International Journal of
Sediment Research
Volume 35, Issue 1
Pages 1-114 (February,
2020)
Numerical simulation of
incipient particle motion
Ali Nasrollahi, Ali Akbar
Salehi Neyshabouri, Goodarz Ahmadi, Masoud Montazeri Namin
Pages 1-14
Two-dimensional numerical
simulation of sediment transport using improved critical shear stress methods
Zhiyong Feng, Guangming
Tan, Junqiang Xia, Caiwen Shu, Peng Chen, Ran Yi
Pages 15-26
Experimental study of
near-bed concentration and sediment vertical mixing parameter for vertical
concentration distribution in the surf zone
Yang Zhang, Zhili Zou,
Wushan Xue, Dapeng Sun
Pages 27-41
Turbulence characteristics
of flow past submerged vanes
Himanshu Sharma,
Zulfequar Ahmad
Pages 42-56
The uncertainty of the
Shannon entropy model for shear stress distribution in circular channels
Amin Kazemian-Kale-Kale,
Hossein Bonakdari, Azadeh Gholami, Bahram Gharabaghi
Pages 57-68
Appraisal of the carbon
to nitrogen (C/N) ratio in the bed sediment of the Betwa River, Peninsular
India
Madavi Venkatesh,
Anshumali
Pages 69-78
Linear spectral unmixing
algorithm for modelling suspended sediment concentration of flash floods, upper
Tekeze River, Ethiopia
Hagos G. Gebreslassie,
Assefa M. Melesse, Kevin Bishop, Azage G. Gebremariam
Pages 79-90
Bioelectricity generation
and remediation of sulfide contaminated tidal flat sediment
M. Azizul Moqsud
Pages 91-96
Regularity of sediment
transport and sedimentation during floods in the lower Yellow River, China
Qingchao Guo, Zhao Zheng,
Liemin Huang, Anjun Deng
Pages 97-104
Measuring the geometry of
a developing scour hole in clear-water conditions using underwater sonar
scanning
Ashley Rogers, Costantino
Manes, Toru Tsuzaki
Pages 105-114
===========================================
Ali Nasrollahi, Ali Akbar
Salehi Neyshabouri, Goodarz Ahmadi, Masoud Montazeri Namin,
Numerical simulation of
incipient particle motion,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages1-14,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.006.
(https://www.sciencedirect.com/science/article/pii/S1001627918303809)
Abstract
A two-dimensional (2D)
computational model for simulation of incipient sediment motion for
non-cohesive uniform and non-uniform particles on a horizontal bed was
developed using the Discrete Element Method (DEM). The model was calibrated and
verified using various experimental data reported in the literature and
compared with different theories of incipient particle motion. Sensitivity
analysis was done and the effects of relevant parameters were determined. In
addition to hydrodynamic forces such as drag, shear lift and Magnus force, the
particle-particle interaction effects were included in the model. The
asymptotic critical mobility number was evaluated for various critical particle
Reynolds numbers (R*) in the range of very small and very large R*. The
obtained curve is classified into four regions. It was found that in the linear
region, the drag force has the principal role on the initiation of motion.
Moreover, the critical mobility number is independent of particle diameter. A
procedure for estimating the critical shear velocity directly from the
information on particle diameter and roughness height was developed. Finally,
the mechanism of incipient motion for the different regions was studied and the
effect of different forces on the incipient particle motion was obtained. It
was found that the maximum effects of lift and Magnus forces were,
respectively, less than ten and twenty percent of the total force. The drag
force, however, was typically the dominant force accounting for majority of the
net hydrodynamic force acting on sediment particles at the onset of incipient
motion.
Keywords
Incipient motion; Shields
curve; Numerical simulation; Drag force; Lift force; Magnus force; Discrete
Element Method
Zhiyong Feng, Guangming
Tan, Junqiang Xia, Caiwen Shu, Peng Chen, Ran Yi,
Two-dimensional numerical
simulation of sediment transport using improved critical shear stress methods,
Volume 35, Issue 1,
2020,
Pages15-26,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.10.003.
(https://www.sciencedirect.com/science/article/pii/S100162791830369X)
Abstract
Research on the critical
shear stresses for erosion and deposition for cohesive sediment has attracted
substantial attention from both engineering and theoretical viewpoints due to
their importance in sediment transport theory. Previous studies have proposed a
large number of empirical and semi-empirical methods to estimate the critical
erosion and deposition shear stress, but comparative analyses and validation of
the existing methods are still lacking, leaving questions regarding the
applicability ranges of the methods. The current paper evaluates the
performance and applicability range of five critical erosion shear stress
methods derived from different hypotheses on sediment transport for flume
experiments and natural tidal rivers using a process-based model. In addition,
the effect of the critical deposition shear stress on sediment transport is
investigated. The results show that the different critical erosion shear stress
methods yield distinctly different prediction results, and their performance and
applicability ranges are discussed by comparing their predictions with measured
sediment concentrations from the Shenzhen River and measured geometric changes
from the Partheniades' flume experiment. The hiding and exposure effect has
been recognized as a crucial factor in the incipient motion of sediment on
nonuniform beds. A sensitivity analysis of selective deposition and continuous
deposition justifies the existence of the critical deposition shear stress. The
current study highlights the performance and applicability ranges of the
existing critical shear stress methods in sediment transport modeling for
uniform and nonuniform beds, which will enrich understanding of the underlying
mechanisms of erosion and deposition of cohesive sediment.
Keywords
Cohesive sediment; Critical
shear stress; Hiding and exposure effect; Numerical modeling; Shenzhen river
Yang Zhang, Zhili Zou,
Wushan Xue, Dapeng Sun,
Experimental study of
near-bed concentration and sediment vertical mixing parameter for vertical concentration
distribution in the surf zone,
Volume 35, Issue 1,
2020,
Pages27-41,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.004.
(https://www.sciencedirect.com/science/article/pii/S1001627918301756)
?Abstract
Abstract
Two formulae for the near-bed
concentration（`Ca）and
the sediment vertical mixing parameter (m) are established based on a large
scale wave flume experiment. The advantage of the new formulae is that the
turbulent kinetic energy induced by wave breaking can be taken into account;
the formula for`Ca is in terms
of the near-bed, time-averaged turbulent kinetic energy, and the formula for m
is in terms of depth- and time-averaged turbulent kinetic energy. A new
expression for suspended sediment load also is established by depth integration
of the vertical distribution of the suspended sediment concentration obtained
on basis of the new formulae. Equation validation is done by comparing the
predicted`Ca and m to
measurements for different types of waves (regular wave, wave group, and
irregular wave), and good agreement is found. The advantages of the proposed
formulae over previous formulae also are discussed.
Keywords
Near-bed concentration; Sediment
vertical mixing parameter; Turbulent kinetic energy; Surf zone; Wave type
Himanshu Sharma,
Zulfequar Ahmad,
Turbulence
characteristics of flow past submerged vanes,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages 42-56,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.002.
(https://www.sciencedirect.com/science/article/pii/S1001627918302312)
Abstract
Submerged vanes are
hydrofoils utilized to manage the sediment transport through the river by
generating the turbulence in the flow in the form of helical currents. The
vanes are placed in the flow with respect to its direction at angle of 10o
to 40o. In the current study, an attempt has been made to study the
effect of the introduction of vanes in form of rows on parameters like
turbulence intensities, Reynolds stresses, turbulent kinetic energy, anisotropy
index, and the velocity profile of the flow. It is observed that the profile of
variation of turbulence intensities, turbulent kinetic energy, vertical
Reynolds stress and velocity over three different marked verticals on a transect
are nearly identical whereas a large scatter is observed in the variation of
transverse Reynolds stress over the vertical of the aforementioned vertical
locations. This observation suggests that flow turbulence is homogeneous over
the vertical while scattering in the variation of the transverse Reynolds
stress component may be attributed to the presence of secondary currents in the
flow. After introducing rows of submerged vanes, the bed turbulence is reduced,
hence, helping reduce many scour related phenomenon. It is also observed that a
vortex occurred at 0.85 times the height of the vane and the variation of
turbulence quantities in the presence of vanes shows the existence of a peak in
these quantities. It is observed that as flow moves away from the vane rows,
due to the interaction of vortices and the action of vorticity, vortices
dampens down and the flow regains homogeneity. After the introduction of
submerged vane rows, bed shear stress reduces as fluid from the surface
replaces the slow-moving fluid near the bed due to the secondary currents
generated by the vanes leading to reduction in the magnitude of turbulence
intensities, Reynolds stresses, and turbulent kinetic energy near the bed. The
anisotropy index is observed to increase near the bed as induced secondary
currents enhanced the turbulence production in the near bed region. All the
profiles of parameters obtained in the current study show the existence of a
peak or inflexions at a height of 0.85H from bed (Where, H is the height of the
submerged vane). Profiles of parameters obtained in the current study suggest
that as the vorticity dampens the vane-generated secondary currents, the
scattering in the profiles along the vertical reduces and profiles are observed
to regain the variation which they had before the introduction of vane rows,
suggesting that flow turbulence has regained its homogeneity.
Keywords
Turbulence; Anisotropy; Submerged
vanes; Secondary currents; Turbulence parameters
Amin Kazemian-Kale-Kale,
Hossein Bonakdari, Azadeh Gholami, Bahram Gharabaghi,
The uncertainty of the
Shannon entropy model for shear stress distribution in circular channels,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages57-68,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.001.
(https://www.sciencedirect.com/science/article/pii/S1001627918302695)
Abstract
The shear stress
distribution at alluvial stream beds and banks is one of the essential
parameters in channel stability analysis. In the current paper, a novel uncertainty
analysis method based on the framework of a Bayesian Forecasting System (BFS)
is presented to evaluate the Shannon entropy model for prediction of the shear
stress distribution in both circular rigid-bed and alluvial-bed channels. The
Johnson and Box-Cox transformation functions were applied to select the optimum
sample size (SS) and corresponding transformation factor for determining a 95%
confidence bound (CB) for the Shannon entropy model. The Shapiro-Wilk (SW) test
is applied according to the SS used to evaluate the power of transformation
functions in the data normalization. The results show that the error
distribution between predicted and experimental shear stress values generated
using the Box-Cox transformation is closer to a Gaussian distribution than the
generated using the Johnson transformation. The indexes of the percentage of
the experimental values within the CB (Nin) and Forecast Range Error
Estimate (FREE) are applied for the uncertainty analyses. The lower values of
FREE equal to 1.724 in the circular rigid-bed channel represent the low
uncertainty of Shannon entropy in the prediction of shear stress values
compared to the uncertainty for the circular alluvial-bed channel with a FREE
value equal to 7.647.
Keywords
Uncertainty analysis; Shear
stress distribution; Shannon entropy; Confidence bound; Johnson transformation;
Box-Cox transformation; Circular with sediment bed
Madavi Venkatesh,
Anshumali,
Appraisal of the carbon
to nitrogen (C/N) ratio in the bed sediment of the Betwa River, Peninsular
India,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages69-78,
ISSN 100-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.003.
(https://www.sciencedirect.com/science/article/pii/S1001627918303202)
Abstract
Bed sediment carbon to
nitrogen (C/N) ratio is one of the essential variables reflecting sources of
organic matter in river basins. In order to explore the spatial variability in
sources of sediment C/N ratios, and the influence of land use and land cover
(LULC) changes on the Betwa River basin in Peninsular India, 51 river bed
sediment samples were collected in December 2016. The coefficient of variation
(CV) was >35% indicating highly variable biogeochemical parameters. The
sediment C/N ratio varied from 2.94 to 10.09, 3.21–56.40, and 6.50–76.97 in
upstream, mid-stream, and downstream regions, respectively, indicating a
progressive change in sources of organic matter and depositional environment.
The positive correlation between total carbon (TC) and C/N ratio was increasing
in the downstream direction [upstream (+0.560) < mid-stream (+0.603) <
downstream (+0.838)], which is an indication of high deposition and slow decomposition
of sedimentary terrigenous organic matter distant from the regions of urban
pollution. The LULC change analysis done by remote sensing and Geographic
Information System (GIS) methods revealed an adverse change for the forests and
barren land and a positive change for the agricultural land and built-up areas.
The sediment C/N ratio mapping showed the impact of LULC changes on the
sediment quality. The spatial distribution of bed sediment C/N ratio in the
Betwa River basin has important reference value for managing organic matter
transport in the downstream Yamuna River and Ganga River basin.
Keywords
Bed sediment; C/N ratio; ANOVA
analysis; Bundelkhand region; Marginal alluvial plain
Hagos G. Gebreslassie,
Assefa M. Melesse, Kevin Bishop, Azage G. Gebremariam;
Linear spectral unmixing
algorithm for modelling suspended sediment concentration of flash floods, upper
Tekeze River, Ethiopia;
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages 79-90,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.007.
(https://www.sciencedirect.com/science/article/pii/S1001627918300635)
Abstract
Flash floods are the
highest sediment transporting agent, but are inaccessible for in-situ sampling
and have rarely been analyzed by remote sensing technology. Laboratory and
field experiments were done to develop linear spectral unmixing (LSU) remote
sensing model and evaluate its performance in simulating the suspended sediment
concentration (SSC) in flash floods. The models were developed from continuous
monitoring in the laboratory and the onsite spectral signature of river bed
sediment deposits and flash floods in the Tekeze River and in its tributary,
the Tsirare River. The Pearson correlation coefficient was used to determine
the variability of correlations between reflectance and SSCs. The coefficient
of determination (R2) and root mean square of error (RMSE) were used to
evaluate the performance of the generated models. The results found that the
Pearson correlation coefficient between SSCs and reflectance varied based on
the level of the SSCs, geological colors, and grain sizes. The performance of
the LSU model and empirical remote sensing approaches were computed to be R2 =
0.92, and RMSE = ±0.76 g/l in the Tsirare River and R2 = 0.91, and RMSE = ±0.73
g/l in the Tekeze River and R2 = 0.81, RMSE = ±2.65 g/l in the Tsirare river
and R2 = 0.76, RMSE = ±10.87 g/l in the Tekeze River, respectively. Hence, the
LSU approach of remote sensing was found to be relatively accurate in
monitoring and modeling the variability of SSCs that could be applied to the
upper Tekeze River basin.
Keywords
Empirical remote sensing;
Flash floods; Linear spectral unmixing; Suspended sediment concentration; Tekeze
River
M. Azizul Moqsud,
Bioelectricity generation
and remediation of sulfide contaminated tidal flat sediment,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages 91-96,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.08.006.
(https://www.sciencedirect.com/science/article/pii/S1001627918303780)
Abstract
A dramatic decrease in
the catch of shellfish has been observed due to the high amount of Acid
Volatile Sulfide (AVS) in the tidal flats in Japan. In the current study, an
evaluation of simultaneous bioelectricity generation and remediation of sulfide
contaminated tidal flat sediment has been done. The sediment samples collected
from Tokyo Bay and Yamaguchi Bay, Japan, have been used in the laboratory test.
A 2 L cylindrical shaped Sediment Microbial Fuel Cell (SMFC) has been used to
evaluate the remediation of both sediment samples in the laboratory. Three
different electrode materials carbon felt, carbon fiber and bamboo charcoal were
used in the experiments to compare their efficiency to reduce the AVS from the
sediment and generate bioelectricity. It was observed that the AVS reduction
was higher at 5 cm depths for the Tokyo Bay sediment (100%) compared to the
Yamaguchi Bay sediment (60%). The larger grain size for the Tokyo Bay sediment
was the probable reason for this. The maximum voltage was around 100 and 80 mV
for Tokyo Bay and Yamaguchi Bay, respectively.
Keywords
Acid volatile sulfide; Bioelectricity;
Remediation; Tidal flat; Sediment microbial fuel cell; Sediment
Qingchao Guo, Zhao Zheng,
Liemin Huang, Anjun Deng,
Regularity of sediment
transport and sedimentation during floods in the lower Yellow River, China,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages97-104,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.08.001.
(https://www.sciencedirect.com/science/article/pii/S1001627919300319)
Abstract
The flood season is the
main period of flow, sediment transport, and sedimentation in the lower Yellow
River (LYR). Within the flood season, most of the flow, sediment transport, and
sedimentation occurs during flood events. Because of the importance of floods
in forming riverbeds in the LYR, the regularity of sediment transport and
sedimentation during floods in the LYR was studied. Measured daily discharge
and sediment transport rate data for the LYR from 1960 to 2006 were used. A
total of 299 floods were selected; these floods had a complete evolution of the
flood process from the Xiaolangdi to the Lijin hydrological stations. For five
hydrological stations (Xiaolangdi, Huayuankou, Gaocun, Aishan, and Lijin), a
correlation was first established for floods of different magnitudes between
the average sediment transport rate at a given station and the average sediment
concentration at the closest upstream station. The results showed that the
sediment transport rate at the downstream station was strongly correlated with
the inflow (upstream station) sediment concentration during a flood event. A
relation then was established between sedimentation in the LYR and the average
sediment concentration at the Xiaolangdi station during a flood event. From
this relation, the critical sediment concentrations were obtained for absolute
erosion, sedimentation equilibrium, and absolute deposition during floods of
different magnitudes in the LYR. The results of the current study contribute to
a better understanding of the mechanisms of sediment transport and the
regularity of sedimentation in the LYR during floods, and provide technical
support to guide the joint operation of reservoirs and the regulation of the
LYR.
Keywords
Sediment transport; Floods;
Sedimentation; Lower Yellow River
Ashley Rogers, Costantino
Manes, Toru Tsuzaki,
Measuring the geometry of
a developing scour hole in clear-water conditions using underwater sonar
scanning,
International Journal of
Sediment Research,
Volume 35, Issue 1,
2020,
Pages 105-114,
ISSN 1001-6279,
https://doi.org/10.1016/j.ijsrc.2019.07.005.
(https://www.sciencedirect.com/science/article/pii/S1001627918303482)
Abstract
A novel scanning
technique using a rotating-head sonar profiler attached to a slider mechanism
is presented as a means to directly measure the complex erosion and deposition
features of local scour holes developing in clear-water conditions around
vertical cylinders mimicking bridge piers. Extensive validation shows that the
method produces high-density elevation surfaces to within ?1.5
± 2 mm accuracy in a quasi-non-invasive manner. This equates to 0.5 ± 0.7%
relative to the flow depth which sonar resolution is well known to scale with.
Experimental data from three trials using different cylinder diameters indicate
that monitoring of the entire scour hole over time (instead of only the maximum
depth as is commonly done in laboratory experiments) can reveal important
information about local scour evolution. In particular, results show that the
scour-hole volume scales with the maximum scour depth cubed (
)through
three linear regimes. The transition to the third linear regime was found to
represent a step change in the scour evolution process. Following the recent
theoretical framework proposed by Manes and Brocchini (2015), this change, termed
the crossover point, was interpreted as the point where the production of
turbulent kinetic energy plateaus which corresponds to a stabilization in the
erosive power of the horseshoe vortex. Scour development beyond the crossover
point is characterised by a significant reduction in the rate of volumetric
scour, relative to the steadily-increasing maximum scour depth. This overall
reduction in volume-development is attributed to a balance between erosion from
in-front of the pier and deposition around the sides using topography analysis.
It is speculated that the existence of the crossover point may help to identify
the characteristic length and time scales describing the evolution of local
scour, which may be used for modeling purposes.
Keywords
Local scour; Scour volume;
Clear water; Sonar; Scour hole geometry; Similarity
