Field Testing and Calibration of a Hydrophone System for Surrogate Bedload Measurement

Project ID: 9342
Principal Investigator: Robert Hilldale
Research Topic: Sediment Management and River Restoration
Funded Fiscal Years: 2015
Keywords: hydrophone, bedload, surrogate sediment measurement

Research Question

The proposed research intends calibrate a field-deployable hydrophone system to measure bedload in mountain streams. After a calibration is obtained, it will be necessary to examine the data to determine what sort of recording intervals can be used for long-term deployments. Because hydrophone data are large and require significant storage capacity, there may be times when the data collection is not continuous. What intervals can/should be used? Can we cut out 50% of the data by collecting for a minute and shutting down for a minute? Perhaps a 5 minute interval is more appropriate. At the end of the proposed data collection we should be able to answer these questions as well as provide a calibration for the hydrophone system in small streams.
This project builds on knowledge gained over the past three years of investigation. Recent research funded by the Science and Technology Program (#4864) has advanced the state of the science for measuring bedload with hydrophones. Lab and field deployments have provided answers to questions previously unexplored in this field through collaboration among Reclamation offices, other federal agencies, universities, and private consultants. The research has matured to the point where a field-deployable hydrophone system has been designed and fabrication will be completed in time for testing and calibration during spring runoff in 2015.

Need and Benefit

Measuring bedload in streams and rivers is extremely difficult, can pose a significant safety risk during floods, is very costly, and cannot be done continuously using classic methods. There are currently few research projects investigating the continuous measurement of fluvial bedload using surrogate technologies, although there is a significant parallel effort for measuring suspended sediment loads. Classic means for physical measurements of river sediment also show the same disparity, with only two bedload samplers approved by the Federal Interagency Sedimentation Project (FISP) and over a dozen samplers approved for measuring suspended sediment.
Coarse sediment is largely responsible for a river's form and much of its ecological function. Additionally, coarse sediment comprises a significant amount of delta material in reservoirs. Because the transport and fate of coarse sediment has a significant impact on ecology, riparian infrasrtucture, and reservoirs it is imperative that we are able to obtain an increased understanding through continuous, accurate measurements.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Field Testing and Calibration of a Hydrophone System for Surrogate Bedload Measurement (final, PDF, 1.6MB)
By Robert Hilldale
Publication completed on September 30, 2015

Past research by this team to correlate the movement of coarse bed load with acoustic signals from a hydrophone has shown positive results. However, we are beginning to better understand the challenges facing us regarding the acoustic field and propagation of acoustic signals in a fluvial environment. Past data collection for bed load has taken place on medium sized rivers, where hydrophone deployment is difficult. In our latest effort, we have measured bed load and recorded self-generated noise from gravel particle collisions in Halfmoon Creek, a small stream near Leadville, CO. Physical bed load measurements were collected across the channel using Bunte bed load traps and acoustic data were collected 1 meter upstream for correlation. Additional information was gathered regarding the acoustic environment in Halfmopn Creek. This report details the data collection of both physical bed load measurements and acoustic data. Preliminary conclusions are included however the data are still being analyzed for a correlation between acoustic data and physical bed load measurements. Future plans are included at the end of the document

The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.

Listening to Bed Load (final, PDF, 416KB)
By Robert C. Hilldale (PI)
Publication completed on September 30, 2016

This bulletin summarizes the research results and potential application to Reclamation's mission.

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Last Updated: 6/22/20