WSP04999

• File Number: 8054
• Description: Water Salvage
• State: CO
• Basin: Statewide
• Date: 6/1/1975
• Author: Utah Water Research
• Title: Water Salvage Potentials in Utah - Volume II - Evaporation Suppression by Reservoir Destratification
• Water Supply Pro - Doc Type: Report/Study

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35

Draw down = 86' Average (Historic Data)

30
End of 12th Month
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Co After heat decay
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10

Jan.

Feb. Mar.
Time of Initiol

Apr.
Mixing

May

Figure 14. Lake Powell mhlnllStactuP time.

temperature profiles are not available. Several
parameters were combined in many different
functional forms during the model building
process. The only parameters other than water
temperature which appear to be significant in
determining suppression are depth, flow index,
and elevation. The function derived is:

Suppression = 5.434 + 10.908 Log (D) - 5.3411
Log (el) + 15.479 Flow

in which D is maximum depth in feet, EI is
elevation in feet, and Flow is the flow index
described previously. The correlation coefficient R
for this function is 0.940. The dominate correlation
parameter is depth. Both maximum depth and
average depth during the suppression season were
compared and they both gave equally good

correlation. Maximum depths were therefore used
in the model because accurate data on average
depths were not available for many reservoirs.

The parameter which contributes the second
highest improvement in correlation is the flow
index. In fact, almost the same correlation (R =
.939) can be achieved by eliminating elevation as
follows:

Supp. = -42.49 + 11.291 Log (D) + 16.248 Flow

Unfortunately. data to calculate the flow index are
not available for many reservoirs and a desirable
model for estimating suppression on a statewide
basis would be one which excludes flow. The best
such function is:

3S