9513

• UCREFRP Catalog Number: 9513
• Author: Kuhn, G. and C. A. Williams.
• Title: Evaluation of Streamflow Losses Along the Gunnison River from Whitewater Downstream to the Redlands Canal Diversion Dam, near Grand Junction Colorado, Water Years 1995-2003.
• USFW Year: 2004.
• USFW - Doc Type: Reston, VA.
• Copyright Material: NO

18 Evaluation of Streamflow Losses Along the Gunnison River from Whitewater Downstream to the Redlands Canal Diversion
Dam, near Grand Junction, Colorado, Water Years 1995-2003
650
625
Z
O
w 600
Q
w
a
w
w
LL
CJ 575
m
U
Z
W
C7
= 550
U
525
500
• Discharge measurement at station
Maximum
~ 75th percentile
~ Mean
Median
25th percentile
Minimum
^
^

. ~
C
0
.~
y
E
c `0
-
o

.
- °
ur
~ a
C
N
N ~
a3i ~ g ~ ~ 3
L N N N N ~
(~ (~ _
CI1 _
[n m
(See figure 1 and table 1 for station and site details)
I I
I
I I.
I I I
10 11 12 13
DISTANCE DOWNSTREAM FROM WHITEWATER STATION, IN RIVER MILES
Figure 11. Distribution of unit discharges for stations at the upstream and downstream ends of the Gunnison River
study reach and distribution of discharge measurements made at miscellaneous discharge-measurement sites along
the reach during measurement set 1, February 5-6, 2003.
much larger discharge; and (2) the changes likely would not be
proportionally larger because the much smaller traveltime
during the higher flow would minimize any localized changes
in discharge. Therefore, site M2, being nearest to the midpoint
of the study reach, was the only miscellaneous site at which dis-
charge measurements were made. A temporary staff gage was
not installed at site M2 for measurement set 2.
Five discharge measurements made at site M2 ranged from
1,668 to 2,117 ft3/s, and all but one were rated good; one mea-
surement was made May 14 and four measurements were made
May 15 (fig. 12). One measurement, 2,730 ft3/s (rated good),
was made at the Whitewater station, but the measurement was
not made until May 16 (not shown in fig. 12) because of equip-
mentproblems. One measurement, 1,268 ft3/s (rated good), was
made at the below-Redlands-dam station; and one measure-
ment, 819 ft3/s (rated good), was made at the Redlands-Canal
station (not shown in fig. 12).
Because of the change in discharge during measurement
set 2 (fig. 12), consideration of traveltime is of critical impor-
tance in evaluating any streamflow losses. Traveltimes through
the study reach were estimated by comparing the unit-discharge
hydrographs at the Whitewater and below-Redlands-dam
stations; the estimated traveltimes then were used to lag the
recorded unit discharges at the Whitewater station through the
study reach. Using an estimated traveltime of about 1.5 hours,
the discharge measurements made at site M2 correlated closely
with the discharges recorded about 1.5 hours earlier at the
Whitewater station (fig. 12). Using an estimated traveltime of
about 3.5 hours, the sum of the unit discharges at the below-
Redlands-dam and Redlands-Canal stations, correlated closely
to the unit discharges recorded about 3.5 hours earlier at the
Whitewater station (fig. 12). The use of constant traveltimes
likely resulted in some error in the lagging of the unit discharges
because the traveltime most certainly varied with changes in
discharge. Results of measurement set 2 also indicate no sub-
stantial streamflow loss along the study reach. Based on the
results of the mass-balance analyses and the two measurement
sets, and discussion of the results with the cooperators, the addi-
tional measurement sets that were planned were not made.