On the formation of periodic sandy mounds

Porcile, Gaetano; Blondeaux, Paolo; Vittori, Giovanna

doi:10.1016/j.csr.2017.07.011

Cited by 10 publications

(16 citation statements)

References 27 publications

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“…Further insights into the formation of starved river bedforms could be obtained either by new laboratory experiments or by numerical simulations possibly based on the procedure outlined in Porcile et al. (), who evaluated the flow field over tidal starved bedforms by means of a perturbation approach founded on the assumption that the amplitude of the bottom forms is much smaller than the local water depth. After an appropriate validation, the numerical model would allow for an exhaustive investigation of the effects that sediment starvation has on the formation of fluvial dunes spanning the whole parameter space.…”

Section: Discussionmentioning

confidence: 99%

“…Further insights into the formation of starved river bedforms could be obtained either by new laboratory experiments or by numerical simulations possibly based on the procedure outlined in Porcile et al (2017), who evaluated the flow field over PORCILE ET AL. 1238 tidal starved bedforms by means of a perturbation approach founded on the assumption that the amplitude of the bottom forms is much smaller than the local water depth.…”

Section: Discussionmentioning

confidence: 99%

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Starved versus alluvial river bedforms: an experimental investigation

Porcile

Blondeaux

Colombini

2020

Earth Surf Processes Landf

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Laboratory experiments were conducted to investigate the formation of river bedforms under sediment supply‐limited conditions, i.e. when a motionless substratum is bared by the dynamics of the mobile sediments. Three series of experiments were organized in a laboratory flume by fixing all the hydrodynamic and morphodynamic parameters but varying the thickness normalΔ of the initial layer of mobile sediments which covers the rigid bottom of the flume. At the end of all the experiments, which lasted for the same amount of time, the formation of transverse sand dunes was observed. For decreasing normalΔ, the rigid bottom of the flume was bared progressively earlier during the experiment and the measurements showed a clear tendency of the bedforms to lengthen, i.e. to increase their crest‐to‐crest distance. Moreover, under strong supply limitation, the two‐dimensional transverse dunes turned into three‐dimensional barchanoid forms and into isolated barchan dunes characterized by an abrupt reduction in bedform heights. A two‐dimensional Fourier analysis of the bottom profile was performed, providing the amplitude of the main streamwise and spanwise harmonic components of the bottom morphology as a function of normalΔ. © 2019 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

“…Further insights into the formation of starved river bedforms could be obtained either by new laboratory experiments or by numerical simulations possibly based on the procedure outlined in Porcile et al (2017), who evaluated the flow field over PORCILE ET AL. 1238 tidal starved bedforms by means of a perturbation approach founded on the assumption that the amplitude of the bottom forms is much smaller than the local water depth.…”

Section: Discussionmentioning

confidence: 99%

Starved versus alluvial river bedforms: an experimental investigation

Porcile

Blondeaux

Colombini

2020

Earth Surf Processes Landf

Self Cite

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“…The resulting evolution equations [see Eq. (36)] are thus characterised by a diagonal matrix, and hence, no coupling.…”

Section: Reference Case: No Couplingmentioning

confidence: 99%

“…Other model studies have extended the approach of Hulscher [24] and identified additional processes affecting the initial growth of sand waves. For instance, migration due to wind [14,31] and tidal asymmetry [5], suspended sediment transport and turbulence formulation [6,7], varying grain sizes [49] and sand scarcity [36]. Moreover, it has been shown that the presence of benthic organisms can influence the initial growth of sand waves [10].…”

Section: Introductionmentioning

confidence: 99%

Modelling the two-way coupling of tidal sand waves and benthic organisms: a linear stability approach

Damveld¹,

Roos²,

Borsje³

et al. 2019

Environ Fluid Mech

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We use a linear stability approach to develop a process-based morphodynamic model including a two-way coupling between tidal sand wave dynamics and benthic organisms. With this model we are able to study both the effect of benthic organisms on the hydro-and sediment dynamics, and the effect of spatial and temporal environmental variations on the distribution of these organisms. Specifically, we include two coupling processes: the effect of the biomass of the organisms on the bottom slip parameter, and the effect of shear stress variations on the biological carrying capacity. We discuss the differences and similarities between the methodology used in this work and that from 'traditional' (morphodynamics only) stability modelling studies. Here, we end up with a 2 × 2 linear eigenvalue problem, which leads to two distinct eigenmodes for each topographic wave number. These eigenmodes control the growth and migration properties of both sand waves and benthic organisms (biomass). Apart from hydrodynamic forcing, the biomass also grows autonomously, which results in a changing fastest growing mode (FGM, i.e. the preferred wavelength) over time. As a result, in contrast to 'traditional' stability modelling studies, the FGM for a certain model outcome does not necessarily have to be dominant in the field. Therefore, we also analysed the temporal evolution of an initial bed hump (without perturbing biomass) and of an initial biomass hump (without perturbing topography). It turns out that these local disturbances may trigger the combined growth of sand waves and spatially varying biomass patterns. Moreover, the results reveal that the autonomous benthic growth significantly influences the growth rate of sand waves. Finally, we show that biomass maxima tend to concentrate in the region around the trough and lee side slope of sand waves, which corresponds to observations in the field.

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“…e model by Hulscher (1996) was later extended in many other studies, for example by including wind-driven (Németh et al, 2002) and tide-driven (Besio et al, 2004) migra-tion, turbulence formulation (Komarova et al, 2000;Blondeaux et al, 2005b;Blondeaux et al, 2005a), suspended sediment transport (Blondeaux et al, 2005b;Blondeaux et al, 2005a), grain size dependencies (Van der Veen et al, 2006), heterogeneous sediment transport (Van Oyen et al, 2009a;Van Oyen et al, 2009b), biology (Borsje et al, 2009b;Borsje et al, 2009c), sand scarcity (Porcile et al, 2017) and storm processes (Campmans et al, 2017).…”

Section: 1: Linear Stability Analysismentioning

confidence: 99%

The feedbacks among tidal sand waves, benthic organisms and sediment sorting processes

Damveld¹

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On the formation of periodic sandy mounds

Cited by 10 publications

References 27 publications

Starved versus alluvial river bedforms: an experimental investigation

Starved versus alluvial river bedforms: an experimental investigation

Modelling the two-way coupling of tidal sand waves and benthic organisms: a linear stability approach

The feedbacks among tidal sand waves, benthic organisms and sediment sorting processes

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