RGDSS_Historic_CUreport_20040601

• Title: RGDSS - Rio Grande Historic Crop Consumptive Use Analysis
• Description: The documentation is for the Rio Grande Basin Historic Crop Consumptive Use Analysis, developed during the RGDSS implementation for the period 1950 through 2002. It includes 100 percent of the crop consumptive use in the basin for the period. Documentation consists of the final Historic Crop Consumptive Use Analysis Report and supporting appendices.
• Decision Support - Doc Type: Modeling Dataset Documentation
• Date: 6/1/2004
• DSS Category: Consumptive Use
• DSS: Rio Grande
• Basin: Rio Grande
• Contract/PO #: C153863
• Grant Type: Non-Reimbursable
• Bill Number: HB98-1189, SB99-173
• Prepared By: Leonard Rice Engineering

3.0 Model Development
The Rio Grande historic crop consumptive use analysis was performed using StateCU, a
generic data driven consumptive use model and graphical user interface. The objective of
the model is to develop monthly consumptive use estimates for the assessment of historic
and future water management policies.
The model originated at the USBR and has undergone substantial enhancements while
being applied to the Colorado River Decision Support System and the Rio Grande
Decision Support System. The StateCU Documentation provides a complete description
of the model and its capabilities.
3.1 Modeling Approach
To perform the historic crop consumptive use analysis, irrigated acreage and their
associated crop types were assigned to three types of structures; key, aggregated and
ground water only. As presented in Table 2, key diversion structures, which generally
represent large or administratively important structures, represent approximately 87
percent of the irrigated acreage in the basin. Aggregated structures, which are a
geographical grouping of non-key structures, represent approximately four percent of the
basin irrigated acreage. Ground water only structures, which are a geographical grouping
of lands without a surface water supply, represent approximately nine percent of the basin
irrigated acreage.
Table 2
1998 Irrigated Acreage by Structure Type
Structure T e 1998 Acres Percent of Total
Ke 541,151 87%
Aggregated 23,721 4%
Ground Water Onl 57,996 9%
Total All Structures 622,868 100%
The general methodology used to estimate historic consumptive use for the Rio Grande
Basin is as follows (See the StateCU Documentation for a more complete description of
the calculation methods):
1. A Rio Grande Basin scenario was developed that includes 100% of the consumptive
use for the Rio Grande using the key, aggregated and ground water only structures
and their associated acreage and crop patterns.
2. Climate stations were assigned to each structure based on the County and HUC where
the majority of the structure's irrigated acreage is located.
3. The irrigation water requirement was determined using the SCS Modified Blaney-
Criddle consumptive use methodology with locally calibrated crop parameters and the
SCS effective rainfall method outlined in the SCS publication Irrigation Water
Requirements Technical Release No. 21 (TR-21).
cureport_6-2004.doc 13 of 48 June, 2004