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Evaluating the Effects of Large Woody Debris Restoration in an Urban Headwater Stream

Grap, Peter
http://orcid.org/0009-0003-3604-0995
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712916685493113

Abstract Details

2024, MS, University of Cincinnati, Arts and Sciences: Biological Sciences.
Urbanization is associated with increased erosion and habitat homogenization in stream ecosystems. This habitat degradation often has biological consequences, such as decreased species richness. Conventional stream restoration practices are costly, and projects are limited to small areas with easy access. A scalable, low-cost method of stream restoration is needed to address the widespread degradation occurring in urban streams. Large woody debris (LWD) is an important element in stream ecosystems which is typically abundant in forested watersheds and low in urban streams. LWD can reduce water velocities, generate pool habitat, decrease erosion, and provide cover for aquatic organisms. In this study, we performed experimental LWD installations to assess the capacity of LWD restoration to improve habitat and reduce sediment transport in an urban headwater stream in Cincinnati, OH. We tracked the geomorphic effects of these installations using a before-after-control-impact study design in four 60-meter reaches, two treatment and two control, over a 1.5-year period to investigate the following questions: (1) will unanchored LWD additions remain stable in a flashy urban stream, (2) will LWD additions increase the availability of pool habitat, and (3) will wood additions increase bed stability and modify sediment size distributions. We found that LWD installations rapidly increased pool habitat availability (size) around stable jams, but a majority of the LWD jams were frequently mobilized and reconfigured by high-flow events. LWD additions had no significant impact on the probability of stream bed mobilization, likely due to the instability of LWD, however, the distance particles traveled once mobilized significantly decreased. While LWD additions can increase the availability of pool habitat in urban headwater streams, further investigation is needed to understand the stability of such structures and the environmental context where these additions will be most beneficial. For the second part of this project, we studied the movement of streambed particles in an urban stream. Urban streambeds experience greater mobilization resulting in channel enlargement and habitat homogenization. Because of the critical role bedload transport plays in shaping stream ecosystems, scientists have been attempting to predict streambed mobilization for decades, however, these predictions are often inaccurate. Improving bedload transport predictions could help scientists and resource managers plan and evaluate stream restoration projects. While the effects of particle size are well understood, the effects of shape are not, although theory suggests that particle shape influences many aspects of bedload transport. We tracked the movement of 320 rocks to answer the following questions: (1) does particle size affect bedload transport, (2) does particle shape bedload transport, and (3) what measures of particle size and shape best predict bedload transport? We found that both size and shape were relevant to particle entrainment when using simple measures, however, when using the effective diameter as a measure of size, shape had no effect on entrainment. We also found that shape was relevant to the distance particles moved, however size was not. These results suggest that utilizing particle shape in predictions of bedload transport could increase their accuracy.
Michael Booth, Ph.D. (Committee Chair)
Dylan Ward, Ph.D. (Committee Member)
Stephen Matter, Ph.D. (Committee Member)
109 p.
Ecology
urban streams; restoration; bedload transport; large woody debris; habitat

Recommended Citations

Citations

  • Grap, P. (2024). Evaluating the Effects of Large Woody Debris Restoration in an Urban Headwater Stream [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712916685493113

    APA Style (7th edition)

  • Grap, Peter. Evaluating the Effects of Large Woody Debris Restoration in an Urban Headwater Stream. 2024. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712916685493113.

    MLA Style (8th edition)

  • Grap, Peter. "Evaluating the Effects of Large Woody Debris Restoration in an Urban Headwater Stream." Master's thesis, University of Cincinnati, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1712916685493113

    Chicago Manual of Style (17th edition)

ucin1712916685493113
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This open access ETD is published by University of Cincinnati and OhioLINK.