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, rivers, and in industry. [LISST is a trademark of Sequoia Scientific, Inc.]
Laser Diffraction In ‐ line Holography New: LISST ‐ ABS: 8MHz Acoustic Backscatter
TM instrument is used to study The LISST ‐ SL 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)
Measure: • Multi ‐ angle scattering; • Optical Transmission Derive: • Particle Size Distribution • Concentration
Lifting Point Underwater Connector Outlet Pitot Tube Intake
• Fish ‐ shaped samplers • Contained a bottle • Sample analyzed in lab P ‐ 61 sampler
• Depth • Optical Transmission • Velocity (from Pitot tube) • Particle Size Distribution • Concentration • Water Temperature • Pump control, and • State of Battery
Topside Control Box B ‐ Reel Pitot tube Intake nozzle
Size Class # 26 27 28 29 30 31 32 Diameter 131 155 183 216 255 302 352 [µm] u * 5.2 5.2 5.3 5.6 6.1 6.9 8.3 [cm/sec] u * = ( D * I * g ) 1/2 ; D = 4m => I =2 x 10 ‐ 4 (USGS reports 3 x 10 ‐ 4 for Cowlitz River)
100 90 2.83 80 70 60 2.57 mg/L 50 1.96 40 30 1.6 20 1.14 0.69 10 0.21 0 9 8 7 6 5 4 3 2 1 Size, phi units
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
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.
200 ‐ 500 m 75 ‐ 200 m <75 m TOTAL SSC
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
8000 25,000 7000 20,000 6000 Concentration (mg/l) Concentration (mg/l) 5000 15,000 4000 120 min interval 10,000 3000 2000 5,000 1000 30 min interval 5 min interval 0 0 25 26 27 28 29 30 31 01 02 03 05 06 07 08 09 May-Jun'11 Oct'11
1200 Mode = 90 mg/l 1000 Number of occurrences 800 600 400 Mean = 235 mg/l 200 0 0 500 1000 1500 2000 Suspended Sediment Concentration (mg/l)
250,000 200,000 Tons of Sediment 150,000 100,000 50,000 Q = 40 m3/s Q = 52 m3/s 0 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Months, 2011-2012
200,000 200-500 µm 75-200µm 2.5-75µm 150,000 Tons of Sediment 100,000 50,000 0 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Months, 2011-2012
LISST ‐ SL and LISST ‐ Infinite instruments Data from a river suggest far superior method for sediment work. Real ‐ time data at a Hydro Power plant warns operators for turbine protection.
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