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Water
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Cohesive Sediment Transport Processes
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Cohesive Sediment Transport Processes

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Erosion and Sediment Transport".

Deadline for manuscript submissions: closed (15 December 2023) | Viewed by 6717

Special Issue Editor

Dr. Bommanna Krishnappan

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Guest Editor
Retired Research Scientist, National Water Research Institute, Environment Canada, Burlington, ON, Canada
Interests: river dynamics; cohesive sediment transport; environmental hydraulics; mathematical modelling; diffusion and dispersion processes; water quality
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Cohesive sediments play a major role in the transportation of contaminants and nutrients in aquatic environments. A thorough understanding of the transport processes of cohesive sediments is essential for the development of ecosystem models that can predict the transport, fate and bioaccumulation of highly toxic and persistent chemicals generated from industrial, agricultural and urban developmental activities in a river basin. Transport processes include flocculation, erosion, deposition, consolidation, entrapment and bio-stabilization, just to name a few.

Cohesive sediment transport processes have been the subjects of intense research for over a century, and much progress has been made on processes such as flocculation, erosion, deposition and consolidation. However, more research is still needed for processes such as entrapment and bio-stabilization. In order to highlight the progress on cohesive sediment transport processes research, we are assembling a Special Issue to publish high-quality research papers that improve the state-of-the-art in this area. We invite the submission of original research articles and review papers outlining the progress in these processes. Submitted papers will go through a peer-review process performed by independent reviewers.

Dr. Bommanna Krishnappan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • flocculation
  • erosion and deposition processes
  • consolidation
  • entrapment
  • bio-stabilization
  • ecosystem models

Published Papers (4 papers)

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Research

15 pages, 6362 KiB  
Article
Evaluating Effective Particle Size Distributions of Cohesive Sediment under Varying Shear Stress and Bed Configurations in a Rotating Annular Flume
by Rafaela Maltauro, Micheal Stone, Adrian L. Collins and Bommanna G. Krishnappan
Water 2024, 16(4), 546; https://doi.org/10.3390/w16040546 - 09 Feb 2024
Viewed by 763
Abstract
Despite the environmental significance and ecological importance of cohesive sediment (<63 μm), improved knowledge of how effective particle size distributions (EPSDs) change due to flocculation under different conditions of shear stress and bed configuration is required to better understand in situ transport and [...] Read more.
Despite the environmental significance and ecological importance of cohesive sediment (<63 μm), improved knowledge of how effective particle size distributions (EPSDs) change due to flocculation under different conditions of shear stress and bed configuration is required to better understand in situ transport and storage properties and refine existing sediment transport models. Here, a rotating annular flume was used to (i) evaluate EPSDs under different shear stress and bed types (plane-impermeable and -porous gravel bed) for deposition and erosion experiments; (ii) assess flocculation processes with EPSDs; and (iii) compare flume and field EPSDs observations with respect to measured shear stress. While deposition experiments over the impermeable bed led to an EPSD equilibrium in all shear conditions (constant EPSD percentiles), the ingress experiment over the gravel bed resulted in varying EPSDs, and no equilibrium was observed. During the erosion experiment, deposited flocs became coarser due to bed consolidation, and no particle breakage was observed once particles were resuspended. The ingress experiment showed high efficiency in entrapping suspended particles (~95% of initial suspended sediment), and no exfiltration or resuspension was recorded. Flocculation ratios calculated using EPSDs showed negative correlations with shear stress, indicating that increasing flow energy promoted flocculation for flume and field observations. Our results showed that both suspended and bed sediments can flocculate into coarser flocs that, in turn, are preferentially ingressed and stored in the substrate when in suspension. These findings have important implications regarding legacy impacts, as substrate-stored particles can potentially extend the effects of upstream landscape disturbances. Full article
(This article belongs to the Special Issue Cohesive Sediment Transport Processes)
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22 pages, 5827 KiB  
Article
Flocculation Patterns Related to Intra-Annual Hydrodynamics Variability in the Lower Grijalva-Usumacinta System
by Klever Izquierdo-Ayala, Juan Antonio García-Aragón, Maria Mercedes Castillo-Uzcanga, Carlos Díaz-Delgado, Laura Carrillo and Humberto Salinas-Tapia
Water 2023, 15(2), 292; https://doi.org/10.3390/w15020292 - 10 Jan 2023
Cited by 1 | Viewed by 1485
Abstract
Particle aggregation modifies sediment dynamics, which is a determining factor for morphodynamic and ecological processes in deltaic plains. Here, we investigated the link between intra-annual hydrodynamics variability and flocculation in the Grijalva-Usumacinta system. Monthly (2016–2017) and seasonal (2021–2022) river data was processed using [...] Read more.
Particle aggregation modifies sediment dynamics, which is a determining factor for morphodynamic and ecological processes in deltaic plains. Here, we investigated the link between intra-annual hydrodynamics variability and flocculation in the Grijalva-Usumacinta system. Monthly (2016–2017) and seasonal (2021–2022) river data was processed using analytical methods and the simplified sonar equation. Flocs were reformed and characterized in the laboratory, validating the in situ settling velocities (0.5–3.8 mm/s) and the existence of large low-density macro-flocs (>300 μm). We verified that flocculation prevailed, exhibiting seasonal patterns; (1) the highest aggregation rates matched the increase in total suspended solids at rising-flow (>100 mg/L), (2) periods of high-flow showed stable aggregation rates, and (3) an influence of marine conditions occurred at low-flow. Particulate phosphorous and organic fraction showed seasonal patterns linked to flocculation. Due to damming, the shear rates varied slightly (7–11 L/s) in the Grijalva, leading to high flocculation intensities affecting the diffusivity ratio. In the Usumacinta, aggregation was limited by shear rates that normally exceed 15 1/s. We found seasonal Rouse parameters representative of sediment dynamics. Full article
(This article belongs to the Special Issue Cohesive Sediment Transport Processes)
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18 pages, 5529 KiB  
Article
Physical and Rheological Characteristics of Sediment for Nautical Depth Assessment in Bushehr Port and Its Access Channel
by Farzin Samsami, Seyyed Abbas Haghshenas and Mohsen Soltanpour
Water 2022, 14(24), 4116; https://doi.org/10.3390/w14244116 - 16 Dec 2022
Cited by 7 | Viewed by 2553
Abstract
Sedimentation in ports and waterways covered with fine deposits is a significant challenge in harbor management. The top layer of the bed in such areas typically consists of fluid mud, for which dredging is complicated and less efficient. The goal of this paper [...] Read more.
Sedimentation in ports and waterways covered with fine deposits is a significant challenge in harbor management. The top layer of the bed in such areas typically consists of fluid mud, for which dredging is complicated and less efficient. The goal of this paper is to investigate physical and rheological characteristics of sediment for nautical depth assessment in Bushehr Port and its access channel. In this study the fluid mud layer was detected by hydrographic surveys with a dual-frequency echo sounder. Moreover, sediment properties in various parts of the channel and port were analyzed through a comprehensive sediment sampling in the field and complementary laboratory studies, including sediment grain-size analysis and distribution, carbonate and organic matter content, rheometry, and consolidation and settling tests. It was found that water contents and concentration, and clay-size fractions are the most important factors in rheological characteristics of sediment in the study area. The results indicated that the clay-size fraction in the surficial bed was between 18 and 31%, which categorized it as fine and cohesive sediment. In terms of mineralogy, the sediment was mostly carbonate mud with carbonate content between 52.9 and 57.2%. The results showed that the sediment concentration and yield stress in most samples were lower than 1030 kg/m3 and 123 Pascals, respectively. Based on the hydrographic surveys and obtained sediment characteristics, it is concluded that the nautical bottom approach can be practically implemented in the Bushehr Port and its access channel. Full article
(This article belongs to the Special Issue Cohesive Sediment Transport Processes)
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14 pages, 3586 KiB  
Article
Estimation of Fractal Dimension of Suspended Sediments from Two Mexican Rivers
by Hilda Zepeda Mondragon, Juan Antonio Garcia Aragon, Humberto Salinas Tapia and Bommanna G. Krishnappan
Water 2022, 14(18), 2774; https://doi.org/10.3390/w14182774 - 06 Sep 2022
Cited by 1 | Viewed by 1292
Abstract
Sampling programs for suspended sediment were carried out in the Usumacinta River and its tributary Grijalva River in Mexico during the years 2016 and 2017. Suspended sediment samples collected during these sampling programs were analyzed in the laboratory using a Rotating Annular Flume [...] Read more.
Sampling programs for suspended sediment were carried out in the Usumacinta River and its tributary Grijalva River in Mexico during the years 2016 and 2017. Suspended sediment samples collected during these sampling programs were analyzed in the laboratory using a Rotating Annular Flume (RAF) fitted with a Particle Tracking Velocimetry (PTV) to obtain the 2D images of the suspended sediment particles as they were undergoing floc reconstruction, and subsequently using a glass settling column fitted with inline digital holography set up to obtain 3D holograms of the fully flocculated sediment particles. From these high-resolution hologram images, the fractal dimension of the flocculated sediment particles was obtained using the classical box-counting method and an improved Triangular box-counting method. The estimated fractal dimension of flocculated sediment, which is a measure of floc compactness and structure that control the settling velocity of flocculated sediment was used to validate two empirical models to estimate the fractal dimension in terms of the floc sizes of suspended sediments of these two rivers. It is shown in this study that the floc characteristic can be analyzed in laboratory experiments after floc reconstruction with the use of an RAF and it offers a viable alternative to the costly in-situ sampling that is often carried out in ocean research. The digital holography method employed in this research offers an efficient methodology to obtain the floc fractal dimension. Regarding the innovative aspects and new contribution to science, we can say that we have developed a laboratory protocol to test river waters to establish floc properties such as fractal dimensions of flocs in this research which will help to test river waters on a routine basis with manageable costs. We can also say that we have developed models to predict the relationship between floc fractal dimension and floc size, which did not exist before. Full article
(This article belongs to the Special Issue Cohesive Sediment Transport Processes)
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