State Water Resources Research Institute Program

Project ID: 2008OR102B
Title: Effects of sediment barrier removal on geomorphic complexity and habitat
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2009
Congressional District: 5th
Focus Categories: Geomorphological Processes, Floods, Hydrology
Keywords: culvert replacement, barrier removal, habitat,
Principal Investigator: Tullos, Desiree D. (Oregon State University)
Federal Funds: $ 9121
Non-Federal Matching Funds: $ 42309
Abstract: People have tended to focus on dams and culverts as barriers to fish passage, but the need to evaluate them as barriers to downstream sediment passage and as geomorphological control points is also important. It is currently unclear whether changes in channel morphology that occur upstream and downstream of the former barrier may hinder (e.g. channel incision and disconnection of the channel from its floodplain) or benefit (e.g. increase local scour and deposition thus creating greater geomorphic and habitat diversity) ecological integrity. Therefore, we propose a field-based study to address hypotheses regarding the processes of channel adjustment and success of predictive tools for forecasting likely channel responses to sediment barrier removal. We will compare pre- and post-removal changes through field surveys of the channel, sediments, and habitats before and after a culvert (Oak Creek) replacement and a small dam (Brownsville) removal. By testing hypotheses about the role of changing sediment supply (via dimensionless bedload transport ratio, Shield's stress, competent median grain size relative bed stability) on habitat diversity (via SHDI, RBS, grain size variability, EMAP habitat scores, and ODFW habitat scores), recommendations can be made regarding the need for (or redundancy of) structural controls (e.g. large wood, boulders) to encourage channel complexity in future culvert and small dam removals. Thus, results of this project will contribute to knowledge regarding how restoration resources can be balanced for the long term. In addition to training opportunities for undergraduate students, we will be developing baseline information as a long-term teaching resource for Tullos' River Engineering course. Results will be communicated through a variety of channels, including preparation of a manuscript for submission to a refereed journal, presentation at scientific meetings and informal seminars, and other informal outlets (e.g., online publication of annotated bibliography and project web page).

Progress/Completion Report, PDF

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