Numerical modelling of suspended sediment transport in tidal estuaries: A comparison between the Tagus (Portugal) and the Scheldt (Belgium-the Netherlands)

Portela, L. I.; Neves, Ramiro

doi:10.1007/bf02334201

Cited by 24 publications

(10 citation statements)

References 14 publications

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“…This density value, however, contrasts sharply with values of 0.16 g cm -3 calculated from laboratory data reported by DITTMANN (1987) for northern Wadden Sea mussels, and also with 1.02-1.2 gcm -3 and 0.325 g cm -3 quoted for fluid estuarine muds by TEN BRINKE andDRONKERS (1993) andPORTELA andNEVES (1994), respectively. Comparisons between different geographic areas therefore remain problematic as long as site specific bulk sediment densities are not quoted in the literature (e.g.…”

Section: Biodepositioncontrasting

confidence: 74%

Biodeposition in a juvenile mussel bed of the east Frisian Wadden Sea (Southern North Sea)

Flemming

Delafontaine

1994

Netherlands Journal of Aquatic Ecology

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Seasonal trends of biodeposition and animal coverage in backbarrier beds of the mussel Mytilus edulis in the East Frisian Wadden Sea were documented and quantified to assess the effects of physical disturbance by storms and to develop a conceptual model for the interpretation of biodeposits in the stratigraphic record. Accretion and erosion of biogenic muds (faeces and pseudofaeces) were quantified by repeated precision levelling of a 12 m 2 test area. Animal coverage was documented by vertical photography prior to each levelling survey. Levelling and photography were conducted from a bridge and rail system to avoid physical disturbance by trampling. Four surveys, covering a period of different weather conditions, showed variable mean accretion/erosion rates of biodeposits ranging from +0.56 mmd -1 (accretion) to -1.34 mm d -1 (erosion) and areal coverage of mussels ranging from 39.1% to 0%. A pronounced seasonal trend in the biodepositional pattern was observed. Mean accretion rates were high (>0.5 mmd -1) during the summer season, whereas in the winter season net deposition decreased to zero or showed erosional trends. Longterm sediment budgets are thus composed of highly variable mean annual rates which, in turn, comprise highly variable seasonal and even monthly rates, depending on the local weather pattern. This forms the basis for a conceptual model, in terms of which the stratigraphic record of fossil biodeposits can be meaningfully interpreted.

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Section: Biodepositioncontrasting

confidence: 74%

Biodeposition in a juvenile mussel bed of the east Frisian Wadden Sea (Southern North Sea)

Flemming

Delafontaine

1994

Netherlands Journal of Aquatic Ecology

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“…These represent about 43% of the total estuarine surface [13]. The estuary is part of a transnational river basin with a catchment area of more than 80,000 km 2 , discharging an average annual flow of more than 12,500 hm 3 with a high sediment influx, making the estuary a turbid region [14].…”

Section: Overviewmentioning

confidence: 99%

“…The first modeling study published in the 1990s presented a model to simulate suspended sediment transport in two tidal estuaries: the Scheldt (Belgium-The Netherlands) an the Tagus estuary [14]. This model application relied on a 2-dimensional regularly spaced grid (600 m resolution) for the lower estuary and adjacent coastal waters, combined with a 1-dimensional grid for the upper estuary and upstream fluvial section.…”

Section: The 1990smentioning

confidence: 99%

The Tagus Estuary as a Numerical Modeling Test Bed: A Review

et al. 2019

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The Tagus Estuary is the largest estuarine system in the Iberian Peninsula. Located in a heavily populated metropolitan area (Lisbon), the estuary-coastal continuum is subject to significant natural variability (e.g., tidal variations, winds, river inflow, etc.) and human pressures (e.g., sewage outflow, infrastructures, coastal reclamation, dredging, etc.). Since the 1980s, the estuary has been a natural laboratory for a great number of multidisciplinary studies, but also a numerical laboratory to test models and to develop new ideas and numerical methodologies. Hydrodynamic and biogeochemical models have been used ever since to ascertain the main spatial and temporal features of the Tagus system, connecting its dynamic to its biogeochemical cycles, providing numerical tools used to increase knowledge and to manage the estuary and nearby coastal waters. The main objective of this paper is to present a synopsis of the scientific output related to numerical studies in the Tagus system, by reviewing more than fifty papers published over the past four decades. Our work provides a historical background and description of the numerical models implemented to address estuarine hydrodynamics, nutrient uptake, primary production, light availability, seasonal and annual cycles and the link between physical, biological and chemical estuarine oceanography.

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“…Many of the calibration parameters in a cohesive sediment transport model rely on assumptions (or 'secondary hypotheses'; cf Oreskes et al 1994) in the absence of adequate fi eld measurements. For example, u* d , u* e , and M are intrinsically diffi cult to determine in situ and are typically estimated with reference to published results from intensive mud transport studies; u* d is usually assigned a uniform value and spatialization of u* e and M is often based on an assumed down-estuary variation bounded by physically-plausible values (Tattersall et al, 2003), or according to discrete depth zones (Portela and Neves, 1994) or bed types (subtidal channel, tidal fl at, saltmarsh, etc.). Improved instrumentation makes in situ determination of w c a more practical proposition (Manning and Bass, 2006;Benson and French, 2007), although here too a submodel (with additional assumptions and parameters) is needed for temporal and spatial variation in w c outside the limits of data acquisition.…”

Section: Depth-averaged Hydrodynamic Modelmentioning

confidence: 99%

Critical perspectives on the evaluation and optimization of complex numerical models of estuary hydrodynamics and sediment dynamics

French

2009

Earth Surf Processes Landf

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Numerical hydrodynamic and sediment transport models provide a means of extending inferences from direct observation and for advancing our understanding of estuarine processes. However, their parametric complexity invites questions concerning the extent to which model output can be assessed with respect to data. This paper examines the basis for evaluating the performance of complex hydrodynamic and sediment transport models, with reference to a case study of a muddy meso-tidal estuary. Sophisticated and computationally-intensive models should be evaluated using robust objective functions, but conventional measures of fi t and model effi ciency invoke restrictive assumptions about the nature of the errors. Furthermore, they offer little insight into causes of poor performance. Optimization of tidal hydrodynamic models can usefully combine conventional performance measures with harmonic analysis of modelled shallow water tidal constituents that are diagnostic of the interactions between tidal propagation, bathymetry and bottom friction. Models with similar effi ciencies can thus be distinguished and likely sources of error pinpointed. Hydrodynamic models have a predictive power that is rooted in a more-or-less complete representation of the physical processes and boundary conditions that are well-constrained with respect to data. In contrast, fi ne sediment models rely on a less complete conceptualization of a broader set of processes and, crucially, have a parametric complexity that is unmatched by the quantity and quality of observational data. Their performance as measured by conventional objective functions is weaker and it is important to match the structural complexity of model errors with analyses that can localize the scales and times of poor performance. Wavelet analysis is potentially useful here as a means of identifying aspects of the model that need improvement. The context in which such models are deployed is also important. Used heuristically, what might otherwise be dismissed as weak models can still provide mechanistic support for empirically-derived inferences concerning specifi c aspects of system behaviour.

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Numerical modelling of suspended sediment transport in tidal estuaries: A comparison between the Tagus (Portugal) and the Scheldt (Belgium-the Netherlands)

Cited by 24 publications

References 14 publications

Biodeposition in a juvenile mussel bed of the east Frisian Wadden Sea (Southern North Sea)

Biodeposition in a juvenile mussel bed of the east Frisian Wadden Sea (Southern North Sea)

The Tagus Estuary as a Numerical Modeling Test Bed: A Review

Critical perspectives on the evaluation and optimization of complex numerical models of estuary hydrodynamics and sediment dynamics

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