7239

• UCREFRP Catalog Number: 7239
• Author: Smith, G. R. and R. G. Green.
• Title: Flaming Gorge Consolidated Hydrology Report -Draft.
• USFW Year: 1990.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

5.4 Model Calibration

5.4.1 Mitten Park and Jensen

The calibration work at all sites concentrated on aligning the peaks in terms
of timing and magnitude. Using this criteria, the Service was able to
calibrate the model so that peaks aligned within 1 hour at Mitten Park.
Validation of results was accomplished by correlating observed flows with
calculated flows at Mitten Park. A high correlation coefficient or "r" value
indicates that the two independent variables (recorded flow and calculated
flow) are highly correlated. High "r" values of .98 were calculated for both
Mitten Park and Jensen. These high "r" values demonstrate that the timing of
the flow routing was as accurate as possible using a 1 hour time step. Volume
checks were also made for Mitten Park and Jensen; calculated flows matched
observed flows within 6.8 percent at Mitten Park and 3.8 percent at Jensen,
which were used as calibration check points. These statistics were based
upon a 3 day, or 72 hour calibration period which represents a period
necessary for most peak releases from Flaming Gorge to travel to Tia Juana
Bottom (travel times to other locations are found in table 5-1). Peaking
operation during the calibration period ranged to 3,000 cfs from a base flow
of 800 cfs. This process took repeated model runs and yielded results which
are presented in Summary Table 5-5. Figure 5-5 and 5-6 display graphically
the relationship between recorded and calculated flow at Mitten Park and
Jensen.

5.4.2 Ouray Refuge

Calibration at the Ouray Refuge site was accomplished using the same criteria
and time period as Mitten Park. The model was operated with flow being routed
from Jensen to Ouray with no intervening inflows or diversions. Travel time
and routing phases were adjusted until the simulated flows matched recorded
flows to the best extent possible. The trial and error calibration process
continued until the timing of peaks matched to within 1 hour, and simulated
and recorded flows tended to follow the same general pattern. Calibration of
flows at the Ouray Refuge was within .09 percent over a 72 hour period.
Simulated and recorded flow were also compared for the same 72 hour period and
correlation statistics were prepared. An "r" value of .95 was calculated for
the Ouray site which demonstrated that selected timing parameters are good.

With Flaming Gorge peaking at 3,000 cfs from a base flow of 800 cfs, travel
time' to Ouray Refuge was 60 hours with a stage change of .75 feet. For
peaking to 4,200 cfs, travel time was shortened to 56 hours and the stage was
increased by 1.45 feet. Calibration results were based upon a single flow
event (release from Flaming Gorge Reservoir) which was observed and measured
at each recorder location for a period of 72 hours. Figure 5-7 displays
graphically the results of the calibration process at Ouray Refuge. The
information discussed above is displayed in Summary Tables 5-1 and 5-2.

5-3