Start Date
2-11-2019 3:20 PM
End Date
2-11-2019 3:30 PM
Abstract
The stable isotopic composition of surface water (δ18O and δD) is used extensively to constrain water evolution throughout the hydrologic cycle. The isotopic composition of meteoric water varies globally based on latitude, elevation, distance from its source, and environmental conditions during and after precipitation. Existing data show that the isotopic signatures of the Willamette and Columbia Rivers are distinct from one another with δ18O values of approximately -10.5‰ and -16.2‰ respectively. Sauvie Island lies at the confluence of these two rivers. It is an 84.8 km2 floodplain containing wetlands, channels, and lakes. I collected water samples throughout the region, including sites upstream of the confluence, downstream, and across Sauvie Island itself. The isotopic composition of collected samples was analyzed to develop a mass-balance model that shows how the rivers mix throughout the study area. Analysis of Sturgeon Lake water samples from Sauvie Island constrain the effect of evaporation on the isotopic composition of river wetlands. This study improves our understanding of the interaction between the Columbia and Willamette Rivers, providing a foundation for future studies of river dynamics along a critical transportation corridor in the Pacific Northwest.
Subjects
Geology, Hydrology
Persistent Identifier
https://archives.pdx.edu/ds/psu/33802
Rights
© Copyright the author(s)
IN COPYRIGHT:
http://rightsstatements.org/vocab/InC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
DISCLAIMER:
The purpose of this statement is to help the public understand how this Item may be used. When there is a (non-standard) License or contract that governs re-use of the associated Item, this statement only summarizes the effects of some of its terms. It is not a License, and should not be used to license your Work. To license your own Work, use a License offered at https://creativecommons.org/
Mixing of the Willamette and Columbia Rivers across Sauvie Island, Oregon based on stable isotopes (δ18O and δD) of surface water
The stable isotopic composition of surface water (δ18O and δD) is used extensively to constrain water evolution throughout the hydrologic cycle. The isotopic composition of meteoric water varies globally based on latitude, elevation, distance from its source, and environmental conditions during and after precipitation. Existing data show that the isotopic signatures of the Willamette and Columbia Rivers are distinct from one another with δ18O values of approximately -10.5‰ and -16.2‰ respectively. Sauvie Island lies at the confluence of these two rivers. It is an 84.8 km2 floodplain containing wetlands, channels, and lakes. I collected water samples throughout the region, including sites upstream of the confluence, downstream, and across Sauvie Island itself. The isotopic composition of collected samples was analyzed to develop a mass-balance model that shows how the rivers mix throughout the study area. Analysis of Sturgeon Lake water samples from Sauvie Island constrain the effect of evaporation on the isotopic composition of river wetlands. This study improves our understanding of the interaction between the Columbia and Willamette Rivers, providing a foundation for future studies of river dynamics along a critical transportation corridor in the Pacific Northwest.