Projections of climate change impacts on hydrology in the Pacific Northwest region of the USA

Mar 26, 2010 (Last modified Jul 13, 2010)
Created by Dominique Bachelet
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Description
The map of change in summer runoff between 1913 and 2003 shows a decrease in in the Olympic Peninsula and The Cascades. This can due to a decrease in precipitation or an increase in evaporation due to warming air temperatures and increasing vapor pressure deficit. It could also be due to increase retention (creation of reservoirs ex).
The next map of change in runoff between 1950 and 2050 shows again a decrease in runoff on the Peninsula and the Cascades north of Seattle.
The next GIS layer showing the proportion of precipitation as snow shows that the decrease in runoff occurs in places where stream are snowfed. A decrease in snowpack would decrease streamflow and runoff. The Climate Impacts Group in Seattle has in fact published maps of the decline in snowpack in Washington state.
Finally, projections of stream temperatures show examples of good conditions (green) for stream water that still persist at high elevations to dangerous (yellow) or even lethal (red, water too warm) for salmonids. The increase in stream temperature can occur due to the loss of shading when riparian vegetation is eliminated but also when streamflow decreases (decrease in the volume of water, greater warming by sunlight) due to for ex. a decrease in snowpack for snowfed streams or reduction in groundwater discharge (cold) due to a decrease in recharge (decrease precipitation) or an increase demand (urbanization, industry).

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Dominique Bachelet
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Creative Commons LicenseThis work is licensed under a Creative Commons Attribution 3.0 License.
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About the Map Author

Dominique Bachelet
climate change scientist with Oregon State University

Dominique received her Master’s degree in 1978 in Lille (France) and her Ph.D. in 1983 from Colorado State University with a thesis focused on biogeochemical cycles in the shortgrass prairie. In 1984 she went to U.C. Riverside as a postdoc simulating nitrogen fixing shrubs in the Sonoran desert then...