Residence time, exposure time and connectivity in the Scheldt Estuary

Brauwere, Anouk de; Brye, Benjamin de; Blaise, Sébastien; Deleersnijder, Éric

doi:10.1016/j.jmarsys.2010.10.001

Cited by 90 publications

(59 citation statements)

References 52 publications

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“…Bolin and Rodhe (1973) propose that the term residence time can be used to describe the average time for newly incorporated particles (or water masses) to leave an estuary. This umbrella definition applies to many of the uses of the term, such as to refer to localized timescales of transport (Barcena et al 2012), or as the time for a particle or water parcel to leave an estuary for the first time in contrast to accounting for subsequent reentries due to the tidal nature of estuaries (de Brauwere et al 2011), but it is not specific to any one of these interpretations. Similar terms such as turnover time and flushing time are often employed, sometimes as synonyms of residence time.…”

Section: Introductionmentioning

confidence: 99%

“…In order to avoid ambiguity in the application of any of these timescales, at least the boundaries of the estuary or the local region being flushed, the initial position or concentration of the water (or tracer, or particles) being flushed, and the initial time should be explicitly defined (Monsen et al 2002;de Brauwere et al 2011). In this analysis, these parameters as well as the methodology and specific assumptions underlying each timescale are specified.…”

Section: Introductionmentioning

confidence: 99%

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A Comparison of Bulk Estuarine Turnover Timescales to Particle Tracking Timescales Using a Model of the Yaquina Bay Estuary

Lemagie

Lerczak

2014

Estuaries and Coasts

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The ability to determine a bulk estuarine turnover timescale that is well defined under realistic conditions is in high demand for estuarine research and management. We compare how turnover timescales vary with tidal and river forcing from idealized forcing scenarios using a threedimensional circulation model of the Yaquina Bay estuary in order to understand the limitations and benefits of different timescale methods for future application. Using model results, we compare bulk formula approaches-the tidal prism method, freshwater fraction method, and a relatively new estuarine timescale calculation method based on the total exchange flow (TEF)-to directly calculated timescales from particle tracking in order to assess the utility of the bulk formula timescales. All of the timescales calculated had similar magnitudes during high river discharge but varied significantly at low discharge and had different dependences on tidal amplitude. Even in the application of a single estuary-averaged timescale, we did not find that any of the bulk timescales described the estuary over a realistic range of tidal and river discharge forcing. During high discharge, the Yaquina Bay timescale is on the order of 2-5 tidal cycles based on the particle tracking analysis, but during low discharge, the turnover time varies across methods and spatial considerations appear to be more important.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Comparison of Bulk Estuarine Turnover Timescales to Particle Tracking Timescales Using a Model of the Yaquina Bay Estuary

Lemagie

Lerczak

2014

Estuaries and Coasts

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“…However, to determine the mean residence time, a particle tracking model needs to track a large number of particles, which can lead to a high computational cost, especially in a large-scale domain. The Eulerian tracer transport model, on the other hand, is a suitable tool to compute an integrative transport time scale, such as the mean residence time (e.g., [2,26,27]). …”

Section: Methodsmentioning

confidence: 99%

“…Transport time scales, such as residence time-the time taken by a water parcel or its constituents to leave a defined region of interest through its outlets to the sea [1,2], or flushing time-a bulk or integrative parameter that describes the general exchange characteristics of a waterbody without its spatial distribution [3]-are usually used as first-order metrics of transport to assess the health and integrity of estuarine and coastal ecosystems. For example, the concept of residence time has been used to study pollutant concentrations [4], distributions of plankton [5,6], harmful algal blooms [7,8], pelagic bacteria [9], and dissolved nutrients [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Riverine flow influences water renewal through gravitational circulation induced by freshwater-induced baroclinic/barotropic forcing. For example, [2] showed that the residence time in Scheldt Estuary, located in Belgium and the Netherlands, is much longer in summer than in winter, mainly because of lower river discharge into the estuary during summer. Ref.…”

Section: Introductionmentioning

confidence: 99%

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Residence Time of a Highly Urbanized Estuary: Jamaica Bay, New York

Marsooli

Orton

Fitzpatrick³

et al. 2018

JMSE

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Using a validated coupled hydrodynamic-tracer transport model, this study quantified the mean residence time in Jamaica Bay, a highly eutrophic lagoonal estuary in New York City. The Bay is a well-mixed to partially-stratified estuary with heavily-dredged bathymetry and substantial wastewater treatment plant effluent inputs that lead to seasonal hypoxia in some poorly-flushed deep-water basins. Residence time was computed for Jamaica Bay and its largest isolated deep basin, Grassy Bay. The response of residence time to freshwater discharge and wind forcing during summer 2015 was also investigated. The model results showed that the mean residence time, which represents the time required to flush out 63% of tracers released into the region of interest, was 17.9 days in Jamaica Bay and 10.7 days in Grassy Bay. The results also showed that some regions in Jamaica Bay retained their tracers much longer than the calculated residence time and, thus, are potentially prone to water quality problems. Model experiments demonstrated that summertime wind forcing caused a small increase in residence time, whereas freshwater discharge substantially reduced residence time. Freshwater inputs were shown to strongly enhance the two-layer estuarine gravitational circulation and vertical shear, which likely reduced residence time by enhancing shear dispersion. Due to the Bay's small, highly-urbanized watershed, freshwater inputs are largely derived from the municipal water supply, which is fairly uniform year-round. This water helps to promote bay flushing, yet also carries a high nitrogen load from wastewater treatment. Lastly, the tidal prism method was used to create a simple calibrated model of residence time using the geometry of the study area and the tidal range and period.

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Observed and modeled drifters at a tidal inlet

Spydell

Feddersen

Olabarrieta

et al. 2015

J. Geophys. Res. Oceans

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Material transport and dispersion near the mouth of a tidal inlet (New River Inlet, NC) are investigated using GPS-tracked drifters and numerical models. For ebb tide releases, velocities are largest (>1 m s 21 )in two approximately 30 m wide channels that bisect the 1-3 m deep ebb shoal. In the channels, drifter and subsurface current meter velocities are similar, consistent with strong vertical mixing and 2-D hydrodynamics. Drifters were preferentially entrained in the channelized jets where drifter cluster lateral spreading rates l in were small (l in % 0:5 m 2 s 21 ). At the seaward edge of the ebb shoal, jet velocities decrease linearly with distance (to 0:2 m s 21 , about 1 km from shore), and cluster spreading rates are larger with l out % 3 m 2 s 21 .Although the models COAWST and NearCom generally reproduce the observed trajectory directions, certain observed drifter properties are poorly modeled. For example, modeled mean drifter velocities are smaller than observed, and upon exiting the inlet, observed drifters turn north more than modeled drifters. The model simulations do reproduce qualitatively the spreading rates observed in the inner inlet, the flow deceleration, and the increase in l out observed in the outer inlet. However, model spreading rates increase only to l out < 1 m 2 s 21 . Smaller modeled than observed l out may result from using unstratified models. Noncoincident (in space) observations show evidence of a buoyant plume (Dq51 kg m 23 ) in the outer inlet, likely affecting drifter lateral spreading. Generally, drifter-based model performance is good within the inlet channels where tidal currents are strongest, whereas model-data differences are significant farther offshore.

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Residence time, exposure time and connectivity in the Scheldt Estuary

Cited by 90 publications

References 52 publications

A Comparison of Bulk Estuarine Turnover Timescales to Particle Tracking Timescales Using a Model of the Yaquina Bay Estuary

A Comparison of Bulk Estuarine Turnover Timescales to Particle Tracking Timescales Using a Model of the Yaquina Bay Estuary

Residence Time of a Highly Urbanized Estuary: Jamaica Bay, New York

Observed and modeled drifters at a tidal inlet

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