Deployment of a single frequency acoustic attenuation system for measuring fine suspended sediments in stream channels

The use of ultrasonic acoustic technology to measure the concentration of fine suspended sediments has the potential to greatly increase the temporal and spatial resolution of sediment measurements while reducing the need for personnel to be present at gauging stations during storm events. In collaboration with the U.S. Department of Agriculture, The National Center for Physical Acoustics at The University of Mississippi has developed a single frequency acoustic attenuation system to monitor the concentration of suspended fine sediments (less than 60 micrometers in diameter) in rivers and streams. The field unit consists of two immersion ultrasonic transducers measuring attenuation of 20 Megahertz acoustic signals propagated through suspended particles. The system was operated in the Goodwin Creek Watershed near Batesville, Mississippi, USA from November 2019-Februry 2023. The calibrated acoustic measurements of fine sediment concentration agreement well with discharge and pump samples while providing greatly improved time resolution in the data. The basic design parameters, calibration methodology, and examples of results of field use of the prototype will be presented.