Water Research,
Год журнала:
2025,
Номер
282, С. 123534 - 123534
Опубликована: Апрель 6, 2025
Despite
the
significance
of
rivers
and
streams
in
transporting
terrestrial
microplastics
(MP)
to
oceans,
limited
research
has
focused
on
role
aquatic
vegetation
their
complex
geometry
shaping
underlying
mechanisms
governing
MP
mixing
dispersion
processes
riverine
environments.
This
study,
for
first
time,
investigates
transport
fate
non-buoyant
MPs,
specifically
those
with
diameters
188
nm
6μm
a
density
1.04
g/cm3,
floating
Eichhornia
crassipes
canopies
under
flow
conditions
typical
natural
(0.0167-0.0667
m/s).
Physical
modelling
tests
reveal
that
significantly
alters
hydrodynamic
structure
enhances
dissipation
turbulence
water
column,
leading
decreased
velocities,
diversified
length
scales,
increased
turbulent
kinetic
energy
(TKE)
regions
higher
frontal
areas.
turbulence,
turn,
facilitated
momentum
exchange
vertical
mixing,
particularly
most
pronounced
area
changes.
Wider
canopy
spacing
promoted
evolution
wake
expansion
throughout
generating
coherent
structures
effectively
doubled
integral
scales
increasing
distance
between
from
0.5
m
1.5
m.
adjustment
resulted
more
uniformly
dispersed
downstream
movement
MPs.
Notably,
presence
amplified
diffusivity
by
10-40
times
compared
equivalent
unvegetated
conditions,
transitioning
primary
mechanism
shear-induced
velocity
gradients
enhanced
plant-flow
interactions.
study
offers
robust
framework
quantifying
predicting
longitudinal
coefficients
within
vegetated
flows,
developing
models
depict
profiles
TKE
featured
morphology
spacing.
The
insights
this
make
significant
contribution
towards
improving
our
ability
predict
MPs
environments
underscore
necessity
incorporating
dynamics
into
environmental
management
risk
assessments.
Soil
erosion
on
the
slope
is
a
major
problem
in
northern
region
of
Pakistan,
causing
hill
instability
and
landslides.
Previous
research
focused
assessment
soil
hilly
regions
caused
by
intense
flooding.
However,
there
still
gap
investigating
impact
vegetation
patterns
densities
reduction
region.
Therefore,
current
fills
this
with
an
experimental
investigation
various
for
using
physical
model
regions.
Experiments
were
performed
under
diverse
scenarios
including
two
Froude
numbers
(Fr
=
0.17
0.20),
(G/d
2.13
1.09,
where
G:
between
elements,
d:
diameter
element),
three
slopes
(10°,
15°,
20°)
controlled
laboratory
setting.
The
findings
indicate
significant
contribution
denser
to
erosion.
Moreover,
newly
modified
pattern
was
introduced
modifying
existing
gaps
strips
followed
cutting
rate
9%
12%
compared
regular
arrangement
similar
scenarios.
Consequently,
outcomes
may
be
useful
establishing
bio-shields
as
environmentally
friendly
method
mitigating
Water Resources Research,
Год журнала:
2022,
Номер
58(10)
Опубликована: Сен. 22, 2022
Abstract
Understanding
the
mechanisms
controlling
downstream
water‐level
variations
after
operation
of
Three
Gorges
Dam
is
important
for
riverine
flood
and
drought
management.
However,
our
quantitative
understanding
multiple
controls
river
morphology,
vegetation,
floodplain
resistance
on
water
levels
in
Middle
Yangtze
River
(MYR)
remains
limited.
Here,
we
analyze
changes
channels
MYR
using
450
cross‐sectional
profiles
as
well
data
discharge,
levels,
sediment,
satellite
images
from
2003
to
2015.
Results
show
an
overall
decline
low‐flow
water‐levels
(at
a
given
small
discharge)
due
severe
incisions
caused
by
sharp
reduction
∼90%
sediment
loads
1950–2002
2003–2020.
In
contrast,
high‐flow
large
display
minor
changes.
Our
analysis
shows
that
notably
increased
vegetation
growth
likely
dominant
factor
elevating
water‐levels,
followed
riverbed
coarsening
greater
fluctuations
longitudinal
profiles.
findings
further
geomorphic
response
dam
their
impacts
have
implications
management
dammed
systems.
Water Resources Research,
Год журнала:
2022,
Номер
58(8)
Опубликована: Авг. 1, 2022
Abstract
Laboratory
experiments
examined
the
longitudinal
evolution
of
near‐bed
velocity,
turbulent
kinetic
energy
(TKE),
and
net
deposition
in
a
model
Phragmites
australis
canopy
occupying
1/3
channel
width.
The
canopies
were
constructed
from
P
.
with
real
morphology
solid
volume
fraction
between
0.003
0.018.
An
exponential
was
modified
to
predict
velocity
inside
canopy,
which
TKE
can
be
predicted.
By
combining
predicted
probability,
we
proposed
distribution
canopy.
TKE,
good
agreement
measurements.
Relative
an
upstream
reference,
within
enhanced
when
two
conditions
met:
in‐canopy,
smaller
than
critical
value
for
resuspension,
resuspension
took
place
bare
channel.
Above
vegetation
density
(defined
by
ϕ
c
),
spatially‐averaged
surpassed
that
adjacent
provides
way
estimate
always
diminished
over
some
flow
adjustment
distance,
L
d
(distance
leading
edge
fully
developed
flow).
When
length
greater
0.4
,
canopy‐averaged
relative
Finally,
same
length,
differences
plant
morphologies
did
not
have
strong
impact
on
in‐canopy
distribution.
Water,
Год журнала:
2023,
Номер
15(1), С. 176 - 176
Опубликована: Янв. 1, 2023
Aquatic
vegetation
appears
very
often
in
rivers
and
floodplains,
which
significantly
affects
the
flow
structure.
In
this
study,
experiments
have
been
conducted
to
investigate
effects
of
submerged
arrangement
patterns
density
on
Deflected
non-bending
is
arranged
square
staggered
configurations
channel
bed
a
large-scale
flume.
Results
showed
that
configuration
leads
intensified
streamwise
velocity,
turbulence
kinetic
energy
(TKE),
Reynolds
shear
stress
(RSS)
compared
configuration.
When
low
(λ
=
0.04
λ
0.07),
produced
wake
rear
more
expansive
than
with
high
0.09
0.17)
because
velocity
center
four
elements
lower
middle
two
density.
TKE
zone
deflected
indicate
maximum
root-mean-square
fluctuations
occur
at
sheath
section
(z/H
0.1)
top
0.4).
behind
elements,
value
RSS
occurred
slightly
above
interface
between
non-vegetation
layer,
showing
Kelvin–Helmholtz
instability
associated
inflectional
points
longitudinal
velocity.
Within
range
study
(0.04
<
≈<
0.23),
as
increases,
negative
positive
values
throughout
depth
increase.
