Stream habitat connectivity in the Canadian Arctic: an on-site approach to design and construction

• Published in: Canadian Journal of Civil Engineering
• Main Authors: Courtice, Gregory J., Baki, Abul Basar M., Zhu, David Z., Cahill, Christopher L., Tonn, William M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2016
• Subjects: General Environmental Science; Civil and Structural Engineering; Arctic
• Online Access: http://dx.doi.org/10.1139/cjce-2015-0241; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjce-2015-0241; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjce-2015-0241

We developed a successful on-site approach for design and construction of stream modifications that addressed challenging remote-site conditions of limited field data and available construction materials. Fish habitat connectivity enhancements were constructed within an Arctic headwater stream containing a naturally impassable cascade section with 13% slope, which was bypassed in a newly constructed channel at 5% slope with nature-like fishpass structures. Primary design considerations included (1) creating suitable hydraulic characteristics for fish passage in periods of high and low discharges; (2) reducing drop heights and creating unimpeded flow paths; (3) improving hydraulic complexity for a variety of stream habitats; and (4) salvaging and incorporating vegetation disturbed from construction activities into riparian and in-stream habitat structures. In high gradient reaches (2.5%–5%), we constructed boulder weirs, boulder chokes, and deflection boulders to overcome migration impediments. In medium gradient reaches (1.5–2.5%), rock ramps, boulder chokes, and deflection boulders were constructed to control hydraulic characteristics to ensure an unimpeded flow path, suitable hydraulic complexity, and resting zones. At lower gradients (<1.5%), we incorporated a softer approach using riparian vegetation and in-stream woody debris to ensure a similar quality of fish habitat as created in the higher gradient reaches. Initial hydraulic responses to the modifications indicated this reconstructed channel provided suitable hydraulic and habitat characteristics for habitat connectivity throughout the entire stream. Our findings advance understanding of headwater stream hydraulics in the Canadian Arctic and will assist in designing future stream restoration and fish habitat compensation projects on small and remote systems. This case study supports the feasibility of successfully constructing future habitat compensation projects in challenging remote environments when using an on-site, adaptive design and ...