Cross‐shore sediment transport and the equilibrium morphology of mudflats under tidal currents

Pritchard, David; Hogg, Andrew J.

doi:10.1029/2002jc001570

Cited by 86 publications

(84 citation statements)

References 33 publications

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“…In particular, the characteristic convex profile described theoretically by Friedrichs and Aubrey (1996) and empirically by Kirby (2000) is reproduced, and the flats are found to have a tendency to accumulate sediment over long times. We find that the cross-shore width of the flats is almost independent of tidal range, and increases with sediment supply, as predicted by Pritchard and Hogg (2001). We have found that flood-or ebb-dominated tides lead to a steeper equilibrium profiles, and that ebb-dominance may lead to a flat which retreats over long times.…”

Section: Discussionsupporting

confidence: 57%

“…The model which we develop is an extension of that of Roberts et al (2000), including more complete dynamics, and integrated using a numerical method (canute) which has been designed to represent the dynamics accurately in very shallow water, in order to avoid the physically unrealistic velocities seen by Roberts et al We compare our results with analytical predictions, obtained by extending the work of Friedrichs and Aubrey (1996), which are described in more detail elsewhere (Pritchard and Hogg, 2001). …”

Section: Introductionsupporting

confidence: 50%

“…10. It can be seen that the form of the equilibrium profiles is still reasonably well described by the assumption of uniform peak stress, and in fact the value of U max is reasonably well predicted by the theory of Pritchard and Hogg (2001), which suggests that when a symmetrical tide is imposed on the flat, U max should equal 0:244 m s À1 : A flood-dominant regime, however, enhances the tendency for the flat to accumulate sediment and prograde, while an ebb-dominant regime leads to the export of sediment, so the flat retreats landwards over long times.…”

Section: Flood-and Ebb-dominated Tidesmentioning

confidence: 68%

“…This mechanism is discussed in more detail elsewhere (Pritchard and Hogg, 2001). This effect is observed in many tidal situations (Dyer, 1986), and over intertidal flats it appears to be associated with onshore sediment transport (Christie et al, 1999;Bassoullet et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…(Where there is some variation, we have taken U max to be the maximum velocity reached within the computational domain: this generally occurs below MSL). In Table 1, we summarise the results of our experiments, and compare the theoretical predictions of Pritchard and Hogg (2001) for the same conditions.…”

Section: Dependence On Forcing Conditions and Comparison With Theoretmentioning

confidence: 99%

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Morphological modelling of intertidal mudflats: the role of cross-shore tidal currents

Pritchard

Hogg

Roberts

2002

Continental Shelf Research

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We describe a mathematical model of the sediment transport resulting from cross-shore tidal currents on an intertidal mudflat. The model is integrated numerically to determine the long-term (''equilibrium'') behaviour of the morphodynamic system, and to investigate how the morphology of the flats depends on tidal range and sediment supply.Under a sinusoidal tide, the equilibrium flat is approximately linear below mean sea level (MSL) and convex above MSL, and advances seawards over long timescales. The cross-shore width of the flat is independent of tidal range, and increases with increasing sediment supply. Tidal asymmetry (flood-or ebb-dominance) leads to a steeper flat, and ebbdominance can cause the flat to retreat landwards in the long term. Under a spring-neap tidal cycle, the shape of the equilibrium profile is very similar to that for a fixed tidal range, but the rate of accretion is significantly reduced. r

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Section: Discussionsupporting

confidence: 57%

Section: Introductionsupporting

confidence: 50%

Section: Flood-and Ebb-dominated Tidesmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: Dependence On Forcing Conditions and Comparison With Theoretmentioning

confidence: 99%

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Morphological modelling of intertidal mudflats: the role of cross-shore tidal currents

Pritchard

Hogg

Roberts

2002

Continental Shelf Research

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A comparative study of physical and numerical modeling of tidal network ontogeny

et al. 2014

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We investigate the initiation and long-term evolution of tidal networks by comparing controlled laboratory experiments and their associated scaling laws with outputs from a numerical model. We conducted numerical experiments at both the experimental laboratory scale (ELS) and natural estuary scale (NES) and compared these simulations with experimental data and field observations. Sensitivity tests show that initial bathymetry, frictional parametrization, sediment transport, and bed slope terms play an important role in determining the morphodynamic evolution and the final landscape. Consistent with experimental observations, the morphodynamic feedbacks between flow, sediment transport, and bathymetry gradually lead the system to a less dynamic state, finally reaching a stable network configuration. In both the ELS and NES simulations, the initially planar lagoon with large intertidal areas is subject to erosion, indicating ebb-dominance. Based on quantitative analyses of the ELS and the NES simulations (e.g., geometric characteristics and relationship between modified tidal prism and cross-sectional area), we conclude that numerical simulations are consistent with laboratory experiments and show that both type of models provide a realistic, albeit simplified, representation of natural systems. The combination of laboratory and numerical experiments also allowed us to explore the possibility of reaching a long-term morphodynamic equilibrium. Both the physical and numerical models approach a dynamic equilibrium characterized by negligible gradients in sediment fluxes. The equilibrium configuration appears to be consistent with traditional relationships linking tidal prism and cross-sectional area of the inlet. Finally, this contribution highlights the significance of complementary research between experimental and numerical modeling in investigating long-term morphodynamics of tidal networks.

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The role of river flow and tidal asymmetry on 1‐D estuarine morphodynamics

et al. 2014

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Numerous research efforts have been devoted to understanding estuarine morphodynamics under tidal forcing. However, the impact of river discharge on estuarine morphodynamics is insufficiently examined. Inspired by the Yangtze Estuary, this work explores the morphodynamic impact of river discharge in a 560 km long tidal basin based on a 1-D model (Delft3D). The model considers total load sediment transport and employs a morphodynamic updating scheme to achieve long-term morphodynamic evolution. We analyze the role of Stokes drift, tidal asymmetry, and river discharge in generating tidal residual sediment transport. Model results suggest that morphodynamic equilibrium is approached within millennia by vanishing spatial gradients of tidal residual sediment transport. We find that the interaction between ebb-directed Stokes return flow/river flow with tides is an important mechanism that flushes river-supplied sediment seaward. Increasing river discharge does not induce continuously eroded or accreted equilibrium bed profiles because of the balance between riverine sediment supply and sediment flushing to the sea. An intermediate threshold river discharge can be defined which leads to a deepest equilibrium bed profile. As a result, the shape (concavity or convexity) of the equilibrium bed profiles will adapt with the magnitude of river discharge. Overall, this study reveals the significant role of river discharge in controlling estuarine morphodynamics by supplying sediment and reinforcing ebb-directed residual sediment transport.

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Cross‐shore sediment transport and the equilibrium morphology of mudflats under tidal currents

Cited by 86 publications

References 33 publications

Morphological modelling of intertidal mudflats: the role of cross-shore tidal currents

Morphological modelling of intertidal mudflats: the role of cross-shore tidal currents

A comparative study of physical and numerical modeling of tidal network ontogeny

The role of river flow and tidal asymmetry on 1‐D estuarine morphodynamics

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