Date of Award:

2014

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Patrick Belmont

Abstract

A better understanding of transport and deposition of fine sediment in alluvial rivers, including their floodplains, is essential for improved understanding of sediment budgets and prediction of river morphological changes. Previous work in the Root River indicates that channel-floodplain sediment exchange exerts strong control on the sediment flux of this system. In addition, improvements in agricultural practices and increases in high and low flows during the past five decades have led us to believe that sediment sources in the Root River may be shifting from uplands to near-channel sources. This thesis estimated the total amount of fine sediment contributed to the channel from near-channel sources due to the processes of lateral channel adjustment (channel migration and channel widening) using a quantitative approach based on the use of multiple epochs of aerial photographs (1930s-2010s), lidar data available for the entire watershed from 2008, and other GIS analysis. The results obtained in this thesis serve as another line of evidence to constrain a sediment budget for the Root River watershed and to improve our understanding of the sediment dynamics within the watershed. In addition, we found that the Root River presents a marked division between its lateral channel adjustment trends before and after the 1970s. We also found that while increases in flows have affected lateral channel adjustment rates throughout the entire channel network, other factors like sediment supply and riparian vegetation may be playing an equally important role.

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