WSPC06213

• File Number: 8283.200
• Description: Colorado River Basin-Colorado River Computer Models-Colorado River Decision Support System-Ray
• State: CO
• Water Division: 5
• Date: 4/5/1994
• Title: Consumptive Use Modeling-Task 1.14a-Evaluation of Consumptive Use Models-Consumptive Use Data Input Requirements
• Water Supply Pro - Doc Type: Report/Study

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Task 1.14(a) - Evaluation of Consumptive Use Models

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Table 2: Baseline Scenario Data

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Unit It: core From
Consumptive Use Model Input Type String Type /to: Entlty(s)
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Beginning date of CU calculation Date Character String 1!. scenarioa
(defautt value current date) or Integer
Ending date of CU calculation Date Character String It scenario
(defautt value one year from current date or Integer
Application depth (L) for computation of length Float /to scenario
effective precipitation?
Area for CU calculation Area Integer /to scenario
Weighted values denoting the reliabiltty of Unttless Integer It climate station
the data for each climate station

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3.0 Agricultural Crop Evapotranspiration Data Input

The most important factor in the determination of the expected water use fOT agricultural
land is crop evapotranspiration (ET). Evapotranspiration is a combination of wateT loss
through evaporation and plant water use or transpiration. For calculating crop ET, more than
one method will probably be available.

3.1 Methods for Estimating Crop Evapotranspiration
The Soil Conservation Service (SCS) Modified Blaney-Criddle will be used and another
method using a reference crop equation will probably be used

SCS Modified Blaney-Criddle
Several of the inputs are static values, sucn as crop type (20 types), crop ET
coefficients, etc. 1]!ese-values will be incorporated into the oveTall CRDSS database, but
have no current default location-- i.e. physical characteristics DB, historical DB, etc,

Reference 000 EQuation
In accordance with current developments in the irrigation science community, a
reference crop equation may be adopted for estimation of ET along with otheT methods.
Reference crop equations calculate the evapotranspiration rate for well-watered reference
crops and then subsequently apply crop coefficients to determine the evapotranspiration
Tates of otheT crops.

3.2 Data Needs for Each Crop
There are standard values fOT cro characteristics that will be obtained from current ~
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literature or references. ~ is not data that needs to be collecl"ct fmm source arid it is a "
relatively small amount of information. These values will be used to calculate CU fOT each
individual type of crop. Table 3 displays some of the inputs that will be needed. It is
assumed that the useT will be able to customize these values for particular modeling needs.

4/5/94 - Evaluation Document (for internal use) 3

Database Requirements: esu- AD05