Final.HCI.Report.HDR

• Title: Hydro-Climate Index Study
• Prepared For: CWCB & Colorado River WCD
• Prepared By: HDR Engineering Inc.
• Date: 12/28/2007
• County: Statewide
• State: CO
• Country: USA
• Weather Modification - Doc Type: Scientific Study

Yampa:
A reasonable connection with the SOI and the AMO exists, however, it is less
firm than the basins listed immediately above. To potentially improve any outlook would
be to cross check the SOI and the
Plateau Creek:
For this basin, a very robust (relatively speaking) relationship exists with the
ENSO (preferably the SOI) and the 2 -year average for peak runoff in Plateau Creek.
Some connection exists with the AMO as well and cross index connection might be
examined to see if improved relationships exist.
Table 12. Summary of Apr. -Sept. Multi (2 -year) Naturalized Streamflow /HCI Relationships for the
Colorado /Gunnison/Yampa -White basins (dark `X' indicates a relatively strong relationship and
light 'X' indicates a relatively weak relationship).
Runoff Timing:
An attempt was made to determine what impacts, if any did the HCI potentially
have on the timing of the runoff in the basin. For the Colorado River basin, the analysis
was confined to the timing of what is commonly called `Combined Reservoir
Operations'. This operation is tied to the inflows on four main reservoirs, Green
Mountain Reservoir on the Blue River branch of the Upper Colorado, Williams Fork
Reservoir on the Fraser River branch of the Upper Colorado, Wolford Reservoir on the
Muddy Creek branch of the Upper Colorado and Rudei Reservoir on the Roaring Fork
River. The primary question was centered around whether there was any `predicability'
about the date which a combined 5000 cfs flows into these reservoirs.
In summary, there was not a significant tie -in between the date of sustained 5000
cfs and the HCI values that could be reasonably used for planning purposes. It should be
noted that the data sample points are limited to only 22 points. This is because of two
factors 1) there are only 31 years which detailed naturalized flows are available in the
basin available from the State (it should be noted that the State is working on expanding
this dataset but, it is time - consuming).
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PDO
MEI
SOI
Nino 3.4
NAO
AMO
Upper Colo.
X
Middle Colo.
X
Eagle
X
X
Roaring Fork
X
X
Gunnison
X
X
Uncompaghre
X
X
White
Yampa
Runoff Timing:
An attempt was made to determine what impacts, if any did the HCI potentially
have on the timing of the runoff in the basin. For the Colorado River basin, the analysis
was confined to the timing of what is commonly called `Combined Reservoir
Operations'. This operation is tied to the inflows on four main reservoirs, Green
Mountain Reservoir on the Blue River branch of the Upper Colorado, Williams Fork
Reservoir on the Fraser River branch of the Upper Colorado, Wolford Reservoir on the
Muddy Creek branch of the Upper Colorado and Rudei Reservoir on the Roaring Fork
River. The primary question was centered around whether there was any `predicability'
about the date which a combined 5000 cfs flows into these reservoirs.
In summary, there was not a significant tie -in between the date of sustained 5000
cfs and the HCI values that could be reasonably used for planning purposes. It should be
noted that the data sample points are limited to only 22 points. This is because of two
factors 1) there are only 31 years which detailed naturalized flows are available in the
basin available from the State (it should be noted that the State is working on expanding
this dataset but, it is time - consuming).
39