Water quality modelling of the western Scheldt estuary

Ouboter, Maarten; Eck, Bert T. M. Van; Gils, J.A.G. van; Sweerts, Jean Pierre; Villars, M.T.

doi:10.1007/978-94-017-3573-5_8

Cited by 8 publications

(13 citation statements)

References 2 publications

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“…Similarly to Ouboter et al (1998), in our model about one third of the total oxygen consumption in the estuary is due to nitrification; oxygen consumption by oxic mineralisation is comparable to oxygen consumption by nitrification, similar to conditions reported by Regnier et al (1997). To be noted, however, is that integrated over the whole estuary, oxic mineralisation consumes more oxygen per year than nitrification which is in accordance with experimental findings of Gazeau et al (2005).…”

Section: Oxygen Budgetsupporting

confidence: 90%

“…This transport approach incorporates longitudinal dispersion coefficients which parametrise a variety of physical mechanisms, including effects of either vertical or horizontal shear in tidal currents (Monismith et al, 2002). Advective-dispersive transport Tr C of chemical species C is expressed as given in Thomann and Mueller (1987) and used amongst others by Soetaert and Herman (1995b) and Ouboter et al (1998) for the Scheldt estuary:…”

Section: Advective-dispersive Transportmentioning

confidence: 99%

“…14), while the rest is exported to the Southern Bight of the North Sea. This shows a clear downwards trend in the percentage of N 2 production, as in the eighties 21-25% of the total nitrogen imported into the Scheldt (Soetaert and Herman, 1995a;Ouboter et al, 1998), and in the seventies around 40% (Soetaert and Herman, 1995a;Billen et al, 1985) of the total nitrogen import into the estuary was removed within the estuary, mainly due to denitrification. This phenomenon is likely due to improved oxygen conditions in the Scheldt from the seventies until now (Soetaert and Herman, 1995a;Soetaert et al, 2006), moving the zone of denitrification more into the narrow upstream regions and generally allowing for less denitrification because of the limited area of sediments, the prime location of denitrification, in the upstream regions.…”

mentioning

confidence: 91%

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Present nitrogen and carbon dynamics in the Scheldt estuary using a novel 1-D model

2008

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Abstract.A 1-D, pelagic, reactive-transport model of a completely mixed, turbid, heterotrophic estuary -the Scheldt estuary -is presented. The model resolves major carbon and nitrogen species and oxygen, as well as pH. The model features two organic matter degradation pathways, oxic mineralisation and denitrification, and includes primary production as well as nitrification. Apart from advectivedispersive transport along the length axis, the model also describes O 2 , CO 2 , and N 2 air-water exchange. The aim of this study is to present a model which is as simple as possible but still fits the data well enough to determine the fate and turnover of nutrients entering the estuary and their spa-

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Section: Oxygen Budgetsupporting

confidence: 90%

Section: Advective-dispersive Transportmentioning

confidence: 99%

mentioning

confidence: 91%

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Present nitrogen and carbon dynamics in the Scheldt estuary using a novel 1-D model

2008

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“…Internally, Delft3D-WAQ multiplies fluxes with concentrations to obtain masses across internal and external boundaries. Delft3D-WAQ has been used successfully in the simulation of dredging plumes, thermal discharges and various water pollution studies (Van Gils et al 1993, Van der Molen et al 1994, Ouboter et al 1997.For the modelling of eelgrass seed transport, we distinguished 3 different fractions: (1) floating seeds in reproductive eelgrass shoots; (2) suspended seeds; and (3) eelgrass seeds on the bottom. Vertically, the water column in the model was subdivided into 4 layers (through aggregation of the original 10 layers of the hydrodynamic model) covering 10, 40, 40 and 10% of the water depth, respectively.…”

mentioning

confidence: 99%

Eelgrass seed dispersal via floating generative shoots in the Dutch Wadden Sea: a model approach

Erftemeijer¹,

Beek²,

Ochieng³

et al. 2008

Mar. Ecol. Prog. Ser.

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Potential long-distance dispersal of eelgrass seeds via floating generative shoots from a 256 ha meadow in the Ems Estuary (Wadden Sea) was studied by means of computer-simulation modelling. Flowering shoot density (peaking at 7.8 m -2 ) and total seed production (1094 million seeds yr -1 ) of this meadow was determined in the field and used as model input. Dispersal of floating generative shoots dislodged by increased water turbulence during autumn was modelled using a 3D transport model (Delft3D-WAQ). Transport of eelgrass seeds contained in floating reproductive shoots with the prevailing hydrodynamic regime revealed maximum dispersal distances of up to 130 km from the source of seed production. The effect of wind speed and direction on seed transport was assessed by applying a wind drag function (3% of wind speed) on surface currents in the model using actual wind data from 10 consecutive years (1993 to 2002). Main transport direction under average autumn wind conditions was northeastward. Easterly winds (occurring at an average frequency of 15%) were responsible for some westward transport of eelgrass seeds (at densities > 0.2 seeds m -2 ) up to 20 km from the estuary. Westward eelgrass colonization of suitable areas in the Dutch Wadden Sea appears to be limited by seed supply due to transport limitations posed by the prevailing hydrodynamic regime. Extreme events, such as prolonged Eastern storms, might promote seed dispersal further westwards, allowing for natural recovery of eelgrass in this area; this theory is supported by observations of localized eelgrass patches up to 40 km west of the estuary. KEY WORDS: Seed dispersal · Zostera marina · Transport modelling · Wind effects · Recruitment limitation · Wadden SeaResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 358: 115-124, 2008 exists (McMillan 1991), Zostera marina seeds are not viable beyond their first season (Orth et al. 2000). Successful eelgrass regeneration will therefore depend on the dispersal of seeds from existing eelgrass stands, the subsequent retention of these seeds in potentially suitable locations, and their successful germination and establishment (Hootsmans et al. 1987, Greve et al. 2005.The potential for reproductive shoots of eelgrass to become dislodged and raft over great distances was investigated in Chesapeake Bay (USA) by Harwell & Orth (2002). Dislodgement of reproductive shoots under the influence of extreme hydrodynamic conditions depended on their biomechanical properties, such as breaking stress, breaking strain, elasticity modulus and toughness (Patterson et al. 2001). Once detached, floating reproductive shoots were found to remain positively buoyant for 2 to 3 wk and to retain mature seeds for up to 3 wk before release, allowing for substantial transport of seed-containing, floating generative shoots from source populations by a combination of tidal currents and wind influences (Harwell & Orth 2002).Recent genetic and field studies have shown greater variati...

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“…Delft3D-FLOW) for the same model area. DELWAQ has been used successfully for many different types of applications, including the simulation of dredging plumes, thermal discharges and various water pollution studies (Van Gils et al, 1993;Van der Molen et al, 1994;Ouboter et al, 1998;Van Gils, 1998).…”

Section: Description Of the 'Gem' Modelmentioning

confidence: 99%

GEM: a generic ecological model for estuaries and coastal waters

Blauw

Los

Bokhorst³

et al. 2008

Hydrobiologia

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The set-up, application and validation of a generic ecological model (GEM) for estuaries and coastal waters is presented. This model is a comprehensive ecological model of the bottom of the foodweb, consisting of a set of modules, representing specific water quality processes and primary production that can be combined with any transport model to create a dedicated model for a specific ecosystem. GEM links different physical, chemical and ecological model components into one generic and flexible modelling tool that allows for variable sized, curvilinear grids to accomodate both the requirements for local accuracy while maintaining a relatively short model run-time. The GEM model describes the behaviour of nutrients, organic matter and primary producers in estuaries and coastal waters, incorporating dynamic process modules for dissolved oxygen, nutrients and phytoplankton. GEM integrates the best aspects of existing Dutch estuarine models that were mostly dedicated to only one type of ecosystem, geographic area or subset of processes. Particular strengths of GEM include its generic applicability and the integration and interaction of biological, chemical and physical processes into one predictive tool. The model offers flexibility in choosing which processes to include, and the ability to integrate results from different processes modelled simultaneously with different temporal resolutions. The generic applicability of the model is illustrated using a number of representative examples from case studies in which the GEM model was successfully applied. Validation of these examples was carried out using the 'cost function' to compare model results with field observations. The validation results demonstrated consistent accuracy of the GEM model for various key parameters in both spatial dimensions (horizontally and vertically) as well as temporal dimensions (seasonally and across years) for a variety of water systems without the need for major reparameterisation.

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Water quality modelling of the western Scheldt estuary

Cited by 8 publications

References 2 publications

Present nitrogen and carbon dynamics in the Scheldt estuary using a novel 1-D model

Present nitrogen and carbon dynamics in the Scheldt estuary using a novel 1-D model

Eelgrass seed dispersal via floating generative shoots in the Dutch Wadden Sea: a model approach

GEM: a generic ecological model for estuaries and coastal waters

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