Climate change impacts on reservoir operations in the Columbia River Basin

Matthew Morrow McDonald

Research conducted in this study explores the implications of climate change on reservoir operations and management in the Columbia River basin. With around 70% of the Pacific Northwest's power supplied by hydroelectric facilities, consideration of the potential impacts on this supply due to a changing climate is crucial. In addition, climate change can alter flood storage capability and refill of reservoirs. Much of the hydropower generation and flood control in the region results from provisions outlined in the Columbia River Treaty between the United States and Canada. Changes to the treaty could take effect as early as 2024 with notice given by 2014, so reservoir managers are currently examining possible changes in operations under a new treaty. For this analysis, Libby Dam in the state of Montana was used as a case study to determine how flood storage, power generation, and other operational objectives could be impacted by changes in future climate. A simulation model of the dam was constructed using HEC-ResSim from the U.S. Army Corps of Engineers and used to examine potential changes in v the dam's operational objectives. Streamflows resulting from a set of climate scenarios for the 2020s and 2040s were used to drive the model and test the sensitivity of different objectives to climate change. Results indicated changes in the ability to meet operational objectives are imminent. In general, shifts in streamflow often resulted in exceeding reservoir target elevations during spring. The potential for hydropower generation significantly increased throughout spring and decreased throughout summer. Overall, the 2020s scenarios resulted in a 3% increase in average generation during winter months and a 7% decrease during summer months. On a yearly basis, generation increased by an average of nearly 8%. By the 2040s, a 5% increase in average generation during winter months and a 14% decrease during summer months was seen, with an average yearly increase of approximately 9%. Due to uncertainty in future climate and its impact on water timing and availability, this work has shown that impacts on reservoir operations are foreseeable. Flexibility in reservoir operations will ultimately be required to adapt to such effects.

Climate change impacts on reservoir operations in the Columbia River Basin

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