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

This information along with technical data relating to outlet capacity, head,
and tailwater elevation was converted into a basic network and table format to
describe the physical characteristics of Flaming Gorge Reservoir. This
information along with the basic operational criteria as used to model the
operation of Flaming Gorge Reservoir. Operational simulation was accomplished
by building upon known operational characteristics and using a trial and error
methodology.

The model was calibrated through a series of trials where different reservoir
operations were modeled and the outcome of the trials evaluated. The trials
first began with short time periods of 1 to 3 years and were expanded as
results improved to cover the 1930 to 1982 period of record for the Green
River. Generally the model was operated for a period when Flaming Gorge was
in operation and the results were compared with actual reservoir operations on
a month by month basis. When the reservoir operated properly and the results
appeared reasonable the runs were were circulated for reviewed. Through this
process the operation of the model was refined and validation of model results
was achieved. The results of this process confirmed our conclusion that the
simulation of Flaming Gorge was as good as possible without some type of
expert system built into the model.

The next step is to use the model to run operational scenarios for the
Opinion. One particular scenario which may be addressed is the interim flow
agreement which has constrain releases from Flaming Gorge in the months of
August and September during 1986 and 1987 to improve habitat conditions for
Colorado Squawfish fry. Releases were be constrained to a maximum of 100,000
acre-feet per month and would vary between 800 and 2,600 cfs on a daily basis.
The way HYDROSS is now set up and calibrated it can be used to model this
scenario and other scenarios with only minor modifications.

4.7 Conclusion

The HYDROSS model was setup and calibrated on the Green and Colorado Rivers
and can be used to model any monthly Flaming Gorge release scenario developed
for the Opinion. The model is capable of modeling changing scenarios, keeping
track of many levels of development, and analyzing changes between these
scenarios. The model has limitations in actively operating reservoirs, and
much of the initial setup is trial and error until the characteristics of the
reservoir and inflow are quantified.

The uses of the model to track depletions and establish an environmental
baseline have been established on the Colorado and Yampa Rivers where the
model is routinely used for Section 7 consultations. The model can also be
used for quantifying the test releases from flaming Gorge and identifying
impact when releases are shifted from the summer to the fall and winter.

4-3