9614

• UCREFRP Catalog Number: 9614
• Author: Bowen, Z. H. and e. al.
• Title: Habitat Measurement and Modeling in the Green and Yampa Rivers.
• USFW Year: 2001.
• USFW - Doc Type: \
• Copyright Material: NO

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Table 4. Summary of runoff flows in the Green and Yampa Rivers for representative wet,
normal, and dry years under pre- and post-Flaming Gorge conditions. Percentage
differences refer to the amount and direction of change from the pre-dam condition.
Green river Yampa River
Condition Pre-dam Post-dam Difference Pre-dam Post-dam Difference
(m3/s) (m3/s) (%) (m3/s) (m3/s) (%)
Wet 389.4 319.1 -22.0 295.5 319.1 +43.1
Normal 368.5 241.0 -34.6 220.2 205.0 -6.9
Dry 180.8 164.9 -8.8 100.8 99.3 -1.6
Table 5. Summary of annual peak discharges in the Green and Yampa Rivers for
representative wet, normal, and dry years under pre- and post-Flaming Gorge conditions.
Percentage differences refer to the amount and direction of change from the pre-dam
condition.
Green river Yampa River
Condition Pre-dam Post-dam Difference Pre-dam Post-dam Difference
(m3/S) (m3/S) (%) (m3/S) (m3/S) (%)
Wet 816 510 -37.5 581 555 -4.5
Normal 751 470 -37.4 479 496 +3.5
Dry 337 314 -6.8 254 217 -14.6
years average daily and peak discharges were about the same for both pre- and post-dam
periods. The peak discharges in the wet year comparison were also similar, but the mean
daily discharges were considerably higher for the post-dam runoff period. The opposite
phenomenon was observed in the dry year comparison, where the average daily flows for
the period were essentially the same, but the peaks differed by nearly 15%.
Several aspects of the runoff period are noteworthy. First, the runoff hydrographs
for the Yampa River and the Green River were commonly bimodal or polymodal. These
multiple spikes were more dramatic during normal and dry water years, and represented
two or more distinct snowmelt periods. Early-season peaks were probably associated
with snowmelt from the south-facing drainages, and late-season peaks from north-facing