Bureau of Reclamation Banner

Investigation of Climate Change Impact on Reservoir Capacity and Water Supply Reliability

Project ID: 8990
Principal Investigator: Paula Makar
Research Topic: Water Resource Data Analysis
Priority Area Assignments: 2010 (Climate Change and Variability Research), 2011 (Climate Change and Variability Research)
Funded Fiscal Years: 2010 and 2011
Keywords: None

Research Question

This research aims to investigate methods to assess the effects of climate change on reservoir sedimentation.

* How is projected climate change expected to affect watershed sediment yield?

* How would changes in sediment yield affect rate of reservoir sedimentation and associated lost storage capacity?

* How might these latter effects interact with hydrologic (water supply) impacts to ultimately affect water delivery reliability?

The research aims to assess the effects of climate change on reservoir sedimentation. Reservoir sediment supply depends on the sediment sources from the upland areas and flows to erode and transport them. Foreseeable perturbations to the hydrological condition caused by climate change are expected to change future sediment supply, thus affecting the life expectancy of a reservoir. Such impacts, in conjunction with climate change impacts on reservoir inflow patterns, could affect future operations and water delivery reliability.

A parallel effort by the U.S. Army Corps of Engineers (Corps) and Reclamation is planned. Two basins will be selected with Corps and Reclamation reservoirs in each basin. Preliminary Reclamation reservoir selections are: 1. Bighorn Lake in Montana and Wyoming, and 2. Elephant Butte Reservoir in New Mexico. Preliminary Corps reservoir selections are: 1. Garrison Reservoir in North Dakota, and 2. Cochiti Reservoir in New Mexico.

Need and Benefit

Reservoir sediment supply depends on the sediment sources from the upland areas and flows to erode and transport them. Foreseeable perturbations to the hydrological condition caused by climate change are expected to change future sediment supply, thus affecting the life expectancy of a reservoir. Such impacts, in conjunction with climate change impacts on reservoir inflow patterns, could affect future operations and water delivery reliability.

One of Reclamation's primary purposes is to store water in our reservoirs for use by irrigation districts, downstream communities, recreationalists, fish and wildlife, and many others. Water supply management for beneficial uses is also an authorized purpose at many Corps reservoirs. The availability of the stored water is largely dependent upon the inflows to the reservoirs and the amount of sediment accumulations that can rob the reservoir of valuable storage space.

Estimates of sediment accumulations for each reservoir are made during the final engineering assessments, previously called Definite Plan Reports. Throughout the life of the reservoir, periodic sediment resurveys are undertaken to re-evaluate the rate of sediment accumulation in the reservoir.

Climate change and reservoir sedimentation can each act to reduce the reliability of the reservoir water supply. Increased hydrologic variability will lead to more floods and droughts, even if the long-term mean reservoir inflow remains the same. The increased flood intensity will deliver more sediment to the reservoir. The increased drought severity and reservoir sedimentation will result in less reservoir storage capacity. Increases in sedimentation rates could seriously affect the users of the reservoirs. The decrease in available reservoir storage over time could reduce the ability of Reclamation and Corps to provide a firm annual yield to users each year. This could affect the repayment contracts with the districts and all other facets of reservoir use.

A parallel effort by the Corps and Reclamation is planned with separate funding by each. Two basins have been selected with Corps and Reclamation reservoirs in each basin. Reclamation reservoir selections are: 1. Bighorn Lake in Montana and Wyoming, and 2. Elephant Butte Reservoir in New Mexico. Corps reservoir selections are: 1. Garrison Reservoir in North Dakota, and 2. Cochiti Reservoir in New Mexico. This research will:

* Feature a period-change approach to the climate and hydrologic analysis, but in a novel manner that still incorporates ensembles of climate projection within each of the study basins. Hydrologic analyses use applications of the Variable Infiltration Capacity (VIC) hydrologic model.

* Calibrate reservoir inflow sediment rating curves to match the sediment loads with historical reservoir survey data.

* Apply existing operations models to assess how projected hydrology and reservoir sedimentation would impact on water delivery reliability under otherwise existing operating conditions.

* Prepare a peer-reviewed journal article describing the methodology for reservoir sedimentation analysis under climate change and the implications for water delivery reliability in the case study basins.

By evaluating the influences of global climate change on the timing and flow volume of the inflows and the sediment transported, Reclamation and Corps could provide invaluable information to their users on the availability of reservoir storage content.

In summary, there is a need to understand how climate change may affect reservoir sedimentation and the resulting impacts on water resources.

Contributing Partners

Albuquerque Area Office, Upper Colorado Region
Great Plains Regional Office, Great Plains Region
U.S. Army Corps of Engineers, Department of Defense

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.

Investigation of Climate Change Impact on Reservoir Capacity and Water Supply Reliability (final, PDF, 17KB)
By Jianchun Victor Huang
Research Product completed on May 22, 2014

This study investigates the impacts of projected climate changes on flow and sediment loads into reservoirs. This is a joint research between the Bureau of Reclamation (Reclamation) and the United States Army Corps of Engineers (USACE). Reclamation selected Bighorn Lake in MT and WY and Elephant Butte Reservoir in NM. USACE selected Garrison Reservoir in ND and Cochiti Reservoir in NM.
Keywords: reservoir sedimentation

This information was last updated on July 22, 2014
Contact the Research and Development Office with questions or comments about this page