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Effects of whitewater parks on fish passage: a spatially explicit hydraulic analysis




Stephens, Timothy A., author
Bledsoe, Brian P., advisor
Myrick, Christopher A., committee member
Nelson, Peter A., committee member

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Whitewater parks (WWPs) provide a valuable recreational and economic resource that is rapidly growing in popularity throughout the United States. WWPs were originally thought to enhance aquatic habitat; however, recent studies have shown that the hydraulic conditions required to meet recreational needs can act as a partial barrier to upstream migrating trout and that WWP pools may contain lower densities of fish compared to natural pools. There is limited knowledge of the direct effects of WWPs on fish passage. Managers and policy makers are forced to review WWP designs and make permit decisions without sound scientific evidence. It is also difficult to make design recommendations for future WWPs and possibly retrofitting existing WWPs to allow for successful fish passage without improved understanding of the factors contributing to suppression of movement in WWPs. We describe novel approaches combining fish movement data and hydraulic results from a three-dimensional computational fluid dynamics model to examine the physical processes that limit upstream movement of trout in an actual WWP in Lyons, Colorado. These methods provide a continuous and spatially explicit description of velocity, depth, vorticity, and turbulent kinetic energy (TKE) along potential fish swimming paths in the flow field. Variation in the magnitude and distribution of velocity and depth relative to fish swimming ability is reflective of variation in passage success among WWP structures and size classes of fish. Logistic regression analyses indicate a significant influence of velocity and depth on limiting passage success and accurately predict > 86 percent observed fish movements. Relationships emerge at individual WWP structures that highlight unique hydraulic characteristics and their effect on passage success. The methods described in this study provide a powerful approach to quantify hydraulic conditions at a scale meaningful to a fish and mechanistically evaluate the effects of hydraulic structures on fish passage. The results of these analyses can be used for management and design guidance, have implications for fishes with lesser swimming abilities, and demonstrate the need to assess additional WWPs of various sizes.


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Whitewater Park
fish passage
flow complexity
hydraulic modeling


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