Article
Environmental Sciences
Nargess Moghaddassi, Seyed Habib Musavi-Jahromi, Mohammad Vaghefi, Amir Khosrojerdi
Summary: The study shows that changing the mean velocity-to-critical velocity ratio significantly affects the maximum scour depth and sedimentary height at the downstream bend of a meandering channel. Additionally, incipient motion occurs at the upstream and downstream bends under different ratio conditions.
Article
Engineering, Environmental
Koray Deniz Goral, Hasan Gokhan Guler, Bjarke Eltard Larsen, Stefan Carstensen, Erik Damgaard Christensen, Nils B. B. Kerpen, Torsten Schlurmann, David R. R. Fuhrman
Summary: This research demonstrates that the Shields diagram is applicable for predicting incipient motion thresholds of both native sediments and microplastic particles. The study investigates various regular and irregular microplastic particle groups in a flume and combines data from the literature for analysis. A new framework is proposed to account for the effects of static friction, hydraulic roughness, and hiding-exposure on predicting incipient motion conditions for foreign particles, reconciling them with the Shields diagram.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Environmental Sciences
Sanaz Hadian, Hossein Afzalimehr, Jueyi Sui
Summary: This experimental study investigates the characteristics of turbulent flow in channels with vegetated banks and varying channel width under the incipient motion of bed material. The results show that streamwise velocities have maximum and minimum values at the narrowest and widest sections, respectively. Secondary currents cause the maximum velocity to occur below the water surface when the aspect ratio is less than 5. Vegetation on the channel sidewalls leads to a Z-shaped profile of Reynolds shear stress. By increasing the channel bed slope, near-bed parameters decrease, indicating the dominance of gravity effects over pressure gradient effects. The Shields method is ineffective for assessing the incipient motion of bed material in channels with varying width and vegetation on the sidewalls.
Article
Engineering, Civil
Nian-Sheng Cheng, Puer Xu, Yesheng Lu, Maoxing Wei
Summary: This study validates Bagnold's approximation in his bedload formula by comparing the critical near-bed flow velocity and the particle settling velocity.
JOURNAL OF HYDRAULIC ENGINEERING
(2022)
Article
Engineering, Ocean
Hualing Zhai, Dong-Sheng Jeng, Zhen Guo, Titi Sui
Summary: This study investigates the impact of three-dimensional seepage on sediment incipient motion in coastal environments, introducing a new modified coefficient (R) to represent this impact. The results show that horizontal seepage significantly affects hydrodynamic characteristics and sediment incipient motion beside the pile, but can be ignored at positions before and behind the pile.
APPLIED OCEAN RESEARCH
(2021)
Article
Mechanics
Xiang Wang, Shuolin Li, Zhong-hua Yang, Wen-xin Huai
Summary: This study aims to quantify the critical conditions of sediment particle movement in open-channel flows with vegetation. By proposing a new formula for critical flow velocity and validating it through experiments, it was found that the critical flow velocity can effectively quantify this movement.
JOURNAL OF HYDRODYNAMICS
(2022)
Article
Environmental Sciences
Khabat Khosravi, Amir H. N. Chegini, Luca Mao, Jose F. Rodriguez, Patricia M. Saco, Andrew D. Binns
Summary: The study found that angular sediments have a higher critical shear velocity than rounded sediments for incipient motion. It also showed that although critical shield stress and relative roughness increased with bed slope, the particle Froude number decreased. Furthermore, graded sediments had a higher critical shear stress compared to finer uniform sediments, with finer fractions of the mixture having a higher particle Froude number but coarser fractions showing lower stability.
Article
Mathematics
Kaixiang Shen, Zhenqiang Xu, Guoshuai Ju, Yingsheng Wang, Zijian Li
Summary: This study investigates the incipient motion law of particles on the surface of a cuttings bed when the drilling fluid resumes circulation, aiming to improve hole-cleaning efficiency. It analyzes the effects of well inclination angle, cuttings size, and density on the critical velocity of particle motion. An analytical formula and a critical velocity model are derived based on stress analysis and boundary layer flow. The study has important implications for drilling operations and cuttings transport management.
Article
Multidisciplinary Sciences
Xingyu Yuan, Fei Ye, Wenxi Fu, Lina Wen
Summary: The critical shear stress is a key indicator for soil erosion. This study proposes an equation based on the force equilibrium of a single particle to estimate the critical shear stress for incipient particle motion of a cohesive soil slope. The influence of different parameters on the critical shear stress is analyzed through validation and comparison of different formulas.
SCIENTIFIC REPORTS
(2022)
Article
Environmental Sciences
Mahsa Ghazian Arabi, Ali Farhadzadeh
Summary: Laboratory flume experiments were conducted to investigate the effects of soil characteristics on the critical shear stress of low fines content soil samples from the Montauk shores in New York. The results showed that the critical shear stress increases with fines content and effective cohesion, and soils with optimum initial water content exhibited higher erosion resistance. The influence of fines content on the critical shear stress was overshadowed by higher relative density, and denser soils compacted at optimum initial water content showed the highest resistance against erosion.
INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH
(2022)
Article
Geography, Physical
Chenge An, Marwan A. Hassan, Carles Ferrer-Boix, Xudong Fu
Summary: Results from experiments show that conditioning flow can reduce sediment transport rate during subsequent floods, but this effect is limited to a relatively short time at the beginning of the flood event. The stress history effect induced by bed reorganization during conditioning phase is likely to be erased with increasing flow and sediment transport intensity during the subsequent flood event.
EARTH SURFACE DYNAMICS
(2021)
Article
Engineering, Civil
Wan Hanna Melini Wan Mohtar, Charles Hin Joo Bong, Aminuddin Ab Ghani, Mir Jafar Sadegh Safari, Aizat Mohd Taib, Haitham Abdulmohsin Afan, Ahmed EL-SHAFIE
Summary: This paper analyzes experimental data on sediment incipient motion with varying sediment bed thickness and evaluates the effect of deposited bed. It is found that higher critical mean velocity is needed for shallower deposits.
Article
Engineering, Geological
Hussein Bizimana, Abdusselam Altunkaynak
Summary: This study evaluates the impact of different bed roughness on the comprehension of bedforms in rectangular and circular cross-sectional rigid boundary channels, as well as the resistance against flow and critical conditions of sediment motion. The novel hybrid GENOFIS approach outperformed ANFIS and linear regression models, providing a new data-driven solution for complex incipient motion problems.
GEOTECHNICAL AND GEOLOGICAL ENGINEERING
(2021)
Article
Geosciences, Multidisciplinary
Scott A. Feehan, Scott W. Mccoy, Joel S. Scheingross, Michael H. Gardner
Summary: Predicting thresholds of sediment motion is crucial for sediment transport applications, but they can vary significantly for a single flow and bed configuration. This study quantifies the variability in incipient-motion thresholds using a grain-scale force-balance model and shows that it is mainly influenced by the lift coefficient and grain protrusion, with secondary effects from the drag coefficient. The mean threshold of motion and its variability can be predicted using power laws, and these laws can be adjusted with site-specific parameter distributions for applications on different planetary bodies.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Engineering, Marine
Hualing Zhai, Dong-Sheng Jeng, Zhen Guo
Summary: This study examines the key factor of seabed instability - sediment incipient motion in offshore pipeline projects, including a modification of the conventional Shields number with consideration of two-dimensional seepage. The results show that horizontal seepage flow around the pipeline has a significant impact on sediment motion in both flat and sloping seabeds, especially in cases of large waves, shallow water, seabeds with large shear modulus and permeability, and pipelines with larger diameter and smaller flow gap ratios.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2021)
Article
Geosciences, Multidisciplinary
S. Naqshband, D. Hurther, S. Giri, R. W. Bradley, R. A. Kostaschuk, J. G. Venditti, A. J. F. Hoitink
Summary: The research found that the slipface angle of dunes adjusts to the imposed flow at similar time scales as the evolution of dune height and length. Flow separation intensifies through scour, accelerating dune growth, and gradients in sediment transport and dune growth rates are inherently linked to spatial variations in slipface angles.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2021)
Article
Geography, Physical
Morgan Wright, Jeremy G. Venditti, Tingan Li, Max Hurson, Shawn Chartrand, Colin Rennie, Michael Church
Summary: The width and depth of rivers are generally inversely related, with the highest correlation between these two variables in alluvial channels. In bedrock-bound canyons, there is substantial variation in the relation between width and depth.
EARTH SURFACE PROCESSES AND LANDFORMS
(2022)
Article
Geosciences, Multidisciplinary
Lekui Zhu, Dong Chen, Marwan A. Hassan, Jeremy G. Venditti
Summary: The stability of meandering rivers in floodplains is influenced by the type of vegetation present. Meanders developed in rainforests are the most stable due to their established root systems and clay-rich soils. On the other hand, meanders in cropland areas are the most unstable due to the lack of vegetation cover and frequent land disturbances associated with cultivation. Meanders in grasslands and North American forests have intermediate migration rates, with grassland meanders showing lower migration rates possibly due to higher sinuosity, lower gradients, and layered banks.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Santiago J. Benavides, Eric Deal, Matthew Rushlow, Jeremy G. Venditti, Qiong Zhang, Ken Kamrin, J. Taylor Perron
Summary: The study discusses how sediment transport near the threshold of grain motion is influenced by rare transport events, making it difficult to calibrate sediment transport laws and define a clear threshold for grain entrainment. The research presents a model to capture this intermittency and utilize noisy statistics of sediment transport to predict the sediment entrainment threshold and fluid stress variations. The findings suggest strategies for improving measurements and predictions of sediment flux and hint at potential changes in the sediment transport law near the threshold of motion.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Tingan Li, Jeremy G. Venditti, Colin D. Rennie, Peter A. Nelson
Summary: Approximating the stresses on the bed and walls of confined, narrow bedrock rivers is crucial for accurately understanding hydraulic roughness, sediment transport, bedrock erosion, and the dynamics of bedrock channels. Through the use of the ray-isovel model (RIM) and field observations, this study found that the distribution of shear stress across an idealized trapezoidal channel is influenced by the angle of the river banks and the width-to-depth ratio. The study also revealed that the complex flow structure in bedrock canyons affects the distribution of bed and wall stresses, with the bedrock walls contributing more hydraulic roughness than predicted by the RIM model.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Geosciences, Multidisciplinary
Zhihao (Eric) Cao, Jeremy G. Venditti, Tingan Li
Summary: The morphology of rivers cutting into rock and the interaction between flow and sediment in this process have been studied. It has been found that lateral constrictions in rock-bound rivers lead to plunging flows and the formation of pools. The primary pool formed at the canyon entrance reaches equilibrium morphology by cutting a slot, which is deep enough to maintain a permanent alluvial cover. Downstream of the primary pool, intermittent alluvial covers develop, causing flow to plunge and carving secondary pools. The near-bed velocity is strongly correlated with alluviation patterns and erosion rate, suggesting it may be a practical way to calculate rock erosion rates in non-uniform flows.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Geosciences, Multidisciplinary
Qiong Zhang, Eric Deal, J. Taylor Perron, Jeremy G. Venditti, Santiago J. Benavides, Matthew Rushlow, Ken Kamrin
Summary: Bedload sediment transport plays a crucial role in shaping landscapes, but the relationship between sediment flux and driving factors is not well understood. In this study, the researchers experimentally validated a numerical scheme and explored the parameter space controlling sediment transport. The results showed that the dimensionless transport rate is not influenced by several factors for gentle slopes at a medium to high fixed Shields number. The study also highlighted the significance of fluid torque near the threshold in sediment transport.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Geosciences, Multidisciplinary
Debsmita Das, Vamsi Ganti, Ryan Bradley, Jeremy Venditti, Arjan Reesink, Daniel R. Parsons
Summary: Fluvial cross strata are depositional products that record the formative flow and sediment transport conditions on planetary bodies. The study found that the evolution of bedforms and the thickness of preserved sets have a parabolic dependence on transport stage, with maximum values observed at intermediate transport stages. The results suggest that transport stage is a key control on the flow-depth-normalized set thickness.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
Eric Deal, Jeremy G. Venditti, Santiago J. Benavides, Ryan Bradley, Qiong Zhang, Ken Kamrin, J. Taylor Perron
Summary: Bed load sediment transport is a critically important mechanism in various contexts, but predictions of sediment flux are often imprecise. While many studies have focused on grain size variability as a source of uncertainty, the role of grain shape, which can influence transport rates, has been less investigated. This study shows that grain shape can significantly modify bed load transport rates, and proposes a shape-corrected sediment transport law. The findings improve predictions of sediment transport and reconcile theories developed for spherical particles with natural sediment grains.
Article
Geosciences, Multidisciplinary
Santiago J. Benavides, Eric Deal, Jeremy G. Venditti, Ryan Bradley, Qiong Zhang, Ken Kamrin, J. Taylor Perron
Summary: Near the threshold of grain motion, sediment transport is intermittent, with rare bursts and long periods of low transport. The origin of intermittency is found in the velocity distributions of rolling grains, rather than the activity of grains. Incorporating this type of intermittency into sediment transport models can lead to improved predictions of sediment flux.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
D. W. Haught, J. G. Venditti
Summary: Measurement of sediment in large rivers is difficult and expensive, but crucial for managing these systems in the face of climate change and rising sea levels. Acoustic methods are used to estimate suspended sediment, and a sediment-index methodology is presented and assessed for the Lower Fraser River.
WATER RESOURCES RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Tingan Li, Jeremy G. Venditti, Leonard S. Sklar, Michael P. Lamb
Summary: We developed a mechanistic model to study the erosion process of bedrock channel banks. The model predicts high erosion rates near the bed, decreasing towards the water surface. It also suggests that erosion within the suspended load layer is greater than the bedload layer under typical sediment supply and transport conditions. Comparison with a previously derived model shows that the rates predicted by our model are generally higher, except for limited conditions where sediment is close to the threshold of motion and the bed is fully covered in sediment. Both advection-abrasion and deflection-abrasion processes occur in bedrock rivers simultaneously, and the resulting combined-abrasion model indicates that lateral erosion rates increase with transport stage and relative sediment supply.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Geography, Physical
Michael Curran, Aaron T. Steelquist, Jeff Larimer, Erin Seagren, Tingan Li, Derek Heathfield, Brian Menounos, John J. Clague, Michael Church, Jeremy G. Venditti
Summary: This study investigates the alignment of the Fraser River in southwestern British Columbia with specific faults within the Fraser River Fault zone. The results show that the regional alignment of the river is controlled by the main fault, while individual canyons align with subsidiary faults. It is suggested that canyons deviating from faults were formed due to large sediment inputs, creating epigenetic canyons. Overall, the river orientations in the Fraser River Fault zone are influenced by both main and subsidiary fault structures.
EARTH SURFACE PROCESSES AND LANDFORMS
(2023)
Article
Geosciences, Multidisciplinary
Elizabeth H. Dingle, Jeremy G. Venditti
Summary: River bed sediments often lack fine gravel between 1 and 5 mm, a phenomenon referred to as the grain size gap. This study investigated the behavior of grain size gap material during the gravel-sand transition. It was found that the presence of sand deposition enhanced the mobility of gap gravel, suggesting that gap particles may be transported to other environments.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Environmental Sciences
A. M. Anderson, D. M. Allen, J. G. Venditti
Summary: The amount of fresh water in coastal deltas is controlled by subsurface structures. This study explores the range of subsurface permeability and hydraulic gradient in three types of deltas (fluvial, wave, and tidal) using morphodynamic models. The results show that deltaic landforms have a median permeability of 4.0 x 10-12 m2, an average hydraulic gradient of 3.9 x 10-4, and a mean specific discharge of 1.3 x 10-8 m/s. The study also finds that high permeability bodies are associated with channelization and that morphodynamic influences and geomorphic characteristics have a significant impact on the subsurface permeability and connectivity.
WATER RESOURCES RESEARCH
(2023)