Environmental Engineering Reference
In-Depth Information
(a)
(b)
Fig. 1.17
Double Bubbler Pressure Differential Instrument. (a) controller and orifi ce bar,
(b) air compressor and tank assembly, and (c) in-stream components before installation.
Photographs a and b courtesy of Design Analysis Associates, Inc. (2008).
(c)
Bubbler in the Paria River was predicated on the
hypothesis that the expected large weight densities,
ranging up to about double that of pure water under
hyperconcentrated streamfl ow conditions (Beverage
& Culbertson 1964), would prove to be within the
Double Bubbler's operating range.
Double Bubbler data were collected, at 5-minute
intervals, during periods of elevated fl ow at the Paria
River streamgage from July 2004 through September
2006. Data collected from 14 periods of storm runoff
were examined and compared with results from
suspended-sediment samples collected during the
storm runoff. The samples were collected using a
combination of automated-pump samplers, depth-
integrating samplers in a single vertical and deployed
in the cross section, and dip samples (Nolan
et al
.
2005; Edwards & Glysson 1999). The elevated fl ows
had peaks ranging from about 7-90 m
3
/s; the
maximum SSC measured was 382 g/L in water from
an automated-pump sampler. A total of 261 sus-
pended-sediment samples were collected during the
14 storm-runoff periods, and 86% of those samples
had SSC values larger than 50 g/L. Double-Bubbler
data were collected only during periods when water
levels immersed both pressure sensors (the instru-
ment was not fully submerged during normal shallow
fl ows).
Double Bubbler data were fi ltered to remove out-
liers but not smoothed, because smoothing appeared
to have little effect on reducing signal noise for data
collected at this site. Water-temperature data were
continuously recorded near the Double-Bubbler ori-
fi ces. The weight density of suspended sediment and
dissolved solids was calculated by subtracting the
weight density of pure water, corrected for tempera-
ture, from the fi ltered data.
Similar to data collected at the Río Caguitas in
Puerto Rico, the Double Bubbler data collected at
the USGS streamgage on the Paria River at Lees
Ferry, Arizona, USA, had a large amount of signal
noise, also making interpretation diffi cult. Relations
between measured SSC and SSC calculated from
