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Abstract: Session D  2:20 pm (Back to Session D)
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Techniques for Fish-Passage Evaluation through Hydraulic Structures

Michael Scurlock
RiverRestoration.org
Carbondale, CO

Authors: S. Michael Scurlock, Scott E. Prins, Jason P. Carey, RiverRestoration.org

Evaluation and design of hydraulic structures for fish passage commonly relies on threshold metrics, generally grounded in literature, which are readily applied to hydraulic model output or field measurements. Swimming energetics functions ubiquitous to the fisheries biology literature are generally distilled to either a sustained swimming threshold (in the case of passage evaluation) or burst threshold (in the case of barrier evaluation). Spatial hydraulics distributions and biological energetic budgets are simplified into instantaneous criteria and fish swim-speed criteria maybe misapplied. Large degrees of fish swimming biomechanics knowledge is disregarded by using threshold criteria.

A method is proposed where energetics functions from the fisheries biology literature are applied to spatial distributions of hydraulics though restoration structures. Flow fields are resolved through both two- and three-dimensional computational dynamics modeling. Endurance-time curves are interpolated along velocity-space distributions to assess barrier presence across varying fish species, body lengths, and swimming performance. Passage success may then be estimated for a given structure or river environment depending on fish energy expenditure.

The proposed method is applied to instream hydraulic structures in the Rocky Mountain Region, including restoration-specific structures, recreational whitewater parks, and specific fish-passage channels. Results are compared to threshold methods in both required efforts and conclusions. Methods provide a readily applied tool for existing structure evaluations and design optimizations for a wide range of structure types and fish species.