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Ecohydraulics of Nature-Like Fishways and Applications in Arctic Aquatic Ecosystem Connectivity
- Author / Creator
- Kupferschmidt, Cody P.L.
Northern Canada is currently undergoing rapid mineral extraction development. As part of this development there is a need to perform fish habitat compensation projects and build effective fish passage facilities. There is currently limited information available on the hydraulics of nature-like fishways, as well as the behaviour of fish within these structures. Two studies were conducted: one laboratory study and one field study to improve the understanding of ecohydraulics and fish behaviour in nature-like fishways.
In the laboratory study a pool-weir style fishway was constructed using both natural rocks and concrete spheres. Weirs were constructed in a flume with one of three geometries: v-facing upstream, v-facing downstream, and horizontal. For the v-shaped weirs an angle of 140 degrees was used on the inside of the v. The aim of this experiment was to examine the influences of slope, discharge, and weir geometry on horizontal velocity, vertical velocity, turbulent kinetic energy, turbulence intensity, Reynolds stresses, and volumetric power dissipation in rock-weir fishways. An acoustic Doppler velocimeter (ADV) and point gauge were used to measure velocity and water surface profiles, respectively, for discharges between 30 and 150 l/s at bed slopes between 1.5% and 5.0%.
An effective operating range was identified for the proposed fishway design and a diagram was developed to aid designers in selecting appropriate discharge and bed slopes based on volumetric power dissipation. Two flow regimes were observed: plunging and transitional. A stage-discharge relationship was also developed to provide an improved estimate of discharge when compared with existing equations. Finally, a new method of weir construction was proposed that allows rock-weirs to be constructed off site, reducing installation time and resulting in a more flexible final design.
In the field study the performance of a habitat connectivity project in the Canadian Barrenlands was evaluated where a stream was modified through the construction of nature-like fishway structures to increase habitat connectivity for Arctic Grayling (Thymallus arcticus). Under this project the total length of West Island Stream (WIS) was increased from 430 to 470 m and the slope of a steep cascade section deemed a barrier to fish passage was reduced. Five pools were selected in the steep lower-reach of WIS to evaluate for resting suitability for Arctic Grayling.
A diesel pump was used to manipulate the flow in WIS (1.0, 9.9, and 21.9 l/s) and an acoustic Doppler velocimeter to measure point velocities within each study pool. Adult Arctic Grayling were placed in the pools and their resting behaviour was observed under each flow condition using visual fish surveys and video recordings. This study showed that stream-scale flow manipulation can be an effective tool in evaluating habitat compensation projects. The results indicated that only one of the study pools would provide acceptable resting habitat during all flow conditions expected during spawning. Based on the observations of the use of pools by fish, it is recommended that future resting pools for Artic Grayling have a minimum surface area of 1.4 m2, a minimum depth of 0.6 m, horizontal velocity magnitudes less than 0.2 m/s, and near-zero vertical velocities.
- Graduation date
- Fall 2015
- Type of Item
- Master of Science
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.