Field deployment of a continuous suspended sediment load surrogate

Authors: AUBUCHON, JONATHAN - Us Army, Ccdc Chemical Biological Center; POSNER, ARI - Bureau Of Reclamation; CARPENTER, WAYNE - University Of Mississippi

Submitted to: Government Publication/Report
Publication Type: Government Publication
Publication Acceptance Date: 1/12/2020
Publication Date: 1/25/2020
Citation: Aubuchon, J., Posner, A., Carpenter, W. 2020. Field Deployment of a Continuous Suspended Sediment Load Surrogate. Government Publication/Report. ST-2016-7839-1, p. 1-104.

Interpretive Summary: The transport of sediment in rivers is a critical question for managers concerned with river restoration, irrigation and water diversion projects, and water quality. To understand the relationship between water and sediment requires the collection of data. How sediment is transported in rivers, through irrigation facilities, and into reservoirs is a growing area of interest for Reclamation managers. Over the decades, the techniques for collecting sediment data have been refined, and more recently surrogate techniques have allowed more rapid data collection. One of the more promising suspended sediment surrogate technologies is active acoustics, which has been successfully tested in a variety of environments, including gravel and sand bed rivers. The majority of the testing on the sand bed rivers has been in large rivers, like the Colorado or the Green, that have sufficient depth of flow to separate out the effects of bed load and suspended load. Testing on shallow sand bed rivers has been limited to areas where the local geology provides a sufficient flow depth at various discharge stages. But what if the local geology doesn't afford this opportunity? Will acoustic techniques still work? Can these acoustic setups capture continuous suspended sediment load information over the range of expected discharge? The premise of the research was that the Middle Rio Grande (MRG) is an ideal testing ground to answer these questions. The high suspended sediment load of uncontrolled tributaries to the Rio Grande also allowed examination of the upper limitations for suspended sediment concentration measurements with the acoustical instruments.

Technical Abstract: Rivers have captured our imagination for centuries. The relationship between the movement of water and sediment create complexities that refresh our souls, pique our interest, and demand our attention. The study and understanding of complexities, such as sediment transport, requires the collection of data. Over the decades, the techniques for collecting sediment data have been refined and more recently surrogate techniques have expanded the temporal range of the collected data. One of the more promising surrogate technologies is active acoustics, which have been successfully tested in a variety of fluvial environments, including gravel and sand bed rivers, where morphological changes are minimal. Application of this technology to shallow sand bed rivers though has been limited to areas where the local geology provides a sufficient flow depth at various discharge stages and the local morphology is stable. A site was identified on the Middle Rio Grande that provided the opportunity to explore the robustness of the developed technology in recording continuous suspended sediment data in an environment where the morphology is not stable. Challenges were present in implementation of the developed technology, but with some caveats the developed technology can be utilized in shallow sand rivers with changing morphology.