Submitted to: Hydraulics and Hydrology Workshop
Publication Type: Proceedings
Publication Acceptance Date: 8/30/2002
Publication Date: 9/16/2002
Citation: Wren, D., Vadakapurapu, S., Kuhnle, R.A., Chambers, J., Barkdoll, B. 2002. Suspended-sediment measurements in laboratory flumes using acoustic techniques. Hydraulic Measurements and Experimental Methods. In: Proceedings of the Specialty Conference, Estes Park, CO, 10 pp. Interpretive Summary: The rate of sediment movement through the streams and rivers of agricultural watersheds is important information which is necessary for the responsible management of watersheds to allow sustainable production of food and fiber in an environmentally friendly manner. Current state of the art techniques for sampling sediment in streams and rivers, however, are expensive and require personnel to be on site during potentially dangerous storms. In this study important developments of an acoustic technique to measure sediment in streams and rivers were achieved using data collected in a laboratory stream channel. This technique is being developed in cooperation with researchers from the National Center for Physical Acoustics at the University of Mississippi. The use of acoustics has the potential to dramatically reduce the cost of collecting sediment samples in steams and rivers and to allow improved estimates of the rate of sediment movement. Improved information on sediment movement will enable managers to more effectively manage agricultural watersheds for sustainable production while protecting the soil and water resources.
Technical Abstract: Automated measurement of suspended sediments is crucial to the study of sediment transport. The short duration, high-intensity flows that are responsible for a large fraction of sediment movement are best observed by continuous monitoring systems. Acoustic systems are ideal for continuous monitoring and add the advantage of non-intrusively measuring through the water column. In the present work, a single-frequency acoustic system for measuring suspended-sediment concentration in fluvial environments is described. The equipment and procedures used in developing hardware and software for the acoustic technique in two sets of laboratory flume experiments will be presented. Both implicit and explicit methods were used to convert backscatter data into sediment concentrations. The implicit method yielded 39 percent error and the explicit, 20 percent.