Pilot Studies of Reservoir Sustainability Options - Large Reservoirs

Project ID: 9344
Principal Investigator: Robert Hilldale
Research Topic: Sediment Management and River Restoration
Funded Fiscal Years: 2016, 2017 and 2018
Keywords: None

Research Question

How can we develop tools and the means to manage sediment in reservoirs that cannot be drawn down to sluice
or flush sediment? Particularly, using at least one location for a pilot study, how can we improve the planning and
process of implementing reservoir sustainability options where the reservoir water surface elevation remains at
normal operating levels?
This study builds upon the research project titled 'Developing Guidelines for Formulating Reservoir Sustainability
Plans' Project ID 6080, from Fiscal Years 2013 and 2014 (funded by the S&T Program), where a framework of the
process of defining available options, new potential alternatives, and additional needs to achieve reservoir
sustainability were developed.
Based on the outcomes of 'Formulating Guidelines for Formulating Reservoir Sustainability Plans', options to be
evaluated and learned are dredging, venting turbid density, and other methods that manage sediment while
keeping a reservoir at normal storage levels.

Need and Benefit

Reservoir sedimentation will eventually impact all facilities located on a waterbody that naturally transports
sediment. The urgency of mitigating the impacts of sedimentation on reservoir storage and dam operations is
often stifled by the hidden nature of the problem. Regardless of volume or extent, reservoir sediment deposits
often cannot be seen through the water by the naked eye and are therefore ignored. Failure to measure or
estimate sediment inflow or deposition rates can result in severe impacts including the loss of reservoir storage
capacity, power generation down-time, burial of outlet works, burial of recreational facilities, downstream erosion,
and habitat loss in the reservoir and in downstream rivers..
Taking a proactive approach in developing a reservoir sedimentation management strategy for Reclamation
reservoirs will help avoid loss of project benefits and expensive retirement options. The annual cost to manage
inflowing reservoir sediment is much less than the cost of trying to recover decades of past reservoir
sedimentation. The 'no action' strategy to reservoir sediment management will eventually lead to the retirement of
Reclamation reservoirs that no longer provide water storage benefits. A proactive and sustainable approach to
reservoir sediment management would mean that a reservoir would be able to provide project benefits
A sustainable sediment management strategy would require upfront and continual operational and maintenance
costs (including monitoring), but these continual costs can be feasible and significantly lower than the final costs
associated with dam decommissioning. Methods and alternatives identified and developed by this research will
help determine future possible outcomes for any Reclamation facilities and reservoirs owned by other entities that
may be impacted by reservoir sedimentation impacts.
Options such as dredging and/or venting turbid density currents is an option in a suite of sustainable sediment
management strategies, and is key in keeping a large reservoir full during extended periods of drought and
maintaining reservoir storage.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Please contact research@usbr.gov about research products related to this project.

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Last Updated: 6/22/20