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Sound BASIS for Relating Sediment Flow, Stream Health

In their version of "keeping an ear to the ground," scientists at the Agricultural Research Service's National Sedimentation Laboratory in Oxford, Miss., are finding ways to diagnose watershed health and stability by keeping a high-tech "ear" in the water.

ARS hydraulic engineer Roger Kuhnle is leading efforts at Oxford to use updated acoustic technology to monitor concentrations of sediment flow within water systems. With this technology, he's "listening" for clues that could indicate changes--and problems--in these water systems.

The project is being done with the University of Mississippi on a model stream channel at the lab's Channel and Watershed Process Research Unit and in nearby Goodwin Creek.

The project has led to development by the university, in collaboration with ARS, of the Bedform and Sediment Information System (BASIS). This monitoring method emits a pulse of acoustic energy and gauges the strength and travel time of the echo to detect and measure sediment's location and concentration.

Like its predecessor, BASIS locates sediment on a stream's bottom, which can indicate sediment erosion or accumulation. But what makes the new system novel is that it can also detect sediment suspended in water.

BASIS converts acoustic data into a digital image showing suspended sediment as a cloud, in a multitude of colors signifying concentrations. Its main unit is compact, and the entire system can run remotely from a laptop computer.

Accurate determinations of sediment flow are needed because sediment can reduce reservoir capacity, fill channels and cause flooding, degrade water quality and destabilize channel banks. Researchers say physical, chemical and biological damage associated with sediment flow in North America costs around $16 billion annually.

Kuhnle says BASIS technology is now available for use by private firms and government agencies. More sophisticated technology for total suspended-sediment load sampling should become available after up to five more years of experimentation and testing.

Read more about this research in the October 2003 issue of Agricultural Research magazine.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.