WSP03161

• File Number: 8276.150
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1976
• Title: Draft - Grand Valley Salinity Study
• Water Supply Pro - Doc Type: Report/Study

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structures and land leveling to permit control and uniformity in the

amount of water appl ied during each irrigation, C3t subsurface drains

for existing open drains to combine fields into more efficient units,

and (~) control of surface water leaving the fields.

The objective of each level of improvement was to efficiently apply the

net irrigation application determined for the soil and crop, and to

determine .the number of irrigations needed to provide: the seasonal

water requirements of the crop. Irrigation managemert factors which

the irrigator can control are the time of set, the flow rate to each

furrow in the field, and the number and timing of irrigations during

the season. These were the managementvariables used in the following

analysis of improvement levels. A basic assumption in irrigation water

management is that soil moisture to be replaced is a fixed amount for

each irrigation depending on soil moisture storage capacity. The

frequency of irrigation will vary during the irrigation season with

the variation in daily water requirements of each crop grown.

Present On-going Program - Present irrigation conditions were determined

to establ ish a base for recommending improvements and to measure the

effects of those improvements. It should be noted that results from

evaluating the present conditions are conservatively stated. The

procedure contained no basis for considering effects of unleveled

fields or of inaccuracy in water measurement. Therefore, present deep

percolation losses may be somewhat higher than Indicated because of the

lack of uniform water application on unleveled fields.

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