CONICET | Buscador de Institutos y Recursos Humanos

A software tool has been developed and is currently undergoing testing for using acoustic backscatter from commercially available acoustic Doppler current profilers (ADCPs) as a surrogate for suspended sediment concentration (SSC). This tool requires the use of suspended sediment profiles at one or more locations in the river along with concurrent or nearly-concurrent ADCP acoustic backscatter data. The goal of this work is to explore techniques that would allow acoustic backscatter from moving boat ADCP transects to be used to reliably compute suspended sediment transport in a cross section. This tool is currently being evaluated with data from numerous sites in Illinois and Washington. The data consist of concurrent measurements of acoustic backscatter from a down-looking 1200 kHz ADCP and suspended sediment profiles from a composite of P-61 point samples and LISST measurements. For each measurement, a calibration is developed with a stationary profile and then applied to cross section data. Cross section plots are created showing SSC and sediment load at the same resolution as ADCP velocity data. Preliminary analyses indicate a good calibration between acoustic backscatter from down-looking ADCPs and SSC that is repeatable at different sites in a range of fluvial environments. Standard methods for measuring SSC in rivers are time-consuming, relatively expensive, and have limited spatial and temporal resolution, but it is shown that this technique resolves spatial and temporal variation in SSC that is far beyond what can be done with traditional physical samplers. Additionally, since ADCPs are used routinely for streamflow measurements, using acoustic backscatter from ADCPs as a surrogate for SSC has the potential to revolutionize sediment measurements by providing rapid measurements of sediment flux and distribution in space and time.

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