8252

• UCREFRP Catalog Number: 8252
• Author: Allred, T. M. and J. C. Schmidt.
• Title: Channel Narrowing of the Green River Near Green River, Utah
• USFW Year: 1999.
• USFW - Doc Type: History, Rates, and Processes of Narrowing.
• Copyright Material: NO

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Powell floated through this open valley on July 13, 1869. Graf (1978) and
Andrews (1986) both studied this reach, and came to different conclusions
about the timinQ and cause of channel narrowing. We initiated this study to
resolve this disagreement and because revisions in the operations of Flaming
Gorge Dam, located 475 km upstream, have been proposed in part to maintain
habitat diversity and to inhibit narrowing. We sought to understand whether
channel narrowing had actually been caused by the dam.
Graf (1978) and Andrews (1986) showed that channel narrowing has
occurred in areas of both restricted and fixed meander planform. Grams (1997)
showed that narrowing also has occurred in the debris fan-affected canyons of
the eastern Uinta Mountains. These studies document the existence of inset
. alluvial deposits that comprise a new floodplain. It is important to note that
these inset floodplains often occur in areas where lateral migration is restricted;
thus, these deposits must form by some process other than lateral accretion.
No studies exist that demonstrate the rate or mechanism by which inset
floodplains form. There is a clear need to understand how these deposits form
because many geomorphic settings limit channel migration.
One part of this study utilizes previously unanalyzed archived discharge
records of the US GeOlogical Survey's (USGS) streamflow gaging station
"Green River at Green River, Utah" (station number 09315000). Although
Thompson (1984) and Andrews (1986) had analyzed the sediment transport
data collected at the gage, no analysis had been completed of the more than