Date of Award

6-1997

Degree Name

Master of Science

Department

Geological and Environmental Sciences

Department

Geosciences

First Advisor

Dr. W. Thomas Straw

Second Advisor

Dr. William B. Harrison III

Third Advisor

Dr. Alan Kehew

Access Setting

Masters Thesis-Open Access

Abstract

Closure of Flaming Gorge Dam in 1962 reduced the flow rate and variability of discharge on the Green River below this dam. These changes, coupled with the decreased sediment load due to stilling and sporadic peaking in response to demand for hydroelectric power and controlled releases of up to 4500 cfs to cope with snowmelt have impacted the channel morphology and ecosystems of the main stem Green River between the Dam and the Gates of Lodore. Detailed comparative analysis of channel shape and riparian ecosystems or pre-dam and post-dam aerial photographs revealed that significant changes occurred after closure. Channel width has decreased by up to 80 percent and channel banks have shifted by as much as 467 ft. Field studies confirmed that altered hydrology and extensive colonization by Tamarisk have stabilized point bars and channel banks. Controlled releases with peak flows much lower than preclosure high flows preclude recolonization of cottonwood trees, but because bank erosion occurs at flows of 1000 cfs this riparian system continues to adjust to anthropogenic manipulation.

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