NWDTW 2024

The LISST-ABS sensor, developed by Sequoia Scientific, was designed as an alternative to turbidimeters which rely on optical back scatter (OBS) for estimating suspended-sediment concentrations (SSCs) in surface waters. The acoustic backscatter sensor (ABS) emits an 8-megahertz (MHz) acoustic signal that returns to the sensor as backscatter, the intensity of which is directly translated to a sediment concentration. The relation between the signal and backscatter intensity is nearly constant beyond the Raleigh limit at 8 MHz for grain sizes larger than about 60 micrometers (µm; Agrawal and others, 2019). However, the ABS fails to accurately quantify concentrations containing large amounts of fine grains (< 60 µm). Therefore, a pairing factor is needed to predict SSC more accurately for systems transporting large amounts of grains