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

Discussion of Streamflow Losses 19
3,000
2,700
0 2,400
z
O
U
w
w 2,100
a
w
w
w
U 1,800
m
U
Z
~ 1,500
U
~_
~ 1,200
900
600
1200 1600 2000 0000 0400 0800 1200 1600 2000 0000
MAY 14 I MAY 15
Figure 12. Unit discharges for stations at the upstream and downstream ends of the Gunnison River study reach
and discharge measurements made at site M2 during measurement set 2, May 14-15, 2003.
Discussion of streamflow Losses
Results of the mass-balance analyses shown in table 2 and
figures 7-9 clearly show that, for WYs 1995-2002, the sum of
recorded discharges at stations below-Redlands-dam and
Redlands-Canal generally tend to be less than recorded dis-
charges at the Whitewater station. Even on the basis of that time
period alone, however, it cannot be concluded that the study
reach is, in fact, a losing stream reach because
1. The lack of a final, quality-assured daily discharge record
for the below-Redlands-dam station does not provide a
quantitative estimate of the error in that discharge record,
especially in light of the seemingly better discharge
record during WY 2003 following the changes in equip-
ment.
2. The water-year differences listed in table 1, even without
any quantitative estimate of the error in the discharge
record for the below-Redlands-dam station, mostly are
less than 5 percent and within the stated 5-percent
accuracy of the discharge measurements and the final,
quality-assured daily discharge records for the
Whitewater and Redlands-Canal stations.
3. Although some differences between daily mean discharge
at the downstream and upstream stations are large, some
of the differences are attributable to traveltime of
Streamflow through the reach, which is not entirely
accounted for in the discharge record, especially in the
daily mean values.
Additionally, results of the mass-balance analysis for
WY 2003, which seem to indicate a change in the observed
trend of streamflow losses during WYs 1995-2002 (table 2),
and results of the two measurement sets, indicate that these
losses only might be "perceived" because of inaccuracies in the
real-time data and the effects of traveltime.
Those involved in administration of water-use rights and
management of water resources in the Gunnison River basin
frequently look at web-based real-time discharge data for the
three stations along the study reach. Often, there is some differ-
ence between the sum of the discharges at the two downstream
stations (below-Redlands-dam and Redlands-Canal) and the
upstream station (Whitewater). Because the study of stream-
flow losses in the reach described in this report indicated that
there likely are no measurable losses, the differences between
real-time upstream and downstream discharge primarily can be
attributed to (1) traveltime of streamflow through the reach,