8157

• UCREFRP Catalog Number: 8157
• Author: Pitlick, J., M. V. Steeter, B. Barkett, R. Cress and M. Franseen.
• Title: Geomorphology and Hydrology of the Colorado and Gunnison Rivers and Implications for Habitats Used by Endangered Fishes.
• USFW Year: 1999.
• USFW - Doc Type: \
• Copyright Material: NO

Colorado River
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100
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0
10 100
Grain Size (mm)
10 100
Grain Size (mm)
Figure 6. Grain size distributions of surface and subsurface sediment samples from the
upper Colorado River. Samples were taken throughout the area (see Tables A-1, A-2).
Gunnison River
1
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u
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CL
UV
------------
--- Surface
------------
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1
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10 100 10 100
Grain Size (mm) Grain Size (mm)
Figure 7. Grain size distributions of surface and subsurface sediment samples from the
Gunnison River. Samples were taken throughout the study area (see Tables A-3, A-4).
In addition to these reach-scale measurements, we selected seven additional sites on the Colorado
River where we made more detailed measurements of the channel to model the relation between
discharge and average boundary shear stress. The locations of these sites are shown in Figure 2
and their average characteristics are summarized in Table 2. These sites are all in single thread
reaches approximately 0.5 km long. At each site we surveyed 6 to 8 cross sections spaced about
one channel-width apart. Subsequently, we made additional measurements of water surface
elevations at different flow levels to calibrate a one-dimensional hydraulic model. Whous (1998)
has done similar work at one site on the Gunnison River. Later in this report we discuss his
results, and provide additional estimates of thresholds for gravel transport on the Gunnison River.
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