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

Discharge Correlation with Upstream Levee Logger Data and USGS Gaging Station Discharges
' The level logger data was reduced and converted to a river stage similar to the derivation
of the rating curve for the staff gage. A simple Fortran computer program LOGGER was written
to extract the data from the level logger file, convert the level logger pressure data to stage, and
compute the river discharge from the rating curve derived for the level logger location. The level
logger records date, time, day of year, depth in feet below the water surface, and water
temperature every 30 minutes (every 15 minutes in 1995). The program averaged the data to
' determine a daily discharge or temperature. The average daily discharges are computed using the
power regression equation for the level logger and are written to file using the 24 hour period
' starting at time 00:00 (midnight). The data and- computer output results are available from the
U.S. Fish and Wildlife Service, Water Resources Division, Denver, Colorado.

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Utilizing the computed discharge from the upstream level loggers and strip chart
recorders, and estimated USGS gaging station discharge, Figures 5 and 6 were developed
showing the relationship between the river discharge in Canyonlands and the upstream discharge
hydrographs. The Canyonlands level logger discharge is shown to correlate well with the Below
While River and Desolation level logger discharge. There is some variation in the Canyonlands
data around the peak when the shift in the level logger pipe occurred due to the loosened
mounting bolts. The Canyonlands discharge does not correlate as well with the USGS Green
River gage discharge data.
These figures indicate that there is some variation in the Green River gage data over the
course of the high flow season. The USGS Green River gage appears to be subject to rating
curve shifts related to sediment movement in the alluvial channel. This phenomena was also
noted in the FLO Engineering 1995a report. As the channel bed elevation varies with bed scour
or deposition, additional discharge measurements are needed to recalibrate the USGS gage.
During the 1996 high flow season, three discharge measurements were made by the USGS at the
Green River gage on Apri125, May 23 and June 25 and the corresponding rating curve shift was
2.4, -0.23 and 1.4 respectively. Reviewing Figure 6 indicates a peak discharge at the Green
River gage of 1,000 cfs to 2,500 cfs in excess of the peak flows at Desolation and Canyonlands.
On the recessional limb of the hydrograph, the discharge at Green River is consistently less than
the discharge at both the Desolation and Canyonlands level loggers. A 1,000 cfs drop in the
discharge is observed in the Green River data over a three day period from June 12 to June 14
that is not noted in any of the other gages.
Temperature Data
The level loggers also record temperature data in conjunction with the time interval stage
measurement. The Canyonlands temperature data was reduced and plotted as a mean daily
temperature in Figure 7 along with the other level logger temperatures and the Green River gage
hydrograph. The LOGGER program was applied to compute the mean daily temperature. The
correlation between the level logger temperature data is excellent.
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