WSP05604

• File Number: 8220.101.10.D
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 1/1/1999
• Author: Topping et al.
• Title: Linkage Between Grain-Size Evolution and Sediment Depletion During Colorado River Floods
• Water Supply Pro - Doc Type: Report/Study

92 GRAIN-SIZE EVOLUTION DURING FLOODS

Flood Deposits
. Mile 61 ,. Mile 122
. Mile 63 . Mile 136
... Mile 72
1.0
A
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3:0 0,08 0,10 D50 (mm)
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D99 (mm)

Suspended Sediment
."U'-- National eyn. gage
--.-'V--..122-M\leeddy
--- -0'-- Grand Cyn, gage

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Figure 6. (Al Plot of median grain size (050) as function of normalized height within the 1996 Rood deposits. and plot
of (he median grain size of the suspended sedimem in the main channel at the Grand Canyon (P-61 samples only) and
National Canyon gages, and in the 122-mile eddy as a normalized function of lime during the 1996 comrolled flood. (8)
PIOI of D99 as function of normalized heighl within the 1996 flood deposits, and plol of 099 of {he suspended sediment
in the main channel allhe Grand Canyon (P-61 samples only) and Nalional Canyon gages. and in Ihe 122-mile eddy as a
normalized funclion of lime during Ihe 1996 conlrolled flood. (C) Plot of median grain size (D50) and D99 as funclion
of normahzed height wi\hin the pre-dam t\ood deposils.

6, VERTICAL TRENDS IN THE GRAIN-SIZE DlSTRI.
BUTION OF COLORADO RIVER FLOOD DEPOSITS

Rubill el ai, [1990], To build on this earlier work and to
couple the sedimentology of deposits produced during the
1996 conlrolled flood to the grain-size distributions of
suspended sediment measured during the 1996 controlled
Ilood. we sampled deposits of the 19961100d in trenches on
5 eddy bars between Lees Ferry and Diamond Creek, At 3
of these sites, identtlicalion of Ihe base of the Hood deposit
was aided by scour chains thaI were emplaced prior to the

6,/, Deposirs oflhe /996 Flood

Th~ sedimentology of fine-grained deposits in GrJnd
Canyon was previously invesligated by McKee [19381.
Howard alld Dolall [1981 J, Schmidl alld Graf [1990J. and