Modelling of sediment transport and morphological evolution under the combined action of waves and currents

Franz, Guilherme; Delpey, Matthias; Brito, David; Pinto, Lı́gia; Leitão, Paulo C.; Neves, Ramiro

doi:10.5194/os-13-673-2017

Cited by 21 publications

(9 citation statements)

References 36 publications

(42 reference statements)

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“…Actually, biofilms on and within both bed and suspended sediments influence nearly all sediment processes notably the settling, erosion, and resuspension. With appropriate consideration of other forcings (tide, wave, wind, and surge; e.g., see Brown et al, ; Franz et al, ; Li et al, ; Santoro et al, ; Zhang et al, ; Zhang et al, ) in estuarine and coastal waters, numerical models considering biofilm effects on aggregates could better predict both short‐term sediment dynamics and long‐term morphological evolutions. This study, nevertheless, only focuses on biofilms around suspended sediment particles.…”

Section: Discussionmentioning

confidence: 99%

An Approach to Modeling Biofilm Growth During the Flocculation of Suspended Cohesive Sediments

et al. 2019

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The floc size distribution (FSD) is crucial to predict cohesive sediment dynamics in aquatic environments. Recently, increasing attention has been given to biofilm effects on the FSDs of suspended particles since the presence of biofilms on particle surfaces may lead to larger flocs and thus higher settling velocities. In this study, results from a settling column experiment conducted by Tang and Maggi (2018; https://doi.org/10.1002/2017JG004165) under nutrient‐free and biomass‐free, nutrient‐affected and biomass‐free, and nutrient‐affected and biomass‐affected conditions, with different suspended sediment concentrations, shear rates, and nutrient concentrations, have been used to validate modeled FSDs that is based on the population balance equation solved by the quadrature method of moments. In addition to the processes of aggregation and breakage, the effects of biofilm are expressed in the growth term of the population balance equation. The logistic growth pattern is used to account for an increase in biomass, which is primarily controlled by the specific growth rate and the carrying capacity. In this study, the biofilm growth rate is assumed nutrient dependent, and the carrying capacity of floc size is hypothesized to be proportional to the Kolmogorov microscale. With eight size classes to interpret a simulated FSD, the predicted and observed FSDs exhibit a reasonable match for all nutrient‐free and biomass‐free, nutrient‐affected and biomass‐free, and nutrient‐affected and biomass‐affected conditions. This simplified bioflocculation model fills the gap between the simulations of the FSDs of cohesive sediments without and with biofilms and has the potential to be included in large‐scale models in the future.

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Section: Discussionmentioning

confidence: 99%

An Approach to Modeling Biofilm Growth During the Flocculation of Suspended Cohesive Sediments

et al. 2019

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“…This is due to the so-called sheltering effect, caused by Hel Peninsula (Różyński 2010). However, it does not change the fact that a more comprehensive approach to the subject requires taking into account both the wave-induced current velocities and the coupled wave-current model (as it has recently been done, for example, by Franz et al 2017), which is planned for the authors' future research work.…”

Section: Hydrodynamic Conditionsmentioning

confidence: 99%

Assessment of the potential for dredged material dispersal from dumping sites in the Gulf of Gdańsk

et al. 2018

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Purpose Environment-friendly management of sites used for disposal of locally generated sedimentary material involves designation of an optimal dumping site location which will render the dredged material re-usable for beneficial purposes. The objective of this research was to determine whether wind, waves, and currents can induce transport of sediment from offshore dumping sites located at intermediate depths in the southern Baltic. Materials and methods The problem was addressed by exploring potential sediment transport from two sites located in the Gulf of Gdańsk at depths of about 20 m. A total of 29 combinations of hydrodynamic variables, representing the most extreme possible situations in the area, including eight theoretical uniform wind fields over the entire Baltic Sea from the W, NW, N, NE, E, SE, S, and SW sectors, the wind speed of 30 m s −1 , as well as 21 historical extreme storms, retrieved from the HIPOCAS project database, were used. Results and discussion The bottom velocities resulting from waves and currents at the dumping sites considered were computed using wave models (WAM, SWAN) and the M3D hydrodynamic model (based on the POM model). To estimate the velocities critical for bedload transport, formulae developed by Soulsby (1997) and Sawamoto and Yamashita (Proc Coastal Sediments 87:415-423, 1987) were used. The volumetric bedload transport was computed based on Meyer-Peter and Müller (1948). The model simulations demonstrated that, for the storm conditions analyzed, the current velocity in the area of the two dumping sites would be so low that it would practically not affect the magnitude of the bottom sediment transport. Thus, the resultant volume of bedload transported would be equal to that generated by the wave action. For the heaviest historical storm, the maximum transport is about 3 × 10 −5 m 2 s −1. Conclusions Under conditions of theoretical storms, the bottom orbital velocities would be higher and the resultant sediment transport would reach almost 7 × 10 −5 m 2 s −1 for northerly winds. However, this value is still very low compared with the volume of sediment being dumped. The findings of this study may prove useful in designation of future dumping sites.

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“…Laju sedimentasi di Perairan Teluk Benoa berkisar antara 1,08x10 -6 sampai 24,88 kg/m 2 /hari dengan rata-rata 0,57 kg/m 2 /hari. Tingginya laju sedimentasi di perairan diakibatkan karena rendahnya kecepatan arus, sehingga TSS cenderung akan mulai mengendap menuju dasar perairan (Franz et al, 2017). Laju sedimentasi di Teluk Benoa memiliki nilai yang tinggi pada daerah yang dekat dengan muara sungai serta daerah yang memiliki konsentrasi TSS yang tinggi pada lapisan dasar perairan seperti pada kanal yang berada pada bagian barat teluk dan perairan yang memiliki kanal yang merupakan jalur lalu lintas kapal.…”

Section: Laju Sedimentasi DI Teluk Benoaunclassified

Prediksi Laju Sedimentasi di Perairan Teluk Benoa Menggunakan Pemodelan Numerik

Maharta¹,

Hendrawan²,

Suteja³

2018

J. Mar. Aquat. Sci.

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Benoa Bay is one of the unique ecosystems on the island of Bali because it is a shallow estuary area and has an ecosystem that is important for the waters of the mangrove ecosystem and seagrass. In recent years, Benoa Bay has been reported to have undergone siltation due to sedimentation. However, there has not been much scientific study of the sedimentation rate occurring in Benoa Bay. The study of sedimentation will provide an overview of the rate of sedimetation in the study area. Numerical modeling is one of the most commonly used methods to describe hydrodynamic processes in waters, which are the main drivers of the process of movement of pollutants in waters such as waste, sediment, and others. Thus, the study of sedimentation rate, either spatially or temporally, needs to be done in the waters of Benoa Bay using numerical modeling. The results of this study show that sedimentation rates in Benoa Bay have a minimum value of 1.08x10-6 and a maximum of 24.88 kg/m2/day with an average of 0.57 kg/m2/day. High sedimentation rates occur in the western part of the bay, on the river route, and in the northern part of the bay, between Serangan Island and Mertasari beach. Areas that potentially experience silting in Benoa Bay include the southern port of Benoa Harbor which reaches 0.23 m/year, the waters north of Serangan Island reaching 0.008 m/year, and the area close to the estuary which reaches 0.35 m/year.

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Modelling of sediment transport and morphological evolution under the combined action of waves and currents

Cited by 21 publications

References 36 publications

An Approach to Modeling Biofilm Growth During the Flocculation of Suspended Cohesive Sediments

An Approach to Modeling Biofilm Growth During the Flocculation of Suspended Cohesive Sediments

Assessment of the potential for dredged material dispersal from dumping sites in the Gulf of Gdańsk

Prediksi Laju Sedimentasi di Perairan Teluk Benoa Menggunakan Pemodelan Numerik

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