Variability of residual fluxes of suspended sediment in a multiple tidal-inlet system: the Dutch Wadden Sea

Sassi, M.G.; Duran‐Matute, Matias; Kessel, Thijs van; Gerkema, Theo

doi:10.1007/s10236-015-0866-2

Cited by 34 publications

(41 citation statements)

References 28 publications

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“…Higher‐order positive‐definite advection schemes are used for the advection of momentum, temperature, salinity, and turbulent quantities k (turbulent kinetic energy) and ε (dissipation of k into heat). High‐resolution coastal ocean simulations using GETM including drying and flooding of intertidal flats have for example been carried out before for the Dutch Wadden Sea [ Duran‐Matute et al ., ; Sassi et al ., ], the East Frisian Wadden Sea [ Stanev et al ., ; Staneva et al ., ], the Sylt Rømø bight in the North Frisian Wadden Sea [ Burchard et al ., ; Purkiani et al ., ], the Elbe estuary [ Burchard et al ., ], and Willapa Bay in Washington State [ Banas et al ., ].…”

Section: Methodsmentioning

confidence: 99%

A numerical model for the entire Wadden Sea: Skill assessment and analysis of hydrodynamics

et al. 2016

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A baroclinic three‐dimensional numerical model for the entire Wadden Sea of the German Bight in the southern North Sea is first assessed by comparison to field data for surface elevation, current velocity, temperature, and salinity at selected stations and then used to calculate fluxes of volume and salt inside the Wadden Sea and the exchange between the Wadden Sea and the adjacent North Sea through the major tidal inlets. The model is simulating the reference years 2009–2011. An overview of tidal prisms and residual volume fluxes of the main inlets and their variability is given. In addition, data from an intensive observational campaign in a tidal channel south of the island of Spiekeroog as well as satellite images and observations of sea surface properties from a ship of opportunity are used for the skill assessment. Finally, the intensity of estuarine overturning circulation and its variability in the tidal gullies are quantified and analyzed as function of gravitational and wind straining using various estimates including Total Exchange Flow (TEF). Regional differences between the gullies are assessed and drivers of the estuarine circulation are identified. For some inlets, the longitudinal buoyancy gradient dominates the exchange flow, for some others wind straining is more important. Also the intensity of tidal straining (scaled covariance of eddy viscosity and vertical shear) depends on buoyancy gradient and wind forcing in different ways, depending on local topography, orientation toward the main wind direction, and influence by freshwater run off inside or outside the tidal basin.

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Section: Methodsmentioning

confidence: 99%

A numerical model for the entire Wadden Sea: Skill assessment and analysis of hydrodynamics

et al. 2016

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“…A more detailed comparison between the model results and the results of the TESO ferry measurements was carried out by Sassi et al . [], who also compared the residual volume transport through the Texel inlet. All these thorough comparisons with observations gives us confidence in using the simulations to study the residual volume transport in a realistic way.…”

Section: Numerical Setup and Computation Of Tidally Averaged Quantitiesmentioning

confidence: 99%

Quantifying the residual volume transport through a multiple-inlet system in response to wind forcing: The case of the western Dutch Wadden Sea

Duran‐Matute

Gerkema

Sassi

2016

J. Geophys. Res. Oceans

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In multiple‐inlet coastal systems like the western Dutch Wadden Sea, the tides (and their interaction with the bathymetry), the fresh water discharge, and the wind drive a residual flow through the system. In the current paper, we study the effect of the wind on the residual volume transport through the inlets and the system as a whole on both the short (one tidal period) and long (seasonal or yearly) time scales. The results are based on realistic three‐dimensional baroclinic numerical simulations for the years 2009–2011. The length of the simulations (over 2000 tidal periods) allowed us to analyze a large variety of conditions and quantify the effect of wind on the residual volume transport. We found that each inlet has an anisotropic response to wind; i.e., the residual volume transport is much more sensitive to the wind from two inherent preferential directions than from any other directions. We quantify the effects of wind on the residual volume transport through the system and introduce the concept of the system's conductance for such wind driven residual transport. For the western Dutch Wadden Sea, the dominant wind direction in the region is close to the direction with the highest conductance and opposes the tidally driven residual volume transport. This translates in a large variability of the residual volume transport and a dominance of the wind in its long‐term characteristics in spite of the episodic nature of storms.

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“…Recent studies are directing to the importance of wind-driven circulation (e.g., Duran-Matute et al 2016). In the Wadden Sea, winddriven flow is capable of pushing large amounts of water and steer the sediment pathways so they overshoot the channel network and cross the watersheds between the sub-basins (Sassi et al 2015). Baroclinic processes (Burchard et al 2008;Jay and Musiak 1996), penetration of ocean swells (Talke and Stacey 2008), variability in composition and erodibility of the seabed (Friedrichs et al 1998), lateral-exchange processes (Ralston and Stacey 2005) can all play a role.…”

Section: Residual Transport and Balancing Mechanismsmentioning

confidence: 99%

“…Wind and wave forcing influence the sediment transport patterns in the basin Lettmann et al 2009;Sassi et al 2015). In this paper, we direct our attention to the erosion of sediment by small-amplitiude waves, which has been recognized as a process of major importance for morphodynamics of tidal flats (Green and Coco 2007;Green 2011;Green and Coco (2014;Talke and Stacey 2008;Friedrichs 2012).…”

Section: Introductionmentioning

confidence: 99%

Net sediment transport in tidal basins: quantifying the tidal barotropic mechanisms in a unified framework

2017

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Net sediment transport in tidal basins is a subtle imbalance between large fluxes produced by the flood/ebb alternation. The imbalance arises from several mechanisms of suspended transport. Lag effects and tidal asymmetries are regarded as dominant, but defined in different frames of reference (Lagrangian and Eulerian, respectively). A quantitative ranking of their effectiveness is therefore missing. Furthermore, although wind waves are recognized as crucial for tidal flats' morphodynamics, a systematic analysis of the interaction with tidal mechanisms has not been carried out so far. We review the tide-induced barotropic mechanisms and discuss the shortcomings of their current classification for numerical process-based models. Hence, we conceive a unified Eulerian framework accounting for wave-induced resuspension. A new methodology is proposed to decompose the sediment fluxes accordingly, which is applicable without needing (semi-) analytical approximations. The approach is tested with a one-dimensional model of the Vlie basin, Wadden Sea (The Netherlands). Results show that lag-driven transport is dominant for the finer fractions (silt and mud). In absence of waves, net sediment fluxes are landward and spatial (advective) lag effects are dominant. In presence of waves, sediment can be exported from the tidal flats and temporal (local) lag effects are dominant. Conversely, sand transport is dominated by the asymmetry of peak ebb/flood velocities. We show that the direction of lag-driven transport can be estimated by the gradient of hydrodynamic energy. In agreement with previous studies, our results support the conceptualization of tidal flats' equilibrium as a simplified balance between tidal mechanisms and wave resuspension.

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Variability of residual fluxes of suspended sediment in a multiple tidal-inlet system: the Dutch Wadden Sea

Cited by 34 publications

References 28 publications

A numerical model for the entire Wadden Sea: Skill assessment and analysis of hydrodynamics

A numerical model for the entire Wadden Sea: Skill assessment and analysis of hydrodynamics

Quantifying the residual volume transport through a multiple-inlet system in response to wind forcing: The case of the western Dutch Wadden Sea

Net sediment transport in tidal basins: quantifying the tidal barotropic mechanisms in a unified framework

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