Spatial and temporal variations in sediment grain size in tidal wetlands, Yangtze Delta: On the role of physical and biotic controls

Yang, S.L.; Li, H.; Ysebaert, Tom; Bouma, Tjeerd J.; Zhang, W.X.; Wang, Y.Y.; Li, P.; Li, M.; Ding, Pingxing

doi:10.1016/j.ecss.2007.10.024

Cited by 223 publications

(153 citation statements)

References 45 publications

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“…2), and b predicted values calculated by changing the drag coefficient in our revised Dean (1978) model from 2 to 1.3−3.8, according to the relative water depth (Table 2). H 2M : measured transmitted wave height; H 2P : predicted transmitted wave height; R E root mean square error; r correlation coefficient; P significance level transect (Yang et al 2008). As suggested in Table 1, the wave attenuation rate over the S. alteniflora marsh at the present study site was 1 to 2 magnitudes higher than that on the adjacent mudflat.…”

Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 55%

“…A comparative wave attenuation rate (0.54%/m) was found across a salt marsh in Essex, UK, formed of similar vegetation species (Möller and Spencer 2002). In the Yangtze Estuary, a significant wave height attenuation rate of 0.95%/m was measured across a marsh formed of taller (0.5 m) native S. mariqueter vegetation (Yang et al 2008). Comparatively, the present study recorded much higher wave attenuation rates across a marsh formed of the tall (up to 2 m high) introduced species S. alterniflora (1.3%/m to 6.0%/m).…”

Section: Locationsmentioning

confidence: 91%

“…The average elevation gradient of the marsh transect (including the cliff at Site 2) was 12‰ (caption to Fig. 1), which is 10 times higher than that of the mudflat (Yang et al 2008). In other words, the higher wave attenuation rate over the marsh transect (relative to the mudflat) is due to both the presence of marsh vegetation and the increase in marsh elevation gradient.…”

Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 92%

“…In 2001, Spartina alterniflora was introduced to the northern marsh in Eastern Chongming with the aim of enhancing sediment accretion. Since then, Spartina has spread rapidly and replaced the much shorter (∼50 cm in height), native pioneer species Scirpus mariqueter (Yang et al 2008). The border between mudflat and marsh is indented, with tussocks occasionally found on the seaward side (Fig.…”

Section: Field Settingmentioning

confidence: 99%

“…For Tides 5, 6, and 10, the measured water depths and wave heights at Site 1 (7.5 m seaward from the marsh edge and 1 cm lower in elevation than at Site 2 at the marsh edge) were utilized as the initial conditions of wave height and water depth. The wave decay across this 7.5 m mudflat was considered by referring to a previously determined wave attenuation rate (0.006%/m) over a mudflat 2 km north of the present study site (Yang et al 2008). The loss of wave height across the 7.5 m mudflat was calculated to be <0.5%.…”

Section: Cross-shore and Temporal Changes In Wave Attenuation Rate Inmentioning

confidence: 99%

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Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Yang

Shi

Bouma

et al. 2011

Estuaries and Coasts

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To quantify wave attenuation by (introduced) Spartina alterniflora vegetation at an exposed macrotidal coast in the Yangtze Estuary, China, wave parameters and water depth were measured during 13 consecutive tides at nine locations ranging from 10 m seaward to 50 m landward of the low marsh edge. During this period, the incident wave height ranged from <0.1 to 1.5 m, the maximum of which is much higher than observed in other marsh areas around the world. Our measurements and calculations showed that the wave attenuation rate per unit distance was 1 to 2 magnitudes higher over the marsh than over an adjacent mudflat. Although the elevation gradient of the marsh margin was significantly higher than that of the adjacent mudflat, more than 80% of wave attenuation was ascribed to the presence of vegetation, suggesting that shoaling effects were of minor importance. On average, waves reaching the marsh were eliminated over a distance of ∼80 m, although a marsh distance of ≥100 m was needed before the maximum height waves were fully attenuated during high tides. These attenuation distances were longer than those previously found in American salt marshes, mainly due to the macrotidal and exposed conditions at the present site. The ratio of water depth to plant height showed an inverse correlation with wave attenuation rate, indicating that plant height is a crucial factor determining the efficiency of wave attenuation. Consequently, the tall shoots of the introduced S. alterniflora makes this species much more efficient at attenuating waves than the shorter, native pioneer species in the Yangtze Estuary, and should therefore be considered as a factor in coastal management during the present era of sea-level rise and global change. We also found that wave attenuation across the salt marsh can be predicted using published models when a suitable coefficient is incorporated to account for drag, which varies in place and time due to differences in plant characteristics and abiotic conditions (i.e., bed gradient, initial water depth, and wave action).

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Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 55%

Section: Locationsmentioning

confidence: 91%

Section: Causes Of Differences In Wave Attenuation Between Salt Marshmentioning

confidence: 92%

Section: Field Settingmentioning

confidence: 99%

Section: Cross-shore and Temporal Changes In Wave Attenuation Rate Inmentioning

confidence: 99%

See 3 more Smart Citations

Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Yang

Shi

Bouma

et al. 2011

Estuaries and Coasts

Self Cite

141

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Do intertidal flats ever reach equilibrium?

et al. 2015

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Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying the long-term behavior of the intertidal system, restricting ourselves to unvegetated intertidal flats that are controlled by cross-shore tidal currents and wind waves and applying a 1-D cross-shore morphodynamic model. The results indicate that by an adjustment of the profile slope and shape, an initial imbalance between deposition and erosion is minimized within a few decades. What follows is a state of long-term seaward progradation or landward retreat of the intertidal flat, in which the cross-shore profile shape is largely maintained and the imbalance between deposition and erosion is not further reduced. These long-term trends can be explained by positive feedbacks from the morphology onto the hydrodynamic forces over the flat: initial accretion (erosion) decreases (increases) the shear stresses over the flat, which induces further accretion (erosion). This implies that a static equilibrium state cannot exist; the flat either builds out or retreats. The modeled behavior is in accordance with observations in the Yangtze Estuary. To treat these unbalanced systems with a one-dimensional numerical model, we propose a moving (Lagrangian) framework in which a stable cross-sectional shape and progradation speed can be derived for growing tidal flats, as a function of the wave climate and the sediment concentration in deeper water.

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Coastal wetland response to sea‐level rise in a fluvial estuarine system

et al. 2016

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Coastal wetlands are likely to lose productivity under increasing rates of sea-level rise (SLR).This study assessed a fluvial estuarine salt marsh system using the Hydro-MEM model under four SLR scenarios. The Hydro-MEM model was developed to apply the dynamics of SLR as well as capture the effects associated with the rate of SLR in the simulation. Additionally, the model uses constants derived from a 2-year bioassay in the Apalachicola marsh system. In order to increase accuracy, the lidar-based marsh platform topography was adjusted using Real Time Kinematic survey data. A river inflow boundary condition was also imposed to simulate freshwater flows from the watershed. The biomass density results produced by the Hydro-MEM model were validated with satellite imagery. The results of the Hydro-MEM simulations showed greater variation of water levels in the low (20 cm) and intermediate-low (50 cm) SLR scenarios and lower variation with an extended bay under higher SLR scenarios. The low SLR scenario increased biomass density in some regions and created a more uniform marsh platform in others. Under intermediate-low SLR scenario, more flooded area and lower marsh productivity were projected. Higher SLR scenarios resulted in complete inundation of marsh areas with fringe migration of wetlands to higher land. This study demonstrated the capability of Hydro-MEM model to simulate coupled physical/biological processes across a large estuarine system with the ability to project marsh migration regions and produce results that can aid in coastal resource management, monitoring, and restoration efforts.

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Spatial and temporal variations in sediment grain size in tidal wetlands, Yangtze Delta: On the role of physical and biotic controls

Cited by 223 publications

References 45 publications

Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Wave Attenuation at a Salt Marsh Margin: A Case Study of an Exposed Coast on the Yangtze Estuary

Do intertidal flats ever reach equilibrium?

Coastal wetland response to sea‐level rise in a fluvial estuarine system

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