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Laboratory Evaluation of Acoustic Backscatter and LISST Methods for Measurements of Suspended Sediments

View Article: PubMed Central - PubMed

ABSTRACT

The limitation of traditional sampling method to provide detailed spatial and temporal profiles of suspended sediment concentration has led to an interest in alternative devices and methods based on scattering of underwater sound and light. In the present work, acoustic backscatter and LISST (the Laser In Situ Scattering Transmissometry) devices, and methodologies were given. Besides a laboratory study was conducted to compare pumping methods for different sediment radiuses at the same concentration. The glass spheres (ballotini) of three different radiuses of 115, 137 and 163 μm were used to obtain suspension in the sediment tower at laboratory. A quite good agreement was obtained between these methods and pumping results with the range at 60.6-94.2% for sediment concentration and 91.3-100% for radius measurements. These results and the other studies show that these methods have potential for research tools for sediment studies. In addition further studies are needed to determine the ability of these methods for sediment measurement under different water and sediment material conditions.

No MeSH data available.


Sediment radius results of ABS measurements.
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f5-sensors-08-00979: Sediment radius results of ABS measurements.

Mentions: The backscatter voltage values, sediment concentration and radius results for each measurement of ABS are shown figures 3, 4 and 5. The backscatter voltages drop with increasing range from transducer. Similar results are given by Thorne at all (1991) [23] and are explained with water and particle attenuation and spreading of the beam. The nearfield region of the transducer was seen in the first 0.2 m range, and the reflections from the paddle were seen at about 0.9 m and 1.25 m. Therefore, sediment concentrations and radius were determined for 0.2-0.8 m range.


Laboratory Evaluation of Acoustic Backscatter and LISST Methods for Measurements of Suspended Sediments
Sediment radius results of ABS measurements.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927532&req=5

f5-sensors-08-00979: Sediment radius results of ABS measurements.
Mentions: The backscatter voltage values, sediment concentration and radius results for each measurement of ABS are shown figures 3, 4 and 5. The backscatter voltages drop with increasing range from transducer. Similar results are given by Thorne at all (1991) [23] and are explained with water and particle attenuation and spreading of the beam. The nearfield region of the transducer was seen in the first 0.2 m range, and the reflections from the paddle were seen at about 0.9 m and 1.25 m. Therefore, sediment concentrations and radius were determined for 0.2-0.8 m range.

View Article: PubMed Central - PubMed

ABSTRACT

The limitation of traditional sampling method to provide detailed spatial and temporal profiles of suspended sediment concentration has led to an interest in alternative devices and methods based on scattering of underwater sound and light. In the present work, acoustic backscatter and LISST (the Laser In Situ Scattering Transmissometry) devices, and methodologies were given. Besides a laboratory study was conducted to compare pumping methods for different sediment radiuses at the same concentration. The glass spheres (ballotini) of three different radiuses of 115, 137 and 163 μm were used to obtain suspension in the sediment tower at laboratory. A quite good agreement was obtained between these methods and pumping results with the range at 60.6-94.2% for sediment concentration and 91.3-100% for radius measurements. These results and the other studies show that these methods have potential for research tools for sediment studies. In addition further studies are needed to determine the ability of these methods for sediment measurement under different water and sediment material conditions.

No MeSH data available.