9625

• UCREFRP Catalog Number: 9625
• Author: Friedel, M. J.
• Title: Probable Effects of the Proposed Sulphur Gulch Reservoir on Colorado River Quantity and Quality Near Grand Junction, Colorado.
• USFW Year: 2004.
• USFW - Doc Type: \
• Copyright Material: NO

DESCRIPTION OF THE MODEL 11
diversion profiles provided in figures 4 and 5. By contrast, eval-
uation of the diversion profiles further reveals the presence of a
seasonal dependence. Because individual profiles generally are
not related to hydrologic condition, the variability surrounding
these seasonal diversions is modeled in this study as a set of
independent random variables; therefore, individual probability
distribution functions are fit to the various seasonal components
between days 100 to 300. For example, three probability func-
tions are fit and used to replicate diversion behavior for the
GVIC, whereas five probability functions are fit and used to
replicate diversion behavior for the GHC.
A summary of fitted probability distributions for each of
the streamflow diversions is presented in table 4. Because the
GHC delivers water to the Mesa County Irrigation District,
Palisade Irrigation District, Mesa County Irrigation District,
and Grand Valley Water Users Association, individual distribu-
tions are fit to each of their corresponding records. Whereas
the random variability of Colorado River streamflow near
1,200
0
Oz 1,000
U
w
w
a
~ 800
w
w
w
U
m
v 600
z
z
O
~ 400
w
O
~ 200
0
De Beque, Cameo, and Palisade reflects documented natural
variability, the quantity and quality of runoff in Sulphur Gulch
are uncertain. The primary reason for runoff uncertainty is the
lack of direct measurements in this ephemeral tributary. To
better define uncertainty that exists in the Sulphur Gulch runoff
component, hydrograph separation was performed using dis-
charge measurements from the adjacent Dry Fork watershed
and USGS software (Rutledge, 1998).
By using the computed Dry Fork baseflow hydrograph, the
corresponding streamflow hydrograph was normalized by
drainage area to obtain a unit runoff hydrograph for use in the
Sulphur Gulch drainage. A Weibull probability distribution was
fit to the corresponding derived runoff time series. Anecdotal
evidence in the form of debris along the canyon walls together
with the approximate cross sectional area provided information
to compute an upper bound on the probability distribution that
was set to 1,000 ft~/s. For a comprehensive review of mathe-
matical formulae describing these probability distribution
DAY OF YEAR
EXPLANATIQN
Average annual hydrologic condition
Dry annual hydrologic condition
• Wet annual hydrologic condition
1974 1975 1976 1977 1978 1979 1980
1981 1982 1983 ~ 1984 ~ 1985 ® 1986 1987
1988 1989 1990 1991 1992 1993 1994
~ 1995 1996 ®1997 1998 1999 2000
Figure 4. Historical flow diversions at the Grand Valley Irrigation Canal.
0 100 200 300 400