ABSTRACT
Monitoring of sediment load in rivers is an essential task for a sustainable management of rivers and reservoirs. Reliable measurements of the Total Suspended Sediments (TSS) are mostly achieved by taking water samples. Acoustic backscatter technology is a promising technology to conduct measurements of suspended sediment loads in water, where such “acoustic surrogate metrics” require taking water samples for calibration. A multi-frequency backscatter model has been developed utilizing four ultrasonic frequencies from 0.5 to 4 MHz to overcome calibration. The new instrument was tested under laboratory conditions showing a performance of ±10% for TSS concentrations from 50 mg/l up to 50 g/l and grain sizes from 20 µm to 1000 µm. First field tests with an instrument prototype have been conducted in a river in Vietnam comparing measurements with laboratory analysis. The non-calibrated instrument achieved a median absolute deviation of ±14% to ±20% of the TSS compared to laboratory data.
