Adequate spawning habitats are crucial for the success and productivity of fish populations. Instream boulders can create favorable spawning sites by creating depressions or riffles where fish can deposit their eggs. Habitat restoration projects are put in place to offset the destruction of spawning grounds and improve habitat functionality. Our research aims to provide insight on which boulder concentrations and arrangements yield minimal disturbance of local bed substrate and sediment transport rates. An Ecohydraulics flume was used to evaluate local the sediment transport and scour (erosion of the local bed) patterns of four different boulder arrangements with boulder concentrations of: λ = 0, 2.45, 4.42, and 6.38% on a streambed slope of 0.5%. Using the Structure from Motion technique, before and after photos of the bed were taken and turned into a 3D digital elevation model of the bed, allowing for the comparison of changes in scour patterns and bed morphology. The sediment transport rate was monitored by capturing and measuring sediment discharge at the downstream outlet of the flume with a scale taken at intervals observed with a stopwatch. Our expected results are to see the boulder concentration of λ= 4.42% provide minimal sediment transportation and disturbance of local bed substrate. In application, boulder concentrations resulting in low sediment transportation rates and local scour can prevent the washout of fish egg deposits, increasing the habitat suitability for spawning. Much research has been conducted on the salmonid species, however more studies on species that use similar habitats for spawning grounds are needed to show how a variety of substrate spawning and species benefit from these habitat restoration methods. This interdisciplinary study combining my research area of ecology with environmental engineering has aided in my career path by building my experience in the field and expanding my knowledge in habitat restoration.
Authors: Sarah McKillop, Muhammad Ziaur Rahman, Abul Baki
Advisor(s): Abul Baki, Civil and Environmental Engineering
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