9608

• UCREFRP Catalog Number: 9608
• Author: FLO Engineering Inc.
• Title: Establishment of a Green River Gage in Canyonlands National Park, Utah 1995-1996.
• USFW Year: 1997.
• USFW - Doc Type: Breckenridge, CO.
• Copyright Material: NO

1
t Results
' General
The principal product of the data collection effort is a discharge rating curve for the staff
' gage and level logger in Canyonlands. With the rating curve, researchers in Canyonlands can
estimate the river discharge while working on site. In the FLO report (1995b), the discharge in
Canyonlands was correlated with the Green River and San Rafael gage data. A comparison of
t the 1995 and 19961evel logger data with the Green River gage discharge indicates that there is a
frequent shift in stage occurring at the Green River gage. The USGS estimates of the discharge
' at this gage poorly correlated with both upstream and downstream level loggers. As a result, an
equation correlating the Canyonlands level logger discharge and the Green River gage discharge
was not determined for the 1996 data as it was for the 1995 discharge data.
Derivation of a Rating Curve
It was necessary to derive two ratings curves, one for the staff gage and one for the level
logger. The level logger rating curve relates the level logger stage data to a river discharge.
' Figure 4 depicts the rating curve for the staff gage. An equation has been developed for each
rating curve which can be applied to estimate the discharge for a given stage reading. For the
staff gage the discharge Q equation is:
Q = 551.92 (stage)1~488
' where,
stage = 2.99 + lower staff gage reading or
stage = 8.38 + upper staff gage reading
' The are two staff gages, one higher than the other, to enable very high flow or very low flow
river stage to be read. The coefficient of determination (rz) was 0.996 for the staff gage equation.
The stage values determined from the above equations represent the water surface elevation
above elevation 3940.00. The coefficient and exponent in this equation varied only slightly from
the inclusion of the 1996 data and the coefficient of determination improved slightly. Either the
' equation or Figure 2 can be used to determine the river discharge after reading the staff gage and
converting the reading to obtain the stage.
' The rating curve from the level logger is:
' Q = 210.68 (stage)1~818
where the stage is the water surface elevation above 3940.00. The coefficient of determination
' for this equation is 0.997. The level logger equation was applied to the level logger data base in
the LOGGER Fortran program to compute a daily discharge. The level logger rating curve is
plotted on Figure 3.
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