Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Hu, Zhan; Wal, Daphne van der; Cai, Huayang; Belzen, Jim van; Bouma, Tjeerd J.

doi:10.1016/j.geomorph.2018.03.025

Cited by 27 publications

(22 citation statements)

References 50 publications

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“…Descriptions of ecosystem engineering have a particular relevance in predicting changes in landscape evolution (Pearce, 2011). Process-based models of bioturbation effects as those we presented may contribute to the prediction of both long and short-term morphodynamic trends (Hu, et al, 2015;Hu, et al, 2018) also as response to human modifications of coastal landscapes (Cozzoli, et al, 2017;Valdemarsen, et al, 2018). Having such a metabolismbased relationship does enable extrapolations on how change in benthic community metabolism may influence bioturbation effects on sediment resuspension.…”

Section: Accepted Manuscript Application Potentialmentioning

confidence: 99%

A process based model of cohesive sediment resuspension under bioturbators' influence

Cozzoli

Gjoni

Pasqua

et al. 2019

Science of The Total Environment

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Macrozoobenthos may affect sediment stability and erodibility via their bioturbating activities, thereby impacting both the short-and long-term development of coastal morphology. Process-based models accounting for the effect of bioturbation are needed for the modelling of erosion dynamics. With this work, we explore whether the fundamental allometric principles of metabolic activity scaling with individual and population size may provide a framework to derive general patterns of bioturbation effect on cohesive sediment resuspension. Experimental flumes were used to test this scaling approach across different species of marine, soft-sediment bioturbators. The collected dataset encompasses a range of bioturbators functional diversity, individual densities, body sizes and overall population metabolic rates. Measurements were collected on a range of hydrodynamic stress from 0.02 to 0.25 Pa. Overall, we observed that bioturbators are able to slightly reduce the sediment resuspension at low hydrodynamic stress, whereas they noticeably enhance it at higher levels of stress. Along the whole hydrodynamic stress gradient, the quantitative effect of bioturbators on sediment resuspension can be efficiently described by the overall metabolic rate of the bioturbating benthic communities, with significant variations across the bioturbators' taxonomic and functional diversity. One of the tested species (the gallery-builder Polychaeta Hediste diversicolor) had an effect that was partially deviating from the general trend, being able to markedly reduce sediment resuspension at low hydrodynamic stress compared to other species. By combining this trend with hydrodynamic forces, we were able to produce a process-based model of biota-mediated sediment resuspension.

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Section: Accepted Manuscript Application Potentialmentioning

confidence: 99%

A process based model of cohesive sediment resuspension under bioturbators' influence

Cozzoli

Gjoni

Pasqua

et al. 2019

Science of The Total Environment

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“…In order to assess whether short-term fluctuations need to be included when studying long-term morphodynamics, it is key to understand the patterns in short-term bed level dynamics (defined as the bed level changes over ∼days, i.e., variations in the bed level evolution). Seasonal changes are relatively well described 17 , but the understanding of the role of storm events on the morphological evolution and bed level dynamics is still developing [18][19][20][21] . As bed level dynamics affect benthic macrofauna 22,23 and salt marshes 24 , this understanding has also ecological relevance.…”

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confidence: 99%

Variations in storm-induced bed level dynamics across intertidal flats

Vet

Prooijen

Colosimo

et al. 2020

Sci Rep

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Hydrodynamic forces on intertidal flats vary over a range of temporal and spatial scales. These spatiotemporal inhomogeneities have implications for intertidal flat morphodynamics and ecology. We determine whether storm events are capable of altering the long-term morphological evolution of intertidal flats, and unravel the contributions of tidal flow, wind-driven flow, waves, and water depth on inhomogeneities in bed level dynamics (bed level changes over ~days) across these areas. We complement decades of bed level measurements on eight intertidal flats in two estuaries in the Netherlands with an extensive 1-month field campaign on one of those flats. Across this intertidal flat, the hydrodynamics and morphodynamics of a storm event were captured, including the poststorm recovery. We show that individual events can persistently alter the morphological evolution of intertidal flats; magnitudes of some bed level changes are even comparable to years of continuous evolution. The morphological impacts of events are largely controlled by the relative timing of the forcing processes, and not solely by their magnitudes. Spatiotemporal variations in bed level dynamics of intertidal flats are driven by a combination of: (1) the inhomogeneous distributions of the hydrodynamic forcing processes (including the under-explored role of the wind); and (2) the linear proportionality between bed level dynamics and the local bed slope.

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“…In addition to reworking by these local environmental conditions, we hypothesize that tidal erosion across the flats may explain the overall low sediment accumulation rates in the tidal flat. Observations and modelling indicate that tidal flats maintain an equilibrium elevation relative to mean sea level through competition between deposition and erosion by wind waves (Fagherazzi et al 2006(Fagherazzi et al , 2007Defina et al 2007;Hu et al 2018). Given this potential geomorphic process, and no observed conversion of tidal flats to marshes across Joppa Flats, it is tempting to conclude that any increase in sediment accumulation in the Merrimack River estuary larger than that preserved and recorded here was possibly balanced by erosion, forcing the maintenance of near-equilibrium elevations in the estuary.…”

Section: Proximal Human and Natural Influences On Estuarine Sediment mentioning

confidence: 60%

Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary

Shawler

Hein

Canuel

et al. 2019

Anthropocene Coasts

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Land clearing, river impoundments, and other human modifications to the upland landscape and within estuarine systems can drive coastal change at local to regional scales. However, as compared with mid-latitude coasts, the impacts of human modifications along sediment-starved formerly glaciated coastal landscapes are relatively understudied. To address this gap, we present a late-Holocene record of changing sediment accumulation rates and sediment sources from sediment cores collected across a tidal flat in the Merrimack River estuary (Mass., USA). We pair sedimentology, geochronology, bulk- and stable-isotope organic geochemistry, and hydrodynamic simulations with historical data to evaluate human and natural impacts on coastal sediment fluxes. During the 17th to 19th centuries, accumulation rates increased by an order of magnitude in the central tidal flat, likely in response to enhanced delivery of terrestrial sediment resulting from upland deforestation. However, the overall increase in accumulation (0.56–2.6 mm/year) within the estuary is subtle and spatially variable across the tidal flats because of coincident anthropogenic land clearing and dam building, upland sediment storage, and estuarine hydrodynamics. This study provides insight into the response of formerly glaciated fluvial-coastal systems to human modifications, and underscores the role of estuarine environmental conditions in modifying upland signals of land-use change.

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Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

Cited by 27 publications

References 50 publications

A process based model of cohesive sediment resuspension under bioturbators' influence

A process based model of cohesive sediment resuspension under bioturbators' influence

Variations in storm-induced bed level dynamics across intertidal flats

Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary

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