International Journal of River Basin Management,
Год журнала:
2022,
Номер
22(3), С. 333 - 349
Опубликована: Ноя. 17, 2022
Hydraulic
modelling
of
natural
floodplain
vegetation
using
leaf
area
index
(LAI)
has
been
applied
successfully
for
non-submerged
conditions
whereas
its
suitability
submerged
requires
further
development.
This
study
investigates
the
vegetative
flow
resistance
at
low
relative
submergences
and
extends
existing
LAI-based
approaches
building
upon
new
flume
data
prior
experiences
from
field-scale
applications.
We
provide
advanced
formulas
emergent
to
conditions,
with
water
depth
up
three
times
higher
than
height.
Such
are
highly
relevant
in
hydraulic
analyses
riverbank
flows
but
not
adequately
represented
formulas.
The
use
deflected
height
as
characteristic
provided
most
accurate
results,
undeflected
resulted
significant
errors.
As
a
development
we
proposed
von
Kármán
scaling
factor
improved
model
predictions.
Overall,
results
proved
that
is
suitable
also
wide
range
densities
(LAI
=
1–5)
mean
velocities
(0.05–1.2
m
s−1).
For
both
slightly
overtopped
JAR
VAS
outperformed
BAPmod-LAI
approach
does
account
reconfiguration.
modellers,
workflow
guidance
on
newly
developed
1D/2D
hydrodynamic
models
conditions.
Water,
Год журнала:
2021,
Номер
13(2), С. 116 - 116
Опубликована: Янв. 6, 2021
Vegetation
on
the
banks
and
flooding
areas
of
watercourses
significantly
affects
energy
losses.
To
take
latter
into
account,
computational
models
make
use
resistance
coefficients
based
evaluation
bed
walls
roughness
besides
to
flow
offered
by
vegetation.
This
paper,
after
summarizing
classical
approaches
descriptions
pictures,
considers
recent
advancements
related
analytical
methods
relative
both
rigid
flexible
In
particular,
emergent
vegetation
is
first
analyzed
focusing
for
determining
drag
coefficient,
then
submerged
analyzed,
highlighting
briefly
principles
which
different
are
recalling
comparisons
made
in
literature.
Then,
used
case
highlighted.
As
vegetation,
paper
reminds
conditions
that
cause
lay
channel
bed,
laws
were
developed
design
irrigation
canals.
The
most
developments
presented.
Since
turbulence
studies
should
be
considered
as
basis
resistance,
even
though
path
toward
practical
still
long,
new
field
3D
numerical
reviewed,
presently
assess
characteristics
transport
sediments
pollutants.
remote
sensing
map
riparian
estimating
biomechanical
parameters
analyzed.
Finally,
some
applications
presented,
aimed
at
highlighting,
real
cases,
influence
exerted
water
depth
maintenance
interventions.
Journal of Hydrology,
Год журнала:
2021,
Номер
601, С. 126593 - 126593
Опубликована: Июнь 29, 2021
River
flows
are
greatly
influenced
by
floodplain
vegetation
with
implications
on
hydrological
and
hydraulic
conditions
from
cross-sectional
to
river
reach
scales.
Flow
models
need
reliably
reflect
changes
in
the
riverine
environment,
such
as
growth
associated
altered
flow
regimes,
increased
sediment
loads
eutrophication.
Leaf
area
index
(LAI)
based
approaches
increasingly
used
tools
predict
resistance
caused
natural
vegetation.
However,
current
LAI-based
modelling
involves
uncertainty
at
low
high
densities
velocities
due
a
lack
of
research
validation
outer
ranges.
The
aim
this
paper
is
investigate
for
mixture
flexible
consisting
woody
plants
understory
grasses
(LAI
=
1–5)
over
wide
range
mean
(0.05–1.2
m/s)
relative
submergences
1–2.
A
novel
flume
setup
was
designed
using
high-accuracy
pressure
sensors
measure
force
plant
drag
forces.
decreased
35–90%
when
submergence
H/hv
1
2,
which
highly
relevant
flows.
results
provided
new
evidence
that
vegetative
friction
factors
can
be
extended
LAI
values
non-submerged
adjustments
existing
required
water
stages
higher
than
height.
Furthermore,
cannot
neglected
often
assumed
literature
especially
cases
submergences.
Water Resources Research,
Год журнала:
2021,
Номер
57(3)
Опубликована: Фев. 12, 2021
Abstract
Natural
riparian
vegetation
generally
presents
a
complex
hydrodynamic
behavior
governed
by
plant
morphology
and
flexibility.
By
contrast,
processes
in
partly
vegetated
channels
are
conventionally
simulated
using
simplified
model
vegetation,
such
as
arrays
of
rigid
cylinders.
The
aim
this
study
is
to
investigate
the
impacts
embedding
natural
features
experimental
simulation
flow
channels.
Unique
comparative
experiments
were
carried
out
with
both
reconfiguring
made
natural‐like
shrubs
grasses,
While
lateral
distributions
properties
presented
high
similarity
shear
layer
differential
velocity
ratio,
bulk
vegetative
drag,
presence
large‐scale
vortices,
flexibility‐induced
mechanisms
markedly
affected
at
interface.
Differences
spacing,
dynamic
motion
flexible
foliated
plants
induced
deeper
vortex
penetration
into
vegetation.
normalized
was
6–10
times
greater
than
observed
for
cylinders,
resulting
wider
zones
significantly
exchanging
momentum
adjacent
open
water.
efficiency
transport
up
40%
corresponding
cylinder
case.
Overall,
results
indicated
that
improving
representativeness
critical
step
toward
accurate
settings.
Vegetation
plays
a
crucial
role
in
aquatic
systems
and
characterizes
riverine
ecosystems.
To
predict
changes
environment,
it
is
essential
to
understand
the
influences
of
vegetation
on
flow
structure
sediment
transport.
The
present
study
explores
effects
deflection
flexible
elements
vortex
deposition
around
patch
through
flume
experiments.
First,
velocity
measurement
by
particle
image
velocimetry
(PIV)
was
performed
for
flows
single
upright/inclined
rigid
strip
blade
single/three-row
inclined
blades
investigate
effect
structure.
Second,
flexibility
wake
region
were
explored
vertical
horizontal
PIV
measurements
In
this
part,
we
considered
three
types
models
consisting
rectangular
arranged
square
lattice
array:
(1)
rigid,
emergent
vegetation;
(2)
flexible,
submerged
(3)
vegetation.
case,
rotating
secondary
generated
significantly
contributes
momentum
transport
into
region,
while
turbulent
mixing
or
vortices
determines
behind
patches.
Moreover,
increases
spanwise
fluxes
across
lateral
edges
thereby
enhances
patch.
