Reservoir Debris Management

Project ID: 4781
Principal Investigator: Sean Kimbrel
Research Topic: Sediment Management and River Restoration
Funded Fiscal Years: 2016
Keywords: None

Research Question

Are there new technologies or could new technologies be developed to manage and deal with woody debris to
improve of the capability of passing sediment through grated outlet works intakes?
Many dam in Reclamation's inventory and likely abroad in the US are not designed to pass woody debris that
floats and deposits in reservoirs as the reservoirs fill with sediment. During low reservoir levels or periods when
sediment arrives to an outlet works or hydropower intake, woody debris that is large enough can rack on grated
intakes. What can happen next is reservoir sediment deposits behind the racked members, beginning the process
of limiting sediment passage during flushing and sluicing, and increasing the potential for eventual burial of the
intake.
This type of phenomenon was observed at Paonia Reservoir in Summer/Fall 2014 during drawdown of the
reservoir, and had to be manually cleaned out by laborers to re-open the outlet works intake. This same process
will eventually affect all reservoirs when sediment arrives to the outlet works or hydropower intake.

Need and Benefit

Reservoir sedimentation is impacting all Reclamation (and other public and private) facilities that transport
sediment (river, streams, hillsides) to various extents, some being more extreme. 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 future 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.
Developing a knowledge base and new technologies to deal with reservoir wood debris that inhibits the passage
of sediment downstream is key in reducing the need to re-design outlet works to pass both sediment and debris
downstream, which is a benefit to dam owners and users that would have the burden of retrofitting their dam to
pass sediment downstream.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Reservoir Debris Management (final, PDF, 1.5MB)
By Sean Kimbrel
Publication completed on September 30, 2016

A literature review was performed on how to assess and mitigate against the effects of waterlogged debris at hydraulic control structures. The best source of information was a document written for the Army Corps of Engineers in 1997 known as "Debris Control at Hydraulic Structures in Selected Areas of the United States and Europe" (Wallerstein et al., 1997). This study mainly focused on the management of floating debris at reservoirs, and at lock and dam facilities. Many options were given for the containment of floating debris, but less so for submerged and waterlogged debris. Recommendations for submerged debris management options are included in the final section of the report.

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Last Updated: 6/22/20