CRDSS_Task1_14-8_CUModelTerms

• Title: CRDSS Task 1.14-8 Consumptive Use Model - Consumptive Use Model Terms
• Description: To reduce the confusion caused by having multiple terms with slightly different meanings, the following definitions for consumptive use terms are recommended for the CRDSS.
• Decision Support - Doc Type: Task Memorandum
• Date: 1/9/1995
• DSS Category: Consumptive Use
• DSS: Colorado River
• Basin: Colorado Mainstem
• Contract/PO #: C153658, C153727, C153752
• Grant Type: Non-Reimbursable
• Bill Number: SB92-87, HB93-1273, SB94-029, HB95-1155, SB96-153, HB97-008
• Prepared By: Riverside Technology inc.

Carry Over Soil Moisture (SM)
Carry over soil moisture is moisture that is stored in soil pores in the soil's root zone during the winter
while the plant is dormant and becomes available to meet the consumptive use requirements of crops
during the growing season.
Irrigation Water Requirement (IWR)
The consumptive irrigation requirement is the depth of irrigation water required consumptively for crop
production, exclusive of effective precipitation and carry over soil moisture.
Farm Loss (FL)
Farm loss is the total of incidental losses that occur during irrigation such as deep percolation, runoff,
and/or water applied for leaching.
Farm Head Gate Requirement (FHR)
The depth of irrigation water, exclusive of precipitation, stored soil moisture, or ground water that is
required consumptively for crop production and required for other related uses such as leaching, frost
protection, etc.
Conveyance Loss (CL)
Conveyance loss is the total of all the losses that occur from the diversion source (river head gate) to the
farm head gate. These losses include seepage and evaporation.
River Head Gate Requirement (RHR)
The volume of water required to fully satisfy the on-farm losses, potential evapotranspiration of the crop,
and the conveyance losses.
On-farm Irrigation Efficiency (Ef)
On-farm irrigation efficiency is the irrigation efficiency as measured from the farm head gate.
Conveyance Efficiency (Ec)
Conveyance efficiency is the ratio of the volume of water delivered in an open or closed conveyance
system at the supply source that could be a head gate or well head.
System Irrigation Efficiency (Es)
System irrigation efficiency is the irrigation efficiency as measured from the point of diversion. This is
the ratio of volume of irrigation water required for beneficial use in the specified irrigated area to the
volume of water required to be delivered to this area to achieve the specified amount of beneficial use.
The following are miscellaneous consumptive use terms:
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A275 01.09.95 1.14-8 CSU IDS