Author(s): Channing C. Syms, Mark A. Kirk, Daniele Tonina, Chistopher C. Caudill

Linked Author(s): Daniele Tonina

Keywords: Fish passage; Turbulence; Ecohydraulics; Lamprey;

Abstract: Flow field dynamics, including turbulence-averaged and instantaneous quantities, are of significant importance for understanding fish behavior, especially near hydraulic structures and through fish passages. Several quantities have been previously proposed as predictors of fish passage success. These include mean turbulence kinematic energy, turbulence intensity, vorticity, work and power. However, these quantities do not provide univocal results. Here, we present a novel biologically significant turbulence intensity metric, Ibio. We define Ibio as the ratio between the root square of total kinematic turbulence energy per unit mass and a biological velocity threshold significant for any selected species of interest. We tested this index for predicting the difficulty of passage conditions for Pacific Lampreys (Entosphenus tridentatus) when passing a vertical slot structure. Pacific Lampreys are anadromous, and migrate both toward the ocean and back to their native spawning grounds in the tributaries of the Columbia River, where their migration is challenged by several dams and reservoirs. Previous observations suggest that serpentine weir sections in the upper fishways with high turbulence are a bottleneck for this species. We conducted a set of flume experiments with a vertical slot structure where lamprey behavioral observations were coupled with measurements of the flow field for three different mean flow velocities, three slot lengths and two turbulence treatments. Our analysis shows that our turbulence intensity index, Ibio, performs better than metrics of work and power when predicting the difficulty of lamprey passage conditions.

DOI: https://doi.org/10.3850/38WC092019-0928

Year: 2019