist erosion. However, the attraction forces are too weak to form a stable silt skeleton when the silt content is too small. Based on this finding, a modified critical bed shear stress formula is proposed for silt‐dominated mixtures, which results in a better agreement with experimental data (an averaged bias of 10%), performing better than existing formulas (larger than 30%).
... The shoreline of Batu Pahat practically has no beaches and mostly mudflats which have limited accessible beaches [1,6]. Various coastal tidal flats, particularly those that are tide-dominated, are muddy [7]. However, when compared to sandy beaches, the number of studies on the profile form and surficial sediment distribution of muddy tidal flats is uncertain. ...
Coastal erosion and accretion may be defined to be natural processes for which predicting the coastal magnitude is essential for a better coastal monitoring. The purpose of this study is to investigate the shoreline sediment properties and prediction of coastal erosion in an eroded region in Batu Pahat. Pantai Punggur was chosen as one of the research locations because of the condition of the beaches, which were designated as eroded regions as it is experiencing erosion. Sampling points were separated into four zones to better understand sediment transport: Zones A, B, C, and D. The sediment parameters of the studied samples were determined and described as a result of this research. Moisture content, specific gravity, grain size distribution, pH value, shear strength, and organic content were the studied parameters. Further studies, such as settling velocity and erosion and accretion prediction, were calculated based on those properties. From the analysis, Zones A, B, and D were projected to erode, whereas Zone C was predicted to accrete. The results of this study are useful in terms of comprehending morphological traits, which will aid in the knowledge of sediment transport. Furthermore, these findings are significant for information in the management of coastal concerns.
... The average width of the intertidal flats is 2-6 km, and the average slope is 0.1-0.3% (Zhang, 1992;Kuai et al., 2021). The study area is famous for having the largest radial tidal sand ridges, which protect the intertidal flats from large waves. ...
Current-related bed shear stress is vital for the prediction of the morphological evolution of intertidal flats. The present study develops a simple method to estimate the current-related bed shear stress during the flood phase on intertidal flats, which is based on the easy-to-measure water depth. To verify this simple method, comparisons were made to the current-related shear stress derived from both the LP and the TKE methods based on the measured velocities. The results show that the widely used approach on intertidal flats, which relates the current-related bed shear stress to the square of the depth-averaged velocity with a constant factor, underestimates the bed shear stress for water depths smaller than ca. 0.5 m when high sediment concentrations and significant bed-level changes however usually occur. For water depths smaller than approximately 0.5 m, the uniform horizontal velocity assumption in the vertical direction in the shallow water theory is inappropriate, and velocity shear must be considered. The current-related bed shear stresses could be estimated using the measured water depths during flood phase, even when the water depth is smaller than 0.5 m. The developed method also shows that the scale of current-related shear stress is u‾/h, not u‾2, at least with a water depth smaller than 0.5 m.
