WSP12639

• File Number: 8220.101.10.A
• Description: Colorado River - Water Projects - Glen Canyon Dam-Lake Powell - Glen Canyon AMWG
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/2004
• Author: Schmidt - Topping - Grams - Hazel
• Title: System-Wide Changes in the Distribution of Fine Sediment in the Colorado River Corridor Between Glen Canyon Dam and Bright Angel Creek - Arizona - Final Report - 10-01-04
• Water Supply Pro - Doc Type: Report/Study

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DISTANCE DOWNSTREAM FROM GLEN CANYON DAM,
IN KILOMETERS

100

edcty
sand
(1999)

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, Sand(1956)
/sand(1966)

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Particle size. in miBimeters

1000

Figure 20. (left) Graph showing change in
stage at 150 m'/s. plotted as a function of
distance downstream from Glen Canyon
Dam (Grams et aI., 2004, fig 11)

.

Figure 21. (Below) Graph showing bed
sediment size distribution for samples in
Glen Canyon. Size in 1956 includes the
average of bed surface samples,
distinguishing the average of sand samples
and the average of bore.hole samples of the
underlying gravel. Size in 1966 distinguishes
the average size of gravel armor, gravel
subsurface, and sand Size in 1975 is for
gravel armor. Samples in 1999 were
collected by pipe dredge from a boat at
approximately 1..J<.m intervals, and the
indicated size is the composite of all
samples. Data for 1956 to 1975 are from
25 Pemberton (1976). Figure is from Grams et
al. (2004, fig. 6).

- - - 1956
-1966
1975
1999

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armor matenat (1966)

und~ng
gra"Ve1 (1956)

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III~
I armor matenal (1975)
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,

100

act as the hydraulic controls of the water
surface profile for the 145 km between the
Lees Ferry and Grand Canyon gages. There is
some evidence that many rapids aggraded.
There is limited evidence that the bed of some
pools degraded. There is no evidence of
longitudinally extensive multi-year accumula~
tion of fine sediment on the bed,

5.3 Post.dam Changes in the Bed in Marble
and Upper Grand Canyons

There is no evidence for longitudinally
consistent changes in stagc~discharge relations
in Marble and Grand Canyon. because
bouldery rapids have not eroded. These rapids

.

32 System-wide Changes in the Disthbution of Fine Sediment in the Colorado River CorTidor ...