Numerical modelling of morphodynamics—Vilaine Estuary

Vested, Hans Jacob; Tessier, Caroline; Christensen, Bo Brahtz; Goubert, Évelyne

doi:10.1007/s10236-013-0603-7

Cited by 14 publications

(14 citation statements)

References 16 publications

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“…The typhoon also triggered irregular deposition in the inner estuary, increasing size of bedforms and tidal bars (high spectral energy in the cross‐sectional variations). Similar geomorphic changes were also detected in other estuaries worldwide, with TCs triggering morphodynamic processes that transform estuarine offshore areas in a short time span (Freeman et al, 2015; Nowacki et al, 2015; Vested et al, 2013).…”

Section: Discussionsupporting

confidence: 60%

Tropical Cyclones Significantly Alleviate Mega‐Deltaic Erosion Induced by High Riverine Flow

Wang

Dai

Mei

et al. 2020

Geophysical Research Letters

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The drastic decline in sediment discharge experienced by large rivers in recent years might trigger erosion thus increasing the vulnerability of their extensive deltas. However, scarce information is available on the erosion patterns in mega-deltas and associated physical drivers. Here a series of bathymetries in the South Passage, Changjiang Delta, were analyzed to identify morphodynamic variations during high riverine flow and tropical cyclones (TCs). Results indicate that high river flow during flood season triggers large-scale net erosion along the inner estuary, generating elongated erosion-deposition patches. Erosion magnitude gradually weakens moving seaward with few localized bottom variations in the offshore area. TCs transport sediment landward and are accompanied by an overall weak erosion, with a less organized spatial pattern of erosion-deposition. TCs can therefore significantly alleviate erosion, reducing the sediment loss induced by riverine flows by over 50%. These results highlight the role of TCs on the sediment dynamics of mega-deltas. Plain Language Summary In recent years, climate change and reduced riverine sediment inputs have significantly affected the morphology of large deltas. However, it is unknown whether typhoons cause erosion or deposition in the submerged part of a delta, due to challenge in capturing infrequent events. Here we study the impact of high river flow and typhoons on the South Passage, Changjiang Delta. Results show that high riverine flows can cause large-scale erosion. Typhoons reduce fluvial erosion by transporting offshore sediments in the delta. The relative accretion caused by a typhoon is more than half the net erosion induced by riverine floods. This research sheds light on the sediment budget of large deltas and inform policy measures that can mitigate the effect of increasing anthropogenic pressure, extreme events, and sea level rise on delta morphology.

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Section: Discussionsupporting

confidence: 60%

Tropical Cyclones Significantly Alleviate Mega‐Deltaic Erosion Induced by High Riverine Flow

Wang

Dai

Mei

et al. 2020

Geophysical Research Letters

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“…The sampling site of 'Ouest Loscolo', in Vilaine Bay, is under the direct influence of the Vilaine River ( Table 2). The tidal range varies from 2.5 to 5 m (Vested et al, 2013). In this zone, freshwater influence is also provided by the Loire river (mean annual flow 931 m 3 s À1 ) (David et al, 2012).…”

Section: Study Areamentioning

confidence: 99%

Assessing phytoplankton realized niches using a French national phytoplankton monitoring network

Fariñas

Bacher

Soudant

et al. 2015

Estuarine, Coastal and Shelf Science

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Keywords: phytoplankton environment niche position tolerance kernel density outlying mean index a b s t r a c t Relating environmental factors to species occurrence is a fundamental step in a better understanding of the community structure, the spatial and temporal dynamics of populations and how species may respond to environmental changes. In this paper, we used phytoplankton occurrence data, from a French national phytoplankton monitoring network, and environmental variables with the aim of characterizing the realized ecological niches of phytoplankton groups. We selected 35 phytoplankton taxa representing the most important taxa in terms of occurrence frequency and abundance along the French coast of the eastern English Channel, the Southern Bight of the North Sea and the Atlantic Ocean. We show that environmental variables such as nutrient concentration, water temperature, irradiance and turbidity can be considered key factors controlling phytoplankton dynamics and influencing the community structure. By using a statistical framework based on an ordination technique the community structure was analyzed and interpreted in terms of niche overlap, marginality and tolerance. The most marginal taxon was Dactyliosolen and the most tolerant was Skeletonema. Non-marginal taxonomic units could be generalist and specialist, while marginal taxa were rather specialist. Specialist and marginal taxa globally showed lower values of overlap.

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“…Marsh processes usually included in simplified models, such as the stabilizing effect of vegetation, organogenic accretion, wind waves, and edge erosion, are often neglected in high‐resolution models (Donatelli et al, 2018; Olabarrieta et al, 2018; van der Wegen & Roelvink, 2008, 2012; van Maanen et al, 2013; Zhou et al, 2014). Although studies that include wind waves in a coupled morphodynamic simulation exist, they are typically run for few decades and do not include a marsh evolution module (e.g., Hunt et al, 2015; van Ledden et al, 2006; Vested et al, 2013).…”

Section: Novel Techniques and Challenges In High‐resolution Physicalmentioning

confidence: 99%

Salt Marsh Dynamics in a Period of Accelerated Sea Level Rise

et al. 2020

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Salt marshes are dynamic systems able to laterally expand, contract, and vertically accrete in response to sea level rise. Here, we present the grand challenges that need to be addressed to fully characterize marsh morphodynamics. The review focuses on physical processes and quantitative models. Without predictive models, it is impossible to determine the future marsh evolution under accelerated sea level rise. In these models, one of the challenges is to resolve both horizontal and vertical dynamics within the same framework. Vertically, the marsh has to accumulate enough material to contrast rising water levels. Horizontally, marsh erosion at the ocean side must be compensated by landward expansion in forests, lawns, and agricultural fields. The dynamics of the marsh‐upland boundary are still not fully understood and will require more research in the upcoming years. The complexity of marsh vegetation is seldom captured in predictive models of marsh evolution. More research is needed to understand the effects of each species or species assemblages on hydrodynamics and sediment transport. Here, we further advocate that a sediment budget resolving all sediment fluxes in a marsh complex is the most important metric of marsh resilience. Characterization of these fluxes will enable to connect salt marshes to other landforms and to unravel feedbacks controlling the evolution of the entire coastal system. Current models of marsh evolution rely on sparse data sets collected at few locations. Novel remote sensing techniques will provide high‐resolution spatial data that will inform a new generation of computer models.

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Numerical modelling of morphodynamics—Vilaine Estuary

Cited by 14 publications

References 16 publications

Tropical Cyclones Significantly Alleviate Mega‐Deltaic Erosion Induced by High Riverine Flow

Tropical Cyclones Significantly Alleviate Mega‐Deltaic Erosion Induced by High Riverine Flow

Assessing phytoplankton realized niches using a French national phytoplankton monitoring network

Salt Marsh Dynamics in a Period of Accelerated Sea Level Rise

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