Short course for UNIVERSIDAD NACIONAL DE INGENIERIA January 26-29, 2016
Planning and Design for Rehabilitation of Rivers Using Large Wood Metodología para Reforestar Ríos Degradados por Actividades Humanas usando Técnicas de Bioingeniería
3.0 Three design approaches
Course overview Day I (Jan 26)--Foundational topics • Review of information resources (design handbooks and spreadsheets) for large wood • Is wood appropriate for your site?—criteria for screening (Planning) • Three design approaches • Key issues for large wood design
Day 2 (Jan 27)—Designing large wood structures • Case study I—Little Topashaw Creek, Mississippi • Design life for wood structures/selection of design event or condition
Day 3 (Jan 28)—Risk, uncertainty and construction • Sensitivity and Monte Carlo analyses
• Constructability assessment • Case study II—Trinity River, California • Monitoring
Day 4 (Jan 29)--Field trip
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• Introductions
• Types of wood structures • Findings of recent research on drag and lift coefficients • “Road testing” selected design spreadsheets
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Geomorphic approach • Emphasis on a prior condition
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• Historic or prehistoric wood loading level • Previous channel form and process • Large wood controls on channel migration, avulsion, bank erosion, sediment deposition and storage
• Emulation of naturally stable wood formations • Emphasis on watershed/reach • Problems with this approach?
3 Collins et al. 2012
• Habitat needs and preferences for targeted species • Modifying an existing system to provide certain ranges of depth, velocity, cover or substrate at certain times or seasons • No particular reference to or concern for a previous condition • Rarely emphasizes process— views habitat as a static entity • Usually focuses on reach or site scale
The Russian River Biological Opinion found that summer flows in the upper Russian River and Dry Creek are too high for optimal juvenile coho salmon and steelhead habitat. Current summer flows in the creek range from 110 to 175 cubic feet per second (cfs), which makes it difficult for the young fish to thrive.
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Biological approach
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The Biological Opinion recognizes that large reductions in the summertime flows in Dry Creek would limit the Water Agency’s ability to deliver water to its customers. Therefore, the Biological Opinion requires habitat enhancement of six miles of Dry Creek to improve summer rearing conditions for coho salmon and steelhead while allowing the Water Agency to maintain the existing flow range in Dry Creek of 110 to 175 cfs.
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Biological approach
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Engineering approach • Accepts project objectives as an input
• Borrows from river training/bank stabilization • Usually focuses on a given site, segment or reach • Concerned with forces and maintaining structural integrity • More likely to include risk analysis • Interactions with built infrastructure
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• Channel form/process • Habitat • Erosion/sedimentation control
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Engineering approach Shields Engineering, LLC
• More likely to include modeling • Hydrodynamic • Sediment transport • Habitat • Force and moment analysis
7 Luis F. Castro I.
• Geomorphic • Biological • Engineering Shields Engineering, LLC
Which approach is best for your project or program?
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