Engineering Log Jam Design Standards
This is a scoping proposal to develop engineering design standards for river log jams. Engineered log jams (ELJ) are placements of large woody material in river environments to elicit specific hydraulic, geomorphic, and ecological responses. This is often categorized as restoring river processes and directed towards endangered fish species population recovery. Other common uses include streambank and infrastructure protection.
The question being addressed by this research is specific to the Bureau of Reclamation (Reclamation): How can Reclamation reduce the uncertainty and risk in its ELJ projects through documentation of its design standards?
Need and Benefit
Stream restoration is an emerging science involving fluvial geomorphology, riverine ecology, and hydraulic engineering. New research in geomorphic form/processes relationships, sedimentation engineering, and biostablization has significantly progressed stream restoration design standards. Even hydraulic rock structures have garnered their own attention with advancements in three- dimensional hydraulic modeling. However, the ecological and engineered use of large woody material in fluvial systems lacks the same level of engineering design standards.
ELJs are integral to Reclamation's Tributary Habitat Program operated by the Columbia-Snake Salmon Recovery Office, Pacific Northwest salmon recovery, and stream restoration in general. Reclamation is currently contracting with private consultants for its ELJ projects. Engineered log jams are being designed by State wildlife agencies, private consultants, and Federal water resource agencies with little guidance or standardization. In recognition of the uncertainty involved in ELJ design, the Washington Department of Natural Resource's Aquatic Resources Program is intending to release guidelines for safety and risk assessment in relation to liability.
Uniform design guidelines or standards are needed to clearly state goals, constraints, and assumptions for future ELJ design and implementation to help address perceived liability concerns. Improving the standards for ELJ design would further their application in river restoration efforts. Public and permitting agency acceptance of this technology would also benefit from standardization in documentation.
The research product for this scoping proposal will be a report summarizing the the current state of ELJ design guidelines, present methodologies for designs being used, and the recommneded level of effort (scope or work and budget proposal) to complete ELJ design standards.
This information was last updated on March 12, 2014
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