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CRDSS <br />TASK MEMORANDUM 1.14-5 <br />Consumptive Use Models <br />Consumptive Use Models Included in the Short List <br />1.0 ISSUE <br />The purpose of this task memorandum is to describe the reasons for including consumptive use models in <br />the ?short list.? The short list was composed of five models that went through a more rigorous <br />evaluation phase. <br />2.0 DISCUSSION/ANALYSIS <br />The evaluation criteria were determined with review from the State and applied to the initial long list of <br />consumptive use models. The models described in this memorandum were included in the short list <br />based on the criteria outlined in Task Memorandum 1.14-3. The short list models then went through a <br />more rigorous analysis including testing with sample data sets. <br />XCONS2 <br />XCONS2 was developed by the U. S. Bureau of Reclamation (USBR), Denver Office; the technical <br />contact is Mike Madigan. This model was written in FORTRAN, and it runs on an IBM-compatible PC. <br />This model has also been compiled on a UNIX workstation. This model uses the Soil Conservation <br />Service (SCS) Blaney-Criddle method to estimate monthly and seasonal evapotranspiration (ET) for 20 <br />different crops. <br />The main function of the model is to estimate monthly and seasonal consumptive irrigation requirement <br />(CIR) for specific crops and acreage using weather and crop growing season data. This model calculates <br />the CIR by considering the effective precipitation or the method used by the United States Department of <br />Agriculture, Soil Conservation Service Irrigation Water Requirements Technical Release No. 21, revised <br />in 1970 (TR-21). <br />This model is extensively used by the USBR for estimating the monthly ET and CIR, and has 20 readily <br />available crop coefficient curves that can be easily modified for any location of interest. This model is <br />currently used to prepare the Colorado River System Consumptive Uses and Losses Report, 1981-1985 . <br />The model is in the public domain, and the source code has been obtained and reviewed. The source <br />code is fairly easy to follow, but not very modularly designed. A small effort would be required to <br />modularize the code and add a few comments to make the source code easier to follow. Since the USBR <br />uses this program for the consumptive uses and losses report and the code is in the public domain, it is <br />recommended that this program be selected for use with CRDSS. <br />The testing has verified that XCONS2 correctly calculates crop ET using the SCS TR-21 methodology. <br />The testing involved inputting a data file with different temperature parameters and comparing the <br />results. It is envisioned that after the model is modularized, some of the recommendations to the USBR <br />methods manual can be incorporated into the model in the form of options so the user can evaluate the <br />model in its original form or use an enhanced version of the model. <br />1 <br />A275 01.09.95 1.14-5 CSU IDS <br />