Environmental Engineering Reference
In-Depth Information
Table 2.1
Continued
Requires
wading or
retrieval
during high
fl ows
High
percentage
of channel
width
sampled
Large
opening
relative
to grain
size
Physical
sample
obtained for
sieving
Relatively
long
sampling
duration
Bed-load
sampling
technology
Stream
excavation
required
Disruptive
to fl ow
fi elds
Status of
development
(2003)
Potential use
as calibration
standard
Relative
ease of use
Stream type
Hydrophones
(active and
passive
acoustic
sensor)
Gravel bed
channel
No
No
Depends
on
deploy-
ment
N/A
Continuous Possibly
Easy
No
Early
Additional
develop-
ment
needed
Gravel impact
sensor
Gravel bed
channel
Yes, for
hand-
held
model
No
Not as
currently
designed
N/A
Continuous Yes for
instream
model
Easy under
many
condi-
tions
In fast fl ow
Early
Additional
develop-
ment
needed
Magnetic tracers Gravel bed
with
naturally
magnetic
particles
No
No
Yes
N/A
Continuous Yes
Relatively
easy
Depends on
experi-
mental
setup
Additional
testing
Possible at
appropri-
ate
locations
Magnetic
sensors
Gravel bed
channel
No
No
Yes
N/A
Continuous Yes
Easy under
many
condi-
tions
Minor; fl ush
with
stream
bottom
Early
Additional
verifi cation
needed
Topographic
differencing
Sand-gravel
bed
channel
No
No
Yes
N/A
Episodically
or
continu-
ous
No
Easy
No
Early?
Additional
verifi cation
for gravel
bed
systems
Sonar-measured
debris basin
Gravel bed
channel
No
No
Yes
N/A
Continuous With debris
basin
installa-
tion
Easy under
many
condi-
tions
N/A
Early
High
Underwater
video cameras
Relatively
clear fl ow
Used from
bridges
or boats
No
No
N/A
Continuous No
Easy under
right
lighting
condi-
tions
Slightly
Early
Additional
verifi cation
needed
N/a, Not applicable.
