The landward and seaward mechanisms of fine-sediment transport across intertidal flats in the shallow-water region—A numerical investigation

Hsu, Tian‐Jian; Chen, Shih‐Nan; Ogston, A. S.

doi:10.1016/j.csr.2012.02.003

Cited by 22 publications

(14 citation statements)

References 47 publications

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“…Hsu et al (2013) and Van Maren and Winterwerp (2013) explored the suspended sediment dynamics on a fixed bed. By including a morphodynamic feedback, Pritchard et al (2002) and Pritchard and Hogg (2003) confirmed the (tide forced only) equilibrium profiles by Friedrichs and Aubrey (1996).…”

Section: Introduction Frameworkmentioning

confidence: 99%

Mudflat Morphodynamics and the Impact of Sea Level Rise in South San Francisco Bay

Wegen

Jaffe

Foxgrover

et al. 2016

Estuaries and Coasts

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Estuarine tidal mudflats form unique habitats and maintain valuable ecosystems. Historic measurements of a mudflat in San Fancsico Bay over the past 150 years suggest the development of a rather stable mudflat profile. This raises questions on its origin and governing processes as well as on the mudflats' fate under scenarios of sea level rise and decreasing sediment supply. We developed a 1D morphodynamic profile model (Delft3D) that is able to reproduce the 2011 measured mudflat profile. The main, schematised, forcings of the model are a constant tidal cycle and constant wave action. The model shows that wave action suspends sediment that is transported landward during flood. A depositional front moves landward until landward bed levels are high enough to carry an equal amount of sediment back during ebb. This implies that, similar to observations, the critical shear stress for erosion is regularly exceeded during the tidal cycle and that modelled equilibrium conditions include high suspended sediment concentrations at the mudflat. Shear stresses are highest during low water, while shear stresses are lower than critical (and highest at the landward end) along the mudflat during high water. Scenarios of sea level rise and decreasing sediment supply drown the mudflat. In addition, the mudflat becomes more prone to channel incision because landward accumulation is hampered. This research suggests that sea level rise is a serious threat to the presence of many estuarine intertidal mudflats, adjacent salt marshes and their associated ecological values.

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Section: Introduction Frameworkmentioning

confidence: 99%

Mudflat Morphodynamics and the Impact of Sea Level Rise in South San Francisco Bay

Wegen

Jaffe

Foxgrover

et al. 2016

Estuaries and Coasts

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“…The bottom shear stress during ebb is larger than during flood, resulting in higher suspended sediment concentration at ebb. This pattern is different from the fully unvegetated tidal flat, where the bed shear stress is larger and sediment concentration is higher during flood (Hsu et al 2013). We believe that it is due to the adjustment of tidal circulation by the vegetation patch, which will affect the cross-shore net sediment transport, as will be discussed in the following sections.…”

Section: Sediment Transport On the Partially Vegetated Tidal Flatmentioning

confidence: 85%

“…In the previous section, we showed that sediment concentration during flood is smaller than during ebb on the partially vegetated tidal flat, which is in contrast to the findings on a fully unvegetated tidal flat (Hsu et al 2013). It was postulated that the vegetation canopy significantly changed the tidal flow pattern and the resulting sediment processes.…”

Section: Vegetation Effects On Tidal Flow and Sediment Suspensionmentioning

confidence: 92%

“…The highest sediment concentration at the upper flat is on the order of 1-2 kg/m 3 . This region is referred to the turbid tidal edge (Hsu et al 2013). The sediment concentration at peak ebb is higher than that at peak flood in the turbid tidal edge.…”

Section: Sediment Transport On the Partially Vegetated Tidal Flatmentioning

confidence: 99%

“…The tidal flat has a constant slope of 0.001. The prescribed tide has a sinusoidal tidal level with a tidal range of 4 m. Based on the definitions of Hsu et al (2013), the region between x = 0 and 4 km is completely subtidal. The lower tidal flat is defined as the region from x = 4 to 6 km, while the upper tidal flat is defined as the region from x = 6 to 8 km.…”

Section: Numerical Simulation Of Partially Vegetated Tidal Flatmentioning

confidence: 99%

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Numerical study of sediment transport on a tidal flat with a patch of vegetation

Han

Niroomandi

et al. 2014

Ocean Dynamics

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To understand how vegetation canopies affect sediment transport on tidal flats, a numerical study of tidal flow and sediment transport on an idealized tidal flat with a patch of vegetation is conducted. The numerical model is firstly validated by laboratory measurements of flow and sediment deposition in a partially vegetated open channel. The idealized study shows that a finite patch of vegetation may produce circulation on the tidal flat with converging flow during flood and diverging flow during ebb. The vegetation patch can also generate a tidal phase lag between the vegetated and bare flats. Tidal currents in both zones are asymmetric, with stronger flood current in the vegetated zone and stronger ebb current on the bare flat. The duration of ebb is longer than that of flood. Computed sediment concentration on the bare flat is higher during ebb due to stronger ebb current and larger bottom shear stress. This is in contrast to the tidal flat without a vegetation canopy, where suspended sediment concentration is higher during flood. On the tidal flat without a vegetation canopy, landward net sediment transport occurs on the upper flat, while seaward net sediment transport occurs on the lower flat and subtidal region. On the partially vegetated tidal flat, however, net sediment transport on both the upper and lower flats are in seaward direction. It increases with increasing vegetation density. Alongshore net sediment flux converges inside the canopy and diverges on the bare flat. Sediment exchange rate between the vegetated and bare flats increases with decreasing vegetation density and sediment settling velocity.

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Sensitivity of tidal hydrodynamics to varying bathymetric configurations in a multi‐inlet rapidly eroding salt marsh system: A numerical study

Deb

Abdolali

Kirby

et al. 2022

Earth Surf Processes Landf

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We describe the development of a high‐resolution, two‐dimensional hydrodynamic model for a multi‐inlet rapidly eroding tidal wetland on the western shore of Delaware Bay, using the finite‐volume, primitive equation community ocean model (FVCOM). Topo‐bathymetric surveys, together with water surface and current velocity measurements during calm and stormy conditions, have been conducted to support model validation. The tested model is then used to quantify the tide‐induced residual transport and asymmetry at major inlet entrances to determine the governing hydrodynamics. We chose a skewness method to calculate the tidal asymmetry and serve as a proxy for sediment transport estimates. The effects of the dredging of an artificial entrance channel and progressive channel deepening in shifting wetland hydrodynamics are shown by developing a scenario analysis. Model results show that the artificially dredged channel has altered the volume exchange at other inlet entrances and increased the net seaward export. The changes in the characteristic frequency of the frictional dissipation in the channel and the system's natural frequency are investigated using a simple ocean–inlet–bay analytical model. Subsequently, we have compared the channel friction scale to the inertia scale and observed that the new connection and gradual channel deepening reduce the overall frictional dominance. Ultimately, the study has shown how the short‐ and long‐term channel bathymetry changes, mainly the artificially dredged channel and progressive channel deepening, can affect the connected system's net circulation and trigger internal marsh erosion.

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The landward and seaward mechanisms of fine-sediment transport across intertidal flats in the shallow-water region—A numerical investigation

Cited by 22 publications

References 47 publications

Mudflat Morphodynamics and the Impact of Sea Level Rise in South San Francisco Bay

Mudflat Morphodynamics and the Impact of Sea Level Rise in South San Francisco Bay

Numerical study of sediment transport on a tidal flat with a patch of vegetation

Sensitivity of tidal hydrodynamics to varying bathymetric configurations in a multi‐inlet rapidly eroding salt marsh system: A numerical study

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