Development and Validation of GSTAR-M, Generalized Sediment Transport for Alluvial Rivers - Meandering Rivers

2007 ◽  
Author(s):  
Jianchun Huang ◽  
Blair P. Greimann ◽  
Timothy J. Randle
Keyword(s):  
Sediment Transport ◽  
Meandering Rivers ◽  
Alluvial Rivers ◽  
Development And Validation

Self-organisation of morphology and sediment transport in alluvial rivers

2020 ◽  
Author(s):  
Eric Lajeunesse ◽  
Anais Abramian ◽  
Olivier Devauchelle
Keyword(s):  
Sediment Transport ◽  
Equilibrium Shape ◽  
Boltzmann Distribution ◽  
Physical Review ◽  
Bedload Transport ◽  
Sediment Flux ◽  
Sediment Discharge ◽  
Alluvial Rivers ◽  
Braided Rivers ◽  
Streamwise Streaks

<div> <div> <div> <p>The coupling of sediment transport with the flow that drives it shapes the bed of alluvial rivers. The channel steers the flow, which in turns deforms the bed through erosion and sedimentation. To investigate this process, we produce a small river in a laboratory experiment by pouring a viscous fluid on a layer of plastic sediment. This laminar river gradually reaches its equilibrium shape. In the absence of sediment transport, the combination of gravity and flow-induced stress maintains the bed surface at the threshold of motion (Seizilles et al., 2013). If we impose a sediment discharge, the river widens and shallows to accommodate this input. Particle tracking reveals that the grains entrained by the flow behave as random walkers. Accordingly, they diffuse towards the less active areas of the bed (Seizilles et al., 2014). The river then adjusts its shape to maintain the balance between this diffusive flux, which pushes the grains towards the banks, and gravity, which pulls them towards the center of the channel. This dynamical equilibrium results in a peculiar Boltzmann distribution, in which the local sediment flux decreases exponentially with the elevation of the bed (Abramian et al., 2019). As the sediment discharge increases, the channel gets wider and shallower. Eventually, it destabilizes into multiple channels. A linear stability analysis suggests that it is diffusion that causes this instability, which could explain the formation of braided rivers (Abramian, Devauchelle, and Lajeunesse, 2019).</p> </div> </div> </div><p> </p><p>References:</p><ul><li>Abramian, A., Devauchelle, O., and Lajeunesse, E., “Streamwise streaks induced by bedload diffusion,” Journal of Fluid Mechanics 863, 601–619 (2019).</li> <li>Abramian, A., Devauchelle, O., Seizilles, G., and Lajeunesse, E., “Boltzmann distribution of sediment transport,” Physical review letters 123, 014501 (2019).</li> <li>Seizilles, G., Devauchelle, O., Lajeunesse, E., and M ́etivier, F., “Width of laminar laboratory rivers,” Phys. Rev. E. 87, 052204 (2013).</li> <li> <p>Seizilles, G., Lajeunesse, E., Devauchelle, O., and Bak, M., “Cross-stream diffusion in bedload transport,” Phys. of Fluids 26, 013302 (2014).</p> </li> </ul>

Analysis of geometric relationships of bedrock and alluvial channels: a comparison between rivers from the Scottish Highlands and San Gabriel Mountains (USA)

2021 ◽  
Author(s):  
Mel O. Guirro ◽  
Rebecca A. Hodge ◽  
Fiona Clubb ◽  
Laura Turnbull
Keyword(s):  
Sediment Transport ◽  
Transport Processes ◽  
Sediment Supply ◽  
Spatial Distributions ◽  
Alluvial Channels ◽  
Transport Capacity ◽  
Alluvial Rivers ◽  
Bedrock Rivers ◽  
San Gabriel Mountains ◽  
Scottish Highlands

<p>Sediment transport in rivers depends on interactions between sediment supply, topography, and flow characteristics. Erosion in bedrock rivers controls topography and is paramount in landscape evolution models. The riverbed cover indicates sediment transport processes: alluvial cover indicates low transport capacity or high sediment supply, and bedrock cover demonstrates high transport capacity or low sediment supply. This study aims to evaluate controls on the spatial distributions of bedrock and alluvial covers, by analysing scaling geometric relations between bedrock and alluvial channels. A Principal Component Analysis (PCA) was conducted to evaluate correlations between river slope, depth, width, and sediment size. The two principal components were used to implement a clustering analysis in order to identify differences in alluvial and bedrock sections. Spatial distributions of mixed bedrock-alluvial sections were investigated from two datasets - Scottish Highlands (Whitbread 2015) and the San Gabriel Mountains in the USA (Dibiase 2011)-, representing different environmental conditions, such as erosion rates, lithology, tectonics, and climate. The rock strength of both areas is high, and therefore it is excluded as a factor that explains the difference between the areas. The results of the cluster analysis were different in each environment. The main sources of variation among river sections identified by PCA were slope and width for the San Gabriel Mountains, and drainage area and depth for the Scottish Highlands. The rivers in the Scottish Highlands formed clusters that differentiate bedrock and alluvial patches, showing a clear geometric distinction between channels. However, the river analysis from the San Gabriel Mountains showed no clusters. Bedrock rivers are typically described as narrower and steeper than alluvial rivers, as demonstrated by rivers in the Scottish Highlands (e.g. slope was around 0.1 m/m for bedrock sections and 0.01 m/m for alluvial sections). However, this may not be always the case: both bedrock and alluvial sections in San Gabriel Mountains presented similar slope around 0.1 m/m. The inability to demonstrate significant geometry differences in bedrock and alluvial sections in the San Gabriel Mountains may be due to the frequency and magnitude of sediment supply of that region, which are influenced by tectonics and climate. A major difference in the supply of sediment in rivers of the San Gabriel Mountains is the frequent occurrence of debris flow. Non-linear interactions between hydraulic and sediment processes may constantly modify the geometry of bedrock-alluvial channels, increasing the complexity of analysis at larger temporal and spatial scales. This study is part of the i-CONN project, which links connectivity in different scientific disciplines. A sediment connectivity assessment in different environments and scales may be useful to evaluate the controls on the spatial distribution of bedrock and alluvial rivers.</p><p> </p><p>Dibiase, R.A. 2011. Tectonic Geomorphology of the San Gabriel Mountains, CA. PhD Thesis. Arizona State University, Phoenix, 247pp.</p><p>Whitbread, K. 2015. Channel geometry data set for the northwest Scottish Highlands. British Geological Survey Open Report, OR/15/040. 12pp.</p>

scholarly journals Laboratory observations on meltwater meandering rivulets on ice

2021 ◽  
Vol 9 (2) ◽  
pp. 253-269
Author(s):  
Roberto Fernández ◽  
Gary Parker
Keyword(s):  
Surface Tension ◽  
Laminar Flow ◽  
Flow Velocity ◽  
Flow Regime ◽  
Lateral Migration ◽  
Meandering Rivers ◽  
Alluvial Rivers ◽  
Meandering Channels ◽  
Lateral Incision ◽  
Formation And Evolution

Abstract. We present a set of observations on meltwater meandering rivulets on ice and compare them (qualitatively and quantitatively) to morphologies commonly found in meandering channels in different media. The observations include data from planned centimeter-scale experiments and from incidental self-formed millimeter-scale rivulets. Our data show pulsed lateral migration features, undercut banks and overhangs, meander bend skewness, and meander bend cutoffs. The data also compare well with planform characteristics of alluvial meandering rivers (sinuosity, wavelength-to-width ratios, and meander bend fatness and skewness). We discuss the (ir)relevance of scale in our experiments, which, in spite of being in the laminar flow regime and likely affected by surface tension effects, are capable of shedding light into the processes driving formation and evolution of supraglacial meltwater meandering channels. Our observations suggest that sinuosity growth in meltwater meandering channels on ice is a function of flow velocity and the interplay between vertical and lateral incision driven by temperature differences between flow and ice. In the absence of recrystallization (depositional analog to alluvial rivers), bends are more likely to be downstream-skewed and channels show lower sinuosities.

scholarly journals A Modified Sediment Transport Model for Natural Streams

1982 ◽  
Vol 13 (2) ◽  
pp. 79-92
Author(s):  
Thorkild Thomsen
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Alluvial Rivers ◽  
Sediment Transport Model ◽  
Tracer Particles ◽  
Natural Streams ◽  
Load Transport ◽  
Bed Load Transport ◽  
Particle Velocities

In an earlier investigation of the behaviour of tracer particles for determination of bed load transport in an alluvial stream (Thomsen 1980), specific records were taken of the particle velocities in the upper bed layer. These data aroused the interest for more detailed investigations. The result of the measured surface particle velocities with radioactive tracers, performed in five locatities with different hydraulic conditions in natural alluvial rivers, has been used for determination of the relation UG/Uf'vs. √θ'/θ0. The obtained results have been inserted in the parameters of Engelund and Fredsøe's sediment transport model (1976) and compared with experimental data (Guy et al. 1966). Some reservations and methods for possible improvements of the sediment transport model are finally discussed.

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