Document Type

Thesis

Date of Degree

Summer 2016

Degree Name

MS (Master of Science)

Degree In

Civil and Environmental Engineering

First Advisor

Jacob Odgaard

Abstract

Physical based modeling was conducted to improve channel restoration efforts through direct comparison of submerged structures of various design and orientations. In-stream structure technologies studied are used to provide bank stabilization, flow control, scour and sediment control, as well as ecological enhancement through turbulent dispersion and vertical mass transport. Quantitative analysis evaluates flow effects induced by common channel restoration structures in their ability to provide mixing in our streams and rivers without significant impacts on flooding through excessive energy loss and backwater effect. Physical, fixed-bed flume experiments were performed under high-Reynolds number subcritical steady-state flow conditions. Theoretical energy loss relationships were developed, compared, and evaluated experimentally for stream barbs, spurs, submerged vanes, blocks and boulders. Extensive surface dye-trace experiments were performed to determine centerline mixing and vertical mass transport produced by stream barbs, vanes and boulders. The research presented in this thesis illustrates that the use of dispersion relationships to assess length of vertical mass transport based on the change in energy slope, and estimated shear velocity, of the channel does not properly correct for boundary layer formation and advection or angular motion produced by channel restoration structures. Submerged vanes were found to provide efficient vertical mixing with minimal energy loss or flood risk, as compared to stream barbs, spurs, blocks, and boulders. The deterioration of water quality and the need to provide bank stabilization with limited flood risk require updated NRCS and ASCE design standards and selection tools for vertical mass transport and energy loss relationships of channel restoration structures. The research conducted in these two studies have provided data for a select number of such structures.

Keywords

Backwater, Channel Restoration Structures, Iowa Vane, Re-aeration, Stream Barb, Vertical Mass Transport

Pages

xii, 62 pages

Bibliography

Includes bibliographical references (pages 42-45).

Comments

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Copyright

Copyright 2016 Katie May Snyder

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