The short version: Climate change is expected to affect temperature and precipitation in the Pacific Northwest and change the region’s hydrology. This web site provides streamflow information for the Columbia River and coastal drainages in Washington and Oregon State for the 21st century based on a large number of climate scenarios and model experiments. Detailed information about the study can be found under Documentation, while model results can be found under Data. The project team consisted of researchers in the UW Hydro | Computational Hydrology research group at the University of Washington and the Oregon Climate Change Research Institute at Oregon State University.
The slightly longer version: The Pacific Northwest presents a mosaic of regional hydro-climates. While for many it conjures images of snow-capped peaks, emerald forests, and roaring rivers, it is also home to open plains and inland deserts. Water availability in our region affects local ecosystems, energy generation, water supply, fisheries, agriculture, navigation, and recreation.
The Columbia River, which drains much of the Pacific Northwest, is the fourth-largest river by volume in the United States. Hydroelectric facilities on its main stem and tributaries are responsible for nearly half of total U.S. hydroelectric power generation. Pacific Northwest rivers are also home to anadromous fish, such as salmon, that sustain environmentally, economically, and culturally important fisheries. Northwest rivers provide irrigation water for economically valuable crops and support barge transportation on the lower reaches of the Snake and Columbia Rivers. Northwest forests have important ecological functions and provide lumber and other natural products. Water-dependent recreational activities range from fishing and boating to downhill and cross-country skiing.
These competing uses can result in conflict at times. For example, as a result of habitat degradation, dam construction, reservoir operation, and other interventions, many salmon, trout, and sturgeon populations in the Pacific Northwest are now listed as threatened or endangered. With a rapidly increasing human population in the Pacific Northwest, careful management of water resources is necessary to ensure that the Columbia and other northwest rivers can support a diverse range of uses for the decades to come, from power generation to fisheries, and from recreation to ecosystem services. To this end, Pacific Northwest natural resources agencies and water managers need information about future patterns of water availability in the region, both in time and space.
Much of the Pacific Northwest experiences dry summers and wet winters. Combined with our mountain ranges and generally cold winters east of the Cascades, this winter-dominant precipitation regime has historically resulted in large amounts of snow (Mount Baker still holds the unofficial world record for the greatest recorded snowfall in a single season). Hydrologically, the snow pack acts as a large reservoir, retaining moisture during the winter and releasing it in spring and summer when rainfall amounts in the Pacific Northwest are low.
Climate change can affect the hydrology of the region in a number of ways. Even without changes in precipitation, changes in temperature will affect snow accumulation and melt. Temperature increases will result in more rainfall in winter, less water stored as snow, and earlier melt of these thinner snow packs. For some rivers, peak flows may no longer occur in spring, but may occur in fall and winter instead. Warmer summers may increase drought conditions, especially if less spring and summer runoff is available from mountain snow packs. Changes in precipitation may alleviate or worsen some of these impacts.
This web site provides streamflow information for the Columbia River and coastal drainages in Washington and Oregon State for the 21st century based on a large number of climate scenarios and model experiments. Detailed information about the study can be found under Documentation, while model results can be found under Data. The project team consisted of researchers in the Computational Hydrology group at the University of Washington and the Oregon Climate Change Research Institute at Oregon State University.
The River Management Joint Operating Committee released a report on the general findings of the study, which provides a synopsis of methods as well as results for different regions around the Pacific Northwest.
Funding: This study was partly funded by the Bonneville Power Administration as part of its Technology and Innovation Program (project BPA TIP304 to the University of Washington and Oregon State University), with additional funding to the University of Washington from the United States Bureau of Reclamation and the United States Army Corps of Engineers.
Acknowledgements: While the data sets produced as part of this study are the responsibility of the project teams at the University of Washington and Oregon State University, many people provided input and evaluated successive data set versions. We would like to acknowledge the contributions of the following persons and groups: the UW Hydro | Computational Hydrology Group at the University of Washington, in particular Joe Hamman, Yixin Mao, Mu Xiao (now at UCLA), and Katie Knight; Naoki Mizukami and Martyn Clark at the National Center for Atmospheric Research, Research Applications Laboratory for providing VIC model parameters; Shih-Chieh Kao, Bibi Naz, and Moetasim Ashfaq at Oak Ridge National Laboratories for providing VIC model parameters and dynamically downscaled meteorological data; Ming Pan at Princeton University for providing code and guidance for VIC model calibration; Katherine Hegewisch and John Abatzoglou at the University of Idaho for help with the MACA downscaling method; Eric Salathé for providing code and guidance for the BCSD downscaling method; the members of the technical review team, including Bruce Glabau, Kari Hay, Mariano Mezzatesta, Arun Mylvahanan, Eric Nielsen, Erik Pytlak, Nancy Stephan, and Rick van der Zweep at the Bonneville Power Administration; Pete Dickerson, Keith Duffy, Chris Frans, Jeremy Giovando, Kristian Mickelson, and Jason Ward at the United States Army Corps of Engineers; Bob Lounsbury, Jennifer Cuhaciyan, and Jennifer Johnson at the United States Bureau of Reclamation; and the participants in the many RMJOC-II Transboundary Workshops.
