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Long-term Study of the Effect of In-stream Structures near Bridges on Streambank Erosion and Stream Migration

Jason Vogel, PhD, PE
University of Oklahoma
Norman, Oklahoma

Authors: Adella Kuster, Jason Vogel, Keith Strevett, Grant Graves, Jeffery Volz

Streambank erosion can damage bridges, hydraulic structures, and private property. In-stream structures may be installed to control river migration over time and limit bank erosion during large storm events. Historically, the structures most widely used by the Oklahoma Department of Transportation include Kellner jetties, pile diversions, rip-rap, and bendway weirs. These structures each use different methods to decrease erosion and stream migration; therefore, their effectiveness differs based on stream characteristics and geomorphology. Many of these structures have been installed over 50 years prior on different rivers around Oklahoma, but the streams and structures are not routinely evaluated or surveyed for changes in the river channel or impacts of high flow events on the structures. Previously, two studies completed by the Oklahoma Department of Transportation in 1971 and 1989 have qualitatively evaluated the effectiveness and durability of over 20 in-stream structures near transportation infrastructure. These studies provided photos and descriptions as a baseline for comparison to the current state of the river banks and in-stream structures. In this project, remote evaluations of the changes in physical characteristics of the streams and development of the watersheds over time, along with on-site stream surveys and geomorphological studies, were completed. These surveys included cross-sectional and lateral surveys and stream velocity profiles. The structures that were still exposed were compared to original designs and previous photos, if available, or design criteria to determine the permanency and durability of each structure in different types of rivers. Statistical analysis was completed using logistic regression to determine variables that were significant in determining whether the project was successful over the long term. In this case, successful means that the stream did not erode or migrate behind the structure. This project augments and enhances the previous studies through these quantitative analyses of the durability of the structures, stream characteristics, stream geomorphology, and climate. It also establishes standard methods for future evaluations of in-stream structures, so the study of them can be consistently extended over time. The combination of long-term studies and modern geomorphology provides a unique opportunity to optimize the in-stream structures used in different rivers with varying characteristics and geomorphology based on the results of the study.