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INSTRUCTOR: Bryan Dick, P.E., P.H.

While stream restoration projects rely heavily on the establishment of vegetated banks and floodplains for long term stability, short term stability is often a function of the implementation of in-channel structures such as log vanes, cross vanes, notched sills, toe wood, step pools and other structures in conjunction with a proper channel geometry and floodplain access. This webinar provides a high level evaluation of the evolution of structure use in channel restoration projects and present many design examples of successful and failed implementation of various types of structures and applications. This webinar is a continuation of an introduction to stream restoration for technical professionals and is organized in a manner that does not require attendance of each webinar in this series. The principles of stable channel form and sediment transport will be highlighted in this webinar while providing insights into how the use of in-channel structures may be an asset or a detriment to the objectives of the ecological restoration project.

Purpose and Background

Structures placed within a channel can promote pool maintenance, provide habitat, serve as fail-safes for future channel incision, create dynamic bed features, redirect flows to reduce shear stress on banks, and many other hydromorphic functions. However, structures are not a cure-all, and need to be implemented with a consideration of unintended consequences and the potential for over-hardening a restored stream that is meant to be naturalized. When to use them, how many to use, and where and how to place them is a daunting question for many designers with the answer to these questions coming largely from past project experience and an understanding of the interaction of structures and flow. 

Primary Discussion Topics

• Overview of the principles of stream restoration
• Stable channel form – dynamic equilibrium
• Basic types and configuration on in-channel structures
• Options in different slopes and sizes of channels
• Considerations and guidance for design implementation
• When and where to use structures
• Lessons learned from case studies of multiple projects

Learning Outcome/Benefits

• Gain a basic understanding of the physical principles of flow and structures
• Improve your ability to use structures in channel restoration and stabilization projects
• Develop an appreciation for the short and long term benefits of structures
• Become familiar with how to evaluate type and placement of structures
• Learn from the lessons of successful and failed project examples

Intended Audience

• Professional Engineers
• Environmental Scientist/ Ecologist
• Geologist and Geographers
• Planning professionals
• Engineers in Training who have a basic understanding of engineering design, bid-document preparation and construction practices
• Students of engineering, geology and environmental disciplines

Webinar Outline

• Overview of geomorphology natural channel stability
• General design considerations
• Flow redirection for shear stress reduction
• Grade control structures
• Sediment starved systems
• Steeper channel gradients
• Relative flat channel gradients
• Urban systems and importance of structures in urban design
• Example structures – successes and failures
• Construction challenges

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