•Particle size distribution •Sediment concentration •River flow rate •Sediment flux

LISST-SL2(StreamLinedIsokinetic streamline and other power sourcesThe on-site laser particle size analyzer is from the United States Sequoia The company focuses on river developmentAdopting advanced laser small angle technology Sensors using forward scattering technology, whichSensors are used to detect sediment in rivers Flux and river flow rate Measurement, this sensor is from the United States SequoiaThe company has powerful functionsMulti parameter river sediment measurement instrument.

The LISST-SL2 sensor adopts a full The new streamlined design can be larger Reduce water resistance to a certain extent, sensor tail The two flow deflectors at the end can ensure When the sensor measures in water Hou can always face upwards towards the river Travel. Mud and sand in river water and water bodiespass The pump inside SL2 draws in waterInside the instrument, the system utilizes a magical and fixed airspeed tube for transmissionSensors to ensure the flow of inhaled water Flow at the location of the speed instrument Same speed to ensure data collection Collection is achieved in a state of waiting for power Currently. When the inhaled water passes through the dense When sealing the photoelectric measurement sensor Wait, the forward scattering data of the laser is Collecting. These scattered data are obtained through USGS B Type of cable rolling transmission to waterFace control unit, then transmit to Computers perform real-time processing.

The size distribution and volume concentration of sediment Degree, temperature, average particle size, depth And real-time display of data such as flow rate Display and access on the computer. haveFlow rate, concentration, and depth data Afterwards, the sediment transport capacity of the entire river can be determined To be calculated.

LISST-SL 2 is different from LISST'sHis instrument, it's just a device in water The measurement sensor in, the sensor The collected data is transmitted through two wires of electricity The cable winch is transmitted to the water surface for control Unit, water surface control unit built-in Rechargeable battery pack is used to power sensors Power supply and collect data Transmit data via wireless Bluetooth Collecting and processing computers for real Data processing and storage at the time. TheseData can be obtained through time series or The vertical water depth profile is displayed Show to the operator.

Features:

· Using laser small angle forward scattering technology, measuring range 1-500 Microns, satisfying ISO-13320-1 standard

· Waiting for power, advanced pump control technology

· 2 Special communication protocols can be used in conjunction with the line USGS-B Type cable winch operation

· Real time display of multi parameter measurements: flow velocity, temperature, concentration, depth, and average sediment size

· The new waterless streamlined design ensures the controllability and accuracy of measurement, reducing the conditions for bubble generation

· The dual tail fins ensure that the instrument is parallel to the water flow and always faces upstream

· Real time data processing allows operators to display time series or profile data in real-time

· The software can output point based or integrated depth sediment data

· Bluetooth real-time wireless data transmission avoids the limitations of traditional serial cable direct connection

Technical Indicators:

Optical path length:3.2mm concentration measurement range: 15-13500mg/l concentration resolution:<10mg/l

Particle size range:1-500μm，36 Particle size grade Depth range:0.15-30m@0.02m resolution

Flow velocity measurement range:0-3m/s@0.03m/s resolution

Water temperature measurement range:0-25 degree@0.1

Sampling time:16 Average of individual samples/2 second After averaging, the data is immediately transmitted to the surface control unit

Mechanical and electrical parameters: Underwater sensor size:13cm (diameter) * 75cm (length)

Underwater sensor weight:16kg (air)/7kg (water)

Surface control unit size:40.6cmx31.8cm*16.5cm

Weight of water surface control unit: 8.6kg

Battery life: Can be used after fully charged 6 hours

LISST-SL2 It is a powerful laser sand analyzer for sediment and nearshore/estuarine applications. The sensor adopts a streamlined design Designed with equal power (equal power means that the inlet flow rate of the detector is the same as the actual water flow rate), the instrument can measure depth and permeability Luminosity, flow velocity, water temperature, sediment concentration, and sediment size distribution. Our following example is in the state of Washington, USA Castle Rock The city's Cowlitz Actual measurement of the river.

Data obtained on-site

The above figure shows the processed data, from right to left are the transparency of the river water (similar to turbidity meter measurement), river flow velocity, sediment concentration, and sediment concentration The granularity distribution. The red circle on the sediment concentration map represents the United States USGS The staff collected the actual concentration of sediment after drying and weighing using manual physical methods.

These data intuitively demonstrate that turbidity sensors cannot establish a relationship curve with the true concentration. The fourth figure shows the sediment size of the river profile Distribution, particle size φ6 It has a very good distribution in rivers, and the particle size of river sediment becomes coarser with increasing depth.

Sediment concentration profile

From left to right are 0.2m，0.7m，1.1m，1.6m，2m，2.4m，2.8m The concentration changes of different particle size grades at different depths, pay attention to the increase with depth The concentration gradually increases and the sediment particles become coarser, and intermittent resuspension phenomena occur

Particle size profile and concentration relationship curve

The figure on the left shows the curves of particle concentration with depth for four different sizes. It can be clearly seen that as the depth increases, large-sized particles also begin to increasePlus, it fully conforms to the theory of river sediment distribution. Vertical gradient can be used to calculate friction velocity(u*)The graph on the right shows the flux or sediment per unit depthThe transportation of sediment and the uniform mixing of washed sediment (blue line) in this diagram are different from suspended sediment, and these details have never been obtained before.

Other information that can be obtained

With these high-resolution size distribution files, users can complete tasks such as:

- Time series testing to obtain the fluctuation of sediment of different sizes on the complete time axis. These can be used for scientific research or hydraulic modeling.

- Research on Acoustic Backscatter at Different Frequencies in the Entire Cross Section

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Main applications

This instrument can not only conduct detailed scientific research, but also improve sedimentation management at the inlet of reservoirs and hydropower stations, as well as sand removal management.

The above picture shows the United States USGSIn the state of Washington, USA PuyallupAnother field experiment conducted by the river shows that(i)The closer to the bottom of the riverbed, the larger the sediment particles; (ii) The closer to the bottom of the riverbed, the higher the sediment content(iii)The infrared turbidity meter used synchronously did not show any changes in the results (due to OBS For reactions of large-sized particlesNot sensitive.