Practical implications of tidal flat shape

Kirby, R.

doi:10.1016/s0278-4343(00)00012-1

Cited by 135 publications

(112 citation statements)

References 14 publications

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“…Despite the greater complexity of our model than that of Friedrichs and Aubrey (we include both nonlinear terms and explicit sediment supply), it is apparent that the condition U max ¼ constant provides a reasonable first-order description of the equilibrium dynamics. The shape of the profile, which is convex-upwards above MSL and approximately linear below MSL, is also in accordance with the FA96 model, as well as with the numerical results of Roberts et al (2000), and with the profiles described by Kirby (2000).…”

Section: External Supply Of Sedimentsupporting

confidence: 86%

“…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).…”

Section: Discussionmentioning

confidence: 81%

“…It is only in the last decade that a number of systematic empirical studies (Kirby, 1992;Dyer, 1998;Kirby, 2000) have been made to determine which forms of external forcing are crucial in developing and maintaining the observed ''equilibrium'' morphologies.…”

Section: Introductionmentioning

confidence: 99%

“…The cross-shore profiles of mudflats can be classified according to the relative contributions made by wind waves and tidal currents to the total sediment transport (Kirby, 2000). At one end of the range are erosional flats dominated by windgenerated waves, which are characterised by a concave-upwards profile, while at the other end are tidally dominated flats with a convex-upwards profile, which are believed to have a tendency to accrete over long times.…”

Section: Introductionmentioning

confidence: 99%

“…We shall refer to this profile as an FA96-flat. The FA96-profile provides a good qualitative model for the tidally dominated flats described by Kirby (2000); however, as Lee and Mehta (1997) point out, muddy sediments are easily transported long distances in suspension, and so it may be misleading to consider equilibrium in terms of a local balance. Roberts et al (2000) calculated numerically the currents and sediment transport with morphodynamic feedback, iteratively updating the bed profile according to the net erosion or deposition at each point, and obtained equilibrium profiles under various forcing conditions.…”

Section: Introductionmentioning

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: External Supply Of Sedimentsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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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Interactions between waves, sediment, and turbulence on a shallow estuarine mudflat

MacVean

Lacy

2014

J. Geophys. Res. Oceans

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, suspended-sediment concentrations (SSC) at 15 and 30 cm above the bed (cmab) increased by 1-2 orders of magnitude, and vertical gradients in SSC were strong enough to produce turbulence-limiting stratification, with gradient Richardson numbers exceeding 0.25. Simultaneously, turbulent stresses (decomposed from wave motions) increased by an order of magnitude. The apparent contradiction of energetic turbulence in the presence of strong stratification was reconciled by considering the turbulent kinetic energy (TKE) budget: in general, dissipation and buoyancy flux were balanced by local shear production, and each of these terms increased during wave events. The classic wave-current boundary layer model represented the observations qualitatively, but not quantitatively since the velocity profile could not be approximated as logarithmic. Rather, the mean shear was elevated by the Stokes drift return flow and wind-generated surface stress, which diffused sediment upward and limited stratification. Our findings highlight a pathway for waves to supply energy to both the production and destruction of turbulence, and demonstrate that in such shallow depths, TKE and SSC can be elevated over more of the water column than predicted by traditional models.

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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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Practical implications of tidal flat shape

Cited by 135 publications

References 14 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

Interactions between waves, sediment, and turbulence on a shallow estuarine mudflat

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

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