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Sponsored by ASCE Continuing Education and the  Environmental & Water Resources Institute (EWRI).

Purpose and Background  
 
ASCE has produced a standard approach for stream restoration channel design (Shields et al. 2003, Manual of Practice 110 (Shields et al. 2006), Slate et al. 2007), but many practitioners and regulators prefer other approaches. In fact, some state and federal agencies limit stream restoration project designers to unapproved approaches, presenting professional engineers with potential ethical and liability issues (Slate et al. 2007). This webinar introduces the overall approach to channel design approved by ASCE. It focuses on determining dimensions (width, depth and slope) for one of the two main types of situations recognized by that design approach, threshold channels. A complementary webinar on Designing Channels for Stream Restoration: Alluvial Channel Design is also available in ASCE webinar catalog.

Primary Discussion Topics

• When channel design/reconstruction is not a good idea for stream restoration
• Five approaches to channel design
• Training and credentials for designers
• Handbooks and other resources for designers
• Obtaining data for design
• Examples of threshold channels
• Threshold design equations and solutions
• Threshold design example

Learning Outcomes

• Correctly describe the five approaches to designing stream channel reconstruction for restoration projects, with a sentence or two for each approach
• Identify the difference between the analytical approaches to stream channel design and other approaches to stream channel design, listing the relative strengths and weaknesses of the analytical approach
• The student will be able to specify methods for obtaining values of bed sediment size, design discharge and critical shear stress for use in stream restoration channel design
• The student will be able, given appropriate input data or constraints, to compute reach- average values of channel width, depth and slope that pass the design discharge for a threshold channel without excessive sediment deposition or erosion

Webinar Benefits

• Understand the ASCE approved approach for channel design
• Specify engineering services and perform design functions in a professional and defensible manner
• Reduce the probability of restoration project failure due to channel instability

Intended Audience

• Engineers
• Professionals charged with designing stream restoration projects
• Managers responsible for selecting firms for providing design and other consulting services related to stream restoration design

Webinar Outline

• Efficacy of stream restoration
• Floodplain and watershed approaches
• In-channel  interventions
• Channel design approaches
• Design handbooks and software
• Obtaining data for design
• Design discharge
• Sediment size, load, and critical shear stress
• Definition of threshold channel with examples
• Threshold design equations and solutions
• Threshold design example
• Two-stage channel design and uncertainty
• Summary and conclusions

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