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Sequoia Scientific, Inc. (Bellevue, WA) are makers of LISST‐series field instruments. These are used in coasts, ports, harbors,
- ceans, rivers, and in industry.
Yogi C. Agrawal, President Sequoia Scientific, Inc., Bellevue, - - PowerPoint PPT Presentation
Yogi C. Agrawal, President Sequoia Scientific, Inc., Bellevue, - - PowerPoint PPT Presentation
HORIBA SEQUOIA JOINT WEBINAR Yogi C. Agrawal, President Sequoia Scientific, Inc., Bellevue, Washington Sequoia Scientific, Inc. (Bellevue, WA) are makers of LISST series field instruments. These are used in coasts, ports, harbors, oceans,
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Laser Diffraction In‐line Holography New: LISST‐ABS: 8MHz Acoustic Backscatter
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The LISST‐SL
TM instrument is used to study
Velocity, turbidity, sediment concentration and particle size distribution. We find some remarkable results.
[LISST is a trademark of Sequoia Scientific, Inc.]
(Data courtesy of Chris Curran and Raegan Huffman, USGS Tacoma, WA)
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Measure:
- Multi‐angle scattering;
- Optical Transmission
Derive:
- Particle Size Distribution
- Concentration
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Lifting Point Underwater Connector Intake Pitot Tube Outlet
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- Fish‐shaped samplers
- Contained a bottle
- Sample analyzed in lab
P‐61 sampler
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- Depth
- Optical Transmission
- Velocity (from Pitot tube)
- Particle Size Distribution
- Concentration
- Water Temperature
- Pump control, and
- State of Battery
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Topside Control Box B‐Reel Intake nozzle Pitot tube
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Size Class # 26 27 28 29 30 31 32 Diameter [µm] 131 155 183 216 255 302 352 u* [cm/sec] 5.2 5.2 5.3 5.6 6.1 6.9 8.3
u* = (D*I*g)1/2; D= 4m => I =2 x 10‐4 (USGS reports 3 x 10‐4 for Cowlitz River)
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1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 70 80 90 100
Size, phi units mg/L
0.21 0.69 1.14 1.6 1.96 2.57 2.83
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SSC varies x 2‐3 or more; Xmission does not Strong washload component < ~16 µm
- SMD increases x 3; VMD increases x 5
- Turbidity sensors would miss SSC increase
Vertical gradients of coarse particles yields fairly
consistent u* estimates
Water column mean PSD ~= PSD at half depth
- Due to Rouse; coarse sediment concentration decays
exponentially
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- Coarse grains in high concentrations can
destroy turbines by abrasion;
- Sequoia makes an auto‐dilution Laser
Diffraction system – LISST Infinite
- Real‐time data is displayed at Control
Room
- At hazardous conditions, warning alarms
are sounded.
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TOTAL SSC <75 m 75‐200 m 200‐500 m
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Linear fit used to predict if concentration will
exceed a set value – for warning
If critical value (set by operator) is exceeded,
alarm will sound
Linear fit also predicts when water will clear
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25 26 27 28 29 30 31 01 02 03 1000 2000 3000 4000 5000 6000 7000 8000 May-Jun'11 Concentration (mg/l) 120 min interval 05 06 07 08 09 5,000 10,000 15,000 20,000 25,000 Oct'11 Concentration (mg/l) 30 min interval 5 min interval
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500 1000 1500 2000 200 400 600 800 1000 1200 Number of occurrences Suspended Sediment Concentration (mg/l)
Mode = 90 mg/l Mean = 235 mg/l
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May Jun Jul Aug Sep Oct Nov Dec Jan Feb 50,000 100,000 150,000 200,000 250,000 Months, 2011-2012 Tons of Sediment Q = 40 m3/s Q = 52 m3/s
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May Jun Jul Aug Sep Oct Nov Dec Jan Feb 50,000 100,000 150,000 200,000 Months, 2011-2012 Tons of Sediment 200-500 µm 75-200µm 2.5-75µm
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