Location
Agriculture Science Theater, Oregon State University
Start Date
27-6-2013 1:30 PM
End Date
27-6-2013 1:50 PM
Description
Roughened channels are man-made fish passage structures which are used to retrofit passage through culverts, over dams and other structures. They differ from natural channel designs in that they are usually steeper and/or narrower than adjoining channels. Other names often used with Roughened Channels include rock ramps, step/pool channels, etc. Roughened channel design is different from stream simulation or rock weir drop structures. Stream simulation is more of a reference reach/ geomorphic design process, where fish passage is assumed based on the presence and long term stability of maintaining a natural channel. For rock weirs fish passage is a function of fish leaping over a weir with a plunge pool. For roughened channels, there may be resting areas, but fish usually swim to pass utilizing a low velocity boundary layer either near the bottom or near the water’s edge. There is concern that for smaller fish (salmon fry), the boundary layer can become too turbulent. Two designs will be presented which step through the process of why a roughened channel was selected, how fish passage for various species of Pacific Salmon was calculated and what was learned during the construction phase and two seasons of high water. The projects include Mill Creek in Walla Walla, WA and Green Creek near Raymond, WA.
Concurrent Sessions D: Designing Roughened Channels for Fish Passage - Selection, Design and Construction of Roughened Channels for Fish Passage
Agriculture Science Theater, Oregon State University
Roughened channels are man-made fish passage structures which are used to retrofit passage through culverts, over dams and other structures. They differ from natural channel designs in that they are usually steeper and/or narrower than adjoining channels. Other names often used with Roughened Channels include rock ramps, step/pool channels, etc. Roughened channel design is different from stream simulation or rock weir drop structures. Stream simulation is more of a reference reach/ geomorphic design process, where fish passage is assumed based on the presence and long term stability of maintaining a natural channel. For rock weirs fish passage is a function of fish leaping over a weir with a plunge pool. For roughened channels, there may be resting areas, but fish usually swim to pass utilizing a low velocity boundary layer either near the bottom or near the water’s edge. There is concern that for smaller fish (salmon fry), the boundary layer can become too turbulent. Two designs will be presented which step through the process of why a roughened channel was selected, how fish passage for various species of Pacific Salmon was calculated and what was learned during the construction phase and two seasons of high water. The projects include Mill Creek in Walla Walla, WA and Green Creek near Raymond, WA.
Comments
Pat Powers has been the Principle Engineer and Owner of Waterfall Engineering based in Olympia, WA since 2007. Mr. Powers has 29 years of experience in fish passage assessment, design and construction. He received his Master’s Degree from Jack Orsborn’s Fisheries Engineering Program at Washington State University, in Pullman, WA in 1984, and the worked for the Washington State Department of Fish and Wildlife for 21 years as a project engineer and Chief Engineer for the Habitat Program. More recently he has been focusing on designing habitat restoration and fish passage projects for near shore restoration projects.