Using Fall Streamflows as Predictors of Spring Runoff at the Dalles, Oregon

by Michael A. Deatherage-Newsom, Bonneville Power Administration, Portland, OR, USA,
Kenneth M. Dragoon, Bonneville Power Administration, Portland, OR, USA,

Document Type: Proceeding Paper

Part of: Water Power '87


The Northwest hydropower system is characterized by a drawdown season when normally full reservoirs are drafted to meet firm obligated loads, and a refill season in which the reservoirs are filled with spring runoff. The drawdown season generally begins in August or September and the refill season ends in August. January 1 snowpack forecasts give system operators information about how deeply reservoirs may be drafted in spring (January through July) without significantly jeopardizing their ability to refill by August. These target reservoir drafts determine how much hydro energy to make available for thermal displacement, or for nonfirm sales out of the region. Historical streamflow data at The Dalles, Oregon indicate that when fall streamflows over a certain magnitude occur, the following spring season will have sufficient streamflows to refill the reservoir system and produce at least 10,000 MW-mos of power in excess of firm obligated loads (nonfirm power).

Subject Headings: Streamflow | Runoff | Hydro power | Seasonal variations | Reservoirs | Electric power | Drawdown (hydrology) | Load factors | Oregon | United States

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