Fluvial suspended sediment characteristics by high-resolution, surrogate metrics of turbidity, laser-diffraction, acoustic backscatter, and acoustic attenuation
Landers, Mark Newton
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Sedimentation (erosion, transport, and deposition) is a primary and growing environmental, engineering, and agricultural issue around the world. However, collection of the data needed to develop solutions to sedimentation issues has declined by about three-fourths since 1983. Suspended-sediment surrogates have the potential to obtain sediment data using methods that are more accurate, of higher spatial and temporal resolution, and with less manually intensive, costly, and hazardous methods. The improved quality of sediment data from high-resolution surrogates may inform improved understanding and solutions to environmental, engineering, and agricultural sedimentation problems. The field experiments for this research includ physical samples of suspended sediment collected concurrently with surrogate metrics from instruments including 1.2, 1.5, and 3.0 megahertz frequency acoustic doppler current profilers, a nephelometric turbidity sensor, and a laser-diffraction particle size analyzer. This comprehensive data set was collected over five storms in 2009 and 2010 at Yellow River near Atlanta, Georgia. This research project has proposed, developed, and tested a new method for evaluation of sediment size from theoretical acoustic attenuation; evaluated and further developed recently introduced empirical methods for estimating acoustic attenuation by sediment; found and quantified data mischaracterization issues for laser-diffraction metrics; defined deterministic causes for observed hysteresis and variance in suspended sediment to surrogate relations; compared the accuracy of sediment concentration models and loads for each tested surrogate; and compared sediment surrogate technologies on the basis of reliability and operational considerations.