Tide-induced residual transport of coarse sediment; Application to the EMS estuary

Abstract. This paper describes recent developments based on advances in coastal ocean forecasting in the fields of numerical modeling, data assimilation, and observational array design, exemplified by the Coastal Observing System for the North and Arctic Seas (COSYNA). The region of interest is the North and Baltic seas, and most of the coastal examples are for the German Bight. Several pre-operational applications are presented to demonstrate the outcome of using the best available science in coastal ocean predictions. The applications address the nonlinear behavior of the coastal ocean, which for the studied region is manifested by the tidal distortion and generation of shallow-water tides. Led by the motivation to maximize the benefits of the observations, this study focuses on the integration of observations and modeling using advanced statistical methods. Coastal and regional ocean forecasting systems do not operate in isolation but are linked, either weakly by using forcing data or interactively using two-way nesting or unstructured-grid models. Therefore, the problems of downscaling and upscaling are addressed, along with a discussion of the potential influence of the information from coastal observatories or coastal forecasting systems on the regional models. One example of coupling coarse-resolution regional models with a fineresolution model interface in the area of straits connecting the North and Baltic seas using a two-way nesting method is presented. Illustrations from the assimilation of remote sensing, in situ and high-frequency (HF) radar data, the prediction of wind waves and storm surges, and possible applications to search and rescue operations are also presented. Concepts for seamless approaches to link coastal and regional forecasting systems are exemplified by the application of an unstructured-grid model for the Ems Estuary.

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“…The dominant dynamics in the Ems Estuary are induced by tides (van de Kreeke and Robaczewska, 1993). The M2 amplitude (Fig.…”

Section: Cross-scale Modeling: a Step Towards Linking Estuaries And Omentioning

confidence: 99%

Ocean forecasting for the German Bight: from regional to coastal scales

Stanev¹,

Schulz‐Stellenfleth²,

Staneva³

et al. 2016

Ocean Sci.

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“…4 and 6 cpd comparable in magnitude to the diurnal (K1) contribution. Since the interactions between the semi-diurnal tide and its even overtides are known to contribute to tidal asymmetry and, thus, to drive net sediment transport (van de Kreeke and Robaczewska, 1993;van de Kreeke et al, 1997), the suspended and bedload deposition patterns computed in the present study will be indicative of both spatial and temporal asymmetries in the tidal currents.…”

Section: Model-observations Comparisonmentioning

confidence: 86%

“…(4) and (5), expressions for the critical depth-averaged and near-bottom velocities are given by: (10) and (11) Once threshold conditions are reached, an empirical formula (here, Bagnold, 1963) is used to compute the dimensionless bedload transport: (12) with , where ϕ is the angle of repose and β the angle of bed slope. For simplicity, the angle of repose is held constant with a value of tanϕ = 0.6 (van de Kreeke and Robaczewska, 1993) and a flat bottom is assumed (β = 0). This approximation is generally valid for tidal deltas where topographic gradients are small, but may not necessarily apply to steeper slopes along the sides of the inlet throat.…”

Section: Bedload Particle Transportmentioning

confidence: 99%

Hydrodynamics and sediment transport in a southeast Florida tidal inlet

Fiechter

Steffen

Mooers

et al. 2006

Estuarine, Coastal and Shelf Science

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A three-dimensional ocean circulation model is used to investigate the hydrodynamics of a tidal inlet and deltas system in Southeast Florida, and to understand the consequences for suspended and bedload sediment transport patterns. The model reproduces observed tidal currents and provides insight about residual currents caused by spatial asymmetries in the inlet throat and tidal deltas during ebb and flood flows. A particle-tracking approach for suspended and bedload sediment transport is used to simulate deposition patterns for different particle sizes. The simulation results qualitatively correlate with the distribution of sediment characteristics within the tidal inlet and deltas system and demonstrate sensitivity to the choice of advection velocities (e.g., near-bottom versus depthaveraged) and regions of sediment origin. Furthermore, the distinction between suspended and bedload transport as a function of particle size indicates significant differences in deposition patterns and their potential connection to geomorphologic features of the tidal inlet and deltas system.

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“…The non-linearities originate from the mass balance equation, both the advection term and the friction term in the momentum equation [Parker et al (1991)] and the sediment transport formulation. An example of latter is the effect of the interaction between the M2, M4 and M6 tidal constituents on the bed load transport suggested by Van de Kreeke and Robaczewska (1993). It is highly questionable whether the overtides and the associated tide residual transports will finally disappear.…”

Section: Fbc Relation To Wave Celeritymentioning

confidence: 99%

“…and amongst others, between tidal prism and cross-section (Jarrett, 1967), an equal duration of ebb and flood [Dronkers (1998)], the relation between the M2 and M4 tidal constituents [Friedrichs and Aubrey (1988)], the interactions of M2, M4 and M6 tidal constituents [Van de Kreeke and Robaczewska (1993)] and the hypsometric characteristics of the estuary [Boon and Byrne (1981)]. Further, the impact of the time lag between maximum velocities and maximum water levels has been reported to be a factor of significance [Ahnert (1960), Friedrichs and Aubrey (1988), Jay (1991), Savenije (2001) and , Prandle (2003)].…”

Section: Criteria For Equilibriummentioning

confidence: 99%

Modeling morphodynamic evolution in alluvial estuaries

Wegen¹

2010

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All rights reserved. No part of this publication or the information contained herein may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publishers. Although all care is taken to ensure the integrity and quality of this publication and the information herein, no responsibility is assumed by the publishers nor the author for any damage to the property or persons as a result of operation or use of this publication and/or the information contained herein.Published by: CRC Press/Balkema PO Box 447, 2300 AK Leiden, the Netherlands e-mail: Pub.NL@taylorandfrancis.com www.crcpress.com -www.taylorandfrancis.co.uk -www.ba.balkema.nl Cover image: Computed morphodynamic evolution in a 320 km long tidal embayment with bank erosion after 0, 800 and 6400 years. AbstractEstuaries are valuable areas. Tidal flats, tidally varying water levels and the saltfresh water interface are characteristics that form a unique ecological environment, which is often of international importance. Local fishery, aquaculture and tourism are important sectors that profit from the estuarine richness. Additionally, numerous ports are situated along estuaries, forming the logistical link between ocean transport and the hinterland. It is of utmost importance to understand estuarine processes so that impact of human interference (like dredging) and long-term changes (like sea level rise or a changing discharge regime) can be estimated and evaluated.The main objective of this research is to investigate the governing processes and characteristics that drive morphodynamic evolution in alluvial estuaries by means of application of a process-based numerical model (Delft3D). The Delft3D model numerically solves the shallow water equations, which result in a detailed water level and velocity field at any moment and at any place in the model domain. This information is used to predict sediment transports and the resulting bathymetric evolution.The research starts from a highly schematized configuration (a rectangular tidal basin filled with uniform sand and forced by a semi-diurnal tide) to study characteristic morphodynamic evolution over millennia. In subsequent chapters more processes are added, autonomous behavior is restricted and the timescale is reduced, to finally end up with a model configuration that matches the geometry of a real alluvial estuary and a 'comprehensive' timescale that allows model validation with measured morphological developments. The case studies used for model validation are the Western Scheldt estuary in the Netherlands and San Pablo Bay in California, USA.The models described in the current research did not reach a state of equilibrium in the strict sense. During the simulations tide residual transports and morphodynamic evolution remain continuously present despite the constant forcing conditions. Nevertheless, model results show a decay in (the rates of) energy dissipation and tid...

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Tide-induced residual transport of coarse sediment; Application to the EMS estuary

Cited by 109 publications

References 7 publications

Ocean forecasting for the German Bight: from regional to coastal scales

Ocean forecasting for the German Bight: from regional to coastal scales

Hydrodynamics and sediment transport in a southeast Florida tidal inlet

Modeling morphodynamic evolution in alluvial estuaries

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