Climate change impacts on two high-elevation hydropower systems in California


This paper describes research to estimate the effects of climate change on two high-elevation hydropower systems in California: the Upper American River Project, operated by the Sacramento Municipal Utility District, and the Big Creek system, operated by Southern California Edison. The study builds on a previous model of the Upper American River Project, which is here modified and extended for use to simulate two hydropower systems under various conditions. Future operations of the two high-elevation systems are simulated using climate change scenarios provided for the Second California Assessment. These scenarios suggest reduced precipitation and reduced runoff for both systems, and a shift toward runoff earlier in the year. The change in the hydrograph is somewhat greater for the Upper American River Project system, because its basins lie at a lower elevation. Reduced runoff directly reduces energy generation and revenues from both systems. Because the Upper American River Project system is projected to have greater spills with warmer climate conditions, it also has greater reduction in energy generation and revenues. Both systems continue to meet peak historical power demands in summer under most climate projections. However, if the number of heat waves increases in the late summer (September), reservoir operating strategies may need to be modified.

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We would like to acknowledge Kevin Cini and Tom Watson from Southern California Edison, Scott Flake and Dudley McFadden from Sacramento Municipal Utility District, and Guido Franco from the California Energy Commission. Funding for this project came from the Public Interest Energy Research (PIER) Program of the California Energy Commission (Project No. MR-07-03A).

This paper was prepared as the result of work sponsored by the California Energy Commission (Energy Commission) and the California Environmental Protection Agency (Cal/EPA). It does not necessarily represent the views of the Energy Commission, Cal/EPA, their employees, or the State of California. The Energy Commission, Cal/EPA, the State of California, their employees, contractors, and subcontractors make no warrant, express or implied, and assume no legal liability for the information in this paper; nor does any party represent that the uses of this information will not infringe upon privately owned rights. This report has not been approved or disapproved by the Energy Commission or Cal/EPA; nor has the Energy Commission or Cal/EPA passed upon the accuracy or adequacy of the information in this paper.

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Vicuña, S., Dracup, J.A. & Dale, L. Climate change impacts on two high-elevation hydropower systems in California. Climatic Change 109, 151–169 (2011).

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  • Climate Change Scenario
  • Annual Runoff
  • Variable Infiltration Capacity
  • Independent System Operator
  • Reservoir Release