First Advisor
Stefan A. Talke
Date of Award
Summer 2017
Document Type
Thesis
Department
Civil and Environmental Engineering
Language
English
Subjects
Hydrology -- Oregon -- Columbia River, Water temperature -- Columbia River, Streamflow -- Columbia River, Anadromous fishes, Pacific salmon -- Effect of water temperature on
DOI
10.15760/honors.482
Abstract
The Columbia River is home to anadromous salmon populations that migrate upriver every year to spawn. These fish require cool water temperatures (Tw) to survive. In recent years, high summer Tw in the Columbia River has caused increased mortality of salmon. Different possible explanations for increased Tw include climate change, deforestation, and decreased summertime streamflow (Q) due to dams. In this study, robust linear regression models of Tw based on air temperature (Ta) and Q were developed to examine the change in Tw over time. The data was separated into an historical period (1938-1956) and a modern period (1977-2003). Seasonal regression models were used for May through October (summer) and November through April (winter) for each period. Comparison of these models showed that Tw has become less sensitive to recent atmospheric heating and cooling. By contrast, analysis suggested that Tw has become more sensitive to variations in Q. Of the 1.5ºC increase in maximum summertime Tw, approximately 1.3ºC was due to dams and reservoir management based on changes in regression coefficients and average Q. A smaller, 0.2ºC change was estimated to be caused by increasing Ta since the mid-20th century. While average maximum Tw has increased, both the statistical model and data suggest that the variability in Tw from its climatological average has decreased, probably due to reservoir management.
Rights
© 2017 Corina Christina Mae Overman
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Persistent Identifier
http://archives.pdx.edu/ds/psu/22528
Recommended Citation
Overman, Corina Christina Mae, "A Statistical Investigation of Lower Columbia River Water Temperature, 1915-2003" (2017). Civil and Environmental Engineering Undergraduate Honors Theses. 8.
https://doi.org/10.15760/honors.482
Comments
A thesis submitted in partial fulfillment of the requirement for the degree of Bachelor of Science with Departmental Honors in Civil and Environmental Engineering.