Date of Award:

8-2022

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Brian Crookston

Committee

Brian Crookston

Committee

Belize A. Lane

Committee

Som Dutta

Abstract

The transport and accumulation of driftwood or large woody debris (LWD) in mountain streams is a natural part of catchment health and river connectivity. At hydraulic structures, the presence of LWD may impact flow efficiency and influence upstream water depth. LWD has been studied at a variety of spillways and weir types, however, little is known about its interaction at rock weirs. This study investigated factors affecting the passage of individual LWD elements and any LWD accumulations at rock weirs, as well as potential impacts upstream of LWD accumulations through field-informed scaled model testing. Observations of LWD at rock weirs located on the Blacksmith Fork River, a mountain stream located in Utah, USA, were used to replicate I-and V-shaped rock weirs in a large flume. The river response to rock weirs on the corresponding section of the Blacksmith Fork River was also investigated using historic aerial imagery and field data. Approaches to LWD management typically prioritize either natural processes or hydraulic structure safety and flow conveyance. A new hybrid approach should consider both aspects for rock weirs in mountain streams.

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932319a599b965507f7e7b4d6c246919

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