WSPC04421

• File Number: 8064.100
• Description: Ute Tribes
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 9/1/1986
• Author: Boyle Engineering
• Title: Agricultural Engineering Study - Southern Ute and Ute Mountain - Ute Indian Reservations - Task A Report - On-Farm Water Requirements
• Water Supply Pro - Doc Type: Report/Study

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developed in this area is presented later in this chapter.

Once the crop consumptive use is established, the irrigation

requirement can be determined. The irrigation requirement is crop

ET as modified by soil carryover moisture, effective precipitation,

and leaching requirements.

Carryover moisture is soil moisture stored in the root zone of the

crop as supplied by winter precipitation.

It is available to meet

crop ET in the spring when it starts growing, so is subtracted from

the irrigation requirement.

Effective precipitation is rainfall occurring during the growing

season that is effective in meeting crop ET.

Rainfall effectiveness

is influenced by several factors including crop and soil properties,

irrigation practices, and precipitation patterns.

In general,

frequent light rains intercepted by plant foilage with full ground

cover

effective

rains.

infrequent

than

heavy

are

more

Effectiveness ranges from less than 60 percent to 100 percent.

Leaching requirements are additions to the irrigation requirement

and are needed to leach soluble salts below the root zone.

Sal ts are

concentrated in the root zone by an osmotic process in which the roots

act as a semipermeable membrane~

If left to accumulate they may

become toxic to the crop and result in'reduced yields.

As identified

elsewhere in this report, the leaching requirement for all crops is

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