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Title: Responses of experimental river corridors to engineered log jams

Author
item GALLISDORFER, MICHAEL - University Of Buffalo
item GHANEEIZAD, S - University Of Buffalo
item BENNETT, SEAN - University Of Buffalo
item ATKINSON, JOSEPH - University Of Buffalo
item CAI, D - University Of Buffalo
item SIMON, ANDREW - Cardno Entrix
item Langendoen, Eddy

Submitted to: Proceedings of the World Environmental and Water Resources Congress Conference
Publication Type: Proceedings
Publication Acceptance Date: 9/25/2015
Publication Date: 9/25/2015
Citation: Gallisdorfer, M.S., Ghaneeizad, S.M., Bennett, S.J., Atkinson, J.F., Cai, D., Simon, A., Langendoen, E.J. 2015. Responses of experimental river corridors to engineered log jams. In: Proceedings of the World Environmental and Water Resources Congress 2015, May 17-21, 2015, Austin, TX. 12 pp.

Interpretive Summary: Stream restoration and river engineering projects are increasingly employing engineered log jams to provide both bank protection and improved ecologic function. However, design guidelines that characterize the forces acting on the whole engineered log jam as well as its individual members, and the structures impact on river form are lacking. Scientists at the USDA-ARS National Sedimentation Laboratory in collaboration with researchers from the State University of New York at Buffalo and engineers from industry have constructed a physical scale model of engineered log jams to be installed on the Big Sioux River, SD. The study results show that: (1) local and downstream flow can be markedly affected by the presence of the structures, (2) the structures afforded relatively large regions of bank protection, and (3) the larger the structure, the higher the drag and area of bed erosion. These physical modeling results show that the style and size of engineered log jams can have a significant impact on flow resistance, bank protection, and stream channel responses, which should facilitate practitioners in the effective design of such structures for natural rivers.

Technical Abstract: Physical models of the Big Sioux River, SD, were constructed to assess the impact on flow, drag, and bed erosion and deposition in response to the installation of two different types of engineered log jams (ELJs). A fixed-bed model focused on flow velocity and forces acting on an instrumented ELJ, and a movable-bed model focused on channel morphodynamics. The results show that: (1) downstream flow velocity, as expected, can be markedly affected by the presence of the ELJs, (2) both ELJ types afforded relatively large regions of bank protection, and (3) the relatively larger ELJ had a higher drag coefficient, relatively larger areas of bed deformation, and greater impact on the opposite stream bank as compared to the relatively smaller ELJ. These modeling results show that the style and size of ELJs can have a significant impact on flow resistance, bank protection, and stream channel responses, which should facilitate practitioners in the effective design of ELJs for natural rivers.