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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #340846
Title: Deployment of a hydrophone based passive acoustic bedload monitoring surrogate

Author
item GOODWILLER, BRADLEY - University Of Mississippi
item Wren, Daniel
item Rigby Jr, James
item HILLDALE, ROBERT - University Of Mississippi

Submitted to: American Society of Civil Engineers Hydraulic Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/15/2017
Publication Date: 7/9/2017
Citation: Goodwiller, B.T., Wren, D.G., Rigby Jr, J.R., Hilldale, R.C. 2017. Deployment of a hydrophone based passive acoustic bedload monitoring surrogate. American Society of Civil Engineers Hydraulic Conference Proceedings. Hydraulic Methods and Experimental Methods Conference. University of New Hampsire in Durham, New Hampshire, July 9-12, 2017. 1-6 pp.

Interpretive Summary: The measurement of sediment transported on and near the bed of streams and rivers is an important need for river management, particularly when dams are removed, which creates a need for measuring the release of stored coarse sediments. The collection of bed load samples is very difficult and expensive, making the continued development of instrumentation necessary. Using underwater microphones to record the sounds of rocks impacting one-another is a promising, low-cost method that may lead to a useful measurement technique for bed load measurement. The work described here is field testing of the method. Physical samples of bed load were collected, while recordings of the sound generated by the bed load were made. The two were compared, and the data were used to develop methods for converted the recorded sounds into sediment transport rate.

Technical Abstract: The use of sediment generated noise (SGN) has been studied as a potential surrogate method for determining bedload transport rates. Laboratory and preliminary field experiments have shown multiple characteristics of this acoustic signal that correspond with properties of the bedload in transport. A portable passive-acoustic data collection system was designed by researchers at the National Center for Physical Acoustics at the University of Mississippi along with researchers at the National Sedimentation Laboratory in Oxford, Mississippi. The system uses two hydrophones (High Tech Inc 96 MIN-Exportable) to record the sound generated by course bedload movement. A portable .wav recorder (Zoom H4N) streams the continuous acoustic data to audio files which can then be processed. The data collection hardware was placed in a waterproof container. The system is compact, robust, portable and can operate for long periods of time with minimal user input. A custom hydrophone case was designed to allow multiple mounting techniques, thus providing adaptability to a wide range of gravel-bed fluvial systems. The data collection system was deployed on Halfmoon Creek near Leadville, Colorado during the summer of 2015, collecting nearly one month of continuous acoustic data. The system was also deployed on the Elwha River near Port Angeles, Washington. Multiple analysis techniques have been tested on the data sets, and compared with similar measurements made in laboratory flumes and tanks.