scholarly journals Laboratory flume experiments on the formation of spanwise large wood accumulations Part I: Effect on backwater rise

2019 ◽  
Author(s):  
I. Schalko ◽  
C. Lageder ◽  
L. Schmocker ◽  
V. Weitbrecht ◽  
R.M. Boes
Keyword(s):  
Large Wood ◽  
Flume Experiments ◽  
Laboratory Flume

scholarly journals Laboratory Flume Experiments on the Formation of Spanwise Large Wood Accumulations: Part II-Effect on local scour

2019 ◽  
Vol 55 (6) ◽  
pp. 4871-4885 ◽  
Author(s):  
I. Schalko ◽  
C. Lageder ◽  
L. Schmocker ◽  
V. Weitbrecht ◽  
R. M. Boes
Keyword(s):  
Local Scour ◽  
Large Wood ◽  
Flume Experiments ◽  
Laboratory Flume

Debris flow impact on a flexible barrier: laboratory flume experiments and force-based mechanical model validation

2021 ◽  
Vol 106 (1) ◽  
pp. 735-756
Author(s):  
R. Brighenti ◽  
L. Spaggiari ◽  
A. Segalini ◽  
R. Savi ◽  
G. Capparelli
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Mechanical Model ◽  
Flume Experiments ◽  
Flexible Barrier ◽  
Laboratory Flume

scholarly journals Flume Experiments Evaluating the Efficacy of a Large Wood Trap Featuring Horizontal Rods

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1837
Author(s):  
Mayuko Furukawa ◽  
Daizo Tsutsumi ◽  
Hironori Muto ◽  
Taro Uchida ◽  
Takuro Suzuki ◽  
...  
Keyword(s):  
Relative Length ◽  
Large Wood ◽  
Basic Information ◽  
Trapping Rate ◽  
Supply Rate ◽  
Flume Experiments ◽  
Water And Sediment ◽  
Constant Rate

Large wood (LW) disasters, which often accompany sediment-related disasters, occur worldwide. To prevent and mitigate such disasters, we developed a unique LW trap featuring horizontal rods aligned with the flow. When LW enters the trap, it is scooped up by the rods and thus separated from water and sediment. We explored trapping efficacy using a flume of slope 0.087. Water circulated at a constant rate of 1.8 L/s, LW was added to the flow, and the trapping rates were measured. We focused on the relative wood length (Lw) with respect to the horizontal rod spacing (Sr), the number of LW units supplied, and the supply rate. A longer relative length (Lw/Sr) of LW was associated with a higher trapping rate. The trapping rate was also high when the LW number or supply rate was high. The critical Lw/Sr value was 1.5; below this value, LW was not trapped. This study yields the basic information needed to design traps featuring horizontal rods to mitigate LW-related disasters.

scholarly journals Flume experiments on vegetated alternate bars

2018 ◽  
Vol 40 ◽  
pp. 02034 ◽  
Author(s):  
Giulio Calvani ◽  
Simona Francalanci ◽  
Luca Solari
Keyword(s):  
Hydrological Regime ◽  
Spatial Arrangement ◽  
Flume Experiments ◽  
Rigid Vegetation ◽  
Hydraulic Conditions ◽  
Laboratory Flume ◽  
Alternate Bars ◽  
River Reach ◽  
Bed Slope ◽  
And Migration

The planform morphology of a river reach is the result of the combined actions of sediment motion (erosion, transport and deposition), hydrological regime, development and growth of vegetation. However, the interactions among these processes are still poorly understood and rarely investigated in laboratory flume experiments. In these experiments and also in numerical modelling, vegetation is usually represented by rigid cylinders, although it is widely recognized that this schematization cannot reproduce the effects of root stabilization and binding on riverbed sediment. In this work, we focus on the effects of added vegetation on morphological dynamics of alternate bars in a straight channel by means of flume experiments. We performed laboratory experiments reproducing hydraulic conditions that are typical of gravel bed rivers, in terms of water depth, bed slope and bed load; these conditions led to the formation of freely migrating alternate bars. We then employed rigid vegetation that was deployed on the reproduced alternate bars according to field observations. Various vegetation scenarios, in terms of density and spatial arrangement, were deployed in the flume experiments such to mimic different maintenance strategies. Results show the effects of rigid vegetation on the alternate bar configuration on the overall topographic pattern, the main alternate bar characteristics (such as amplitude and wavelength) and migration rate.

Flume experiments on the geomorphic effects of large wood in gravel-bed rivers

2020 ◽  
pp. 1609-1615
Author(s):  
D. Ravazzolo ◽  
G. Spreitzer ◽  
H. Friedrich ◽  
J. Tunnicliffe
Keyword(s):  
Large Wood ◽  
Flume Experiments ◽  
Gravel Bed ◽  
Gravel Bed Rivers

scholarly journals Evaluating a Laboratory Flume Microbiome as a Window Into Natural Riverbed Biogeochemistry

2021 ◽  
Vol 3 ◽  
Author(s):  
Matthew H. Kaufman ◽  
John G. Warden ◽  
M. Bayani Cardenas ◽  
James C. Stegen ◽  
Emily B. Graham ◽  
...  
Keyword(s):  
16S Rrna Gene Sequencing ◽  
Spatiotemporal Variability ◽  
Rrna Gene ◽  
Natural Ecosystems ◽  
Flume Experiments ◽  
Riverbed Sediments ◽  
Laboratory Flume ◽  
Curtis Dissimilarity ◽  
The Common ◽  
Rrna Gene Sequencing

Riverbeds are hotspots for microbially-mediated reactions that exhibit pronounced variability in space and time. It is challenging to resolve biogeochemical mechanisms in natural riverbeds, as uncontrolled settings complicate data collection and interpretation. To overcome these challenges, laboratory flumes are often used as proxies for natural riverbed systems. Flumes capture spatiotemporal variability and thus allow for controlled investigations of riverbed biogeochemistry. These investigations implicitly rely on the assumption that the flume microbiome is similar to the microbiome of natural riverbeds. However, this assumption has not been tested and it is unknown how the microbiome of a flume compares to natural aquatic settings, including riverbeds. To evaluate the fundamental assumption that a flume hosts a microbiome similar to natural riverbed systems, we used 16s rRNA gene sequencing and publicly available data to compare the sediment microbiome of a single large laboratory flume to a wide variety of natural ecosystems including lake and marine sediments, river, lake, hyporheic, soil, and marine water, and bank and wetland soils. Richness and Shannon diversity metrics, analyses of variance, Bray-Curtis dissimilarity, and analysis of the common microbiomes between flume and river sediment all indicated that the flume microbiome more closely resembled natural riverbed sediments than other ecosystems, supporting the use of flume experiments for investigating natural microbially-mediated biogeochemical processes in riverbeds.

Longitudinal Hillslope Shape Effects on Runoff and Sediment Loss: Laboratory Flume Experiments

2018 ◽  
Vol 144 (2) ◽  
pp. 04017097 ◽  
Author(s):  
João L. M. P. de Lima ◽  
Jorge M. G. P. Isidoro ◽  
M. Isabel P. de Lima ◽  
Vijay P. Singh
Keyword(s):  
Flume Experiments ◽  
Sediment Loss ◽  
Laboratory Flume ◽  
Shape Effects

scholarly journals Observing and modeling bedload sediment transport at the grain-scale

2020 ◽  
Author(s):  
Eric Deal ◽  
Taylor Perron ◽  
Jeremy Venditti ◽  
Qiong Zhang ◽  
Santiago Benavides ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Particle Tracking ◽  
High Speed ◽  
Flume Experiments ◽  
Physical Mechanisms ◽  
Glass Spheres ◽  
Granular Dynamics ◽  
Image Velocimetry ◽  
Laboratory Flume ◽  
Bedload Sediment

<p>Empirical sediment transport models have common characteristics suggestive of the underlying physics, but mechanistic explanations for these characteristics are lacking due to an incomplete understanding of the fundamental physical mechanisms involved. Hydrodynamic interactions at the grain-scale are thought to be key, however, it is a major challenge to either observe or model these processes. In order to improve our understanding of grain-scale dynamics in sediment entrainment and transport we are studying the detailed mechanics of fluid-grain interactions using a combination of laboratory flume experiments, advanced numerical simulations, and granular mechanics theory. </p><p>The flume experiments are conducted with an emphasis on exploring differences and similarities in the behaviour of glass spheres, a common theoretical tool, to naturally sourced river gravel. Using high-speed cameras coupled with computer-vision based particle tracking, we tracked the majority of grains in the grain bed and water column, with 130,000 glass sphere track paths longer than 10 particle diameters. In particular, we introduce a newly developed a machine learning based particle tracking of the natural grains, with 30,000 gravel track paths longer than 10 mean particle diameters. Fluid flow fields are also observed using particle image velocimetry (PIV). We present the comparison of our detailed observations of granular dynamics between spheres and natural gravel, with a focus on how grain shape impacts fluid-grain and grain-grain interactions.</p><p>Using a discrete-element plus Lattice-Boltzmann fluid method (LBM-DEM) we simulate a small portion of the laboratory flume with high temporal and spatial resolution. This method tracks discrete particles interacting with each other through contact laws while mechanically coupled to a dynamic interstitial fluid. We discuss the ability of our simulations to emulate our experiments, the benefits of which are twofold. First, where the simulations work well, we use them to observe grain-scale dynamics that would be difficult or impossible to measure in a laboratory setting or in the field. Second, we learn from situations in which the experiments and simulations diverge, leading to improvements in both the simulations and our understanding of how fluid-grain interactions influence sediment transport.</p>

scholarly journals Hazards due to large wood accumulations: Local scour and backwater rise

2018 ◽  
Vol 40 ◽  
pp. 02003 ◽  
Author(s):  
Isabella Schalko ◽  
Lukas Schmocker ◽  
Volker Weitbrecht ◽  
Robert M. Boes
Keyword(s):  
Shear Stress ◽  
Flood Hazard ◽  
Local Scour ◽  
Bridge Piers ◽  
Bed Shear Stress ◽  
Large Wood ◽  
Flume Experiments ◽  
Governing Parameter ◽  
Bed Material ◽  
Movable Bed

Large wood (LW) in rivers increases the flow variability and provides habitats for various species. During flood events, transported logs can accumulate at river infrastructures and increase the flood hazard. LW accumulations result in an upstream backwater rise and may increase local scour, for instance at bridge piers. Consequently, estimates of the resulting backwater rise and local scour are necessary to improve the flood hazard assessment. This study presents the findings of flume experiments with a movable bed on local scour and backwater rise due to LW accumulations. The approach flow conditions and the bed material were varied systematically for a specific LW accumulation volume. For all experiments, the initial condition for the bed material was defined as weak transport, since the bed shear stress was slightly below the critical bed shear stress for incipient motion. The inflow Froude number was identified as the governing parameter for backwater rise due to LW accumulations. The present study confirms the hypothesis that the resulting local scour reduces backwater rise. For the local scour, the unit discharge and the grain size diameter are the decisive parameters.

Transport of adsorbing metals from stream water to a stationary sand-bed in a laboratory flume

1995 ◽  
Vol 46 (1) ◽  
pp. 209 ◽  
Author(s):  
H Eylers ◽  
NH Brooks ◽  
JJ Morgan
Keyword(s):  
Metal Ions ◽  
Stream Water ◽  
Flow Conditions ◽  
Advective Flow ◽  
Flume Experiments ◽  
Lithium Ions ◽  
Overlying Water ◽  
Experimental Conditions ◽  
Sediment Bed ◽  
Laboratory Flume

The transport of zinc and lithium ions between the overlying water column and the stationary sand-bed in a laboratory flume with bottom bedforms is investigated. Experiments have been performed under simplified conditions in a recirculating laboratory flume with straight impermeable walls and a sand-bed. The sand is well sorted and acid-washed to provide reproducible experimental conditions. The chemical composition of the recirculating water is controlled and steady flow conditions are maintained in the experiments. The concentrations of initially added metal ions are monitored both in the circulating overlying water and in the pore water of the sediment bed. Batch experiments were performed to investigate the chemical partitioning of the metal ions to the sand grain surfaces, and the data were compared with adsorption values obtained from the flume experiments. A model based on pressure-driven advective flow and linear partitioning of the pollutant to the sediment has been developed and accurately predicts the rate of transfer of the metal ions (zinc and lithium) into the bed in the case of stationary bedforms.

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