The river drainages of the arid Southwest United States have undergone significant changes since the Europeans first started colonizing the area. In particular channel width has been observed to be decreasing while channel adjacent levees have been growing on many river segments in the Southwest United States. This has led to less complex channel systems and disconnected floodplains in many places throughout the American Southwest. This study focuses on channel narrowing within Meander Canyon, a little studied reach that makes up the eastern border of Canyonlands National Park in Utah. GIS aerial photo analysis identified geomorphic changes through time while LiDAR, RTK GPS, and bathymetry surveys were combined to create a DEM used in modeling inundation at selected sites. This study confirms that Meander Canyon has narrowed over the last 74 years in magnitudes similar to other rivers in the region through complex interactions between river regulation, climate, and bank stabilization by invasive vegetation. Inundation modeling suggests a previously unidentified process by which floodplains may stay hydraulically connected to the main channel in spite of large, vertically accreted levees: ephemeral tributaries incise the levee allowing for the main river channel to back up into the tributary channel, around the levee, and inundate the floodplain behind it. This finding expands the area of connected floodplain (an important habitat component for many types of endangered wildlife) in Meander Canyon by an order of magnitude from previous analysis. If this finding is found to be widespread it could have important implications for habitat management in Meander Canyon and other arid rivers worldwide.
|Advisor:||Parnell, Roderic A., Grams, Paul|
|Commitee:||Smith, Michael, Kolb, Tom|
|School:||Northern Arizona University|
|Department:||Earth Sciences and Environmental Sustainability|
|School Location:||United States -- Arizona|
|Source:||MAI 81/12(E), Masters Abstracts International|
|Subjects:||Geomorphology, Geology, Environmental science|
|Keywords:||Canyonlands, Channel narrowing, Colorado River, Flooplain inundation, GIS, LiDAR|
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