WSP07957

• File Number: 8276.100
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/21/1983
• Title: Grand Valley Salt Pickup Calculations - Draft Report
• Water Supply Pro - Doc Type: Report/Study

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GRAND VALLEY RIVER BUDGET

CHAPTER II

consumptive use prior to 1972. The Blaney-Criddle method as programmed in

GJTR2l (a modified TR2l) was used to estimate the irrigation season's monthly

consumptive use for the entire period ignoring municipal and barren land

contributions. For the irrigation seasons of the common period, the Blaney-

Criddle results were correlated to the Jensen-Raise results. Using this

regression (coefficient of determination = 0.95), the pre 1972 irrigation

month's Jensen-Raise consumptive use values were estimated. The 000-

irrigation months were assumed to be the average Jensen-Raise value for that

month during the period 1972-1980.

Finally, barren and municipal land consumptive uses were added.

Non-agri- cultural consumptive use is somewhat harder to obtain. Information

on municipal water use was obtained from district records. The other users

such as farmsteads, barren, and phreatophytes were assumed to be a function

of ETP for the 74, 75, 76 budget runs. Because we had no additional

information available we used the ET's used previously (prorated to the 1976

modified ETP) for the current budget study. Barren land consumption was

assumed to equal the precipitation at the Walker Field Weather Station.

The consumptive use has a significant influence on the salt loading

calculations because of the concentrating effect. The agricultural con-

sumptive use calculations are as accurate as current technology and available

data can provide. Non-agricultural consumptive use calculations could

possibly be improved but not without extensive effort.

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