Article
Engineering, Civil
Xiang Wang, Carlo Gualtieri, Wenxin Huai
Summary: The impact of aquatic vegetation on weak bed-load transport rates in riverbeds was investigated through laboratory experiments. It was observed that the transport rate increased with an increase in energy slope and a decrease in vegetation density. The traditional method of calculating bed shear stress was unable to predict the measured transport rate, but a new method considering grain shear stress provided a reasonable prediction. The proposed models were found to be more accurate than existing literature models, improving understanding of bed-load transport in vegetated flows.
JOURNAL OF HYDROLOGY
(2023)
Article
Environmental Sciences
Reza Shahmohammadi, Hossein Afzalimehr, Jueyi Sui
Summary: This experimental study aimed to estimate bed shear stress in shallow water flows by evaluating fluid dynamics characteristics under various conditions. The results showed that certain values were proportional to the shear Reynolds number.
Article
Environmental Sciences
Bommanna G. Krishnappan
Summary: This paper presents a review of a semi-empirical modelling approach for cohesive sediment transport in river systems. A semi-empirical approach is a viable option due to the challenge of mathematical modelling for cohesive sediment transport, which is controlled by numerous parameters. The RIVFLOC model of cohesive sediment is reviewed, and the model parameters that need to be determined using a rotating circular flume are emphasized. The variability of these parameters highlights the importance of site-specific sediment testing to achieve reliable predictions of the RIVFLOC model. Application of the model to various river systems has shown the need to include the entrapment process in cohesive sediment transport models.
Article
Engineering, Civil
M. Stone, B. G. Krishnappan, S. Granger, H. R. Upadhayay, Y. Zhang, C. A. Chivers, Q. Decent, A. L. Collins
Summary: The study focused on the transport characteristics of fine sediment in the upper River Taw in southwest England, providing parameters necessary for modeling fine sediment transport. The experimental data were used to calibrate and test a mathematical model (FLUME model) for cohesive sediments, which showed good agreement between measured and modeled data. The study emphasized the importance of understanding transport parameters for assessing sediment control options and pollution abatement strategies at a catchment scale.
JOURNAL OF HYDROLOGY
(2021)
Article
Mechanics
Yesheng Lu, Nian-Sheng Cheng, Maoxing Wei
Summary: Difficulties in estimating bed shear stress in vegetated flows are addressed in this study using an analytical approach based on the phenomenological theory of turbulence, without empirical partition of bed friction and vegetation resistance. The computed bed-load transport rate in vegetated flows aligns well with the formula for unvegetated flows, and the method is applicable to both uniformly distributed vegetation and vegetation patches. However, further research is necessary to extend the model to flexible and submerged vegetation conditions.
Article
Marine & Freshwater Biology
J. C. de Smit, M. G. Kleinhans, T. Gerkema, T. J. Bouma
Summary: The study discusses the importance of the erosion threshold of cohesive sediments in tidal flats and the need for rapid methods to quantify the critical bottom shear stress. The use of the mobile Oscillatory-Channel Resuspension flume, OsCaR, allows for accurate measurement of wave-generated shear stress on sediment cores and captures the main benthic processes effectively.
ESTUARINE COASTAL AND SHELF SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Wuming Ni, Zhilin Sun, Cong Guo, Zongyu Li, Rong Zheng
Summary: In this paper, a depth-averaged two-dimensional numerical model is established and applied to simulate non-uniform sediment transport in Zhejiang tidal estuaries. The model is validated using data from experiments and observational data from the Jiaojiang estuary. The results show that the model can accurately simulate the aggradation and erosion processes of non-uniform sediment, making it adaptable for simulating flow and sediment transport in tidal estuaries.
APPLIED SCIENCES-BASEL
(2023)
Article
Environmental Sciences
Arman Haddadchi, Calvin W. Rose
Summary: Interpreting the links between fine sediment storage and suspended sediment transport during flood events is crucial for understanding river geomorphology and the impacts on water quality and bed habitats. A physically based model of suspended sediment transport, coupled with fine sediment deposition and re-entrainment processes within the gravel bed, is presented. The model provides valuable information on the dynamics of fine sediment and its effects on river bed changes. Testing the model with data from flood events in the Oreti River in New Zealand shows good agreement between observed and modeled fine sediment concentration and load. The model can be used for routing suspended sediment concentration and changes in fine sediment deposition in river networks.
WATER RESOURCES RESEARCH
(2022)
Article
Environmental Sciences
Dake Chen, Jinhai Zheng, Chi Zhang, Dawei Guan, Yuan Li, Huiming Huang
Summary: This study investigates the incipient motion condition of cohesive sediment considering particle aggregation using fractal theory and van der Waals force. A formula for the critical shear stress for surface erosion of cohesive sediments composed of fractal aggregates is developed, and the contribution rate of aggregate weight to erosion threshold is quantified.
FRONTIERS IN MARINE SCIENCE
(2022)
Article
Geology
Megan L. L. Baker, Jaco H. H. Baas
Summary: Sediment gravity flows with clay are complex and hard to predict. Adding very fine sand can either increase or decrease the mobility of the flows, depending on the balance between turbulent and cohesive forces. The contribution of very fine sand to the cohesive strength of dense clay flows has important implications for flow transformation on submarine fans.
Article
Environmental Sciences
Reza Farshad, Seyed Mahmood Kashefipour, Mehdi Ghomeshi, Giuseppe Oliveto
Summary: This study investigates the maximum scour depth at permeable and angled spur dikes under hydrographs of different duration. The results show that the permeability of the spur dike significantly attenuates the scouring processes compared to impermeable spur dikes, and its effect is generally more beneficial than that of a favorable orientation angle. The study also explores the impact of the hydrograph base-time on the scour depth.
Article
Environmental Sciences
Dake Chen, Jinhai Zheng, Chi Zhang, Dawei Guan, Yuan Li, Yigang Wang
Summary: The study investigates the erosion threshold of sand-mud mixtures by analyzing the momentum balance of particles in the bed surface, and develops a formula for the critical shear stress that also applies to pure sand and mud. The variation in critical shear stress over mud content is attributed to the varying dry bulk density of the mud component in the mixture. The developed formula accurately predicts the critical shear stress of sand-mud mixtures and pure mud during consolidation, offering a convenient application by relating critical shear stress to mud content and dry bulk density.
FRONTIERS IN MARINE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Cesar L. Usma, Sandrine Mariot, Claire Goldmann, Matthieu Roche, Anniina Salonen, Guillaume Tresset
Summary: This study reports on a fluorescent surfactant that allows for the monitoring of Marangoni flows without the need for invasive tracers. The Marangoni zone is clearly visible and its dynamics can be quantitatively probed. In addition, recirculation flows near the bottom of the container are evidenced by fluorescence.
Article
Environmental Sciences
Zelin Cheng, Hua Xu, Yunfeng Xia, Fumin Xu
Summary: This study analyzed the dynamics of sediment resuspension in severely eutrophic Lake Chaohu, China, and found that bed shear stress is closely related to sediment resuspension. The vertical gradient of suspended sediment concentration significantly increases during sediment resuspension events.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Mechanics
Chen Wang, Andrew Gilbert, Joanne Mason
Summary: This paper investigates the instability of shallow-water shear flow with a sheared parallel magnetic field. The study solves the problem of instability in the critical layer and explains the mechanism of instability using the conservation of momentum. It also determines how the magnetic field modifies the purely hydrodynamic stability criterion and analyzes the role of the curvature of the magnetic field profile in the instability.
JOURNAL OF FLUID MECHANICS
(2022)