Date of Award:

5-2015

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Watershed Sciences

Committee Chair(s)

Joseph M. Wheaton

Committee

Joseph M. Wheaton

Committee

Patrick Belmont

Committee

Nicolaas W. Bouwes

Committee

Joel L. Pederson

Committee

John C. Schmidt

Abstract

Braided rivers are characterized by their dynamic nature, and are often significantly reshaped during each flood capable of transporting sediment. Over time, they adjust in response to the frequency and magnitude of floods, along with the amount of sediment available for bar building. Factors such as climate change, dam construction, or land use alteration that change the amount of sediment or water available to braided rivers may subsequently affect channel form. One avenue toward understanding braided channel evolution is to develop simple relationships between channel form and sediment transport, and extrapolate those relationships over extended timescales. With funding from the National Science Foundation ($271,000), I first conducted laboratory experiments that linked the travel distance of sediment during a flood (termed particle path length) and the spacing of bars in braided rivers. I then developed a simple model that predicts channel response to floods by transporting sediment according to specified path lengths. Finally, I employed the model to answer questions regarding the source of sediment used for bar building in braided rivers.

This research provides an important step in linking channel form and sediment transport in gravel-bed braided rivers, although the relationships developed here certainly deserve further testing across a variety of rivers and over floods of varying magnitude and duration. The predictive model developed herein provides a novel method for simulating channel evolution using a simple sediment transport approach. Additionally, the model is built using a modular framework that allows users to easily explore the effect of altering the way processes are represented, or whether they are included at all, on channel evolution.

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