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A Post-Project Assessment of the Provo River Restoration Project: Channel Design, Reconfiguration, and the Re-Establishment of Critical Physical Processes

by Goetz, Randy Ray

Abstract (Summary)
A physical assessment of the Provo River Restoration Project was undertaken in order to determine how alterations to the channel were designed, the nature of as-built channel morphology, and the performance of the reconfigured channel in terms of achieving frequent (2-year recurrence) bankfull discharge and increasing transient storage. Measures of channelized and reconfigured channel morphology were obtained using total station survey, digital aerial photography, and pebble counts. Results of geomorphic analysis were compared with similar measurements made by a regional consulting company, and stream channel design data, in order to determine that intended mitigation included reducing channel capacity, increasing sinuosity, decreasing pool spacing, and decreasing the size of bed material. Reconfiguration of the channel resulted in somewhat enlarged cross-sections with reduced mean velocities, increased sinuosity, decreased pool spacing, and decreased bed substrate size. One-dimensional hydraulic modeling suggests that alterations to channel morphology have increased the bankfull channel capacity in most reaches. Modeling results illustrate the fact that the stage of the 2-year recurrence flood is below bankfull at most cross-sections. This result does not follow the intentions of channel design. However, we have observed floodplain inundation in most years since reconfiguration. The occurrence floodplain inundation is being facilitated by overbank flow at a few point locations illustrating the strengths of incorporating variability into design. Known geomorphic controls on transient storage were reconfigured in manner to potentially increase in-channel and hyporheic components of transient storage. Stream tracer tests were utilized in order to determine the degree to which these alterations affected transient storage. Numerical analysis of stream tracer tests suggests that while the relative area of transient storage increased, average residence time of water in storage, and the mass transfer rate of solute between storage and the stream did not change. This suggests that an extensive hyporheic zone may not have been established. Correlations between hydrologic and geomorphic parameters indicate that in-stream storage may have been increased, and quick-exchange hyporheic flowpaths may have been created. (295 pages)
Bibliographical Information:

Advisor:

School:Utah State University

School Location:USA - Utah

Source Type:Master's Thesis

Keywords:hydrology stream restoration tracer provo river project fluvial geomorphology transient storage hyporheic zone

ISBN:

Date of Publication:05/01/2008

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