The influence of bedforms on flow and sediment transport over intertidal mudflats

Whitehouse, R.J.S.; Bassoullet, Philippe; Dyer, K.R.; Mitchener, Helen; Roberts, W.

doi:10.1016/s0278-4343(00)00014-5

Cited by 88 publications

(37 citation statements)

References 19 publications

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“…These patterns can be observed in the Brouage mud#at as well as the Ske%ing mud#at (e.g. Whitehouse et al, 2000). The formation of the runnels by dewateringinduced sur"cial water #ows is not clearly established, but the contribution of these longitudinal bedforms to drainage is undoubted, despite the fact that they retain water in the runnels at the end of the exposure period.…”

Section: Drainagementioning

confidence: 99%

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Characterization of intertidal flat hydrodynamics

Hir

Roberts

Cazaillet³

et al. 2000

Continental Shelf Research

307

115

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The paper reviews the di!erent physical forcings that control tidal #at hydrodynamics. Tidal propagation and cross-shore or long-shore currents, tidal asymmetry, wind-induced circulation, wave propagation and drainage processes are successively considered. Some simple methods are described for estimating cross-shore currents and wave-induced bottom shear stresses, and the results obtained are compared to "eld measurements on three contrasted sites in Europe. In particular the cross-shore current is shown uniform in the lower part of the #at, and decreasing towards the shore. Bottom friction-induced wave attenuation is simply formulated on gently sloping beds, leading to a maximum wave height that a #at can experience; it is proportional to the water height according to the ratio between the slope and the wave friction factor. The maximum related shear stress occurs at high water and is also proportional to the water depth. Maximum tidal velocities are very similar in the three sites where bottom sediment is muddy, suggesting a relationship between physical stresses and sediment characteristics. The consequences of physical forcings on sediment transport are listed. The bottom shear stress is suggested as the relevant parameter for comparing tidal and wave e!ects. In general, tide induces onshore sediment transport, whereas waves and drainage favour o!shore transport. The processes leading to a possible tidal equilibrium pro"le are analysed: they involve the intrinsic asymmetry that favours net deposition at high water, and an ebb dominance generated by the resulting bottom pro"le convexity. Eroding waves are likely to upset such a balance; this equilibrium then reduces to a trend for the system.

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Section: Drainagementioning

confidence: 99%

“…Drainage can be either due to creeks #owing from the shore at the surface of the #at (e.g. Whitehouse et al, 2000), or due to dewatering within the air-exposed sediment, when the water table is falling with some delay after the water surface (e.g. Anderson and Howell, 1984).…”

Section: Drainagementioning

confidence: 99%

Characterization of intertidal flat hydrodynamics

Hir

Roberts

Cazaillet³

et al. 2000

Continental Shelf Research

307

115

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“…Cohesive sediments free of fauna generally experience high surface stability due to undisturbed growth of microphytobenthos films and the associated high EPS production that binds sediment particles (Austen et al, 1999;Paterson et al, 2000;Whitehouse et al, 2000;Lundkvist et al, 2007a). The almost doubled erosion threshold (u c ) during the 5 days between erosion cycles in our defaunated sediment emphasizes that the development of biostabilization through microphytobenthic EPS production is rapid and efficient.…”

Section: Discussionmentioning

confidence: 83%

Influence of benthic macroinvertebrates on the erodability of estuarine cohesive sediments: Density- and biomass-specific responses

Kristensen

Neto

Lundkvist

et al. 2013

Estuarine, Coastal and Shelf Science

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Regional index term: Portugal Mondego EstuaryKeywords: erosion threshold erosion rate behaviour macrofauna feeding microphytobenthos biostabilization a b s t r a c tThe impact of three dominating benthic invertebrates on sediment stability and erosion conditions of cohesive sediments in the Mondego Estuary, Portugal, was examined in laboratory annular flume experiments. The purpose was to test how the life habits and body size of the three involved species (Hydrobia ulvae, Nereis diversicolor and Scrobicularia plana) in terms of density or biomass influence sediment erosion. All three species decreased the free-stream erosion threshold (u c ) and increased erosion rate (E), since their feeding activities diminished the surface stabilizing effect of extracellular polymeric substances (EPS) produced by microphytobenthos. S. plana had the highest and H. ulvae the lowest impact when related to density (factor of 29 for u c and factor of 19 for E), while H. ulvae was more important than S. plana when related to biomass (factor of 4 for u c and factor of 6 for E). N. diversicolor had intermediate density-specific (4e6 times higher than H. ulvae) and lowest biomass-specific (2e3 times lower than S. plana) effects on erosion. It appears that faunal erosion impacts preferably should be reported in biomass units for comparative purposes because individual behavioural effects of a smallbodied species like H. ulvae functionally can be relatively more important than those of a 100 times heavier S. plana individual. This is clearly evidenced from the strongly diminished response in suspended Chlorophyll-a content in the presence of the former than the latter species, which is caused by an efficient microphytobenthos grazing by H. ulvae. It is also important to emphasize that the total faunal impact on erosion threshold in a certain area is dictated by combination of contributions from individual species. The total outcome is unpredictable and controlled by synergistic and antagonistic speciesspecific effects, species interactions as well as environmental and sediment conditions.

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“…There are three likely causes for the weak relations we found in the Kleine Noordwaard study area: 1) the small gradient in surface topography and a large variation in micro-relief by the presence of mudflat runnels, old furrows, and ditches (Whitehouse et al, 2000;Takekawa et al, 2010;Fagherazzi and Mariotti, 2012); 2) the absence of vegetation (Neubauer et al, 2002;Darke and Megonigal, 2003;Vandenbruwaene et al, 2015), and 3) the small tidal range and water depths (Mariotti and Fagherazzi, 2013). These three factors result in an uniform sediment distribution by 15 firstly, micro topographic flow paths during low water levels (Hupp et al, 2008;Temmerman et al, 2005a); secondly, sheet flow during high water levels (Vandenbruwaene et al, 2015;Temmerman et al, 2005a); or thirdly, a relatively large impact of shear stress (Fagherazzi and Mariotti, 2012) of wind waves and currents, which hamper sediment settling and/or promote sediment redistribution across the tidal flats.…”

Section: Intertidal Flatsmentioning

confidence: 89%

Establishing a sediment budget in the newly created Kleine Noordwaard wetland area in the Rhine-Meuse delta

Deijl¹,

Perk²,

Middelkoop³

2017

Preprint

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Abstract. Many deltas are threatened by accelerated soil subsidence, sea-level rise, increasing river discharge, and sediment starvation. Effective delta restoration and effective river management require a thorough understanding of the mechanisms of aggradation, erosion, and their controls. Sediment dynamics has been studied at floodplains and marshes, but little is known about the sediment dynamics and budget of newly created wetlands. Here we take advantage of a recently opened tidal freshwater system to study both the mechanisms and controls of aggradation and erosion in newly created wetlands. We quantified . This is enough to compensate for the actual rates of sea-level rise and soil subsidence in The Netherlands.

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The influence of bedforms on flow and sediment transport over intertidal mudflats

Cited by 88 publications

References 19 publications

Characterization of intertidal flat hydrodynamics

Characterization of intertidal flat hydrodynamics

Influence of benthic macroinvertebrates on the erodability of estuarine cohesive sediments: Density- and biomass-specific responses

Establishing a sediment budget in the newly created Kleine Noordwaard wetland area in the Rhine-Meuse delta

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