WSP11681

• File Number: 8220.101.17
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 4/1/1995
• Title: Measured and Predicted Velocity and Longitudinal Dispersion at Steady and Unsteady Flow / Colorado River / Glen Canyon Dam to Lake Mead
• Water Supply Pro - Doc Type: Report/Study

Measured and Predicted Velocity and Longitudinal Dispersion at Steady and Unsteady Flow,
Colorado River, Glen Canyon Dam to Lake Mead

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o Steady flow, May 20-25,1991

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DISTANCE FROM INJECTION. IN KILOMETERS

Figure 7, Relation orPeak Concentration to Distance Traveled, Grand Canyon Reach.

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TIME TO CENTROID, IN HOURS

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Figure 8. Relation or Dye-Cloud Variance to Traveltime or the Dye-Cloud Centroid, Grand Canyon Reach.
Equation shown applies only to steady flow.

distance and traveltime during unsteady /low, but the
increase was not systematic (Figure 8). Duration of
the dye cloud, measured from the time of first arrival
of the dye at the site to the time at which concentra-
tion returned to background, was 15.5 hours for
steady flow and 17.5 hours for unsteady flow at the
site 380 km downstream from the injection. For
steady flow, duration increased with traveltime of the
peak concentration according to the relation Td = 2.4
TpO.45, where Td is dye-cloud duration in hours. The

increase in dye-cloud duration is slower than is typi-
cal (Graf, 1986; Kilpatrick et al., 1989).
For the steady-flow measurement, time-concentra-
tion curves at all sites were positively skewed Crable 3
and Figure 9). Skewness decreased with time and dis-
tance, and therefore, curves are closer to normal dis-
tributions toward the downstream end of the study
reach. As discussed above, skewness for sites during
the unsteady-flow measurement is positive or nega-
tive, depending on the way in which discharge
changed during dye passage.

275

WATER RESOURCES BULLETIN

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