Stream Rehabilitation Via Hand-Placed Wood: A Year of Monitoring Documenting Expanded Habitat Complexity and More Natural Flow and Streambed Mobility Regimes
Kurt Cooper
Peter Tower
Sustainable Streams
Louisville, KY
Authors: Kurt Cooper, Peter Tower & Bob Hawley, PhD
Hand-placed log structures mimic naturally occurring stable wood and provide benefits such as enhanced habitat complexity, nitrogen processing, flow attenuation, improved bank stability, and restoration of geomorphic processes such as bar building and vegetation colonization. This presentation draws from over 400 hand-placed log structure installations spanning ~3,500 feet across a variety of stream settings. Sufficient anchoring (e.g., ramping behind existing trees, placed in jams, etc.) is essential to prevent floating during large events. Live stakes can help to augment the vegetation colonization process. The log structures are much lower cost than conventional stream rehabilitation such as bank re-grading; however, they can also have a greater risk of failure and would not be recommended in settings with public safety risks, such as geotechnically unstable banks with existing infrastructure or buildings. In addition to installation guidance, this presentation will share long-term monitoring results from two case studies, including repeat channel surveys, time-lapse photos, and sediment mobility monitoring.
A ~20-ft-long installation of brush bed on the Stillwell Branch project in Larue County, Kentucky, resulted in the restoration of a ~2-ft-thick hyporheic zone, extending nearly 100 ft upstream, and the creation of an ~18-in-deep plunge pool over the course of 9 months, by capturing gravels from the active bed load and raising the channel bed elevation. It remains stable and functional over 2 years later.
A series of hand-placed log jams and beaver dam analogs was installed on the Wolf Run project in Jefferson County, Kentucky, in March 2023. Preliminary monitoring data suggest that these structures were able to attenuate the erosive portion of the hydrograph, converting an event that entrained bed sediment in the upstream control reach into an event that caused no streambed mobility downstream of the structures. Prior to the structure installations, the reaches were observed to have similar levels of streambed mobility, with both reaches experiencing downcutting over a 6-year pre-installation period.
About Kurt Cooper
Kurt Cooper developed his interest in creeks and rivers early on, while swimming, fishing, and canoeing the creeks of South Central Kentucky. After gaining a B.S. in Civil Engineering from Western Kentucky University (2005) and spending more than 5 years working in industrial and commercial site development design, he decided to specialize in the part of his work that he was most passionate about: hydraulics and stream restoration. This led him to Colorado State University (M.S. Civil Engineering, 2012) where he developed an advanced, physically-based understanding of the principles of open channel hydraulics and sediment transport. He has incorporated CSU's multidisciplinary emphasis on stream function, the natural flow regime, and habitat complexity, along with his construction feasibility expertise, into a more holistic approach to stormwater management and stream restoration design.
About Peter Tower
Peter Tower grew up playing in tide pools along the rugged coast of Northern California and his favorite activity was exploring the rivers and waterfalls of Big Sur. He has spent the last 11 years founding and growing a technology-based imaging company. His current and past experience with design, photography, and construction bring a new element to the team that allows Sustainable Streams to offer innovative technologies used for construction observation and post-construction monitoring. With these new tools and skills, Sustainable Streams can enhance and optimize feedback to the construction crews working on-site, while providing clarity and understanding to the clients making decisions. Furthermore, he has assisted with the implementation of wood structures on small ephemeral tributaries, providing a cost-effective and long-lasting solution to stream restoration and watershed design.