9670

• UCREFRP Catalog Number: 9670
• Author: Pitlick, J.
• Title: Channel Monitoring To Evaluate Geomorphic Changes On The Main Stem Of The Colorado River.
• USFW Year: n.d.
• USFW - Doc Type: Boulder, CO.
• Copyright Material: NO

The channel bed material in the 15- and 18-mile reaches consists of gravel- and cobble-sized
sediment. The median grain size, DSO, of the bed surface sediment (armor) in the 15-mile reach,
as determined from point counts of 100-200 rocks on exposed gravel bars, ranges from 40 to 80
mm, with an average DSO of 58 mm (Fig. 2a). The D50 of the bed surface sediment in the 18-mile
reach ranges from 40 to 70 mm, with an average of 51 mm (Fig. 2b).
A
100
RM 183.3
RM 181.5
80
RM 181.3
RM 178.5
d RM 177.3
= 60
E RM 176.5
RM 176
_
4) RM 175.5
i 40 RM 174.2

d RM 171.1
RM 170.2
20 AVERAGE

0
10 100
B
100
RM 168.9
RM 167.4
80
RM 166.2
RM 164.8
L
d
RM 162.4
= 60 RM 159.9 /
RM 159.5
_
d RM 159
d 40 RM 158.5

IL RM 156
RM 154
20 AVERAGE
0

10 100
Grain Size (mm)
Figure 2. Grain size distributions of the bed surface (armor) layer based on
pebble-count samples from (a) the 15 mile reach and (b) the 18 mile reach.
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