WSP05649

• File Number: 8220.101.10.D
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 2/1/2000
• Author: Topping et al.
• Title: Colorado River Sediment Transport
• Water Supply Pro - Doc Type: Report/Study

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C) RIVEA MILE
Figure 13, (a) Median size of the fine sediment on the bed of the Colorado River in Marble Canyon
measured on March 1-5, 1998, on September 15-21, 1998 (immediately [allowing the two large Pari. River
floods), and on May 27-29, 1999. (b) Measured fraction of the fine sediment on the bed of the Colorado River
in Marble Canyon composed o[ 0.0625- to 0.125-mm sand. (c) Measured fraction o[ the fine sediment on the
bed of the Colorado River in Marble Canyon composed of silt and clay.

TOPPING ET AL: COLORADO RtVER SEDIMENT TRANSPORT. 2

561

period was inversely correlated with grain size (Figures I5b).
Throughout Marble Canyon a substantial decrease in the
amount of the 0.0625- to O.077-mm sand occurred between
September 1998 and May 1999 (Figure 15b), but, on average,
a factor of 1.7 more of this size class was present in May 1999
than in March 1998 (Figure I5c). Progressively smaller de-
creases occurred with increasing grain size, such that almost no

change in the amount of 0.105- to O.I25-mm sand occurred
downstream from river mile 7 between September 1998 and
May 1999 (Figures 15b). On average, a [actor of 5.0 more of
this size class was present in Marble Canyon in May 1999 than
in March 1998 (Figure 15c). Thus the bed grain-size data
suggest that some unknown fraction o[ the sand supplied by
the Paria River in Seprembcr 1998 was retained in storage 8.5