Date of Award:
5-2009
Document Type:
Thesis
Degree Name:
Master of Science (MS)
Department:
Geosciences
Department name when degree awarded
Geology
Committee Chair(s)
James P. Evans
Committee
James P. Evans
Committee
John C. Schmidt
Committee
Joel L. Pederson
Abstract
Fluvial adjustment to base level change has its roots in the fundamental concepts of geomorphology. This thesis explores the rate of erosion and sedimentation on the Colorado and Dirty Devil rivers and North Wash Creek under the current base level changes related to the drawdown conditions of Lake Powell. Through cross section and long profile resurveys, the current state of each system is captured and added to the historic record of sedimentation in Lake Powell. All three systems are generally forming narrow and deep incised channels driven by the rapid rate of base level fall. Cross sections that deviate from this are due to site-specific factors, such as channel armoring, the presence of local base levels, or bedrock canyon width in relation to active channel width. In all systems, sediment is being transported through the establishing fluvial regime and is deposited at or below the new base level. This has caused rapid downstream progradation of each delta front. The volume of sediment accumulation and erosion and rates through time are calculated for each system. Deposit volume is proportional to each systems drainage basin area, as are the rates and magnitudes of deposition and erosion. The percentage of sediment eroded versus deposited shows an inverse relationship, with North Wash eroding the greatest percentage of its delta. Field observations and repeat photography on the distribution, orientation, and activity of lateral slumping and mud cracks identify that thick beds of fine-grained and cohesive silts and clays are necessary for these features to form. These features act to destabilize sediment and, in the case of bank failure, deliver it directly to the channel.
Checksum
c91df854c32e0475255164eb5bec07ff
Recommended Citation
Majeski, Adam L., "Fluvial Systems Tied Together Through a Common Base Level: The Geomorphic Response of the Dirty Devil River, North Wash Creek, and the Colorado River to the Rapid Base Level Drop of Lake Powell" (2009). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 291.
https://digitalcommons.usu.edu/etd/291
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Comments
This work was revised and made publicly available electronically on July 26, 2011