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

S40

TOPPING ET AL: COLORADO RIVER SEDIMENT TRANSPORT, 1

. MEASURED CONCENTRATION
- ESTIMATED CONCENTRATION CURVE
USED TO CALCULATE DAILY lOADS
......... WATER DISCHARGE
7 40 60
:>;
"6 35 >
"- 50 -<
30 m
<,; :D
z 25 40 0
0 in
0 20 30 0
.... :r
z >
w 15 Jl
" Cl
i5 10 m
w }
"' 5
0
8) 7.11-537-12-537-13-53 7-14-53 7-15-53 7-16-53 7-17-53 7-18-53 7.19-53
25
.. , 60 ~
! 20 50 n1
cj :D
Z 40 0
8 15 in
0
!z 10 30 ~
w Cl
" 20 m
i5 '3
w 5
<II 10 ~
....~....:~.. .........
0 0
b) 9-7-61 9.8-61 9-9-61 Q-l0..61 Q-1Hil
6 140
.. 120 ~
! 5 -<
m
cj 4 100 J)
0
z in
8 60 0
3 ~
!z 60 :D
W 2 Cl
" 40 m
i5 '3
w
<II 20 '"
'"
0 0
C) 8-12-72 8-13-72 8-14-72 8-15.72 8-16-72 8.17.72 8-18-72

Figure 12, Paria River measured suspended-sediment concentrations, the curves constructed by the USGS
to estimate sediment concentrations between the times of the measurements, and the instantaneous discharge
of water. Measured and estimated concentrations in Figure 12 are from unpublished USGS sediment notes
from the Paria River at Lees Ferry gage; the discharge of water was computed by Topping (1997] using
unpublished raw USGS stage and discharge data from this gage. (a) An example of an unusually well
measured period of tributary sediment loads in 1953. Note that in some. cases, the time of the peak
concentration was assumed to occur at the same time as the flood peak, and, in other cases (especially on July
18 and 19), it was assumed to lag the flood peak. (b) An example of a typically sparsely measured period of
tributary loads in 1961. Note that (1) the concentrations during the entire flood on September 9 were
estimated and not measured and (2) the peak concentration was assumed to be quite high and to occur at the
same time as the flood peak. (c) Another example of a sparsely measured period of tributary sediment loads
(but one in which a different interpretation was used to estimate concentrations) in 1972. In this case, like in
Figure 12b, no measurements of sediment concentration were made during the flood on August 14-15.
However, in this case, the peak concentration was assumed to be much lower than in Figure 12b (even though
the peak discharge of this flood was much larger than that during the September 1961 flood) and was assumed
to lag the flood peak.

trations at the LCR at Cameron, Arizona, water-quality sta-
tion. Unpublished internal USGS memoranda dated Decem-
ber 26, 1950, and November 3. 1952, suggest that the error
associated with the LCR sediment loads ranged from slightly
less than 25% to as much as 50% (memoranda on file in
unpublished USGS annual sediment technical files from the
LCR at Olmeron, water-quality station, 1949, 1951). In the
meml'randum dated November 3,1952, the Regional Chemist
C. S. HI)ward stated that" ... the Geological Survey was get-

ting records at the Cameron Bridge because that was where the
Bureau of Reclamation wanted them but that we in the Survey
knew they were not good records." In this same memorandum
he argued that the sediment records from the LCR at Cam-
eron should not be published and stated that he could not
agree " . . . that the figures may have some definite value to
others." Thus this "sediment-station location" source of error is
extremely difficult to quantify.
The second source of error related 10 determining sediment