Date of Award:

8-2020

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee

Brian M. Crookston

Committee

Blake P. Tullis

Committee

Austin Ball

Abstract

Accumulation of floating and submerged woody debris at flow control structures can result in reduced discharge efficiency (higher upstream head for a given weir discharge). Labyrinth weirs are more prone to debris blockage than less efficient control structures due to their ability to pass large amounts of flow with relatively small heads. Labyrinth weirs also have geometric properties that are more likely to prevent debris from passing over the weir than linear weirs.

A laboratory study was performed to evaluate the interaction between labyrinth weirs and debris sizes. The individual debris tests indicated that debris blockage probability is influenced by trunk diameter, trunk length, and upstream head.

Debris accumulation tests indicated that lower upstream reference heads led to a greater increase in upstream head than higher upstream reference heads. The accumulation tests also showed that larger channel width corresponds with higher increase in upstream head.

Discharge rating curves were also developed for a labyrinth weir with five fabricated submerged woody debris jams. The submerged debris tests showed that both debris volume and jam geometry significantly influenced a reduction to discharge capacity and an increase to upstream head of labyrinth weirs, especially at high flows.

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